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Yang Q, Liu C, Qi K, Xiong Y, Pan Y, Tian C. Imaging and quantification of neuropeptides in mouse pituitary tissue by atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9755. [PMID: 38600731 DOI: 10.1002/rcm.9755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 04/12/2024]
Abstract
RATIONALE Atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) mass spectrometry has enabled the untargeted analysis and imaging of neuropeptides and proteins in biological tissues under ambient conditions. Sensitivity in AP-MALDI can be improved by using sample-specific preparation methods. METHODS A comprehensive and detailed optimization strategy including instrument parameters, matrix spraying and sample tissue washing pretreatment was implemented to enhance the sensitivity and coverage of neuropeptides in mouse pituitary tissues by commercial AP-MALDI mass spectrometry imaging (MSI). RESULTS The sensitivity of a commercial AP-MALDI system for endogenous neuropeptides in mouse pituitary was enhanced by up to 15.2-fold by shortening the transmission gap from the sample plate to the inlet, attaching copper adhesive tape to an indium tin oxide-coated glass slide, optimizing the matrix spray solvent and using sample tissue washing pretreatment. Following careful optimization, the distributions of nine endogenous neuropeptides were successfully visualized in the pituitary. Furthermore, the quantitative capability of AP-MALDI for neuropeptides was evaluated and the concentrations of neuropeptides oxytocin and vasopressin in the pituitary posterior lobe were increased approximately twofold under hypertonic saline stress. CONCLUSION Mouse pituitary neuropeptides have emerged as important signaling molecules due to their role in stress response. This work indicates the potential of modified AP-MALDI as a promising AP MSI method for in situ visualization and quantification of neuropeptides in complex biological tissues.
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Affiliation(s)
- Qi Yang
- Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Keke Qi
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, China
| | - Ying Xiong
- Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Changlin Tian
- Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
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2
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Rein JL, Mackie K, Kleyman TR, Satlin LM. Cannabinoid receptor type 1 activation causes a water diuresis by inducing an acute central diabetes insipidus in mice. Am J Physiol Renal Physiol 2024; 326:F917-F930. [PMID: 38634131 DOI: 10.1152/ajprenal.00320.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 04/01/2024] [Accepted: 04/05/2024] [Indexed: 04/19/2024] Open
Abstract
Cannabis and synthetic cannabinoid consumption are increasing worldwide. Cannabis contains numerous phytocannabinoids that act on the G protein-coupled cannabinoid receptor type 1 (CB1R) and cannabinoid receptor type 2 expressed throughout the body, including the kidney. Essentially every organ, including the kidney, produces endocannabinoids, which are endogenous ligands to these receptors. Cannabinoids acutely increase urine output in rodents and humans, thus potentially influencing total body water and electrolyte homeostasis. As the kidney collecting duct (CD) regulates total body water, acid/base, and electrolyte balance through specific functions of principal cells (PCs) and intercalated cells (ICs), we examined the cell-specific immunolocalization of CB1R in the mouse CD. Antibodies against either the C-terminus or N-terminus of CB1R consistently labeled aquaporin 2 (AQP2)-negative cells in the cortical and medullary CD and thus presumably ICs. Given the well-established role of ICs in urinary acidification, we used a clearance approach in mice that were acid loaded with 280 mM NH4Cl for 7 days and nonacid-loaded mice treated with the cannabinoid receptor agonist WIN55,212-2 (WIN) or a vehicle control. Although WIN had no effect on urinary acidification, these WIN-treated mice had less apical + subapical AQP2 expression in PCs compared with controls and developed acute diabetes insipidus associated with the excretion of large volumes of dilute urine. Mice maximally concentrated their urine when WIN and 1-desamino-8-d-arginine vasopressin [desmopressin (DDAVP)] were coadministered, consistent with central rather than nephrogenic diabetes insipidus. Although ICs express CB1R, the physiological role of CB1R in this cell type remains to be determined.NEW & NOTEWORTHY The CB1R agonist WIN55,212-2 induces central diabetes insipidus in mice. This research integrates existing knowledge regarding the diuretic effects of cannabinoids and the influence of CB1R on vasopressin secretion while adding new mechanistic insights about total body water homeostasis. Our findings provide a deeper understanding about the potential clinical impact of cannabinoids on human physiology and may help identify targets for novel therapeutics to treat water and electrolyte disorders such as hyponatremia and volume overload.
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Affiliation(s)
- Joshua L Rein
- Renal Section, Department of Medicine, James J. Peters Veterans Affairs Medical Center, Bronx, New York, United States
- Barbara T. Murphy Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Ken Mackie
- Gill Center for Biomolecular Medicine, Indiana University, Bloomington, Indiana, United States
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States
| | - Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, United States
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Mishra S, Grewal J, Wal P, Bhivshet GU, Tripathi AK, Walia V. Therapeutic potential of vasopressin in the treatment of neurological disorders. Peptides 2024; 174:171166. [PMID: 38309582 DOI: 10.1016/j.peptides.2024.171166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/18/2024] [Accepted: 01/29/2024] [Indexed: 02/05/2024]
Abstract
Vasopressin (VP) is a nonapeptide made of nine amino acids synthesized by the hypothalamus and released by the pituitary gland. VP acts as a neurohormone, neuropeptide and neuromodulator and plays an important role in the regulation of water balance, osmolarity, blood pressure, body temperature, stress response, emotional challenges, etc. Traditionally VP is known to regulate the osmolarity and tonicity. VP and its receptors are widely expressed in the various region of the brain including cortex, hippocampus, basal forebrain, amygdala, etc. VP has been shown to modulate the behavior, stress response, circadian rhythm, cerebral blood flow, learning and memory, etc. The potential role of VP in the regulation of these neurological functions have suggested the therapeutic importance of VP and its analogues in the management of neurological disorders. Further, different VP analogues have been developed across the world with different pharmacotherapeutic potential. In the present work authors highlighted the therapeutic potential of VP and its analogues in the treatment and management of various neurological disorders.
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Affiliation(s)
- Shweta Mishra
- SGT College of Pharmacy, SGT University, Gurugram, India
| | - Jyoti Grewal
- Maharisi Markandeshwar University, Sadopur, India
| | - Pranay Wal
- Pranveer Singh Institute of Pharmacy, Kanpur, India
| | | | | | - Vaibhav Walia
- SGT College of Pharmacy, SGT University, Gurugram, India.
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4
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Franzén A, Pikkemaat M, Melander O, Bennet L, Enhörning S. The association of copeptin with metabolic risk markers is modified by region of origin. Sci Rep 2023; 13:19651. [PMID: 37949932 PMCID: PMC10638355 DOI: 10.1038/s41598-023-46908-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 11/07/2023] [Indexed: 11/12/2023] Open
Abstract
Iraqi born immigrants in Sweden have higher prevalence of metabolic diseases compared to native Swedes. Copeptin, a marker for vasopressin, is associated with increased risk of metabolic disease. In this cross-sectional population study based on the MEDIM cohort we investigated differences in copeptin levels between Iraqi and Swedish born individuals and if the association between copeptin and cardiometabolic risk markers differed by region of origin. We included 1109 Iraqi and 613 Swedish born participants (58% men, mean age 47 years). The Swedish participants had a higher concentration of copeptin compared to the Iraqi born group after age and sex adjustment (p < 0.001). This difference existed only among male individuals with the highest copeptin concentrations, i.e. belonging to copeptin quartile 4 (median (25th; 75th percentile) 20.07 (15.27;33.28) pmol/L for the Swedish born versus 15.57 (13.91;19.00) pmol/L for the Iraqi born, p < 0.001). We found a significant interaction between copeptin (continuous ln-transformed) and being born in Iraq regarding the association with plasma triglycerides (Pinteraction = 0.006). The association between copeptin and BMI was stronger amongst the Iraqi born individuals compared to the Swedish born. Together, this could indicate that copeptin is a more potent marker of metabolic disease among individuals born in Iraq compared to Sweden.
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Affiliation(s)
- Anna Franzén
- Department of Clinical Sciences in Malmö, Lund University, Clinical Research Center 91:12, Jan Waldenströms gata 35, 21428, Malmö, Sweden.
| | - Miriam Pikkemaat
- Department of Clinical Sciences in Malmö, Lund University, Clinical Research Center 91:12, Jan Waldenströms gata 35, 21428, Malmö, Sweden
| | - Olle Melander
- Department of Clinical Sciences in Malmö, Lund University, Clinical Research Center 91:12, Jan Waldenströms gata 35, 21428, Malmö, Sweden
- Department of Internal Medicine, Skåne University Hospital, Malmö, Sweden
| | - Louise Bennet
- Department of Clinical Sciences in Malmö, Lund University, Clinical Research Center 91:12, Jan Waldenströms gata 35, 21428, Malmö, Sweden
- Clinical Studies Sweden, Forum South, Skåne University Hospital, Lund, Sweden
| | - Sofia Enhörning
- Department of Clinical Sciences in Malmö, Lund University, Clinical Research Center 91:12, Jan Waldenströms gata 35, 21428, Malmö, Sweden
- Department of Internal Medicine, Skåne University Hospital, Malmö, Sweden
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Hernández-Pérez OR, Hernández VS, Zetter MA, Eiden LE, Zhang L. Nucleus of the lateral olfactory tract: A hub linking the water homeostasis-associated supraoptic nucleus-arginine vasopressin circuit and neocortical regions to promote social behavior under osmotic challenge. J Neuroendocrinol 2023; 35:e13202. [PMID: 36283814 PMCID: PMC10027625 DOI: 10.1111/jne.13202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 09/14/2022] [Accepted: 09/14/2022] [Indexed: 11/30/2022]
Abstract
Homeostatic challenges may alter the drive for social interaction. The neural activity that prompts this motivation remains poorly understood. In the present study, we identify direct projections from the hypothalamic supraoptic nucleus to the cortico-amygdalar nucleus of the lateral olfactory tract (NLOT). Dual in situ hybridization with probes for pituitary adenylate cyclase-activating polypeptide (PACAP), as well as vesicular glutamate transporter (VGLUT)1, VGLUT2, V1a and V1b, revealed a population of vasopressin-receptive PACAPergic neurons in NLOT layer 2 (NLOT2). Water deprivation (48 h, WD48) increased sociability compared to euhydrated subjects, as assessed with the three-chamber social interaction test (3CST). Fos expression immunohistochemistry showed NLOT and its main efferent regions had further increases in rats subjected to WD48 + 3CST. These regions strongly expressed PAC1 mRNA. Microinjections of arginine vasopressin (AVP) into the NLOT produced similar changes in sociability to water deprivation, and these were reduced by co-injection of V1a or V1b antagonists along with AVP. We conclude that, during challenge to water homeostasis, there is a recruitment of a glutamatergic-multi-peptidergic cooperative circuit that promotes social behavior.
