Physiology and pathophysiology of the vasopressin-regulated renal water reabsorption

Stroke and Distal Organ Damage: Exploring Brain-Kidney Crosstalk

Stroke and kidney dysfunction represent significant public health challenges, yet the precise mechanisms connecting these conditions and their severe consequences remain unclear. Individuals experiencing chronic kidney disease (CKD) and acute kidney injury (AKI) are at heightened susceptibility to experiencing repeated strokes. Similarly, a reduced glomerular filtration rate is associated with an elevated risk of suffering a stroke. Prior strokes independently contribute to mortality, end-stage kidney disease, and cardiovascular complications, underscoring the pathological connection between the brain and the kidneys. In cases of AKI, various mechanisms, such as cytokine signaling, leukocyte infiltration, and oxidative stress, establish communication between the brain and the kidneys. The bidirectional relationship between stroke and kidney pathologies involves key factors such as uremic toxins, proteinuria, inflammatory responses, decreased glomerular filtration, impairment of the blood-brain barrier (BBB), oxidative stress, and metabolites produced by the gut microbiota. This review examines potential mechanisms of brain-kidney crosstalk underlying stroke and kidney diseases. It holds significance for comprehending multi-organ dysfunction associated with stroke and for formulating therapeutic strategies to address stroke-induced kidney dysfunction and the bidirectional pathological connection between the kidney and stroke.

A cAMP-biosensor-based assay for measuring plasma arginine-vasopressin levels

Arginine-vasopressin (AVP), a cyclic peptide hormone composed of nine amino acids, regulates water reabsorption by increasing intracellular cyclic adenosine monophosphate (cAMP) concentrations via the vasopressin V2 receptor (V2R). Plasma AVP is a valuable biomarker for the diagnosis of central diabetes insipidus (CDI) and is commonly measured using radioimmunoassay (RIA). However, RIA has several drawbacks, including a long hands-on time, complex procedures, and handling of radioisotopes with special equipment and facilities. In this study, we developed a bioassay to measure plasma AVP levels using HEK293 cells expressing an engineered V2R and a cAMP biosensor. To achieve high sensitivity, we screened V2R orthologs from 11 various mammalian species and found that the platypus V2R (pV2R) responded to AVP with approximately six-fold higher sensitivity than that observed by the human V2R. Furthermore, to reduce cross-reactivity with desmopressin (DDAVP), a V2R agonist used for CDI treatment, we introduced a previously described point mutation into pV2R, yielding an approximately 20-fold reduction of responsiveness to DDAVP while maintaining responsiveness to AVP. Finally, a comparison of plasma samples from 12 healthy individuals demonstrated a strong correlation (Pearson's correlation value: 0.90) between our bioassay and RIA. Overall, our assay offers a more rapid and convenient method for quantifying plasma AVP concentrations than existing techniques.

Targeting brain-peripheral immune responses for secondary brain injury after ischemic and hemorrhagic stroke

The notion that the central nervous system is an immunologically immune-exempt organ has changed over the past two decades, with increasing evidence of strong links and interactions between the central nervous system and the peripheral immune system, both in the healthy state and after ischemic and hemorrhagic stroke. Although primary injury after stroke is certainly important, the limited therapeutic efficacy, poor neurological prognosis and high mortality have led researchers to realize that secondary injury and damage may also play important roles in influencing long-term neurological prognosis and mortality and that the neuroinflammatory process in secondary injury is one of the most important influences on disease progression. Here, we summarize the interactions of the central nervous system with the peripheral immune system after ischemic and hemorrhagic stroke, in particular, how the central nervous system activates and recruits peripheral immune components, and we review recent advances in corresponding therapeutic approaches and clinical studies, emphasizing the importance of the role of the peripheral immune system in ischemic and hemorrhagic stroke.

Tonic NMDAR Currents of NR2A-Containing NMDARs Represent Altered Ambient Glutamate Concentration in the Supraoptic Nucleus

NMDA receptors (NMDARs) modulate glutamatergic excitatory tone in the brain via two complementary modalities: a phasic excitatory postsynaptic current and a tonic extrasynaptic modality. Here, we demonstrated that the tonic NMDAR-current (I NMDA) mediated by NR2A-containing NMDARs is an efficient biosensor detecting the altered ambient glutamate level in the supraoptic nucleus (SON). I NMDA of magnocellular neurosecretory cells (MNCs) measured by nonselective NMDARs antagonist, AP5, at holding potential (V holding) -70 mV in low concentration of ECF Mg2+ ([Mg2+]o) was transiently but significantly increased 1-week post induction of a DOCA salt hypertensive model rat which was compatible with that induced by a NR2A-selective antagonist, PEAQX (I PEAQX) in both DOCA-H2O and DOCA-salt groups. In agreement, NR2B antagonist, ifenprodil, or NR2C/D antagonist, PPDA, did not affect the holding current (I holding) at V holding -70 mV. Increased ambient glutamate by exogenous glutamate (10 mM) or excitatory amino acid transporters (EAATs) antagonist (TBOA, 50 mM) abolished the I PEAQX difference between two groups, suggesting that attenuated EAATs activity increased ambient glutamate concentration, leading to the larger I PEAQX in DOCA-salt rats. In contrast, only ifenprodil but not PEAQX and PPDA uncovered I NMDA at V holding +40 mV under 1.2 mM [Mg2+]o condition. I ifenprodil was not different in DOCA-H2O and DOCA-salt groups. Finally, NR2A, NR2B, and NR2D protein expression were not different in the SON of the two groups. Taken together, NR2A-containing NMDARs efficiently detected the increased ambient glutamate concentration in the SON of DOCA-salt hypertensive rats due to attenuated EAATs activity.

The Relationship Between Manifestation of Diabetes Insipidus and Estimated Glomerular Filtration Rate in Brain Death

OBJECTIVES

Systematic reviews have revealed that up to 50% of patients with brain death have residual hypothalamic/pituitary activity based on the absence of central diabetes insipidus (DI). We hypothesized that different degrees of renal dysfunction may impact the presence of DI in patients with brain death.

DESIGN

Single-center prospective data collection.

SETTING

ICUs in a tertiary academic hospital.

PATIENTS

All adult patients declared brain dead over 12 years.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

DI was diagnosed by polyuria, low urine specific gravity, and increasing serum sodium, measured in close proximity. Renal function was assessed by the estimated glomerular filtration rate (eGFR), calculated using the simplified modification of diet in renal disease equation. Analysis was completed in 192 of 234 patients with brain death after excluding those with missing data, those younger than 18 years and those on vasopressin infusions. One hundred twenty-two patients (63.5%) developed DI and 70 patients (36.5%) did not. The proportion of DI decreased significantly with decreasing eGFR: for eGFR greater than 60 mL/min, DI was present in 77.2%; for eGFR 15-60 mL/min, DI was present in 54.5%; for eGFR 14.9-9.8 mL/min, DI was present in 32%; none of the 14 patients with eGFR less than or equal to 9.7 mL/min ever experienced DI ( p < 0.001). Using logistic regression, for every 10 mL/min decrease in eGFR, the odds of DI decreased 0.83 times (95% CI, 0.76-0.90, p < 0.001).

