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Li Y, Shen XZ, Li L, Zhao TV, Bernstein KE, Johnson AK, Lyden P, Fang J, Shi P. Brain Transforming Growth Factor-β Resists Hypertension Via Regulating Microglial Activation. Stroke 2017; 48:2557-2564. [PMID: 28698257 DOI: 10.1161/strokeaha.117.017370] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 06/08/2017] [Accepted: 06/22/2017] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND PURPOSE Hypertension is the major risk factor for stroke. Recent work unveiled that hypertension is associated with chronic neuroinflammation; microglia are the major players in neuroinflammation, and the activated microglia elevate sympathetic nerve activity and blood pressure. This study is to understand how brain homeostasis is kept from hypertensive disturbance and microglial activation at the onset of hypertension. METHODS Hypertension was induced by subcutaneous delivery of angiotensin II, and blood pressure was monitored in conscious animals. Microglial activity was analyzed by flow cytometry and immunohistochemistry. Antibody, pharmacological chemical, and recombinant cytokine were administered to the brain through intracerebroventricular infusion. Microglial depletion was performed by intracerebroventricular delivering diphtheria toxin to CD11b-diphtheria toxin receptor mice. Gene expression profile in sympathetic controlling nucleus was analyzed by customized qRT-PCR array. RESULTS Transforming growth factor-β (TGF-β) is constitutively expressed in the brains of normotensive mice. Removal of TGF-β or blocking its signaling before hypertension induction accelerated hypertension progression, whereas supplementation of TGF-β1 substantially suppressed neuroinflammation, kidney norepinephrine level, and blood pressure. By means of microglial depletion and adoptive transfer, we showed that the effects of TGF-β on hypertension are mediated through microglia. In contrast to the activated microglia in established hypertension, the resting microglia are immunosuppressive and important in maintaining neural homeostasis at the onset of hypertension. Further, we profiled the signature molecules of neuroinflammation and neuroplasticity associated with hypertension and TGF-β by qRT-PCR array. CONCLUSIONS Our results identify that TGF-β-modulated microglia are critical to keeping brain homeostasis responding to hypertensive disturbance.
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Affiliation(s)
- You Li
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Xiao Z Shen
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Liang Li
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Tuantuan V Zhao
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Kenneth E Bernstein
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Alan K Johnson
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Patrick Lyden
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Jianmin Fang
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.)
| | - Peng Shi
- From the School of Life Science and Technology, Tongji University, Shanghai, China (Y.L., T.V.Z., J.F.); The Second Affiliated Hospital of Zhejiang University (P.S.), Institute of Translational Medicine (P.S.), and Department of Physiology (X.Z.S.), Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology (Y.L., L.L., P.L., P.S.) and Department of Biomedical Science (T.V.Z., K.E.B.), Cedars-Sinai Medical Center, Los Angeles, CA; and Pharmacological and Brain Sciences, University of Iowa (A.K.J.).
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Burghardt PR, Krolewski DM, Dykhuis KE, Ching J, Pinawin AM, Britton SL, Koch LG, Watson SJ, Akil H. Nucleus accumbens cocaine-amphetamine regulated transcript mediates food intake during novelty conflict. Physiol Behav 2016; 158:76-84. [PMID: 26926827 DOI: 10.1016/j.physbeh.2016.02.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/24/2016] [Accepted: 02/24/2016] [Indexed: 02/09/2023]
Abstract
Obesity is a persistent and pervasive problem, particularly in industrialized nations. It has come to be appreciated that the metabolic health of an individual can influence brain function and subsequent behavioral patterns. To examine the relationship between metabolic phenotype and central systems that regulate behavior, we tested rats with divergent metabolic phenotypes (Low Capacity Runner: LCR vs. High Capacity Runner: HCR) for behavioral responses to the conflict between hunger and environmental novelty using the novelty suppressed feeding (NSF) paradigm. Additionally, we measured expression of mRNA, for peptides involved in energy management, in response to fasting. Following a 24-h fast, LCR rats showed lower latencies to begin eating in a novel environment compared to HCR rats. A 48-h fast equilibrated the latency to begin eating in the novel environment. A 24-h fast differentially affected expression of cocaine-amphetamine regulated transcript (CART) mRNA in the nucleus accumbens (NAc), where 24-h of fasting reduced CART mRNA in LCR rats. Bilateral microinjections of CART 55-102 peptide into the NAc increased the latency to begin eating in the NSF paradigm following a 24-h fast in LCR rats. These results indicate that metabolic phenotype influences how animals cope with the conflict between hunger and novelty, and that these differences are at least partially mediated by CART signaling in the NAc. For individuals with poor metabolic health who have to navigate food-rich and stressful environments, changes in central systems that mediate conflicting drives may feed into the rates of obesity and exacerbate the difficulty individuals have in maintaining weight loss.