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Affiliation(s)
- Oscar R. Hernández-Pérez
- Department of Physiology, School of Medicine, National Autonomous University of Mexico, Mexico
- Authors contributed equally to this work
| | - Vito S. Hernández
- Department of Physiology, School of Medicine, National Autonomous University of Mexico, Mexico
- Authors contributed equally to this work
| | - Mario A. Zetter
- Department of Physiology, School of Medicine, National Autonomous University of Mexico, Mexico
| | - Lee E. Eiden
- National Institute of Mental Health, National Institute of Health, Bethesda, MD, USA
| | - Limei Zhang
- Department of Physiology, School of Medicine, National Autonomous University of Mexico, Mexico
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Aikins AO, Farmer GE, Little JT, Cunningham JT. Effects of bile duct ligation on the inhibitory control of supraoptic vasopressin neurons. J Neuroendocrinol 2023; 35:e13312. [PMID: 37337093 PMCID: PMC10942741 DOI: 10.1111/jne.13312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/02/2023] [Accepted: 05/11/2023] [Indexed: 06/21/2023]
Abstract
Dilutional hyponatremia due to increased plasma arginine vasopressin (AVP) is associated with liver cirrhosis. However, plasma AVP remains elevated despite progressive hypoosmolality. This study investigated changes to inhibitory control of supraoptic nucleus (SON) AVP neurons during liver cirrhosis. Experiments were conducted with adult male Sprague-Dawley rats. Bile duct ligation was used as a model of chronic liver cirrhosis. An adeno-associated virus containing a construct with an AVP promoter and either green fluorescent protein (GFP) or a ratiometric chloride indicator, ClopHensorN, was bilaterally injected into the SON of rats. After 2 weeks, rats received either BDL or sham surgery, and liver cirrhosis was allowed to develop for 4 weeks. In vitro, loose patch recordings of action potentials were obtained from GFP-labeled and unlabeled SON neurons in response to a brief focal application of the GABAA agonist muscimol (100 μM). Changes to intracellular chloride ([Cl]i) following muscimol application were determined by changes to the fluorescence ratio of ClopHensorN. The contribution of cation chloride cotransporters NKCC1 and KCC2 to changes in intracellular chloride was investigated using their respective antagonists, bumetanide (BU, 10 μM) and VU0240551 (10 μM). Plasma osmolality and hematocrit were measured as a marker of dilutional hyponatremia. The results showed reduced or absent GABAA -mediated inhibition in a greater proportion of AVP neurons from BDL rats as compared to sham rats (100% inhibition in sham vs. 47% in BDL, p = .001). Muscimol application was associated with increased [Cl]i in most cells from BDL as compared to cells from sham rats (χ2 = 30.24, p < .001). NKCC1 contributed to the impaired inhibition observed in BDL rats (p < .001 BDL - BU vs. BDL + BU). The results show that impaired inhibition of SON AVP neurons and increased intracellular chloride contribute to the sustained dilutional hyponatremia in liver cirrhosis.
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Affiliation(s)
- Ato O Aikins
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
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7
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Jin X, Xie J, Yeh CW, Chen JC, Cheng CJ, Lien CC, Huang CL. WNK1 promotes water homeostasis by acting as a central osmolality sensor for arginine vasopressin release. J Clin Invest 2023; 133:e164222. [PMID: 37071482 PMCID: PMC10231991 DOI: 10.1172/jci164222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 04/14/2023] [Indexed: 04/19/2023] Open
Abstract
Maintaining internal osmolality constancy is essential for life. Release of arginine vasopressin (AVP) in response to hyperosmolality is critical. Current hypotheses for osmolality sensors in circumventricular organs (CVOs) of the brain focus on mechanosensitive membrane proteins. The present study demonstrated that intracellular protein kinase WNK1 was involved. Focusing on vascular-organ-of-lamina-terminalis (OVLT) nuclei, we showed that WNK1 kinase was activated by water restriction. Neuron-specific conditional KO (cKO) of Wnk1 caused polyuria with decreased urine osmolality that persisted in water restriction and blunted water restriction-induced AVP release. Wnk1 cKO also blunted mannitol-induced AVP release but had no effect on osmotic thirst response. The role of WNK1 in the osmosensory neurons in CVOs was supported by neuronal pathway tracing. Hyperosmolality-induced increases in action potential firing in OVLT neurons was blunted by Wnk1 deletion or pharmacological WNK inhibitors. Knockdown of Kv3.1 channel in OVLT by shRNA reproduced the phenotypes. Thus, WNK1 in osmosensory neurons in CVOs detects extracellular hypertonicity and mediates the increase in AVP release by activating Kv3.1 and increasing action potential firing from osmosensory neurons.
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Affiliation(s)
- Xin Jin
- Department of Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Jian Xie
- Department of Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | | | - Jen-Chi Chen
- Department of Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Chih-Jen Cheng
- Department of Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Cheng-Chang Lien
- Institute of Neuroscience and
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chou-Long Huang
- Department of Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
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Workeneh BT, Meena P, Christ-Crain M, Rondon-Berrios H. Hyponatremia Demystified: Integrating Physiology to Shape Clinical Practice. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:85-101. [PMID: 36868737 PMCID: PMC9993811 DOI: 10.1053/j.akdh.2022.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 10/05/2022] [Accepted: 11/07/2022] [Indexed: 12/24/2022]
Abstract
Hyponatremia is one of the most common problems encountered in clinical practice and one of the least-understood because accurate diagnosis and management require some familiarity with water homeostasis physiology, making the topic seemingly complex. The prevalence of hyponatremia depends on the nature of the population studied and the criteria used to define it. Hyponatremia is associated with poor outcomes including increased mortality and morbidity. The pathogenesis of hypotonic hyponatremia involves the accumulation of electrolyte-free water caused by either increased intake and/or decrease in kidney excretion. Plasma osmolality, urine osmolality, and urine sodium can help to differentiate among the different etiologies. Brain adaptation to plasma hypotonicity consisting of solute extrusion to mitigate further water influx into brain cells best explains the clinical manifestations of hyponatremia. Acute hyponatremia has an onset within 48 hours, commonly resulting in severe symptoms, while chronic hyponatremia develops over 48 hours and usually is pauci-symptomatic. However, the latter increases the risk of osmotic demyelination syndrome if hyponatremia is corrected rapidly; therefore, extreme caution must be exercised when correcting plasma sodium. Management strategies depend on the presence of symptoms and the cause of hyponatremia and are discussed in this review.
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Affiliation(s)
- Biruh T Workeneh
- Section of Nephrology, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Priti Meena
- All India Institute of Medical Sciences, Bhubaneswar, India
| | - Mirjam Christ-Crain
- Departments of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland
| | - Helbert Rondon-Berrios
- Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, PA.
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Lu HAJ, He J. Aquaporins in Diabetes Insipidus. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:267-279. [PMID: 36717500 DOI: 10.1007/978-981-19-7415-1_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Disruption of water and electrolyte balance is frequently encountered in clinical medicine. Regulating water metabolism is critically important. Diabetes insipidus (DI) presented with excessive water loss from the kidney is a major disorder of water metabolism. To understanding the molecular and cellular mechanisms and pathophysiology of DI and rationales of clinical management of DI is important for both research and clinical practice. This chapter will first review various forms of DI focusing on central diabetes insipidus (CDI) and nephrogenic diabetes insipidus (NDI). This is followed by a discussion of regulatory mechanisms underlying CDI and NDI, with a focus on the regulatory axis of vasopressin, vasopressin receptor 2 (V2R) and the water channel molecule, aquaporin 2 (AQP2). The clinical manifestation, diagnosis, and management of various forms of DI will also be discussed with highlights of some of the latest therapeutic strategies that are developed from in vitro experiments and animal studies.
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Affiliation(s)
- H A Jenny Lu
- Program in Membrane Biology, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Jinzhao He
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
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Hoenig MP, Lecker SH, William JH. What's Old Is New Again: Harnessing the Power of Original Experiments to Learn Renal Physiology. Adv Chronic Kidney Dis 2022; 29:486-492. [PMID: 36371110 DOI: 10.1053/j.ackd.2022.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/02/2022] [Accepted: 03/22/2022] [Indexed: 11/10/2022]
Abstract
Although medical schools across the United States have updated their curricula to incorporate active learning techniques, there has been little discussion on the nature of the content presented to students. Here, we share detailed examples of our experience in using original experiments to lay the groundwork for foundational concepts in renal physiology and pathophysiology. We believe that this approach offers distinct advantages over standard case-based teaching by (1) starting with simple concepts, (2) analyzing memorable visuals, (3) increasing graphical literacy, (4) translating observations to "rules," (5) encouraging critical thinking, and (6) providing historical perspective to the study of medicine. Although we developed this content for medical students, we have found that many of these lessons are also appropriate as foundational concepts for residents and fellows and serve as an excellent springboard for increasingly complex discussions of clinical applications of physiology. The use of original experiments for teaching and learning in renal physiology harnesses skills in critical thinking and provides a solid foundation that will help learners with subsequent case-based learning in the preclerkship curriculum and in the clinical arena.
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Affiliation(s)
- Melanie P Hoenig
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
| | - Stewart H Lecker
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jeffrey H William
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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11
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Palmer LG. Directing two-way traffic in the kidney: A tale of two ions. J Gen Physiol 2022; 154:213433. [PMID: 36048011 PMCID: PMC9437110 DOI: 10.1085/jgp.202213179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The kidneys regulate levels of Na+ and K+ in the body by varying urinary excretion of the electrolytes. Since transport of each of the two ions can affect the other, controlling both at the same time is a complex task. The kidneys meet this challenge in two ways. Some tubular segments change the coupling between Na+ and K+ transport. In addition, transport of Na+ can shift between segments where it is coupled to K+ reabsorption and segments where it is coupled to K+ secretion. This permits the kidney to maintain electrolyte balance with large variations in dietary intake.
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Affiliation(s)
- Lawrence G. Palmer
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, NY,Correspondence to Lawrence G. Palmer:
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12
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Zhang L, Padilla‐Flores T, Hernández VS, Zetter MA, Campos‐Lira E, Escobar LI, Millar RP, Eiden LE. Vasopressin acts as a synapse organizer in limbic regions by boosting PSD95 and GluA1 expression. J Neuroendocrinol 2022; 34:e13164. [PMID: 35666232 PMCID: PMC9787762 DOI: 10.1111/jne.13164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 05/01/2022] [Accepted: 05/10/2022] [Indexed: 12/31/2022]
Abstract
Hypothalamic arginine vasopressin (AVP)-containing magnocellular neurosecretory neurons (AVPMNN) emit collaterals to synaptically innervate limbic regions influencing learning, motivational behaviour, and fear responses. Here, we characterize the dynamics of expression changes of two key determinants for synaptic strength, the postsynaptic density (PSD) proteins AMPAR subunit GluA1 and PSD scaffolding protein 95 (PSD95), in response to in vivo manipulations of AVPMNN neuronal activation state, or exposure to exogenous AVP ex vivo. Both long-term water deprivation in vivo, which powerfully upregulates AVPMNN metabolic activity, and exogenous AVP application ex vivo, in brain slices, significantly increased GluA1 and PSD95 expression as measured by western blotting, in brain regions reportedly receiving direct ascending innervations from AVPMNN (i.e., ventral hippocampus, amygdala and lateral habenula). By contrast, the visual cortex, a region not observed to receive AVPMNN projections, showed no such changes. Ex vivo application of V1a and V1b antagonists to ventral hippocampal slices ablated the AVP stimulated increase in postsynaptic protein expression measured by western blotting. Using a modified expansion microscopy technique, we were able to quantitatively assess the significant augmentation of PSD95 and GLUA1 densities in subcellular compartments in locus coeruleus tyrosine hydroxylase immunopositive fibres, adjacent to AVP axon terminals. Our data strongly suggest that the AVPMNN ascending system plays a role in the regulation of the excitability of targeted neuronal circuits through upregulation of key postsynaptic density proteins corresponding to excitatory synapses.