CONCLUSIONS

Renal dysfunction significantly impacts DI's clinical manifestation in brain death. We report that patients who experience brain death with severe renal dysfunction may not develop clinical signs of DI.

The Impact of Inotropes and Vasopressors on Cerebral Oxygenation in Patients with Traumatic Brain Injury and Subarachnoid Hemorrhage: A Narrative Review

Traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) are critical neurological conditions that necessitate specialized care in the Intensive Care Unit (ICU). Managing cerebral perfusion pressure (CPP) and mean arterial pressure (MAP) is of primary importance in these patients. To maintain targeted MAP and CPP, vasopressors and/or inotropes are commonly used. However, their effects on cerebral oxygenation are not fully understood. The aim of this review is to provide an up-to date review regarding the current uses and pathophysiological issues related to the use of vasopressors and inotropes in TBI and SAH patients. According to our findings, despite achieving similar hemodynamic parameters and CPP, the effects of various vasopressors and inotropes on cerebral oxygenation, local CBF and metabolism are heterogeneous. Therefore, a more accurate understanding of the cerebral activity of these medications is crucial for optimizing patient management in the ICU setting.

Effect of a moderate alcohol dose on physiological responses during rest and prolonged cycling

AIM

We examined the acute effects of a moderate alcohol dose (48 g) ingested before prolonged cycling on acute physiological responses in eight healthy males (mean ± SD; 23 ± 2 years; 1.77 ± 0.04 m; 75.8 ± 4.1 kg).

METHODS

In a randomized order, euhydrated participants completed two experimental sessions with the sequence of 150-min seated at rest, 90-min of cycling at 50% of the maximal rate of oxygen consumption ($\dot{\textrm V}\textrm O$2max), 120-min seated at rest. Participants drank 250 mL of flavored squash with or without alcohol (vodka; ~16 g) at 10, 40, and 70 min of the initial resting phase, giving a cumulative fluid intake of 750 mL with 48 g of alcohol. Heart rate, blood glucose, breath alcohol concentration, and respiratory gasses were recorded throughout the entire trial with cumulative urine volume recorded during both rest phases.

RESULTS

Total carbohydrate (control = 115 ± 19 g: alcohol = 119 ± 21 g; P = 0.303) and lipid (control = 17 ± 4 g: alcohol = 20 ± 7 g; P = 0.169) oxidation was similar between conditions. Average heart rate was 7% higher in the alcohol condition (control = 111 ± 12 bpm; alcohol = 119 ± 11 bpm; P = 0.003). Blood glucose concentrations were similar between conditions during (P = 0.782) and after exercise (P = 0.247). Urine output was initially increased between conditions following alcohol ingestion before diminishing (P < 0.001) with no difference in total cumulative urine output (P = 0.331).

CONCLUSION

Consuming an alcoholic drink containing 48 g of alcohol in the hour before moderate intensity sub-maximal aerobic exercise led to detectable increases in heart rate and rate of urine production with no effect on substrate use.

Molecular Footprints on Osmoregulation-Related Genes Associated with Freshwater Colonization by Cetaceans and Sirenians

The genetic basis underlying adaptive physiological mechanisms has been extensively explored in mammals after colonizing the seas. However, independent lineages of aquatic mammals exhibit complex patterns of secondary colonization in freshwater environments. This change in habitat represents new osmotic challenges, and additional changes in key systems, such as the osmoregulatory system, are expected. Here, we studied the selective regime on coding and regulatory regions of 20 genes related to the osmoregulation system in strict aquatic mammals from independent evolutionary lineages, cetaceans, and sirenians, with representatives in marine and freshwater aquatic environments. We identified positive selection signals in genes encoding the protein vasopressin (AVP) in mammalian lineages with secondary colonization in the fluvial environment and in aquaporins for lineages inhabiting the marine and fluvial environments. A greater number of sites with positive selection signals were found for the dolphin species compared to the Amazonian manatee. Only the AQP5 and AVP genes showed selection signals in more than one independent lineage of these mammals. Furthermore, the vasopressin gene tree indicates greater similarity in river dolphin sequences despite the independence of their lineages based on the species tree. Patterns of distribution and enrichment of Transcription Factors in the promoter regions of target genes were analyzed and appear to be phylogenetically conserved among sister species. We found accelerated evolution signs in genes ACE, AQP1, AQP5, AQP7, AVP, NPP4, and NPR1 for the fluvial mammals. Together, these results allow a greater understanding of the molecular bases of the evolution of genes responsible for osmotic control in aquatic mammals.

Terlipressin for the Prevention and Treatment of Renal Decline in Hepatorenal Syndrome: A Drug Profile

Hepatorenal syndrome stands as one of several potential triggers of acute kidney injury in individuals grappling with either acute or persistent liver ailments. The nature of the decline in kidney function has led to the identification of two variants of hepatorenal syndrome. In cases where terlipressin therapy is accessible, the initial approach involves administering terlipressin alongside albumin. Terlipressin, a synthetic analog of vasopressin, boasts double the preference for vasopressin V1 receptors compared to V2 receptors. The FDA granted approval to terlipressin in September 2022, demonstrating its intrinsic activity, although a significant portion of its function arises from its transformation into lysine vasopressin. This article provides a comprehensive examination of terlipressin's various pharmacodynamic and pharmacokinetic facets, as well as its clinical utility, aiming to keep the scientific community well informed about its safe and efficient utilization.

Microalgae-Based Disinfectant Formulation for Aseptic Processing of Ethiopian Ingredient-Sourced Functional Bread and Its Molecular Docking Analysis to Reduce Hypernatremia

The global prevalence of food-borne infections has become a major concern. Food-borne pathogens like Campylobacter jejuni, Salmonella enterica, and Clostridium botulinum cause food poisoning and even mortality, necessitating the maintenance of aseptic conditions during food processing. The sterilization of food processing facilities often requires chemical and heat treatment. The formulation of many chemical-based disinfectants includes chemicals generating toxic and carcinogenic by-products. The microalgae like Chlorella spp. reportedly exhibit antimicrobial activity and therefore, can be used for formulating safer and eco-friendly natural sanitizers. This study aims to aseptically prepare functional bread using Ethiopian ingredients, highlighting the application of microalgae-based disinfectant formulation and various disinfection techniques. The functional bread was designed to be potentially effective in reducing hypernatremia condition which is indicative of high levels of sodium in serum that can cause an array of symptoms including deaths in serious cases. The physico-chemical and sensory properties of the designed functional bread were analyzed. The interaction of phytochemicals in the ingredients with the target receptor (Vasopressin V2 receptor) and their drug-likeness were determined using molecular docking and Lipinski's rule of five analyses. The results suggest that the designed functional bread incorporating Ethiopian ingredients may serve as an effective dietary strategy to prevent hypernatremia. Aseptic processing of the bread ensures longer shelf life and prevention of spoilage by food pathogens.