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Affiliation(s)
- P R Burghardt
- Department of Psychiatry, University of Michigan, Ann Arbor, MI; Department of Nutrition and Food Science, Wayne State University, Detroit, MI.
| | - D M Krolewski
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - K E Dykhuis
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - J Ching
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - A M Pinawin
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - S L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI; Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI
| | - L G Koch
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | - S J Watson
- Department of Psychiatry, University of Michigan, Ann Arbor, MI; Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - H Akil
- Department of Psychiatry, University of Michigan, Ann Arbor, MI; Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
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Musicki B, Bella AJ, Bivalacqua TJ, Davies KP, DiSanto ME, Gonzalez-Cadavid NF, Hannan JL, Kim NN, Podlasek CA, Wingard CJ, Burnett AL. Basic Science Evidence for the Link Between Erectile Dysfunction and Cardiometabolic Dysfunction. J Sex Med 2015; 12:2233-55. [PMID: 26646025 DOI: 10.1111/jsm.13069] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Although clinical evidence supports an association between cardiovascular/metabolic diseases (CVMD) and erectile dysfunction (ED), scientific evidence for this link is incompletely elucidated. AIM This study aims to provide scientific evidence for the link between CVMD and ED. METHODS In this White Paper, the Basic Science Committee of the Sexual Medicine Society of North America assessed the current literature on basic scientific support for a mechanistic link between ED and CVMD, and deficiencies in this regard with a critical assessment of current preclinical models of disease. RESULTS A link exists between ED and CVMD on several grounds: the endothelium (endothelium-derived nitric oxide and oxidative stress imbalance); smooth muscle (SM) (SM abundance and altered molecular regulation of SM contractility); autonomic innervation (autonomic neuropathy and decreased neuronal-derived nitric oxide); hormones (impaired testosterone release and actions); and metabolics (hyperlipidemia, advanced glycation end product formation). CONCLUSION Basic science evidence supports the link between ED and CVMD. The Committee also highlighted gaps in knowledge and provided recommendations for guiding further scientific study defining this risk relationship. This endeavor serves to develop novel strategic directions for therapeutic interventions.
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Affiliation(s)
- Biljana Musicki
- The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Anthony J Bella
- Division of Urology, Department of Surgery and Department of Neuroscience, Ottawa Hospital Research Institute at the University of Ottawa, Ottawa, ON, Canada
| | - Trinity J Bivalacqua
- The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Kelvin P Davies
- Department of Urology, Albert Einstein College of Medicine, New York, NY, USA
| | - Michael E DiSanto
- Department of Surgery/Division of Urology, Cooper University Hospital, Camden, NJ, USA
| | - Nestor F Gonzalez-Cadavid
- Division of Urology, Department of Surgery, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, CA, USA.,Department of Urology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Johanna L Hannan
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Noel N Kim
- Institute for Sexual Medicine, San Diego, CA, USA
| | - Carol A Podlasek
- Departments of Urology, Physiology, and Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Christopher J Wingard
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Arthur L Burnett
- The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, MD, USA
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Sarga L, Hart N, Koch LG, Britton SL, Hajas G, Boldogh I, Ba X, Radak Z. Aerobic endurance capacity affects spatial memory and SIRT1 is a potent modulator of 8-oxoguanine repair. Neuroscience 2013; 252:326-36. [PMID: 23973402 DOI: 10.1016/j.neuroscience.2013.08.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/08/2013] [Accepted: 08/12/2013] [Indexed: 12/17/2022]
Abstract
Regular exercise promotes brain function via a wide range of adaptive responses, including the increased expression of antioxidant and oxidative DNA damage-repairing systems. Accumulation of oxidized DNA base lesions and strand breaks is etiologically linked to for example aging processes and age-associated diseases. Here we tested whether exercise training has an impact on brain function, extent of neurogenesis, and expression of 8-oxoguanine DNA glycosylase-1 (Ogg1) and SIRT1 (silent mating-type information regulation 2 homolog). To do so, we utilized strains of rats with low- and high-running capacity (LCR and HCR) and examined learning and memory, DNA synthesis, expression, and post-translational modification of Ogg1 hippocampal cells. Our results showed that rats with higher aerobic/running capacity had better spatial memory, and expressed less Ogg1, when compared to LCR rats. Furthermore, exercise increased SIRT1 expression and decreased acetylated Ogg1 (AcOgg1) levels, a post-translational modification important for efficient repair of 8-oxo-7,8-dihydroguanine (8-oxoG). Our data on cell cultures revealed that nicotinamide, a SIRT1-specific inhibitor, caused the greatest increase in the acetylation of Ogg1, a finding further supported by our other observations that silencing SIRT1 also markedly increased the levels of AcOgg1. These findings imply that high-running capacity is associated with increased hippocampal function, and SIRT1 level/activity and inversely correlates with AcOgg1 levels and thereby the repair of genomic 8-oxoG.