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Affiliation(s)
- Limei Zhang
- Department of Physiology, School of MedicineNational Autonomous University of MexicoMexico CityMexico
| | - Teresa Padilla‐Flores
- Department of Physiology, School of MedicineNational Autonomous University of MexicoMexico CityMexico
| | - Vito S. Hernández
- Department of Physiology, School of MedicineNational Autonomous University of MexicoMexico CityMexico
| | - Mario A. Zetter
- Department of Physiology, School of MedicineNational Autonomous University of MexicoMexico CityMexico
| | - Elba Campos‐Lira
- Department of Physiology, School of MedicineNational Autonomous University of MexicoMexico CityMexico
| | - Laura I. Escobar
- Department of Physiology, School of MedicineNational Autonomous University of MexicoMexico CityMexico
| | - Robert P. Millar
- Department of Physiology, School of MedicineNational Autonomous University of MexicoMexico CityMexico
- Centre for Neuroendocrinology, Department of ImmunologyUniversity of PretoriaPretoriaSouth Africa
- Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular MedicineUniversity of Cape TownCape TownSouth Africa
| | - Lee E. Eiden
- Section on Molecular NeuroscienceNIMH‐IRP, NIHBethesdaMarylandUSA
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Mohan S, Lafferty RA, Flatt PR, Moffett RC, Irwin N. Ac3IV, a V1a and V1b receptor selective vasopressin analogue, protects against hydrocortisone-induced changes in pancreatic islet cell lineage. Peptides 2022; 152:170772. [PMID: 35202749 DOI: 10.1016/j.peptides.2022.170772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/11/2022] [Accepted: 02/17/2022] [Indexed: 11/25/2022]
Abstract
The Avpr1a (V1a) and Avpr1b (V1b) receptor selective, vasopressin (AVP) analogue, Ac3IV has been shown to improve metabolism and pancreatic islet structure in diabetes and insulin resistance. The present study further investigates these actions by assessing the ability of Ac3IV to protect against pancreatic islet architectural disturbances induced by hydrocortisone (HC) treatment in transgenic Ins1Cre/+;Rosa26-eYFP mice, that possess beta-cell lineage tracing capabilities. HC intervention increased (p < 0.001) energy intake but reduced (p < 0.01) body weight gain, with no impact of Ac3IV. All HC mice had reduced (p < 0.05) circulating glucose, but plasma insulin and glucagon concentrations remained unchanged. However, HC mice presented with increased (p < 0.001) pancreatic insulin content, which was further augmented by Ac3IV. In addition, Ac3IV treatment countered HC-induced increases in islet-, beta- and alpha-cell areas (p < 0.01), as well as promoting islet number towards control levels. This was accompanied by reduced (p < 0.05) beta-cell growth, but enhanced (p < 0.001) alpha-cell proliferation. There were no changes in islet cell apoptotic rates in any of the groups of HC mice, but co-expression of CK19 with insulin in pancreatic ductal cells was reduced by Ac3IV. Assessment of beta-cell lineage revealed that Ac3IV partially protected against HC-mediated de-differentiation of mature beta-cells, whilst also decreasing (p < 0.01) beta- to alpha-cell transdifferentiation. Our data indicate that sustained activation of V1a and V1b receptors exerts positive islet cell transition effects to help retain beta-cell identity in HC mice.
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Affiliation(s)
- Shruti Mohan
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - Ryan A Lafferty
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - R Charlotte Moffett
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, UK.
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Sanada K, Ueno H, Miyamoto T, Baba K, Tanaka K, Nishimura H, Nishimura K, Sonoda S, Yoshimura M, Maruyama T, Onaka T, Otsuji Y, Kataoka M, Ueta Y. AVP-eGFP was significantly upregulated by hypovolemia in the parvocellular division of the paraventricular nucleus in the transgenic rats. Am J Physiol Regul Integr Comp Physiol 2022; 322:R161-R169. [PMID: 35018823 DOI: 10.1152/ajpregu.00107.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 01/06/2022] [Indexed: 11/22/2022]
Abstract
Arginine vasopressin (AVP) is produced in the paraventricular (PVN) and supraoptic nuclei (SON). Peripheral AVP, which is secreted from the posterior pituitary, is produced in the magnocellular division of the PVN (mPVN) and SON. In addition, AVP is produced in the parvocellular division of the PVN (pPVN), where corticotrophin-releasing factor (CRF) is synthesized. These peptides synergistically modulate the hypothalamic-pituitary-adrenal (HPA) axis. Previous studies have revealed that the HPA axis was activated by hypovolemia. However, the detailed dynamics of AVP in the pPVN under hypovolemic state has not been elucidated. Here, we evaluated the effects of hypovolemia and hyperosmolality on the hypothalamus, using AVP-enhanced green fluorescent protein (eGFP) transgenic rats. Polyethylene glycol (PEG) or 3% hypertonic saline (HTN) was intraperitoneally administered to develop hypovolemia or hyperosmolality. AVP-eGFP intensity was robustly upregulated at 3 and 6 h after intraperitoneal administration of PEG or HTN in the mPVN. While in the pPVN, eGFP intensity was significantly increased at 6 h after intraperitoneal administration of PEG with significant induction of Fos-immunoreactive (-ir) neurons. Consistently, eGFP mRNA, AVP hnRNA, and CRF mRNA in the pPVN and plasma AVP and corticosterone were significantly increased at 6 h after intraperitoneal administration of PEG. The results suggest that AVP and CRF syntheses in the pPVN were activated by hypovolemia, resulting in the activation of the HPA axis.
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Affiliation(s)
- Kenya Sanada
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
- Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Hiromichi Ueno
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
- Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Tetsu Miyamoto
- Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Kazuhiko Baba
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Kentaro Tanaka
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Haruki Nishimura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Kazuaki Nishimura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Satomi Sonoda
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Mitsuhiro Yoshimura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Takashi Maruyama
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Tatsushi Onaka
- Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Shimotsuke, Japan
| | - Yutaka Otsuji
- Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Masaharu Kataoka
- Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
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15
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Mohan S, Lafferty R, Tanday N, Flatt PR, Moffett RC, Irwin N. Beneficial impact of Ac3IV, an AVP analogue acting specifically at V1a and V1b receptors, on diabetes islet morphology and transdifferentiation of alpha- and beta-cells. PLoS One 2021; 16:e0261608. [PMID: 34929019 PMCID: PMC8687525 DOI: 10.1371/journal.pone.0261608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 12/07/2021] [Indexed: 12/18/2022] Open
Abstract
Ac3IV (Ac-CYIQNCPRG-NH2) is an enzymatically stable vasopressin analogue that selectively activates Avpr1a (V1a) and Avpr1b (V1b) receptors. In the current study we have employed streptozotocin (STZ) diabetic transgenic Ins1Cre/+;Rosa26-eYFP and GluCreERT2;Rosa26-eYFP mice, to evaluate the impact of sustained Ac3IV treatment on pancreatic islet cell morphology and transdifferentiation. Twice-daily administration of Ac3IV (25 nmol/kg bw) to STZ-diabetic Ins1Cre/+;Rosa26-eYFP mice for 12 days increased pancreatic insulin (p<0.01) and significantly reversed the detrimental effects of STZ on pancreatic islet morphology. Such benefits were coupled with increased (p<0.01) beta-cell proliferation and decreased (p<0.05) beta-cell apoptosis. In terms of islet cell lineage tracing, induction of diabetes increased (p<0.001) beta- to alpha-cell differentiation in Ins1Cre/+;Rosa26-eYFP mice, with Ac3IV partially reversing (p<0.05) such transition events. Comparable benefits of Ac3IV on pancreatic islet architecture were observed in STZ-diabetic GluCreERT2;ROSA26-eYFP transgenic mice. In this model, Ac3IV provoked improvements in islet morphology which were linked to increased (p<0.05-p<0.01) transition of alpha- to beta-cells. Ac3IV also increased (p<0.05-p<0.01) CK-19 co-expression with insulin in pancreatic ductal and islet cells. Blood glucose levels were unchanged by Ac3IV in both models, reflecting the severity of diabetes induced. Taken together these data indicate that activation of islet receptors for V1a and V1b positively modulates alpha- and beta-cell turnover and endocrine cell lineage transition events to preserve beta-cell identity and islet architecture.
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Affiliation(s)
- Shruti Mohan
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Ryan Lafferty
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Neil Tanday
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Peter R. Flatt
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - R. Charlotte Moffett
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, Ulster University, Coleraine, Northern Ireland, United Kingdom
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16
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Mohiuddin N, Frinak S, Yee J. Sodium-based osmotherapy for hyponatremia in acute decompensated heart failure. Heart Fail Rev 2021; 27:379-391. [PMID: 34767112 DOI: 10.1007/s10741-021-10124-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/25/2021] [Indexed: 10/19/2022]
Abstract
Acute decompensated heart failure (ADHF) accounts for more than 1 million hospital admissions annually and is associated with high morbidity and mortality. Decongestion with removal of increased total body sodium and total body water are goals of treatment. Acute kidney injury (AKI) or chronic kidney disease (CKD) is present in two-thirds of patients with ADHF. The pathophysiology of ADHF and AKI is bidirectional and synergistic. AKI and CKD complicate the management of ADHF by decreasing diuretic efficiency and excretion of sodium and water. Among patients hospitalized with ADHF, hyponatremia is the most common electrolyte abnormality and is classically encountered with volume overload. ADHF represents an additional therapeutic challenge particularly when oligoanuria is present. Predilution continuous venovenous hemofiltration with sodium-based osmotherapy can safely increase plasma sodium concentration without deleteriously increasing total body sodium. We present a detailed methodology that addresses the issue of hypervolemic hyponatremia in patients with ADHF and AKI.
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Affiliation(s)
- Naushaba Mohiuddin
- Division of Nephrology and Hypertension, 2799 West Grand Blvd, CFP-510, Detroit, MI, 48202, USA
| | - Stanley Frinak
- Division of Nephrology and Hypertension, 2799 West Grand Blvd, CFP-510, Detroit, MI, 48202, USA
| | - Jerry Yee
- Division of Nephrology and Hypertension, 2799 West Grand Blvd, CFP-514, Detroit, MI, 48202, USA.
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17
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Opichka MA, Rappelt MW, Gutterman DD, Grobe JL, McIntosh JJ. Vascular Dysfunction in Preeclampsia. Cells 2021; 10:cells10113055. [PMID: 34831277 PMCID: PMC8616535 DOI: 10.3390/cells10113055] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/01/2021] [Accepted: 11/04/2021] [Indexed: 01/22/2023] Open
Abstract
Preeclampsia is a life-threatening pregnancy-associated cardiovascular disorder characterized by hypertension and proteinuria at 20 weeks of gestation. Though its exact underlying cause is not precisely defined and likely heterogenous, a plethora of research indicates that in some women with preeclampsia, both maternal and placental vascular dysfunction plays a role in the pathogenesis and can persist into the postpartum period. Potential abnormalities include impaired placentation, incomplete spiral artery remodeling, and endothelial damage, which are further propagated by immune factors, mitochondrial stress, and an imbalance of pro- and antiangiogenic substances. While the field has progressed, current gaps in knowledge include detailed initial molecular mechanisms and effective treatment options. Newfound evidence indicates that vasopressin is an early mediator and biomarker of the disorder, and promising future therapeutic avenues include mitigating mitochondrial dysfunction, excess oxidative stress, and the resulting inflammatory state. In this review, we provide a detailed overview of vascular defects present during preeclampsia and connect well-established notions to newer discoveries at the molecular, cellular, and whole-organism levels.
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Affiliation(s)
- Megan A. Opichka
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (M.A.O.); (D.D.G.); (J.L.G.)
| | - Matthew W. Rappelt
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA;
| | - David D. Gutterman
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (M.A.O.); (D.D.G.); (J.L.G.)
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA;
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Justin L. Grobe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (M.A.O.); (D.D.G.); (J.L.G.)
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA;
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jennifer J. McIntosh
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (M.A.O.); (D.D.G.); (J.L.G.)
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA;
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Correspondence: ; Tel.: +1-(414)-805-9019
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18
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Hernández VS, Zetter MA, Guerra EC, Hernández-Araiza I, Karuzin N, Hernández-Pérez OR, Eiden LE, Zhang L. ACE2 expression in rat brain: Implications for COVID-19 associated neurological manifestations. Exp Neurol 2021; 345:113837. [PMID: 34400158 PMCID: PMC8361001 DOI: 10.1016/j.expneurol.2021.113837] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 07/12/2021] [Accepted: 08/06/2021] [Indexed: 02/07/2023]
Abstract
We examined cell type-specific expression and distribution of rat brain angiotensin-converting enzyme 2 (ACE2), the receptor for SARS-CoV-2, in the rodent brain. ACE2 is ubiquitously present in brain vasculature, with the highest density of ACE2 expressing capillaries found in the olfactory bulb, the hypothalamic paraventricular, supraoptic, and mammillary nuclei, the midbrain substantia nigra and ventral tegmental area, and the hindbrain pontine nucleus, the pre-Bötzinger complex, and nucleus of tractus solitarius. ACE2 was expressed in astrocytes and astrocytic foot processes, pericytes and endothelial cells, key components of the blood-brain barrier. We found discrete neuronal groups immunopositive for ACE2 in brainstem respiratory rhythm generating centers, including the pontine nucleus, the parafascicular/retrotrapezoid nucleus, the parabrachial nucleus, the Bötzinger, and pre-Bötzinger complexes and the nucleus of tractus solitarius; in the arousal-related pontine reticular nucleus and gigantocellular reticular nuclei; in brainstem aminergic nuclei, including substantia nigra, ventral tegmental area, dorsal raphe, and locus coeruleus; in the epithalamic habenula, hypothalamic paraventricular and supramammillary nuclei; and in the hippocampus. Identification of ACE2-expressing neurons in rat brain within well-established functional circuits facilitates prediction of possible neurological manifestations of brain ACE2 dysregulation during and after COVID-19 infection.