Mechanisms of hyponatremia and diabetes insipidus after acute spinal cord injury: a critical review

The incidence of hyponatremia after spinal cord injury was reported to be between 25 and 80%. Hyponatremia can lead to a variety of clinical symptoms, from mild to severe and even life-threatening. Hyponatremia is often associated with diabetes insipidus, which refers to insufficient arginine vasopressin (AVP) secretion or defective renal response to AVP, with clinical manifestations of syndromes such as hypoosmolality, polydipsia, and polydipsia. Recent mechanistic studies on hyponatremia and diabetes insipidus after acute spinal cord injury have been performed in isolation, without integrating the above two symptoms into different pathological manifestations that occur in the same injury state and without considering the acute spinal cord injury patient's condition as a whole. The therapeutic principles of CSWS and SIADH are in opposition to one another. It is not easy to identify the mechanism of hyponatremia in clinical practice, which makes selecting the treatment difficult. According to the existing theories, treatments for hyponatremia and diabetes insipidus together are contraindicated, whether the mechanism of hyponatremia is thought to be CSWS or SIADH. In this paper, we review the mechanism of these two pathological manifestations and suggest that our current understanding of the mechanisms of hyponatremia and diabetes insipidus after high acute cervical SCI is insufficient, and it is likely that there are other undetected pathogenetic mechanisms.

Quantitative image mean squared displacement (iMSD) analysis of the dynamics of Aquaporin 2 within the membrane of live cells

Nanodomains are a biological membrane phenomenon which have a large impact on various cellular processes. They are often analysed by looking at the lateral dynamics of membrane lipids or proteins. The localization of the plasma membrane protein aquaporin-2 in nanodomains has so far been unknown. In this study, we use total internal reflection fluorescence microscopy to image Madin-Darby Canine Kidney (MDCK) cells expressing aquaporin-2 tagged with mEos 3.2. Then, image mean squared displacement (iMSD) approach was used to analyse the diffusion of aquaporin-2, revealing that aquaporin-2 is confined within membrane nanodomains. Using iMSD analysis, we found that the addition of the drug forskolin increases the diffusion of aquaporin-2 within the confined domains, which is in line with previous studies. Finally, we observed an increase in the size of the membrane domains and the extent of trapping of aquaporin-2 after stimulation with forskolin.

[Hyponatremia : Etiology, diagnosis and acute therapy]

Hyponatremia is one of the most common electrolyte disorders in emergency departments and hospitalized patients. Serum sodium concentration is controlled by osmoregulation and volume regulation. Both pathways are regulated via the release of antidiuretic hormone (ADH). Syndrome of inappropriate release of ADH (SIADH) may be caused by neoplasms or pneumonia but may also be triggered by drug use or drug abuse. Excessive fluid intake may also result in a decrease in serum sodium concentration. Rapid alteration in serum sodium concentration leads to cell swelling or cell shrinkage, which primarily causes neurological symptoms. The dynamics of development of hyponatremia and its duration are crucial. In addition to blood testing, a clinical examination and urine analysis are essential in the differential diagnosis of hyponatremia.

Copeptin: Up-to-date diagnostic and prognostic role highlight

Arginine Vasopressin (AVP) is one of the key hormones in the human body. AVP is clinically important because it maintains body fluid balance and vascular tone. Unfortunately, AVP laboratory measurements are always difficult and with low accuracy. Copeptin, the C-terminal of the AVP precursor, is released in equal amounts with AVP, making it a sensitive marker of AVP release. Despite being a non-specific biomarker, copeptin earned a lot of attention as a novel biomarker due to easy and quick laboratory measurements. Recent studies have reported the critical role of copeptin as a clinical indicator, especially in the diagnosis and prognosis of many diseases. Besides, it was reported that the combination between copeptin and gold standard biomarkers improved the prognostic values of those biomarkers. In this review, the role of copeptin as a new predictive diagnostic and prognostic biomarker of various diseases is highlighted according to the most recent studies. In addition, the importance of using copeptin as a marker in different medical departments and the impact of this on improving healthcare service was discussed.

Global dispersal and adaptive evolution of domestic cattle: a genomic perspective

Domestic cattle have spread across the globe and inhabit variable and unpredictable environments. They have been exposed to a plethora of selective pressures and have adapted to a variety of local ecological and management conditions, including UV exposure, diseases, and stall-feeding systems. These selective pressures have resulted in unique and important phenotypic and genetic differences among modern cattle breeds/populations. Ongoing efforts to sequence the genomes of local and commercial cattle breeds/populations, along with the growing availability of ancient bovid DNA data, have significantly advanced our understanding of the genomic architecture, recent evolution of complex traits, common diseases, and local adaptation in cattle. Here, we review the origin and spread of domestic cattle and illustrate the environmental adaptations of local cattle breeds/populations.

A Case Series of Uncommon Sodium Disorders in Common Clinical Scenarios

Dysnatremias or sodium disorders (either hyponatremia or hypernatremia) are the most common electrolyte problems in clinical medicine. They pose diagnostic and therapeutic challenges and have high mortality. Even mild changes in sodium levels from normal are associated with worse outcomes and considerable morbidity and mortality. We present a series of four patients with either hypo- or hypernatremia in different clinical scenarios requiring immediate treatment with close monitoring to avoid overcorrection. This case series shows that uncommon or unusual sodium disorders can happen in an otherwise usual situation.

Protective Role and Functional Engineering of Neuropeptides in Depression and Anxiety: An Overview

Behavioral disorders, such as anxiety and depression, are prevalent globally and touch children and adults on a regular basis. Therefore, it is critical to comprehend how these disorders are affected. It has been demonstrated that neuropeptides can influence behavior, emotional reactions, and behavioral disorders. This review highlights the majority of the findings demonstrating neuropeptides' behavioral role and functional engineering in depression and anxiety. Gut-brain peptides, hypothalamic releasing hormone peptides, opioid peptides, and pituitary hormone peptides are the four major groups of neuropeptides discussed. Some neuropeptides appear to promote depression and anxiety-like symptoms, whereas others seem to reduce it, all depending on the receptors they are acting on and on the brain region they are localized in. The data supplied here are an excellent starting point for future therapy interventions aimed at treating anxiety and depression.

Controls of Central and Peripheral Blood Pressure and Hemorrhagic/Hypovolemic Shock

The pressure exerted on the heart and blood vessels because of blood flow is considered an essential parameter for cardiovascular function. It determines sufficient blood perfusion, and transportation of nutrition, oxygen, and other essential factors to every organ. Pressure in the primary arteries near the heart and the brain is known as central blood pressure (CBP), while that in the peripheral arteries is known as peripheral blood pressure (PBP). Usually, CBP and PBP are correlated; however, various types of shocks and cardiovascular disorders interfere with their regulation and differently affect the blood flow in vital and accessory organs. Therefore, understanding blood pressure in normal and disease conditions is essential for managing shock-related cardiovascular implications and improving treatment outcomes. In this review, we have described the control systems (neural, hormonal, osmotic, and cellular) of blood pressure and their regulation in hemorrhagic/hypovolemic shock using centhaquine (Lyfaquin^®) as a resuscitative agent.