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Affiliation(s)
- L Sarga
- Research Institute of Sport Science, Faculty of Physical Education and Sport Science, Semmelweis University, Budapest H-1123, Hungary; Department of Microbiology and Immunology, Sealy Center for Molecular Medicine, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
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Burghardt PR, Flagel SB, Burghardt KJ, Britton SL, Gerard-Koch L, Watson SJ, Akil H. Risk-assessment and coping strategies segregate with divergent intrinsic aerobic capacity in rats. Neuropsychopharmacology 2011; 36:390-401. [PMID: 20927049 PMCID: PMC3005980 DOI: 10.1038/npp.2010.144] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metabolic function is integrally related to an individual's susceptibility to, and progression of, disease. Selective breeding for intrinsic treadmill running in rats has produced distinct lines of high- or low-capacity runners (HCR and LCR, respectively) that exhibit numerous physiological differences. To date, the role of intrinsic aerobic capacity on behavior and stress response in these rats has not been addressed and was the focus of these studies. HCR and LCR rats did not differ in their locomotor response to novelty or behavior in the light/dark box. In contrast, immobility in the forced swim test was higher in LCR rats compared with HCR rats, regardless of desipramine treatment. Although both HCR and LCR rats responded to cat odor with decreased exploration and increased risk assessment, HCR rats showed greater contextual conditioning to cat odor. HCR rats exhibited higher expression of corticotropin-releasing hormone in the central nucleus of the amygdala, as well as heavier adrenal and thymus weight. Corticosterone was comparable among HCR and LCR rats at light/dark transitions, and in response to unavoidable cat odor. HCR rats, however, exhibited a greater corticosterone response following the light/dark box. These experiments show that the LCR phenotype associates with decreased risk assessment in response to salient danger signals and passive coping. In contrast, HCR rats show a more naturalistic strategy in that they employ active coping and a more vigilant and cautious response to environmental novelty and salient danger signals. Within this context, we propose that intrinsic aerobic capacity is a central feature mechanistically linking complex metabolic disease and behavior.
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Affiliation(s)
- Paul R Burghardt
- Molecular and Behavioral Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109, USA.
| | - Shelly B Flagel
- Molecular and Behavioral Neuroscience Institute, The University of Michigan, Ann Arbor, MI, USA
| | - Kyle J Burghardt
- College of Pharmacy, The University of Michigan, Ann Arbor, MI, USA
| | - Steven L Britton
- Department of Anesthesiology, The University of Michigan, Ann Arbor, MI, USA
| | - Lauren Gerard-Koch
- Department of Anesthesiology, The University of Michigan, Ann Arbor, MI, USA
| | - Stanley J Watson
- Molecular and Behavioral Neuroscience Institute, The University of Michigan, Ann Arbor, MI, USA
| | - Huda Akil
- Molecular and Behavioral Neuroscience Institute, The University of Michigan, Ann Arbor, MI, USA
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Tweedie C, Romestaing C, Burelle Y, Safdar A, Tarnopolsky MA, Seadon S, Britton SL, Koch LG, Hepple RT. Lower oxidative DNA damage despite greater ROS production in muscles from rats selectively bred for high running capacity. Am J Physiol Regul Integr Comp Physiol 2010; 300:R544-53. [PMID: 21148474 DOI: 10.1152/ajpregu.00250.2010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Artificial selection in rat has yielded high-capacity runners (HCR) and low-capacity runners (LCR) that differ in intrinsic (untrained) aerobic exercise ability and metabolic disease risk. To gain insight into how oxygen metabolism may have been affected by selection, we compared mitochondrial function, oxidative DNA damage (8-dihydroxy-guanosine; 8dOHG), and antioxidant enzyme activities in soleus muscle (Sol) and gastrocnemius muscle (Gas) of adult and aged LCR vs. HCR rats. In Sol of adult HCR rats, maximal ADP-stimulated respiration was 37% greater, whereas in Gas of adult HCR rats, there was a 23% greater complex IV-driven respiratory capacity and 54% greater leak as a fraction of electron transport capacity (suggesting looser mitochondrial coupling) vs. LCR rats. H(2)O(2) emission per gram of muscle was 24-26% greater for both muscles in adult HCR rats vs. LCR, although H(2)O(2) emission in Gas was 17% lower in HCR, after normalizing for citrate synthase activity (marker of mitochondrial content). Despite greater H(2)O(2) emission, 8dOHG levels were 62-78% lower in HCR rats due to 62-96% higher superoxide dismutase activity in both muscles and 47% higher catalase activity in Sol muscle in adult HCR rats, with no evidence for higher 8 oxoguanine glycosylase (OGG1; DNA repair enzyme) protein expression. We conclude that genetic segregation for high running capacity has generated a molecular network of cellular adaptations, facilitating a superior response to oxidative stress.