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Affiliation(s)
- Vito S Hernández
- Dept. Physiology, Laboratory of Systems Neuroscience, School of Medicine, National Autonomous University of Mexico (UNAM, Mexico City, Mexico)
| | - Mario A Zetter
- Dept. Physiology, Laboratory of Systems Neuroscience, School of Medicine, National Autonomous University of Mexico (UNAM, Mexico City, Mexico)
| | - Enrique C Guerra
- Dept. Physiology, Laboratory of Systems Neuroscience, School of Medicine, National Autonomous University of Mexico (UNAM, Mexico City, Mexico)
| | - Ileana Hernández-Araiza
- Dept. Physiology, Laboratory of Systems Neuroscience, School of Medicine, National Autonomous University of Mexico (UNAM, Mexico City, Mexico); School of Medicine University of Maryland, Baltimore, MD, USA
| | - Nikita Karuzin
- Dept. Physiology, Laboratory of Systems Neuroscience, School of Medicine, National Autonomous University of Mexico (UNAM, Mexico City, Mexico); School of Medicine, Pan-American University, Mexico City, Mexico
| | - Oscar R Hernández-Pérez
- Dept. Physiology, Laboratory of Systems Neuroscience, School of Medicine, National Autonomous University of Mexico (UNAM, Mexico City, Mexico)
| | - Lee E Eiden
- Section on Molecular Neuroscience, NIMH-IRP, NIH, Bethesda, MD, USA
| | - Limei Zhang
- Dept. Physiology, Laboratory of Systems Neuroscience, School of Medicine, National Autonomous University of Mexico (UNAM, Mexico City, Mexico).
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Hyponatremia accompanying volatile hypertension caused by baroreflex failure after neck surgery: case report and literature review. J Hypertens 2021; 38:1617-1624. [PMID: 32371768 DOI: 10.1097/hjh.0000000000002436] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
: The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of euvolemic hyponatremia, and many disorders have been associated with it. Baroreflex failure is a rare disorder characterized by extreme blood pressure (BP) fluctuations, most frequently caused by neck or head trauma and irradiation. We report a case of a 48-year-old patient referred to our department for asymptomatic hyponatremia and volatile hypertension. His past medical history included nasopharyngeal carcinoma treated with surgery and bilateral neck radiation. Following the diagnostic algorithm for hyponatremia, the diagnosis of SIADH was made. Ambulatory BP monitoring revealed highly variable BP; extensive autonomic nervous system function testing suggested baroreflex-cardiovagal failure. We propose the hypothesis that not only labile hypertension because of baroreflex failure but also hyponatremia can develop as a late consequence of neck trauma and irradiation.
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20
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Lombardi G, Ferraro PM, Naticchia A, Gambaro G. Serum sodium variability and acute kidney injury: a retrospective observational cohort study on a hospitalized population. Intern Emerg Med 2021; 16:617-624. [PMID: 32776204 PMCID: PMC8049924 DOI: 10.1007/s11739-020-02462-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/24/2020] [Indexed: 12/27/2022]
Abstract
Aim of our study was to analyze the association between serum sodium (Na) variability and acute kidney injury (AKI) development. We performed a retrospective observational cohort study on the inpatient population admitted to Fondazione Policlinico Universitario A. Gemelli IRCCS between January 1, 2010 and December 31, 2014 with inclusion of adult patients with ≥ 2 Na and ≥ 2 serum creatinine measurements. We included only patients with ≥ 2 Na measurements before AKI development. The outcome of interest was AKI. The exposures of interest were hyponatremia, hypernatremia and Na fluctuations before AKI development. Na variability was evaluated using the coefficient of variation (CV). Multivariable Cox proportional hazards and logistic regression models were fitted to obtain hazard ratios (HRs), odds ratios (ORs) and 95% confidence intervals (CIs) for the association between the exposures of interest and AKI. Overall, 56,961 patients met our inclusion criteria. During 1541 person-years of follow-up AKI occurred in 1450 patients. In multivariable hazard models, patients with pre-existent dysnatremia and those who developed dysnatremia had a higher risk of AKI compared with patients with normonatremia. Logistic models suggested a higher risk for AKI in the 3rd (OR 1.41, 95% CI 1.18, 1.70, p < 0.001) and 4th (OR 1.53, 95% CI 1.24, 1.91, p < 0.001) highest quartiles of Na CV with a significant linear trend across quartiles (p trend < 0.001). This association was also independent from Na highest and lowest peak value. Dysnatremia is a common condition and is positive associated with AKI development. Furthermore, high Na variability might be considered an independent early indicator for kidney injury development.
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Affiliation(s)
- Gianmarco Lombardi
- U.O.C. Nefrologia, Azienda Ospedaliera Universitaria Integrata di Verona, Verona, Italy
| | - Pietro Manuel Ferraro
- U.O.C. Nefrologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Via G. Moscati 31, 00168, Rome, Italy.
- Università Cattolica del Sacro Cuore, Rome, Italy.
| | - Alessandro Naticchia
- U.O.C. Nefrologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Via G. Moscati 31, 00168, Rome, Italy
| | - Giovanni Gambaro
- U.O.C. Nefrologia, Azienda Ospedaliera Universitaria Integrata di Verona, Verona, Italy
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21
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Gomes DA, de Almeida Beltrão RL, de Oliveira Junior FM, da Silva Junior JC, de Arruda EPC, Lira EC, da Rocha MJA. Vasopressin and copeptin release during sepsis and septic shock. Peptides 2021; 136:170437. [PMID: 33181268 DOI: 10.1016/j.peptides.2020.170437] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 10/23/2020] [Accepted: 10/26/2020] [Indexed: 12/22/2022]
Abstract
Sepsis is defined as a potentially fatal organ dysfunction caused by a dysregulated host response to infection. Despite tremendous progress in the medical sciences, sepsis remains one of the leading causes of morbidity and mortality worldwide. The host response to sepsis and septic shock involves changes in the immune, autonomic, and neuroendocrine systems. Regarding neuroendocrine changes, studies show an increase in plasma vasopressin (AVP) concentrations followed by a decline, which may be correlated with septic shock. AVP is a peptide hormone derived from a larger precursor (preprohormone), along with two peptides, neurophysin II and copeptin. AVP is synthesized in the hypothalamus, stored and released from the neurohypophysis into the bloodstream by a wide range of stimuli. The measurement of AVP has limitations due to its plasma instability and short half-life. Copeptin is a more stable peptide than AVP, and its immunoassay is feasible. The blood concentrations of copeptin mirror those of AVP in many physiological states; paradoxically, during sepsis-related organ dysfunction, an uncoupling between copeptin and AVP blood levels appears to happen. In this review, we focus on clinical and experimental studies that analyzed AVP and copeptin blood concentrations over time in sepsis. The findings suggest that AVP and copeptin behave similarly in the early stages of sepsis; however, we did not find a proportional decrease in copeptin concentrations as seen with AVP during septic shock. Copeptin levels were higher in nonsurvivors than in survivors, suggesting that copeptin may work as a marker of severity or sepsis-related organ dysfunction.
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Affiliation(s)
- Dayane Aparecida Gomes
- Department of Physiology and Pharmacology, Bioscience Center, Federal University of Pernambuco, Brazil.
| | | | | | | | | | - Eduardo Carvalho Lira
- Department of Physiology and Pharmacology, Bioscience Center, Federal University of Pernambuco, Brazil
| | - Maria José Alves da Rocha
- Department of Basic and Oral Biology, School of Dentistry of Ribeirao Preto, University of Sao Paulo, Brazil
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22
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Dutra SGV, Paterson A, Monteiro LRN, Greenwood MP, Greenwood MP, Amaral LS, Melo MR, Colombari DSA, Colombari E, Reis LC, Hindmarch CCT, Elias LLK, Antunes-Rodrigues J, Murphy D, Mecawi AS. Physiological and Transcriptomic Changes in the Hypothalamic-Neurohypophysial System after 24 h of Furosemide-Induced Sodium Depletion. Neuroendocrinology 2021; 111:70-86. [PMID: 31955161 DOI: 10.1159/000505997] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/17/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Furosemide is a loop diuretic widely used in clinical practice for the treatment of oedema and hypertension. The aim of this study was to determine physiological and molecular changes in the hypothalamic-neurohypophysial system as a consequence of furosemide-induced sodium depletion. METHODS Male rats were sodium depleted by acute furosemide injection (10 and 30 mg/kg) followed by access to low sodium diet and distilled water for 24 h. The renal and behavioural consequences were evaluated, while blood and brains were collected to evaluate the neuroendocrine and gene expression responses. RESULTS Furosemide treatment acutely increases urinary sodium and water excretion. After 24 h, water and food intake were reduced, while plasma angiotensin II and corticosterone were increased. After hypertonic saline presentation, sodium-depleted rats showed higher preference for salt. Interrogation using RNA sequencing revealed the expression of 94 genes significantly altered in the hypothalamic paraventricular nucleus (PVN) of sodium-depleted rats (31 upregulated and 63 downregulated). Out of 9 genes chosen, 5 were validated by quantitative PCR in the PVN (upregulated: Ephx2, Ndnf and Vwf; downregulated: Caprin2 and Opn3). The same genes were also assessed in the supraoptic nucleus (SON, upregulated: Tnnt1, Mis18a, Nr1d1 and Dbp; downregulated: Caprin2 and Opn3). As a result of these plastic transcriptome changes, vasopressin expression was decreased in PVN and SON, whilst vasopressin and oxytocin levels were reduced in plasma. CONCLUSIONS We thus have identified novel genes that might regulate vasopressin gene expression in the hypothalamus controlling the magnocellular neurons secretory response to body sodium depletion and consequently hypotonic stress.