Review novel insights into the diagnostic and prognostic function of copeptin in daily clinical practice

As is shown in previous reports, arginine vasopressin (AVP), as one of the most important hormones within circulation in human beings, is of great clinically significance given that it could maintain the body fluid balance and vascular tone. However, the laboratory measurements AVP in daily clinical practice are shown to be difficult and with low accuracy. Concerning on this notion, it is unpractical to use the serum levels of AVP in diagnosing multiple diseases. On the other hand, another key serum biomarker, copeptin, is confirmed as the C-terminal of the AVP precursor which could be released in equal amounts with AVP, resultantly making it as a sensitive marker of arginine vasopressin release. Notably, emerging recent evidence has demonstrated the critical function of copeptin as a clinical indicator, especially in the diagnosis and prognosis of several diseases in diverse organs, such as cardiovascular disease, kidney disease, and pulmonary disease. In addition, copeptin was recently verified to play an important role in diagnosing multiple acute diseases when combined it with other gold standard serum biomarkers, indicating that copeptin could be recognized as a vital disease marker. Herein, in the current review, the functions of copeptin as a new predictive diagnostic and prognostic biomarker of various diseases, according to the most recent studies, are well summarized. Furthermore, the importance of using copeptin as a serum biomarker in diverse medical departments and the impact of this on improving healthcare service is also summarized in the current review.

Genome-Engineered mpkCCDc14 Cells as a New Resource for Studying AQP2

mpkCCDc14 cells, a polarized epithelial cell line derived from mouse kidney cortical collecting ducts, are known to express the vasopressin V2 receptor (V2R) and aquaporin-2 (AQP2) that are responsive to vasopressin. However, a low abundance of the endogenous AQP2 protein in the absence of vasopressin and heterogeneity of AQP2 protein abundance among the cultured cells may limit the further application of the cell line in AQP2 studies. To overcome the limitation, we aimed to establish mpkCCDc14 cells constitutively expressing V2R and AQP2 via CRISPR/Cas9-mediated genome engineering technology (i.e., V2R-AQP2 cells). 3'- and 5'-Junction PCR revealed that the V2R-AQP2 expression cassette with a long insert size (~2.2 kb) was correctly integrated. Immunoblotting revealed the expression of products of integrated Aqp2 genes. Cell proliferation rate and dDAVP-induced cAMP production were not affected by the knock-in of Avpr2 and Aqp2 genes. The AQP2 protein abundance was significantly higher in V2R-AQP2 cells compared with control mpkCCDc14 cells in the absence of dDAVP and the integrated AQP2 was detected. Immunocytochemistry demonstrated that V2R-AQP2 cells exhibited more homogenous and prominent AQP2 labeling intensity in the absence of dDAVP stimulation. Moreover, prominent AQP2 immunolabeling (both AQP2 and pS256-AQP2) in the apical domain of the genome-edited cells was observed in response to dDAVP stimulation, similar to that in the unedited control mpkCCDc14 cells. Taken together, mpkCCDc14 cells constitutively expressing V2R and AQP2 via genome engineering could be exploited for AQP2 studies.

Vasopressin acts as a synapse organizer in limbic regions by boosting PSD95 and GluA1 expression

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.

Vasopressin Receptor Type-2 Mediated Signaling in Renal Cell Carcinoma Stimulates Stromal Fibroblast Activation

Vasopressin type-2 receptor (V2R) is ectopically expressed and plays a pathogenic role in clear cell renal cell carcinoma (ccRCC) tumor cells. Here we examined how V2R signaling within human ccRCC tumor cells (Caki1 cells) stimulates stromal cancer-associated fibroblasts (CAFs). We found that cell culture conditioned media from Caki1 cells increased activation, migration, and proliferation of fibroblasts in vitro, which was inhibited by V2R gene silencing in Caki1 cells. Analysis of the conditioned media and mRNA of the V2R gene silenced and control Caki1 cells showed that V2R regulates the production of CAF-activating factors. Some of these factors were also found to be regulated by YAP in these Caki1 cells. YAP expression colocalized and correlated with V2R expression in ccRCC tumor tissue. V2R gene silencing or V2R antagonist significantly reduced YAP in Caki1 cells. Moreover, the V2R antagonist reduced YAP expression and myofibroblasts in mouse xenograft tumors. These results suggest that V2R plays an important role in secreting pro-fibrotic factors that stimulate fibroblast activation by a YAP-dependent mechanism in ccRCC tumors. Our results demonstrate a novel role for the V2R-YAP axis in the regulation of myofibroblasts in ccRCC and a potential therapeutic target.

dDAVP Downregulates the AQP3-Mediated Glycerol Transport via V1aR in Human Colon HCT8 Cells

Vasopressin (AVP) plays a key function in controlling body water and salt balance through the activation of the vasopressin receptors V1aR and V2R. Abnormal secretion of AVP can cause the syndrome of inappropriate antidiuresis that leads to hyponatremia, which is an electrolyte disorder often observed in the elderly hospitalized and oncologic patients. Beyond kidneys, the colonic epithelium modulates water and salt homeostasis. The water channel AQP3, expressed in villus epithelial cells is implicated in water absorption across human colonic surface cells. Here, the action of dDAVP, a stable vasopressin analog, was evaluated on the AQP3 expression and function using human colon HCT8 cells as an experimental model. Confocal and Western Blotting analysis revealed that HCT8 cells express both V1aR and V2R. Long-term (72 h) treatment with dDAVP reduced glycerol uptake and cell viability. These effects were prevented by SR49059, a synthetic antagonist of V1aR, but not by tolvaptan, a specific V2R antagonist. Of note, the SR49059 action was impaired by DFP00173, a selective inhibitor of AQP3. Interestingly, compared to the normal colonic mucosa, in the colon of patients with adenocarcinoma, the expression of V1aR was significantly decreased. These findings were confirmed by gene expression analysis with RNA-Seq data. Overall, data suggest that dDAVP, through the V1aR dependent pathway, reduces AQP3 mediated glycerol uptake, a process that is reversed in adenocarcinoma, suggesting that the AVP-dependent AQP3 pathway may represent a novel target in colon diseases associated with abnormal cell growth.

Oxytocin-Cholinergic Central Interaction: Implications for Non-Social Memory Formation

Oxytocin (OT) and vasopressin (AVP) are two closely related neuropeptides implicated in learning and memory processes, anxiety, nociception, addiction, feeding behavior and social information processing. Regarding learning and memory, OT has induced long-lasting impairment in different behaviors, while the opposite was observed with AVP. We have previously evaluated the effect of peripheral administration of OT or its antagonist (AOT) on the inhibitory avoidance response of mice and on the modulation of cholinergic mechanisms. Here, we replicate and validate those results, but this time through central administration of neuropeptides, considering their poor passage through the blood-brain barrier (BBB). When we delivered OT (0.10 ng/mouse) and its antagonist (0.10 ng/mouse) through intracerebroventricular (ICV) injections, the neuropeptide impaired and AOT enhanced the behavioral performance on an inhibitory avoidance response evaluated 48 h after training in a dose-dependent manner. On top of that, we investigated a possible central interaction between OT and the cholinergic system. Administration of anticholinesterases inhibitors with access to the central nervous system (CNS), the activation of muscarinic acetylcholine (Ach) receptors and the increase of evoked ACh release using linopirdine (Lino) (3-10 µg/kg, IP), reversed the impairment of retention performance induced by OT. Besides, either muscarinic or nicotinic antagonists with unrestricted access to the CNS reduced the magnitude of the performance-facilitating effect of AOT's central infusion. We suggest that OT might induce a cholinergic hypofunction state, resulting in an impairment of IA memory formation, a process for which the cholinergic system is crucially necessary.