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Affiliation(s)
- Constance Tweedie
- Muscle and Aging Laboratory, Faculty of Kinesiology, University of Calgary, Calgary Alberta, Canada
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Gruber HJ, Mayer C, Mangge H, Fauler G, Grandits N, Wilders-Truschnig M. Obesity reduces the bioavailability of nitric oxide in juveniles. Int J Obes (Lond) 2008; 32:826-31. [PMID: 18197180 DOI: 10.1038/sj.ijo.0803795] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE There is growing evidence that nitric oxide (NO) is critically involved in obesity and its clinical consequences like cardiovascular disease, hypertension and diabetes. We hypothesize that NO is already involved in the pathophysiology of juvenile obesity. We here determined the role of NO, its metabolites arginine and citrulline in obese and normal weight children. DESIGN We investigated 57 obese and 57 normal weight age- and gender-matched juveniles. Various clinical parameters as well as body measurements and intima media thickness were determined. RESULTS Obese juveniles revealed highly significant alterations in the NO pathway. NOX and citrulline were decreased in obese compared to normal weight juveniles and negatively correlated with body weight. Arginine was increased in obese juveniles and positively correlated with body weight. We found a significant negative correlation between NOX and oxidized low-density lipoprotein. Analysis of gamma-aminobutyric acid (GABA) revealed correlations with the NO pathway as NOX and citrulline were negatively correlated with GABA and arginine showed a positive correlation. CONCLUSION We show here that NO and its metabolites arginine and citrulline are already involved in juvenile obesity that may contribute to atherogenesis via reduced bioavailability of NO. Moreover, we identify GABA as a new parameter in the mechanism of obesity-related NO reduction.
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Affiliation(s)
- H-J Gruber
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria.
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Dehkordi O, Millis RM, Dennis GC, Jazini E, Williams C, Hussain D, Jayam-Trouth A. Expression of alpha-7 and alpha-4 nicotinic acetylcholine receptors by GABAergic neurons of rostral ventral medulla and caudal pons. Brain Res 2007; 1185:95-102. [DOI: 10.1016/j.brainres.2007.09.027] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 09/05/2007] [Accepted: 09/06/2007] [Indexed: 11/17/2022]
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Kvochina L, Hasser EM, Heesch CM. Pregnancy increases baroreflex-independent GABAergic inhibition of the RVLM in rats. Am J Physiol Regul Integr Comp Physiol 2007; 293:R2295-305. [PMID: 17898121 PMCID: PMC2841061 DOI: 10.1152/ajpregu.00365.2007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
During baroreceptor unloading, sympathoexcitation is attenuated in near-term pregnant compared with nonpregnant rats. Alterations in balance among different excitatory and inhibitory inputs within central autonomic pathways likely contribute to changes in regulation of sympathetic outflow in pregnancy. Both baroreflex-dependent and baroreflex-independent GABAergic inputs inhibit sympathoexcitatory neurons within rostral ventrolateral medulla (RVLM). The present experiments tested the hypothesis that influence of baroreflex-independent GABAergic inhibition of RVLM is greater in pregnant compared with nonpregnant rats. Afferent baroreceptor inputs were eliminated by bilateral sinoaortic denervation in inactin-anesthetized rats. In pregnant compared with nonpregnant rats, baseline mean arterial pressure (MAP) was lower (pregnant = 75 +/- 6 mmHg, nonpregnant = 115 +/- 7 mmHg) and heart rate was higher (pregnant = 381 +/- 10 beats/min, nonpregnant = 308 +/- 10 beats/min). Pressor and sympathoexcitatory [renal sympathetic nerve activity, (RSNA)] responses due to bilateral GABA(A) receptor blockade (bicuculline, 4 mM, 100 nl) of the RVLM were greater in pregnant rats (delta MAP: pregnant = 101 +/- 4 mmHg, nonpregnant = 80 +/- 6 mmHg; delta RSNA: pregnant = 182 +/- 23% control, nonpregnant = 133 +/- 10% control). Unexpected transient sympathoexcitatory effects of angiotensin AT(1) receptor blockade in the RVLM were greater in pregnant rats. Although excitatory responses to bicuculline were attenuated by prior RVLM AT1 receptor blockade in both groups, pressor responses to disinhibition of the RVLM remained augmented in pregnant rats. Increased influence of baroreflex-independent GABAergic inhibition in RVLM could contribute to suppressed sympathoexcitation during withdrawal of arterial baroreceptor input in pregnant animals.
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Affiliation(s)
- Lyudmyla Kvochina
- Department of Biomedical Sciences, Univ. of Missouri, 134 Research Park, Columbia, MO 65211, USA
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