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Affiliation(s)
- Sabrina G V Dutra
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Alex Paterson
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Livia R N Monteiro
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Michael P Greenwood
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Mingkwan P Greenwood
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Ludimila S Amaral
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Mariana R Melo
- Department of Physiology and Pathology, School of Dentistry, UNESP, São Paulo State University, Araraquara, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, UNESP, São Paulo State University, Araraquara, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, UNESP, São Paulo State University, Araraquara, Brazil
| | - Luís C Reis
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Charles C T Hindmarch
- Queen's Cardiopulmonary Unit, Department of Medicine, Translational Institute of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Lucila L K Elias
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - José Antunes-Rodrigues
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Translational Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Andre S Mecawi
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil,
- Laboratory of Neuroendocrinology, Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil,
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Kang C, Wang L, Feng J, Zhu W, Hang S. l-Glutamate stimulates cholecystokinin secretion via the T1R1/T1R3 mediated PLC/TRPM5 transduction pathway. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2020; 100:4818-4825. [PMID: 32478409 DOI: 10.1002/jsfa.10541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 05/17/2020] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND It is known that cholecystokinin (CCK) plays an essential role in reducing food intake and driving weight loss. Previous studies demonstrated that amino acids were capable of triggering CCK release through G protein-coupled receptors, but the sensing mechanism remains obscure, especially the intracellular signaling pathway. RESULTS l-Glu, rather than its d-isomer, robustly stimulated CCK secretion in a porcine duodenal model, and the secretory response was augmented by incubation with the allosteric ligand of T1R1, while T1R3 antagonist attenuated it. Upon inhibiting phospholipase C (PLC) or transient receptor potential M5 (TRPM5) activity, l-Glu failed to increase CCK release. Oral administration of monosodium glutamate in rats also suppressed food intake and increased plasma CCK levels, accompanied by elevated expression of T1R1, PLCβ2 and TRPM5 in the duodenum. CONCLUSION These data demonstrated that l-Glu stimulated CCK secretion through the activation of T1R1/T1R3 in a PLC/TRPM5-dependent manner. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Cuicui Kang
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Lvyang Wang
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Jiangyin Feng
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Weiyun Zhu
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Suqin Hang
- National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, China
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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Ueno H, Sanada K, Miyamoto T, Baba K, Tanaka K, Nishimura H, Nishimura K, Sonoda S, Yoshimura M, Maruyama T, Oginosawa Y, Araki M, Sonoda S, Onaka T, Otsuji Y, Ueta Y. Oxytocin-monomeric red fluorescent protein 1 synthesis in the hypothalamus under osmotic challenge and acute hypovolemia in a transgenic rat line. Physiol Rep 2020; 8:e14558. [PMID: 32914562 PMCID: PMC7507703 DOI: 10.14814/phy2.14558] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/18/2020] [Accepted: 07/20/2020] [Indexed: 12/29/2022] Open
Abstract
We generated a transgenic rat line that expresses oxytocin (OXT)-monomeric red fluorescent protein 1 (mRFP1) fusion gene to visualize the dynamics of OXT. In this transgenic rat line, hypothalamic OXT can be assessed under diverse physiological and pathophysiological conditions by semiquantitative fluorometry of mRFP1 fluorescence intensity as a surrogate marker for endogenous OXT. Using this transgenic rat line, we identified the changes in hypothalamic OXT synthesis under various physiological conditions. However, few reports have directly examined hypothalamic OXT synthesis under hyperosmolality or hypovolemia. In this study, hypothalamic OXT synthesis was investigated using the transgenic rat line after acute osmotic challenge and acute hypovolemia induced by intraperitoneal (i.p.) administration of 3% hypertonic saline (HTN) and polyethylene glycol (PEG), respectively. The mRFP1 fluorescence intensity in the paraventricular (PVN) and supraoptic nuclei (SON) was significantly increased after i.p. administration of HTN and PEG, along with robust Fos-like immunoreactivity (co-expression). Fos expression showed neuronal activation in the brain regions that are associated with the hypothalamus and/or are involved in maintaining water and electrolyte homeostasis in HTN- and PEG-treated rats. OXT and mRFP1 gene expressions were dramatically increased after HTN and PEG administration. The plasma OXT level was extremely increased after HTN and PEG administration. Acute osmotic challenge and acute hypovolemia induced upregulation of hypothalamic OXT in the PVN and SON. These results suggest that not only endogenous arginine vasopressin (AVP) but also endogenous OXT has a key role in maintaining body fluid homeostasis to cope with hyperosmolality and hypovolemia.
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Affiliation(s)
- Hiromichi Ueno
- Department of the Second Department of Internal MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Kenya Sanada
- Department of the Second Department of Internal MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Tetsu Miyamoto
- Department of the Second Department of Internal MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Kazuhiko Baba
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Kentaro Tanaka
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Haruki Nishimura
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Kazuaki Nishimura
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Satomi Sonoda
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Mitsuhiro Yoshimura
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Takashi Maruyama
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Yasushi Oginosawa
- Department of the Second Department of Internal MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Masaru Araki
- Department of the Second Department of Internal MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Shinjo Sonoda
- Department of the Second Department of Internal MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Tatsushi Onaka
- Division of Brain and NeurophysiologyDepartment of PhysiologyJichi Medical UniversityShimotsukeJapan
| | - Yutaka Otsuji
- Department of the Second Department of Internal MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
| | - Yoichi Ueta
- PhysiologySchool of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
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Unique Organization of Actin Cytoskeleton in Magnocellular Vasopressin Neurons in Normal Conditions and in Response to Salt-Loading. eNeuro 2020; 7:ENEURO.0351-19.2020. [PMID: 32209611 PMCID: PMC7189486 DOI: 10.1523/eneuro.0351-19.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 12/04/2022] Open
Abstract
Magnocellular neurosecretory cells (MNCs) are intrinsically osmosensitive and can be activated by increases in blood osmolality, triggering the release of antidiuretic hormone vasopressin (VP) to promote water retention. Hence, the activity of magnocellular VP neurons is one of the key elements contributing to the regulation of body fluid homeostasis in healthy organisms. Chronic exposure to high dietary salt leads to excessive activation of VP neurons, thereby elevating levels of circulating VP, which can cause increases in blood pressure contributing to salt-dependent hypertension. However, the molecular basis underlying high-salt diet-induced hyperactivation of magnocellular VP neurons remains not fully understood. Previous studies suggest that magnocellular neurosecretory neurons contain a subcortical layer of actin filaments and pharmacological stabilization of this actin network potentiates osmotically-induced activation of magnocellular neurons. Using super-resolution imaging in situ, we investigated the organization of the actin cytoskeleton in rat MNCs under normal physiological conditions and after a chronic increase in blood osmolality following 7 d of salt-loading (SL). We found that, in addition to the subcortical layer of actin filaments, magnocellular VP neurons are endowed with a unique network of cytoplasmic actin filaments throughout their somata. Moreover, we revealed that the density of both subcortical and cytoplasmic actin networks in magnocellular VP neurons is dramatically increased following SL. These results suggest that increased osmo-responsiveness of VP neurons following chronic exposure to high dietary salt may be mediated by the modulation of unique actin networks in magnocellular VP neurons, possibly contributing to elevated blood pressure in this condition.
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Fortaleza EAT, Busnardo C, Fassini A, Belém-Filho IJA, Almeida-Pereira G, Antunes-Rodrigues J, Morgan Aguiar Corrêa F. Mechanisms involved in the cardiovascular effects caused by acute osmotic stimulation in conscious rats. Stress 2020; 23:221-232. [PMID: 31451018 DOI: 10.1080/10253890.2019.1660771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Both the autonomic nervous system and the neuroendocrine system are activated by osmotic stimulation (OS) evoking cardiovascular effects. The current study investigated the mechanisms involved in the cardiovascular responses evoked by an acute osmotic stimulus with intraperitoneal (i.p.) injection of either isotonic (0.15 M NaCl) or hypertonic saline (0.6 M NaCl) in conscious rats. Hypertonic saline increased mean arterial pressure (MAP) and heart rate (HR) for 30 min, as well as plasma osmolality and sodium content. Urinary sodium and urinary volume were also increased. Pretreatment with the ganglion blocker pentolinium (i.v.) did not affect the pressor response, but significantly decreased the tachycardic response caused by OS. Pretreatment with the V1-vasopressin receptor antagonist dTyr(CH2)5(Me)AVP (i.v.) reduced the pressor response, without affecting the tachycardic response evoked by the hypertonic OS. Neither the pressor nor the tachycardic response to OS was affected by pretreatment with either the oxytocin receptor antagonist atosiban or the α1-antagonist prazosin. Pretreatment with the β1-antagonist atenolol had no effect on the pressor response, but markedly decreased the tachycardic response evoked by OS. Results indicate that i.p. hypertonic OS-evoked pressor response is mediated by the release of vasopressin, with a minor influence of the vascular sympathetic input.LAY SUMMARYIncreased plasma osmolality, such as that observed during dehydration or salt intake, is a potent stimulus yielding to marked cardiovascular and neuroendocrine responses. The intraperitoneal (i.p.) injection of hypertonic saline solution is a commonly used animal model to cause a sustained increase in plasma osmolality, leading to a cardiovascular response characterized by sustained blood pressure and heart increases, whose systemic mechanisms were presently studied. Our findings indicate that the pressor response to the i.p. osmotic stimulus (OS) is mediated mainly by the release of vasopressin into the blood circulation with a minor or even the noninvolvement of the vascular sympathetic nervous system, whereas activation of the sympathetic-cardiac system mediates the tachycardic response to OS.
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Affiliation(s)
| | - Cristiane Busnardo
- Department of Pharmacology, School of Medicine of Ribeirão Preto, São Paulo, Brazil
| | - Aline Fassini
- Department of Pharmacology, School of Medicine of Ribeirão Preto, São Paulo, Brazil
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Abstract
Activation of arginine–vasopressin is one of the hormonal responses to face vasodilation-related hypotension. Released from the post-pituitary gland, vasopressin induces vasoconstriction through the activation of V1a receptors located on vascular smooth muscle cells. Due to its non-selective receptor affinity arginine–vasopressin also activates V2 (located on renal tubular cells of collecting ducts) and V1b (located in the anterior pituitary and in the pancreas) receptors, thereby potentially promoting undesired side effects such as anti-diuresis, procoagulant properties due to release of the von Willebrand’s factor and platelet activation. Finally, it also cross-activates oxytocin receptors. During septic shock, vasopressin plasma levels were reported to be lower than expected, and a hypersensitivity to its vasopressor effect is reported in such situation. Terlipressin and selepressin are synthetic vasopressin analogues with a higher affinity for the V1 receptor, and, hence, potentially less side effects. In this narrative review, we present the current knowledge of the rationale, benefits and risks of vasopressin use in the setting of septic shock and vasoplegic shock following cardiac surgery. Clearly, vasopressin administration allows reducing norepinephrine requirements, but so far, no improvement of survival was reported and side effects are frequent, particularly ischaemic events. Finally, we will discuss the current indications for vasopressin and its agonists in the setting of septic shock, and the remaining unresolved questions.
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28
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Fetissov SO, Meguid MM. Food intake and meal pattern in response to hyperosmotic-induced dehydration in obese and lean Zucker rats. Nutrition 2020; 70S:100011. [DOI: 10.1016/j.nutx.2020.100011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 06/16/2020] [Accepted: 06/21/2020] [Indexed: 10/23/2022]
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Abstract
The Ironman is one of the most popular triathlon events in the world. Such a race involves a great number of tactical decisions for a healthy finish and best performance. Dehydration is widely postulated to decrease performance and is known as a cause of dropouts in Ironman. Despite the importance of hydration status after an Ironman triathlon, there is a clear lack of review and especially meta-analysis studies on this topic. Therefore, the objective was to systematically review the literature and carry out a meta-analysis investigating the hydration status after an Ironman triathlon. We conducted a systematic review of the literature up to June 2016 that included the following databases: PubMed, SCOPUS, Science Direct and Web of Science. From the initial 995 references, we included 6 studies in the qualitative analysis and in the meta-analysis. All trials had two measures of hydration status after a full Ironman race. Total body water, blood and urine osmolality, urine specific gravity and sodium plasma concentration were considered as hydration markers. Three investigators independently abstracted data on the study design, sample size, participants’ and race characteristics, outcomes, and quantitative data for the meta-analysis. In the pooled analysis, it seems that the Ironman event led to a moderate state of dehydration in comparison to baseline values (SMD 0.494; 95% CI 0.220 to 0.767; p = 0.001). Some evidence of heterogeneity and consistency was also observed: Q = 19.6; I2 = 28.5%; τ2 = 2.39. The results suggest that after the race athletes seem to be hypo-hydrated in comparison to baseline values.