Expression Regulation of Water Reabsorption Genes and Transcription Factors in the Kidneys of Lepus yarkandensis

Lepus yarkandensis is a desert-dwelling animal that has various adaptations to cope with drought. The kidney maintains water and acid-base balance mainly through the vasopressin-regulated water reabsorption pathway and proximal tubular bicarbonate reabsorption pathway. In this study, we compared the differentially expressed genes (DEGs) and transcription factors in the kidneys of L. yarkandensis and Oryctolagus cuniculus to explore the relationship between the DEGs in kidneys and the animals’ adaptations. Transcriptome sequencing data were used to predict the differentially-expressed water reabsorption genes and their transcription factors. Quantitative real-time PCR, immunohistochemistry, and western blotting were used to detect and verify the expression of DEGs in the kidney at mRNA and protein levels. Transcriptome analysis of the kidney of L. yarkandensis and O. cuniculus showed that 6,610 genes were up-regulated and 5,727 genes down-regulated in data shared by both species. According to the data, 232 transcription factors and their corresponding target genes were predicted, from which genes and transcription factors related to renal water reabsorption were screened. Quantitative RT-PCR results showed AQP1, AQP2, ADCY3, HIF1A, CREB3, and NFATc1 had higher expression in the L. yarkandensis kidney; in comparison, FXYD2 mRNA expression levels were lower. In western blotting, transcription factors HIF1A, NFATc1, NF-κB1, and critical genes ADCY3, ATPA1, and SLC4A4, were highly expressed in the kidneys of L. yarkandensis. Immunohistochemical results showed that the ADCY3 protein was in the basolateral membrane of the collecting duct, the ATP1A1 protein was in the basolateral membrane and medulla of proximal tubules, and the SLC4A4 protein was in the basolateral membrane of proximal tubules. According to these results can be inferred that HIF1A, NFATc1, and NF-κB1 play a certain role in regulating the expression of genes related to water reabsorption in the kidney of L. yarkandensis, thus improving the water reclamation efficiency of L. yarkandensis, so as to adapt to the arid desert environment.

Copeptin Release in Arterial Hypotension and Its Association with Severity of Disease in Critically Ill Children

Low copeptin levels may indicate inadequate arginine-vasopressin release promoting arterial hypotension, whereas high copeptin concentrations may reflect disease severity. This single-center prospective non-randomized clinical trial analyzed the course of blood copeptin in critically ill normo- and hypotensive children and its association with disease severity. In 164 patients (median age 0.5 years (interquartile range 0.1, 2.9)), the mean copeptin concentration at baseline was 43.5 pmol/L. Though not significantly different after 61 h (primary outcome, mean individual change: −12%, p = 0.36, paired t-test), we detected 1.47-fold higher copeptin concentrations during arterial hypotension when compared to normotension (mixed-effect ANOVA, p = 0.01). In total, 8 out of 34 patients (23.5%) with low copeptin concentrations <10 pmol/L were hypotensive. Copeptin was highest in the adjusted mixed-effect regression analysis within the first day (+20% at 14 h) and decreased significantly at 108 h (−27%) compared to baseline (p = 0.002). Moreover, we found a significant association with vasopressor-inotrope treatment intensity, infancy (1−12 months) and cardiopulmonary bypass (all p ≤ 0.001). In conclusion, high copeptin values were associated with arterial hypotension and severity of disease in critically ill children. This study does not support the hypothesis that low copeptin values might be indicative of arginine-vasopressin deficiency.

Arcuate NPY is involved in salt‐induced hypertension via modulation of paraventricular vasopressin and brain‐derived neurotrophic factor

Chronic high salt intake is one of the leading causes of hypertension. Salt activates the release of the key neurotransmitters in the hypothalamus such as vasopressin to increase blood pressure, and neuropepetide Y (NPY) has been implicated in the modulation of vasopressin levels. NPY in the hypothalamic arcuate nucleus (Arc) is best known for its control in appetite and energy homeostasis, but it is unclear whether it is also involved in the development of salt‐induced hypertension. Here, we demonstrate that wild‐type mice given 2% NaCl salt water for 8 weeks developed hypertension which was associated with marked downregulation of NPY expression in the hypothalamic Arc as demonstrated in NPY‐GFP reporter mice as well as by in situ hybridization analysis. Furthermore, salt intake activates neurons in the hypothalamic paraventricular nucleus (PVN) where mRNA expression of brain‐derived neurotrophic factor (BDNF) and vasopressin was found to be upregulated, leading to elevated serum vasopressin levels. This finding suggests an inverse correlation between the Arc NPY level and expression of vasopressin and BDNF in the PVN. Specific restoration of NPY by injecting AAV‐Cre recombinase into the Arc only of the NPY‐targeted mutant mice carrying a loxP‐flanked STOP cassette reversed effects of salt intake on vasopressin and BDNF expression, leading to a normalization of salt‐dependent blood pressure. In summary, our study uncovers an important Arc NPY‐originated neuronal circuitry that could sense and respond to peripheral electrolyte signals and thereby regulate hypertension via vasopressin and BDNF in the PVN.

Diagnosis and management of hypernatraemia in children

Hypernatraemia is most commonly caused by excessive loss of solute-free water or decreased fluid intake; less often, the aetiology is salt intoxication. Especially infants, young children and individuals with a lack of access to water are at risk of developing hypernatraemia. Diagnosis is based on detailed history, physical examination and basic laboratory tests. Correction of hypernatraemia must be slow to prevent cerebral oedema and irreversible brain damage. This article reviews the aetiology, differential diagnosis and management of conditions associated with paediatric hypernatraemia. Distinguishing states with water deficiency from states with salt excess is important for proper management of hypernatraemic patients.

Anticipated pharmacological role of Aviptadil on COVID-19

Vasoactive intestinal peptide (VIP) is a neuropeptide that is produced by the lymphoid cells and plays a major role in immunological functions for controlling the homeostasis of the immune system. VIP has been identified as a potent anti-inflammatory factor, in boosting both innate and adaptive immunity. Since December 2019, SARS-Cov-2 was found responsible for the disease COVID-19 which has spread worldwide. No specific therapies or 100% effective vaccines are yet available for the treatment of COVID-19. Drug repositioning may offer a strategy and several drugs have been repurposed, including lopinavir/ritonavir, remdesivir, favipiravir, and tocilizumab. This paper describes the main pharmacological properties of synthetic VIP drug (Aviptadil) which is now under clinical trials. A patented formulation of vasoactive intestinal polypeptide (VIP), named RLF-100 (Aviptadil), was developed and finally got approved for human trials by FDA in 2001 and in European medicines agency in 2005. It was awarded Orphan Drug Designation in 2001 by the US FDA for the treatment of acute respiratory distress syndrome and for the treatment of pulmonary arterial hypertension in 2005. Investigational new drug (IND) licenses for human trials of Aviptadil was guaranteed by both the US FDA and EMEA. Preliminary clinical trials seem to support Aviptadil's benefit. However, such drugs like Aviptadil in COVID-19 patients have peculiar safety profiles. Thus, adequate clinical trials are necessary for these compounds.

Functional Rescue of a Nephrogenic Diabetes Insipidus Causing Mutation in the V2 Vasopressin Receptor by Specific Antagonist and Agonist Pharmacochaperones

The urine concentrating function of the kidney is essential to maintain the water homeostasis of the human body. It is mainly regulated by the arginine-vasopressin (AVP), which targets the type 2 vasopressin receptor (V2R) in the kidney. The inability of V2R to respond to AVP stimulation leads to decreased urine concentration and congenital nephrogenic diabetes insipidus (NDI). NDI is characterized by polyuria, polydipsia, and hyposthenuria. In this study, we identified a point mutation (S127F) in the AVPR2 gene of an NDI patient, and we characterized the impaired function of the V2R mutant in HEK293 cells. Based on our data, the S127F-V2R mutant is almost exclusively located intracellularly in the endoplasmic reticulum (ER), and very few receptors were detected at the cell surface, where the receptor can bind to AVP. The overexpressed S127F-V2R mutant receptor has negligible cAMP generation capability compared to the wild-type receptor in response to AVP stimulation. Since certain misfolded mutant proteins, that are retained in the ER, can be rescued by pharmacological chaperones, we examined the potential rescue effects of two pharmacochaperones on the S127F-V2R. We found that pretreatment with both tolvaptan (an established V2R inverse agonist) and MCF14 compound (a cell-permeable high-affinity agonist for the V2R) were capable of partially restoring the cAMP generating function of the receptor in response to vasopressin stimulation. According to our data, both cell permeant agonists and antagonists can function as pharmacochaperones, and serve as the starting compounds to develop medicines for patients carrying the S127F mutation.

Aquaporin-4 expression in the human choroid plexus

The choroid plexus (CP) consists of specialized ependymal cells and underlying blood vessels and stroma producing the bulk of the cerebrospinal fluid (CSF). CP epithelial cells are considered the site of the internal blood-cerebrospinal fluid barrier, show epithelial characteristics (basal lamina, tight junctions), and express aquaporin-1 (AQP1) apically. In this study, we analyzed the expression of aquaporins in the human CP using immunofluorescence and qPCR. As previously reported, AQP1 was expressed apically in CP epithelial cells. Surprisingly, and previously unknown, many cells in the CP epithelium were also positive for aquaporin-4 (AQP4), normally restricted to ventricle-lining ependymal cells and astrocytes in the brain. Expression of AQP1 and AQP4 was found in the CP of all eight body donors investigated (3 males, 5 females; age 74–91). These results were confirmed by qPCR, and by electron microscopy detecting orthogonal arrays of particles. To find out whether AQP4 expression correlated with the expression pattern of relevant transport-related proteins we also investigated expression of NKCC1, and Na/K-ATPase. Immunostaining with NKCC1 was similar to AQP1 and revealed no particular pattern related to AQP4. Co-staining of AQP4 and Na/K-ATPase indicated a trend for an inverse correlation of their expression. We hypothesized that AQP4 expression in the CP was caused by age-related changes. To address this, we investigated mouse brains from young (2 months), adult (12 months) and old (30 months) mice. We found a significant increase of AQP4 on the mRNA level in old mice compared to young and adult animals. Taken together, we provide evidence for AQP4 expression in the CP of the aging brain which likely contributes to the water flow through the CP epithelium and CSF production. In two alternative hypotheses, we discuss this as a beneficial compensatory, or a detrimental mechanism influencing the previously observed CSF changes during aging.

Effects of a Chinese herbal extract on the intestinal tract and aquaporin in Adriamycin-induced nephropathy

Wuling Decoction is a traditional Chinese medicine that has been used to open knots, benefit water, transform Qi, return fluid, and has a significant effect on strengthening the spleen and removing dampness. To explore the effects of Wuling Decoction on the intestinal tract and aquaporin in Adriamycin-induced nephropathy, 45 specific pathogen free (SPF) Wistar rats were randomly divided into a blank control group (5 rats), Dosing control group (10 rats), Adriamycin nephropathy model group (10 rats), diarrhea group (10 rats), and an Adriamycin nephropathy diarrhea model group (10 rats). The tissue localization of aquaporin (AQP) was determined by immunohistochemistry. The expression of AQP mRNA and protein was measured by RT-PCR and western blot analysis, respectively. The results indicated that Wuling Decoction causes excretion of AQP2 through the urine, regulates AQP2 levels, and exerts diuretic and anti-diarrheal effects. It also regulates the levels of antidiuretic hormone (ADH) and arginine vasopressin (AVP), affects water absorption rate, and reduces the level of cyclic adenosine monophosphate (cAMP) in each tissue, thus reducing the absorption of AQP2 to water. Wuling Decoction promoted AQP2 expression in the nephropathy model group and inhibited AQP2 expression in the diarrhea group. Wuling Decoction increased the expression of aquaporin in the intestinal tract, reduced the water content of stool by promoting the absorption of water in the intestinal tract, inhibited the expression of aquaporin and its regulatory factors in nephridia tissue, and reduced the reabsorption of water to increase urine volume, to decrease the occurrence of diarrhea.

A Vasopressin-Induced Change in Prostaglandin Receptor Subtype Expression Explains the Differential Effect of PGE2 on AQP2 Expression

Arginine vasopressin (AVP) stimulates the concentration of renal urine by increasing the principal cell expression of aquaporin-2 (AQP2) water channels. Prostaglandin E₂ (PGE₂) and prostaglandin_2α (PGF_2α) increase the water absorption of the principal cell without AVP, but PGE₂ decreases it in the presence of AVP. The underlying mechanism of this paradoxical response was investigated here. Mouse cortical collecting duct (mkpCCD_c14) cells mimic principal cells as they endogenously express AQP2 in response to AVP. PGE₂ increased AQP2 abundance without desmopressin (dDAVP), while in the presence of dDAVP, PGE₂, and PGF_2α reduced AQP2 abundance. dDAVP increased the cellular PGD₂ and PGE₂ release and decreased the PGF_2α release. MpkCCD cells expressed mRNAs for the receptors of PGE₂ (EP1/EP4), PGF₂ (FP), and TxB₂ (TP). Incubation with dDAVP increased the expression of EP1 and FP but decreased the expression of EP4. In the absence of dDAVP, incubation of mpkCCD cells with an EP4, but not EP1/3, agonist increased AQP2 abundance, and the PGE₂-induced increase in AQP2 was blocked with an EP4 antagonist. Moreover, in the presence of dDAVP, an EP1/3, but not EP4, agonist decreased the AQP2 abundance, and the addition of EP1 antagonists prevented the PGE₂-mediated downregulation of AQP2. Our study shows that in mpkCCD_c14 cells, reduced EP4 receptor and increased EP1/FP receptor expression by dDAVP explains the differential effects of PGE₂ and PGF_2α on AQP2 abundance with or without dDAVP. As the V2R and EP4 receptor, but not the EP1 and FP receptor, can couple to Gs and stimulate the cyclic adenosine monophosphate (cAMP) pathway, our data support a view that cells can desensitize themselves for receptors activating the same pathway and sensitize themselves for receptors of alternative pathways.