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30
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Li Q, Yang C, Zhang X, Yang Z, Zhang T. Arginine vasopressin attenuates dysfunction of hippocampal theta and gamma oscillations in chronic cerebral hypoperfusion via V1a receptor. Brain Res Bull 2019; 153:84-92. [DOI: 10.1016/j.brainresbull.2019.08.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/14/2019] [Accepted: 08/14/2019] [Indexed: 12/26/2022]
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31
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Burton AG, Hopper K. Hyponatremia in dogs and cats. J Vet Emerg Crit Care (San Antonio) 2019; 29:461-471. [DOI: 10.1111/vec.12881] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/04/2017] [Accepted: 09/06/2017] [Indexed: 01/10/2023]
Affiliation(s)
| | - Kate Hopper
- Department of Veterinary Surgical and Radiological SciencesUniversity of California Davis CA
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32
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Lacey J, Corbett J, Forni L, Hooper L, Hughes F, Minto G, Moss C, Price S, Whyte G, Woodcock T, Mythen M, Montgomery H. A multidisciplinary consensus on dehydration: definitions, diagnostic methods and clinical implications. Ann Med 2019; 51:232-251. [PMID: 31204514 PMCID: PMC7877883 DOI: 10.1080/07853890.2019.1628352] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/28/2019] [Accepted: 05/28/2019] [Indexed: 01/02/2023] Open
Abstract
Background: Dehydration appears prevalent, costly and associated with adverse outcomes. We sought to generate consensus on such key issues and elucidate need for further scientific enquiry. Materials and methods: A modified Delphi process combined expert opinion and evidence appraisal. Twelve relevant experts addressed dehydration's definition, objective markers and impact on physiology and outcome. Results: Fifteen consensus statements and seven research recommendations were generated. Key findings, evidenced in detail, were that there is no universally accepted definition for dehydration; hydration assessment is complex and requires combining physiological and laboratory variables; "dehydration" and "hypovolaemia" are incorrectly used interchangeably; abnormal hydration status includes relative and/or absolute abnormalities in body water and serum/plasma osmolality (pOsm); raised pOsm usually indicates dehydration; direct measurement of pOsm is the gold standard for determining dehydration; pOsm >300 and ≤280 mOsm/kg classifies a person as hyper or hypo-osmolar; outside extremes, signs of adult dehydration are subtle and unreliable; dehydration is common in hospitals and care homes and associated with poorer outcomes. Discussion: Dehydration poses risk to public health. Dehydration is under-recognized and poorly managed in hospital and community-based care. Further research is required to improve assessment and management of dehydration and the authors have made recommendations to focus academic endeavours. Key messages Dehydration assessment is a major clinical challenge due to a complex, varying pathophysiology, non-specific clinical presentations and the lack of international consensus on definition and diagnosis. Plasma osmolality represents a valuable, objective surrogate marker of hypertonic dehydration which is underutilized in clinical practice. Dehydration is prevalent within the healthcare setting and in the community, and appears associated with increased morbidity and mortality.
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Affiliation(s)
- Jonathan Lacey
- Institute of Sport Exercise & Health, University College London, London, UK
| | - Jo Corbett
- Department of Sport & Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Lui Forni
- Intensive Care Unit, Royal Surrey County Hospital, Guildford, UK
| | - Lee Hooper
- Norwich Medical School, University of East Anglia, Norwich, UK
| | - Fintan Hughes
- Institute of Sport Exercise & Health, University College London, London, UK
| | - Gary Minto
- Department of Anaesthesia, University Hospitals Plymouth, Plymouth, UK
- Peninsula School of Medicine, Plymouth, UK
| | - Charlotte Moss
- Division of Surgery & Interventional Science, University College London, London, UK
| | - Susanna Price
- Intensive Care Unit, Royal Brompton Hospital, London, UK
| | - Greg Whyte
- Research Institute for Sport & Exercise Science, Liverpool John Moores University, UK
| | - Tom Woodcock
- Formerly Consultant University Hospitals Southampton NHS Trust, Southampton, UK
| | - Michael Mythen
- Institute of Sport Exercise & Health, University College London, London, UK
| | - Hugh Montgomery
- Centre for Human Health and Performance, University College London, London, UK
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33
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Gaspers LD, Pierobon N, Thomas AP. Intercellular calcium waves integrate hormonal control of glucose output in the intact liver. J Physiol 2019; 597:2867-2885. [PMID: 30968953 PMCID: PMC6647271 DOI: 10.1113/jp277650] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 04/08/2019] [Indexed: 11/21/2022] Open
Abstract
Key points Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown. We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production. The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production. The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.
Abstract Glucogenic hormones, including catecholamines and vasopressin, induce frequency‐modulated cytosolic Ca2+ oscillations in hepatocytes, and these propagate as intercellular Ca2+ waves via gap junctions in the intact liver. We investigated the role of co‐ordinated Ca2+ waves as a mechanism for integrating multiple endocrine and neuroendocrine inputs to control hepatic glucose production in perfused rat liver. Sympathetic nerve stimulation elicited localized Ca2+ increases that were restricted to hepatocytes in the periportal zone. During perfusion with subthreshold vasopressin, sympathetic stimulation converted asynchronous Ca2+ signals in a limited number of hepatocytes into co‐ordinated intercellular Ca2+ waves that propagated across entire lobules. A similar synergism was observed between physiological concentrations of glucagon and vasopressin, where glucagon also facilitated the recruitment of hepatocytes into a Ca2+ wave. Hepatic glucose production was significantly higher with intralobular Ca2+ waves. We propose that inositol 1,4,5‐trisphosphate (IP3)‐dependent Ca2+ signalling gives rise to an excitable medium across the functional syncytium of the hepatic lobule, co‐ordinating and amplifying the metabolic responses to multiple hormonal inputs. Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown. We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production. The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production. The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Nicola Pierobon
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
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Hernández-Pérez OR, Hernández VS, Nava-Kopp AT, Barrio RA, Seifi M, Swinny JD, Eiden LE, Zhang L. A Synaptically Connected Hypothalamic Magnocellular Vasopressin-Locus Coeruleus Neuronal Circuit and Its Plasticity in Response to Emotional and Physiological Stress. Front Neurosci 2019; 13:196. [PMID: 30949017 PMCID: PMC6435582 DOI: 10.3389/fnins.2019.00196] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 02/19/2019] [Indexed: 01/01/2023] Open
Abstract
The locus coeruleus (LC)-norepinephrine (NE) system modulates a range of salient brain functions, including memory and response to stress. The LC-NE system is regulated by neurochemically diverse inputs, including a range of neuropeptides such as arginine-vasopressin (AVP). Whilst the origins of many of these LC inputs, their synaptic connectivity with LC neurons, and their contribution to LC-mediated brain functions, have been well characterized, this is not the case for the AVP-LC system. Therefore, our aims were to define the types of synapses formed by AVP+ fibers with LC neurons using immunohistochemistry together with confocal and transmission electron microscopy (TEM), the origins of such inputs, using retrograde tracers, and the plasticity of the LC AVP system in response to stress and spatial learning, using the maternal separation (MS) and Morris water maze (MWM) paradigms, respectively, in rat. Confocal microscopy revealed that AVP+ fibers contacting tyrosine hydroxylase (TH)+ LC neurons were also immunopositive for vesicular glutamate transporter 2, a marker of presynaptic glutamatergic axons. TEM confirmed that AVP+ axons formed Gray type I (asymmetric) synapses with TH+ dendrites thus confirming excitatory synaptic connections between these systems. Retrograde tracing revealed that these LC AVP+ fibers originate from hypothalamic vasopressinergic magnocellular neurosecretory neurons (AVPMNNs). MS induced a significant increase in the density of LC AVP+ fibers. Finally, AVPMNN circuit upregulation by water-deprivation improved MWM performance while increased Fos expression was found in LC and efferent regions such as hippocampus and prefrontal cortex, suggesting that AVPMMN projections to LC could integrate homeostatic responses modifying neuroplasticity.
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Affiliation(s)
- Oscar R Hernández-Pérez
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Vito S Hernández
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Alicia T Nava-Kopp
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Rafael A Barrio
- Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Mohsen Seifi
- School of Pharmacy and Biomedical Sciences, Institute for Biomedical and Biomolecular Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Jerome D Swinny
- School of Pharmacy and Biomedical Sciences, Institute for Biomedical and Biomolecular Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Lee E Eiden
- Section on Molecular Neuroscience, National Institute of Mental Health-IRP, Bethesda, MD, United States
| | - Limei Zhang
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
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35
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Armstrong WE, Foehring RC, Kirchner MK, Sladek CD. Electrophysiological properties of identified oxytocin and vasopressin neurones. J Neuroendocrinol 2019; 31:e12666. [PMID: 30521104 PMCID: PMC7251933 DOI: 10.1111/jne.12666] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/26/2018] [Accepted: 11/29/2018] [Indexed: 12/18/2022]
Abstract
To understand the contribution of intrinsic membrane properties to the different in vivo firing patterns of oxytocin (OT) and vasopressin (VP) neurones, in vitro studies are needed, where stable intracellular recordings can be made. Combining immunochemistry for OT and VP and intracellular dye injections allows characterisation of identified OT and VP neurones, and several differences between the two cell types have emerged. These include a greater transient K+ current that delays spiking to stimulus onset, and a higher Na+ current density leading to greater spike amplitude and a more stable spike threshold, in VP neurones. VP neurones also show a greater incidence of both fast and slow Ca2+ -dependent depolarising afterpotentials, the latter of which summate to plateau potentials and contribute to phasic bursting. By contrast, OT neurones exhibit a sustained outwardly rectifying potential (SOR), as well as a consequent depolarising rebound potential, not found in VP neurones. The SOR makes OT neurones more susceptible to spontaneous inhibitory synaptic inputs and correlates with a longer period of spike frequency adaptation in these neurones. Although both types exhibit prominent Ca2+ -dependent afterhyperpolarising potentials (AHPs) that limit firing rate and contribute to bursting patterns, Ca2+ -dependent AHPs in OT neurones selectively show significant increases during pregnancy and lactation. In OT neurones, but not VP neurones, AHPs are highly dependent on the constitutive presence of the second messenger, phosphatidylinositol 4,5-bisphosphate, which permissively gates N-type channels that contribute the Ca2+ during spike trains that activates the AHP. By contrast to the intrinsic properties supporting phasic bursting in VP neurones, the synchronous bursting of OT neurones has only been demonstrated in vitro in cultured hypothalamic explants and is completely dependent on synaptic transmission. Additional differences in Ca2+ channel expression between the two neurosecretory terminal types suggests these channels are also critical players in the differential release of OT and VP during repetitive spiking, in addition to their importance to the potentials controlling firing patterns.
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Affiliation(s)
- William E Armstrong
- Department of Anatomy & Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Robert C Foehring
- Department of Anatomy & Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Matthew K Kirchner
- Department of Anatomy & Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Celia D Sladek
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado
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Abstract
The syndrome of inappropriate antidiuresis (SIAD) is a common cause of hyponatremia in hospitalized children. SIAD refers to euvolemic hyponatremia due to nonphysiologic stimuli for arginine vasopressin production in the absence of renal or endocrine dysfunction. SIAD can be broadly classified as a result of tumors, pulmonary or central nervous system disorders, medications, or other causes such as infection, inflammation, and the postoperative state. The presence of hypouricemia with an elevated fractional excretion of urate can aid in the diagnosis. Treatment options include fluid restriction, intravenous saline solutions, oral sodium supplements, loop diuretics, oral urea, and vasopressin receptor antagonists (vaptans).
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Affiliation(s)
- Michael L Moritz
- Pediatric Nephrology, Pediatric Dialysis, Division of Nephrology, Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, The University of Pittsburgh School of Medicine, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
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Kanbay M, Aslan G, Afsar B, Dagel T, Siriopol D, Kuwabara M, Incir S, Camkiran V, Rodriguez‐Iturbe B, Lanaspa MA, Covic A, Johnson RJ. Acute effects of salt on blood pressure are mediated by serum osmolality. J Clin Hypertens (Greenwich) 2018; 20:1447-1454. [PMID: 30232829 PMCID: PMC8030773 DOI: 10.1111/jch.13374] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/06/2018] [Accepted: 07/15/2018] [Indexed: 02/06/2023]
Abstract
It is classically thought that it is the amount of salt that is critical for driving acute blood pressure responses. However, recent studies suggest that blood pressure responses, at least acutely, may relate to changes in serum osmolality. Here, we test the hypothesis that acute blood pressure responses to salt can be altered by concomitant water loading. Ten healthy patients free of any disease and medication underwent 4 interventions each a week apart in which they took 300 mL of lentil soup with no salt (visit 1), lentil soup with 3 g salt (visit 2), or lentil soup with 3 g salt and 500 mL water (visit 3) or 750 mL water (visit 4). At each visit, hourly blood measurements and blood pressure measurements (baseline, 1st, 2nd, 3rd, and 4th hour) were performed and plasma osmolarity, sodium and copeptin levels were measured. Patients receiving the 3 g salt showed a 6 mOsm/L change in osmolality with a 2.5 mmol/L change in plasma sodium and 10 mm Hg rise in systolic blood pressure at 2 hours. When the same patients drank salty soup with water, the changes in plasma osmolarity, plasma sodium, and blood pressure were prevented. The ability to raise blood pressure acutely with salt appears dependent on changes in plasma osmolality rather than the amount of salt. Our findings suggest that concurrent intake of water must be considered when evaluating the role of salt in blood pressure.