Clinical, Genetic and Functional Characterization of a Novel AVPR2 Missense Mutation in a Woman with X-Linked Recessive Nephrogenic Diabetes Insipidus

Nephrogenic diabetes insipidus (NDI) is a rare disorder characterized by renal unresponsiveness to the hormone vasopressin, leading to excretion of large volumes of diluted urine. Mutations in the arginine vasopressin receptor-2 (AVPR2) gene cause congenital NDI and have an X-linked recessive inheritance. The disorder affects almost exclusively male family members, but female carriers occasionally present partial phenotypes due to skewed inactivation of the X-chromosome. Here, we report a rare case of a woman affected with X-linked recessive NDI, presenting an average urinary output of 12 L/day. Clinical and biochemical studies showed incomplete responses to water deprivation and vasopressin stimulation tests. Genetic analyses revealed a novel heterozygous missense mutation (c.493G > C, p.Ala165Pro) in the AVPR2 gene. Using a combination of in-silico protein modeling with human cellular models and molecular phenotyping, we provide functional evidence for phenotypic effects. The mutation destabilizes the helical structure of the AVPR2 transmembrane domains and disrupts its plasma membrane localization and downstream intracellular signaling pathways upon activation with its agonist vasopressin. These defects lead to deficient aquaporin 2 (AQP2) membrane translocation, explaining the inability to concentrate urine in this patient.

Environmental Enrichment Protects Against Sepsis-Associated Encephalopathy-Induced Learning and Memory Deficits by Enhancing the Synthesis and Release of Vasopressin in the Supraoptic Nucleus

Background

As a severe complication of sepsis, sepsis-associated encephalopathy (SAE) usually manifests as impaired learning and memory ability in survivors. Previous studies have reported that environmental enrichment (EE) can increase the learning and memory ability in different brain injury models. However, there has been no research on the possible positive effect of EE on SAE.

Aim

The present study aimed to test the effect of EE on SAE-induced impairment of learning and memory and its related mechanisms.

Methods

A Morris water maze test (MWM) was used to evaluate the learning and memory ability of SAE rats that received EE housing or not. The expression of vasopressin (VP) was assessed using immunofluorescence microscopy and enzyme-linked immunosorbent assays (ELISAs). The synthesis of VP in the supraoptic nucleus (SON) was determined using quantitative real-time reverse transcription-PCR analysis. Moreover, inflammatory markers and brain-derived neurotrophic factor (BDNF) were detected using ELISA.

Results

The results showed that SAE induced a decreased learning and memory ability, while EE reversed this impairment. EE also enhanced the synthesis and secretion of VP in the SON. Blocking the action of VP in the hippocampus interrupted the EE-induced amelioration of learning and memory impairment. Moreover, EE induced changes to the levels of BDNF and cytokines in the hippocampus and these effects were mediated by VP binding to the VP receptor 1a.

Conclusion

Our findings demonstrated that the enhanced synthesis and secretion of VP in the SON are a key determinant responsible for EE-induced alleviation of learning and memory deficits caused by SAE.

Conformational selection of vasopressin upon V1a receptor binding

The neuropeptide vasopressin (VP) and its three G protein-coupled receptors (V_1aR, V_1bR and V₂R) are of high interest in a wide array of drug discovery programs. V_1aR is of particular importance due to its cardiovascular functions and diverse roles in the central nervous system. The structure–activity relationships underpinning ligand-receptor interactions remain however largely unclear, hindering rational drug design. This is not least due to the high structural flexibility of VP in its free as well as receptor-bound states. In this work, we developed a novel approach to reveal features of conformational selectivity upon VP-V_1aR complex formation. We employed virtual screening strategies to probe VP’s conformational space for transiently adopted structures that favor binding to V_1aR. To this end, we dissected the VP conformational space into three sub-ensembles, each containing distinct structural sets for VP’s three-residue C-terminal tail. We validated the computational results with experimental nuclear magnetic resonance (NMR) data and docked each sub-ensemble to V_1aR. We observed that the conformation of VP’s three-residue tail significantly modulated the complex dissociation constants. Solvent-exposed and proline trans-configured VP tail conformations bound to the receptor with three-fold enhanced affinities compared to compacted or cis-configured conformations. The solvent-exposed and more flexible structures facilitated unique interaction patterns between VP and V_1aR transmembrane helices 3, 4, and 6 which led to high binding energies. The presented “virtual conformational space screening” approach, integrated with NMR spectroscopy, thus enabled identification and characterization of a conformational selection-type complex formation mechanism that confers novel perspectives on targeting the VP-V_1aR interactions at the level of the encounter complex – an aspect that opens novel research avenues for understanding the functionality of the evolutionary selected conformational properties of VP, as well as guidance for ligand design strategies to provide more potent and selective VP analogues.

Nephronophthisis-Pathobiology and Molecular Pathogenesis of a Rare Kidney Genetic Disease

The exponential rise in our understanding of the aetiology and pathophysiology of genetic cystic kidney diseases can be attributed to the identification of cystogenic genes over the last three decades. The foundation of this was laid by positional cloning strategies which gradually shifted towards next-generation sequencing (NGS) based screenings. This shift has enabled the discovery of novel cystogenic genes at an accelerated pace unlike ever before and, most notably, the past decade has seen the largest increase in identification of the genes which cause nephronophthisis (NPHP). NPHP is a monogenic autosomal recessive cystic kidney disease caused by mutations in a diverse clade of over 26 identified genes and is the most common genetic cause of renal failure in children. NPHP gene types present with some common pathophysiological features alongside a diverse range of extra-renal phenotypes associated with specific syndromic presentations. This review provides a timely update on our knowledge of this disease, including epidemiology, pathophysiology, anatomical and molecular features. We delve into the diversity of the NPHP causing genes and discuss known molecular mechanisms and biochemical pathways that may have possible points of intersection with polycystic kidney disease (the most studied renal cystic pathology). We delineate the pathologies arising from extra-renal complications and co-morbidities and their impact on quality of life. Finally, we discuss the current diagnostic and therapeutic modalities available for disease management, outlining possible avenues of research to improve the prognosis for NPHP patients.