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Affiliation(s)
- Mehmet Kanbay
- Division of Nephrology, Department of MedicineKoc University School of MedicineIstanbulTurkey
| | - Gamze Aslan
- Department of CardiologyKoc University HospitalIstanbulTurkey
| | - Baris Afsar
- Division of Nephrology, Department of Internal MedicineSuleyman Demirel University School of MedicineIspartaTurkey
| | - Tuncay Dagel
- Division of Nephrology, Department of MedicineKoc University School of MedicineIstanbulTurkey
| | - Dimitrie Siriopol
- Department of NephrologyUniversity of Medicine and Pharmacy "Gr. T. Popa"lasiRomania
| | - Masanari Kuwabara
- Division of Renal Diseases and Hypertension, School of MedicineUniversity of Colorado DenverAuroraColorado
- Department of CardiologyToranomon HospitalTokyoJapan
| | - Said Incir
- Department of BiochemistryKoc University HospitalIstanbulTurkey
| | - Volkan Camkiran
- Department of CardiologyKoc University HospitalIstanbulTurkey
| | - Bernardo Rodriguez‐Iturbe
- Instituto Venezolano de Investigaciones CientÍficas (IVIC‐Zulia), Nephrology Service Hospital Universitario, Universidad del ZuliaMaracaiboVenezuela
| | - Miguel A. Lanaspa
- Division of Renal Diseases and Hypertension, School of MedicineUniversity of Colorado DenverAuroraColorado
| | - Adrian Covic
- Department of NephrologyUniversity of Medicine and Pharmacy "Gr. T. Popa"lasiRomania
| | - Richard J. Johnson
- Division of Renal Diseases and Hypertension, School of MedicineUniversity of Colorado DenverAuroraColorado
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Unravelling the intravenous and in situ vasopressin effects on the urinary bladder in anesthetized female rats: More than one vasopressin receptor subtype involved? Eur J Pharmacol 2018; 834:109-117. [DOI: 10.1016/j.ejphar.2018.07.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/02/2018] [Accepted: 07/13/2018] [Indexed: 01/26/2023]
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Stacey MJ, Woods DR, Brett SJ, Britland SE, Fallowfield JL, Allsopp AJ, Delves SK. Heat acclimatization blunts copeptin responses to hypertonicity from dehydrating exercise in humans. Physiol Rep 2018; 6:e13851. [PMID: 30221840 PMCID: PMC6139708 DOI: 10.14814/phy2.13851] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 08/04/2018] [Accepted: 08/10/2018] [Indexed: 11/24/2022] Open
Abstract
Acclimatization favors greater extracellular tonicity from lower sweat sodium, yet hyperosmolality may impair thermoregulation during heat stress. Enhanced secretion or action of vasopressin could mitigate this through increased free water retention. Aims were to determine responses of the vasopressin surrogate copeptin to dehydrating exercise and investigate its relationships with tonicity during short and long-term acclimatization. Twenty-three participants completed a structured exercise programme following arrival from a temperate to a hot climate. A Heat Tolerance Test (HTT) was conducted on Day-2, 6, 9 and 23, consisting of 60-min block-stepping at 50% VO2 peak, with no fluid intake. Resting sweat [Na+ ] was measured by iontophoresis. Changes in body mass (sweat loss), core temperature, heart rate, osmolality (serum and urine) and copeptin and aldosterone (plasma) were measured with each Test. From Day 2 to Day 23, sweat [Na+ ] decreased significantly (adjusted P < 0.05) and core temperature and heart rate fell. Over the same interval, HTT-associated excursions were increased for serum osmolality (5 [-1, 9] vs. 9 [5, 12] mosm·kg-1 ), did not differ for copeptin (9.6 [6.0, 15.0] vs. 7.9 [4.3, 14.7] pmol·L-1 ) and were reduced for aldosterone (602 [415, 946] vs. 347 [263, 537] pmol·L-1 ). Urine osmolality was unchanging and related consistently to copeptin at end-exercise, whereas the association between copeptin and serum osmolality was right-shifted (P = 0.0109) with acclimatization. Unchanging urine:serum osmolality argued against increased renal action of vasopressin. In conclusion, where exercise in the heat is performed without fluid replacement, heat acclimatization does not appear to enhance AVP-mediated free water retention in humans.
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Affiliation(s)
- Michael J. Stacey
- Department of Surgery and CancerImperial College LondonLondonUnited Kingdom
- Department of Military MedicineRoyal Centre for Defence MedicineBirminghamUnited Kingdom
| | - David R. Woods
- Department of Surgery and CancerImperial College LondonLondonUnited Kingdom
- Carnegie Research InstituteLeeds Beckett UniversityLeedsUnited Kingdom
| | - Stephen J. Brett
- Department of Surgery and CancerImperial College LondonLondonUnited Kingdom
| | | | | | | | - Simon K. Delves
- Institute of Naval MedicineAlverstokeHampshireUnited Kingdom
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40
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Deneysel epilepsi modelinde böbrekte bulunan aquaporin4 ve aquaporin2 kanallarının gen ekspresyonları. JOURNAL OF CONTEMPORARY MEDICINE 2018. [DOI: 10.16899/gopctd.441193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Ueno H, Yoshimura M, Tanaka K, Nishimura H, Nishimura K, Sonoda S, Motojima Y, Saito R, Maruyama T, Miyamoto T, Serino R, Tamura M, Onaka T, Otsuji Y, Ueta Y. Upregulation of hypothalamic arginine vasopressin by peripherally administered furosemide in transgenic rats expressing arginine vasopressin-enhanced green fluorescent protein. J Neuroendocrinol 2018; 30:e12603. [PMID: 29682811 DOI: 10.1111/jne.12603] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 04/17/2018] [Indexed: 11/30/2022]
Abstract
Furosemide, which is used worldwide as a diuretic agent, inhibits sodium reabsorption in the Henle's loop, resulting in diuresis and natriuresis. Arginine vasopressin (AVP) is synthesized in the supraoptic nucleus (SON), paraventricular nucleus (PVN), and suprachiasmatic nucleus (SCN) of the hypothalamus. The synthesis AVP in the magnocellular neurons of SON and PVN physiologically regulated by plasma osmolality and blood volume and contributed water homeostasis by increasing water reabsorption in the collecting duct. Central AVP dynamics after peripheral administration of furosemide remain unclear. Here, we studied the effects of intraperitoneal (i.p.) administration of furosemide (20 mg/kg) on hypothalamic AVP by using transgenic rats expressing AVP-enhanced green fluorescent protein (eGFP) under the AVP promoter. The i.p. administration of furosemide did not affect plasma osmolality in the present study; however, eGFP in the SON and magnocellular divisions of the PVN (mPVN) were significantly increased after furosemide administration compared to the control. Immunohistochemical analysis revealed Fos-like immunoreactivity (IR) in eGFP-positive neurons in the SON and mPVN 90 min after i.p. administration of furosemide, and AVP heteronuclear (hn) RNA and eGFP mRNA levels were significantly increased. These furosemide-induced changes were not observed in the suprachiasmatic AVP neurons. Furthermore, furosemide induced a remarkable increase in Fos-IR in the organum vasculosum laminae terminals (OVLT), median preoptic nucleus (MnPO), subfornical organ (SFO), locus coeruleus (LC), nucleus of the solitary tract (NTS), and rostral ventrolateral medulla (RVLM) after i.p. administration of furosemide. In conclusion, we were able to visualize and quantitatively evaluate AVP-eGFP synthesis and neuronal activations after peripheral administration of furosemide, using the AVP-eGFP transgenic rats. The results of this study may provide new insights into the elucidation of physiological mechanisms underlying body fluid homeostasis induced by furosemide. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Hiromichi Ueno
- Department of Physiology
- The Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
| | | | | | | | | | | | | | | | | | - Tetsu Miyamoto
- The Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
| | - Ryota Serino
- Department of Nephrology, Yoshino Hospital, Kitakyushu, 808-0034, Japan
| | - Masahito Tamura
- The Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
| | - Tatsushi Onaka
- Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Shimotsuke, 329-0498, Japan
| | - Yutaka Otsuji
- The Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
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Han SW, Yi JH, Kang KP, Kim HY, Kim SW, Choi HY, Ha SK, Kim GH, Kim YW, Jeong KH, Shin SK, Kim HJ. Safety and Efficacy of Tolvaptan in Korean Patients with Hyponatremia Caused by the Syndrome of Inappropriate Antidiuretic Hormone. J Korean Med Sci 2018; 33:e112. [PMID: 29629516 PMCID: PMC5890082 DOI: 10.3346/jkms.2018.33.e112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 02/26/2018] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The aim of this multicenter study was to evaluate the safety and efficacy of tolvaptan (TLV) in Korean patients with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). METHODS Of 51 enrolled patients with SIADH, 39 patients (16 female patients, aged 70.8 ± 11.3 years) were included in an intention to treat analysis. All patients received 15 mg/day as the initial dose, and the dose was then increased up to 60 mg/day (as needed) until day 4. RESULTS Serum sodium increased significantly from baseline during the first 24 hours (126.8 ± 4.3 vs. 133.7 ± 3.8 mmol/L, P < 0.001), rose gradually between days 1 and 4 (133.7 ± 3.8 vs. 135.6 ± 3.6 mmol/L, P < 0.05), and then plateaued until day 11 (136.7 ± 4.5 mmol/L). The correlation between the change in serum sodium for the first 24 hours and initial serum sodium concentration was significant (r = -0.602, P < 0.001). In severe hyponatremia (< 125 mmol/L), the change was significantly higher (11.1 ± 4.8 mmol/L) than in moderate (6.4 ± 2.5 mmol/L, P < 0.05) or mild hyponatremia (4.3 ± 3.3 mmol/L, P < 0.01). In addition, logistic regression analysis showed that body weight (odds ratio [OR], 0.858; 95% confidence interval [CI], 0.775-0.976; P = 0.020) and body mass index (BMI) (OR, 0.692; 95% CI, 0.500-0.956; P = 0.026) were associated with rapid correction. No serious adverse events were reported, but in 13% of patients hyponatremia was overcorrected. CONCLUSION TLV is effective in correcting hyponatremia and well-tolerated in Korean patients with SIADH. However, those with low body weight, low BMI or severe hyponatremia, could be vulnerable to overcorrection with the initial dose of 15 mg TLV.
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Affiliation(s)
- Sang Woong Han
- Department of Internal Medicine, Hanyang University Guri Hospital, Guri, Korea
| | - Joo Hark Yi
- Department of Internal Medicine, Hanyang University Guri Hospital, Guri, Korea.
| | - Kyung Pyo Kang
- Department of Internal Medicine, Chonbuk National University School of Medicine, Jeonju, Korea
| | - Ha Yeon Kim
- Department of Internal Medicine, Chonnam National University School of Medicine, Gwangju, Korea
| | - Soo Wan Kim
- Department of Internal Medicine, Chonnam National University School of Medicine, Gwangju, Korea
| | - Hoon Young Choi
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Sung Kyu Ha
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Gheun Ho Kim
- Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea
| | - Yang Wook Kim
- Department of Internal Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
| | - Kyung Hwan Jeong
- Department of Internal Medicine, Kyung Hee University School of Medicine, Seoul, Korea
| | - Sug Kyun Shin
- Department of Internal Medicine, National Health Insurance Service Ilsan Hospital, Goyang, Korea
| | - Ho Jung Kim
- Department of Internal Medicine, Hanyang University Guri Hospital, Guri, Korea
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Reis MEMD, Araújo LTFD, de Andrade WMG, Resende NDS, Lima RRMD, Nascimento ESD, Costa MSMDO, Cavalcante JC. Distribution of nitric oxide synthase in the rock cavy (Kerodon rupestris) brain I: The diencephalon. Brain Res 2018; 1685:60-78. [DOI: 10.1016/j.brainres.2018.01.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 12/27/2022]
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Baylis PH, Robertson GL. Plasma Vasopressin Response to Hypertonic Saline Infusion to Assess Posterior Pituitary Function. J R Soc Med 2018; 73:255-60. [PMID: 7241442 PMCID: PMC1437414 DOI: 10.1177/014107688007300408] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Hypertonic saline was infused into 11 volunteers to osmotically stimulate vasopressin secretion. A strong positive correlation between plasma arginine vasopressin (PAVP) and plasma osmolality (Pos) was obtained, defined by the function PAVP = 0.63 (Pos – 284), r = +0.80, P < 0.001. The sensitivity of vasopressin secretion to osmotic stimulation was represented by the slope of the expression and the theoretical threshold of vasopressin release by the abscissal intercept. Plasma osmolality at the onset of thirst was 298.5 ± 1.1 mmol/kg. Application of hypertonic saline infusion to 10 polyuric patients clearly separated those with normal osmoregulation of vasopressin secretion from those with cranial diabetes insipidus.
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45
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Gizowski C, Trudel E, Bourque CW. Central and peripheral roles of vasopressin in the circadian defense of body hydration. Best Pract Res Clin Endocrinol Metab 2017; 31:535-546. [PMID: 29224666 DOI: 10.1016/j.beem.2017.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Vasopressin is a neuropeptide synthesized by specific subsets of neurons within the eye and brain. Studies in rats and mice have shown that vasopressin produced by magnocellular neurosecretory cells (MNCs) that project to the neurohypophysis is released into the blood circulation where it serves as an antidiuretic hormone to promote water reabsorption from the kidney. Moreover vasopressin is a neurotransmitter and neuromodulator that contributes to time-keeping within the master circadian clock (i.e. the suprachiasmatic nucleus, SCN) and is also used as an output signal by SCN neurons to direct centrally mediated circadian rhythms. In this chapter, we review recent cellular and network level studies in rodents that have provided insight into how circadian rhythms in vasopressin mediate changes in water intake behavior and renal water conservation that protect the body against dehydration during sleep.
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Affiliation(s)
- Claire Gizowski
- Center for Research in Neuroscience, Research Institute of the McGill University Health Center, 1650 Cedar Avenue, Montreal, QC, H3G1A4, Canada.
| | - Eric Trudel
- Center for Research in Neuroscience, Research Institute of the McGill University Health Center, 1650 Cedar Avenue, Montreal, QC, H3G1A4, Canada.
| | - Charles W Bourque
- Center for Research in Neuroscience, Research Institute of the McGill University Health Center, 1650 Cedar Avenue, Montreal, QC, H3G1A4, Canada.
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Extracellular volume depletion and resultant hypotonic hyponatremia: A novel translational approach. Math Biosci 2017; 295:62-66. [PMID: 29129646 DOI: 10.1016/j.mbs.2017.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 09/15/2017] [Accepted: 11/08/2017] [Indexed: 11/20/2022]
Abstract
Although several methods currently exist to determine that a person is hypovolemic, it often remains very challenging to accurately estimate the effective circulating volume or amount of intravascular volume depletion in a non-controlled setting. This depletion of intravascular volume can have many causes and is frequently accompanied by hypotonic hyponatremia as a result of hypovolemia-induced release of arginine vasopressin (AVP) from the posterior pituitary gland. Here, we derive a novel, comprehensible equation that provides a theoretical insight into the complex interrelationship between the degree of isotonic volume depletion and the resultant change in plasma sodium concentration. We believe that the presented model can prove to be a valuable tool for the analysis of fluid and electrolyte imbalances.
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47
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Mast TG, Breza JM, Contreras RJ. Thirst Increases Chorda Tympani Responses to Sodium Chloride. Chem Senses 2017; 42:675-681. [PMID: 28981824 DOI: 10.1093/chemse/bjx052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In nature, water is present as a low-salt solution, thus we hypothesized that thirst would increase taste responses to low-salt solutions. We investigated the effect of thirst on the 2 different salt detection mechanisms present in the rat chorda tympani (CT) nerve. The first mechanism is dependent upon the epithelial sodium channel (ENaC), is blocked by benzamil, and is specific to the cation sodium. The second mechanism, while undefined, is independent of ENaC, and detects multiple cations. We expected thirst to increase benzamil-sensitive sodium responses due to mechanistically increasing the benzamil-sensitive ENaC. We recorded CT whole-nerve electrophysiological responses to lingual application of NaCl, KCl (30, 75, 150, 300, 500, and 600 mM), and imitation rainwater in both control and 24-h water-restricted male rats. NaCl solutions were presented in artificial saliva before and after lingual application of 5µM benzamil. Water restriction significantly increased the integrated CT responses to NaCl but not to KCl or imitation rainwater. Consistent with our hypothesis, only the benzamil-sensitive, and not the benzamil-insensitive, CT sodium response significantly increased. Additionally, CT responses to salt were recorded following induction of either osmotic or volemic thirst. Both thirsts significantly enhanced the integrated CT responses to NaCl and KCl, but not imitation rainwater. Interestingly, osmotic and volemic thirsts increased CT responses by increasing both the benzamil-sensitive and benzamil-insensitive CT sodium responses. We propose that thirst increases the sensitivity of the CT nerve to sodium.
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Affiliation(s)
- Thomas G Mast
- Department of Biology, Program in Neuroscience, Eastern Michigan University, Ypsilanti, MI 48197, USA.,Department of Psychology, Program in Neuroscience, Florida State University, 1107 West Call Street, Tallahassee, FL 30306, USA
| | - Joseph M Breza
- Department of Psychology, Program in Neuroscience, Florida State University, 1107 West Call Street, Tallahassee, FL 30306, USA.,Department of Psychology, Program in Neuroscience, Eastern Michigan University, Ypsilanti, MI 48197, USA
| | - Robert J Contreras
- Department of Psychology, Program in Neuroscience, Florida State University, 1107 West Call Street, Tallahassee, FL 30306, USA
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48
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Abstract
OBJECTIVES Hyponatremic encephalopathy, symptomatic cerebral edema due to a low osmolar state, is a medical emergency and often encountered in the ICU setting. This article provides a critical appraisal and review of the literature on identification of high-risk patients and the treatment of this life-threatening disorder. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION Online search of the PubMed database and manual review of articles involving risk factors for hyponatremic encephalopathy and treatment of hyponatremic encephalopathy in critical illness. DATA SYNTHESIS Hyponatremic encephalopathy is a frequently encountered problem in the ICU. Prompt recognition of hyponatremic encephalopathy and early treatment with hypertonic saline are critical for successful outcomes. Manifestations are varied, depending on the extent of CNS's adaptation to the hypoosmolar state. The absolute change in serum sodium alone is a poor predictor of clinical symptoms. However, certain patient specific risks factors are predictive of a poor outcome and are important to identify. Gender (premenopausal and postmenopausal females), age (prepubertal children), and the presence of hypoxia are the three main clinical risk factors and are more predictive of poor outcomes than the rate of development of hyponatremia or the absolute decrease in the serum sodium. CONCLUSIONS In patients with hyponatremic encephalopathy exhibiting neurologic manifestations, a bolus of 100 mL of 3% saline, given over 10 minutes, should be promptly administered. The goal of this initial bolus is to quickly treat cerebral edema. If signs persist, the bolus should be repeated in order to achieve clinical remission. However, the total change in serum sodium should not exceed 5 mEq/L in the initial 1-2 hours and 15-20 mEq/L in the first 48 hours of treatment. It has recently been demonstrated in a prospective fashion that 500 mL of 3% saline at an infusion rate of 100 mL per hour can be given safely. It is critical to recognize the early signs of cerebral edema (nausea, vomiting, and headache) and intervene with IV 3% sodium chloride as this is the time to intervene rather than waiting until more severe symptoms develop. Cerebral demyelination is a rare complication of overly rapid correction of hyponatremia. The principal risk factors for cerebral demyelination are correction of the serum sodium more than 25 mEq/L in the first 48 hours of therapy, correction past the point of 140 mEq/L, chronic liver disease, and hypoxic/anoxic episode.
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Affiliation(s)
- Steven G Achinger
- 1Department of Nephrology, Watson Clinic LLP, Lakeland, FL. 2Renal Consultants of Houston, Department of Research, Houston, TX. 3Department of Nephrology, Hospital Italiano, Buenos Aires, Argentina. 4Department of Nephrology, Hospital Austral, Austral University, Buenos Aires, Argentina. 5Department of Nephrology, University of California, Irvine, CA
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Prager-Khoutorsky M, Choe KY, Levi DI, Bourque CW. Role of Vasopressin in Rat Models of Salt-Dependent Hypertension. Curr Hypertens Rep 2017; 19:42. [PMID: 28451854 DOI: 10.1007/s11906-017-0741-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE OF REVIEW Dietary salt intake increases both plasma sodium and osmolality and therefore increases vasopressin (VP) release from the neurohypophysis. Although this effect could increase blood pressure by inducing fluid reabsorption and vasoconstriction, acute activation of arterial baroreceptors inhibits VP neurons via GABAA receptors to oppose high blood pressure. Here we review recent findings demonstrating that this protective mechanism fails during chronic high salt intake in rats. RECENT FINDINGS Two recent studies showed that chronic high sodium intake causes an increase in intracellular chloride concentration in VP neurons. This effect causes GABAA receptors to become excitatory and leads to the emergence of VP-dependent hypertension. One study showed that the increase in intracellular chloride was provoked by a decrease in the expression of the chloride exporter KCC2 mediated by local secretion of brain-derived neurotrophic factor and activation of TrkB receptors. Prolonged high dietary salt intake can cause pathological plasticity in a central homeostatic circuit that controls VP secretion and thereby contribute to peripheral vasoconstriction and hypertension.
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Affiliation(s)
- Masha Prager-Khoutorsky
- Department of Physiology, McGill University, McIntyre Medical Sciences Bldg., 3655 Promenade Sir-William Osler, Montreal, QC, H3G 1Y6, Canada
| | - Katrina Y Choe
- 2309 Gonda Neuroscience and Genetics Research Center, UCLA Department of Neurology, 695 Charles E. Young Dr. South, Los Angeles, CA, 90095, USA
| | - David I Levi
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Center, Montreal General Hospital, 1650 Cedar Avenue, Montreal, QC, H3G 1A4, Canada
| | - Charles W Bourque
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Center, Montreal General Hospital, 1650 Cedar Avenue, Montreal, QC, H3G 1A4, Canada.
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50
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Montgomery LR, Hubscher CH. Altered vasopressin and natriuretic peptide levels in a rat model of spinal cord injury: implications for the development of polyuria. Am J Physiol Renal Physiol 2017; 314:F58-F66. [PMID: 28877880 DOI: 10.1152/ajprenal.00229.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Urinary dysfunction is a common complaint following spinal cord injury (SCI) and is a leading issue for individuals with SCI that impacts their quality of life. One urinary complication that has received little attention is SCI-induced polyuria, even though individuals with SCI will significantly restrict their fluid intake to decrease urine production, leading to sequelae of medical complications. Understanding the mechanisms instigating the development of polyuria will allow us to target interventions that may alleviate polyuria symptoms, leading to significant improvements in the quality of life and urinary health of individuals with SCI. In a rat SCI contusion model, an increase in the amount of urine excreted over a 24-h period ( P ≤ 0.001) was found at 2 wk postinjury. The urine excreted was more dilute with decreased urinary creatinine and specific gravity ( P ≤ 0.001). Several factors important in fluid balance regulation, vasopressin (AVP), natriuretic peptides, and corticosterone (CORT), also changed significantly postinjury. AVP levels decreased ( P = 0.042), whereas atrial natriuretic peptide (ANP) and CORT increased ( P = 0.005 and P = 0.031, respectively) at 2 wk postinjury. There was also a positive correlation between the increase in ANP and urine volume postinjury ( P = 0.033). The changes in AVP, ANP, and CORT are conducive to producing polyuria, and the timing of these changes coincides with the development of SCI-induced polyuria. This study identifies several therapeutic targets that could be used to ameliorate polyuria symptoms and improve quality of life in individuals with SCI.
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Affiliation(s)
- Lynnette R Montgomery
- Department of Anatomical Sciences and Neurobiology and Kentucky Spinal Cord Injury Research Center, University of Louisville , Louisville, Kentucky
| | - Charles H Hubscher
- Department of Anatomical Sciences and Neurobiology and Kentucky Spinal Cord Injury Research Center, University of Louisville , Louisville, Kentucky
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