The Normal Human Adult Hypothalamus Proteomic Landscape: Rise of Neuroproteomics in Biological Psychiatry and Systems Biology

The human hypothalamus is central to the regulation of neuroendocrine and neurovegetative systems, as well as modulation of chronobiology and behavioral aspects in human health and disease. Surprisingly, a deep proteomic analysis of the normal human hypothalamic proteome has been missing for such an important organ so far. In this study, we delineated the human hypothalamus proteome using a high-resolution mass spectrometry approach which resulted in the identification of 5349 proteins, while a multiple post-translational modification (PTM) search identified 191 additional proteins, which were missed in the first search. A proteogenomic analysis resulted in the discovery of multiple novel protein-coding regions as we identified proteins from noncoding regions (pseudogenes) and proteins translated from short open reading frames that can be missed using the traditional pipeline of prediction of protein-coding genes as a part of genome annotation. We also identified several PTMs of hypothalamic proteins that may be required for normal hypothalamic functions. Moreover, we observed an enrichment of proteins pertaining to autophagy and adult neurogenesis in the proteome data. We believe that the hypothalamic proteome reported herein would help to decipher the molecular basis for the diverse range of physiological functions attributed to it, as well as its role in neurological and psychiatric diseases. Extensive proteomic profiling of the hypothalamic nuclei would further elaborate on the role and functional characterization of several hypothalamus-specific proteins and pathways to inform future research and clinical discoveries in biological psychiatry, neurology, and system biology.

Spatial bias in cAMP generation determines biological responses to PTH type 1 receptor activation

[Figure: see text].

Multiomic analysis of the Arabian camel (Camelus dromedarius) kidney reveals a role for cholesterol in water conservation

The Arabian camel (Camelus dromedarius) is the most important livestock animal in arid and semi-arid regions and provides basic necessities to millions of people. In the current context of climate change, there is renewed interest in the mechanisms that enable camelids to survive in arid conditions. Recent investigations described genomic signatures revealing evolutionary adaptations to desert environments. We now present a comprehensive catalogue of the transcriptomes and proteomes of the dromedary kidney and describe how gene expression is modulated as a consequence of chronic dehydration and acute rehydration. Our analyses suggested an enrichment of the cholesterol biosynthetic process and an overrepresentation of categories related to ion transport. Thus, we further validated differentially expressed genes with known roles in water conservation which are affected by changes in cholesterol levels. Our datasets suggest that suppression of cholesterol biosynthesis may facilitate water retention in the kidney by indirectly facilitating the AQP2-mediated water reabsorption.

The Potential Mechanisms of High-Velocity, Low-Amplitude, Controlled Vertebral Thrusts on Neuroimmune Function: A Narrative Review

The current COVID-19 pandemic has necessitated the need to find healthcare solutions that boost or support immunity. There is some evidence that high-velocity, low-amplitude (HVLA) controlled vertebral thrusts have the potential to modulate immune mediators. However, the mechanisms of the link between HVLA controlled vertebral thrusts and neuroimmune function and the associated potential clinical implications are less clear. This review aims to elucidate the underlying mechanisms that can explain the HVLA controlled vertebral thrust--neuroimmune link and discuss what this link implies for clinical practice and future research needs. A search for relevant articles published up until April 2021 was undertaken. Twenty-three published papers were found that explored the impact of HVLA controlled vertebral thrusts on neuroimmune markers, of which eighteen found a significant effect. These basic science studies show that HVLA controlled vertebral thrust influence the levels of immune mediators in the body, including neuropeptides, inflammatory markers, and endocrine markers. This narravtive review discusses the most likely mechanisms for how HVLA controlled vertebral thrusts could impact these immune markers. The mechanisms are most likely due to the known changes in proprioceptive processing that occur within the central nervous system (CNS), in particular within the prefrontal cortex, following HVLA spinal thrusts. The prefrontal cortex is involved in the regulation of the autonomic nervous system, the hypothalamic-pituitary-adrenal axis and the immune system. Bi-directional neuro-immune interactions are affected by emotional or pain-related stress. Stress-induced sympathetic nervous system activity also alters vertebral motor control. Therefore, there are biologically plausible direct and indirect mechanisms that link HVLA controlled vertebral thrusts to the immune system, suggesting HVLA controlled vertebral thrusts have the potential to modulate immune function. However, it is not yet known whether HVLA controlled vertebral thrusts have a clinically relevant impact on immunity. Further research is needed to explore the clinical impact of HVLA controlled vertebral thrusts on immune function.

Urinary reabsorption in the rat kidney by anticholinergics

Anticholinergics, therapeutic agents for overactive bladder, are clinically suggested to reduce urine output. We investigated whether this effect is due to bladder or kidney urine reabsorption. Various solutions were injected into the bladder of urethane-anesthetized SD rats. The absorption rate for 2 h was examined following the intravenous administration of the anticholinergics imidafenacin (IM), atropine (AT), and tolterodine (TO). The bilateral ureter was then canulated and saline was administered to obtain a diuretic state. Anticholinergics or 1-deamino-[8-D-arginine]-vasopressin (dDAVP) were intravenously administered. After the IM and dDAVP administrations, the rat kidneys were immunostained with AQP2 antibody, and intracellular cAMP was measured. The absorption rate was ~ 10% of the saline injected into the bladder and constant even when anticholinergics were administered. The renal urine among peaked 2 h after the saline administration. Each of the anticholinergics significantly suppressed the urine production in a dose-dependent manner, as did dDAVP. IM and dDAVP increased the intracellular cAMP levels and caused the AQP2 molecule to localize to the collecting duct cells' luminal side. The urinary reabsorption mechanism through the bladder epithelium was not activated by anticholinergic administration. Thus, anticholinergics suppress urine production via an increase in urine reabsorption in the kidneys' collecting duct cells via AQP2.

Vasopressin Induces Urinary Uromodulin Secretion By Activating PKA (Protein Kinase A)

[Figure: see text].

Otorhinolaryngological adverse effects of urological drugs

PURPOSE

To describe the otorhinolaryngological adverse effects of the main drugs used in urological practice.

MATERIALS AND METHODS

A review of the scientific literature was performed using a combination of specific descriptors (side effect, adverse effect, scopolamine, sildenafil, tadalafil, vardenafil, oxybutynin, tolterodine, spironolactone, furosemide, hydrochlorothiazide, doxazosin, alfuzosin, terazosin, prazosin, tamsulosin, desmopressin) contained in publications until April 2020. Manuscripts written in English, Portuguese, and Spanish were manually selected from the title and abstract. The main drugs used in Urology were divided into five groups to describe their possible adverse effects: alpha-blockers, anticholinergics, diuretics, hormones, and phosphodiesterase inhibitors.

RESULTS

The main drugs used in Urology may cause several otorhinolaryngological adverse effects. Dizziness was most common, but dry mouth, rhinitis, nasal congestion, epistaxis, hearing loss, tinnitus, and rhinorrhea were also reported and varies among drug classes.

CONCLUSIONS

Most of the drugs used in urological practice have otorhinolaryngological adverse effects. Dizziness was most common, but dry mouth, rhinitis, nasal congestion, epistaxis, hearing loss, tinnitus, and rhinorrhea were also reported. Therefore, doctors must be aware of these adverse effects to improve adherence to the treatment and to minimize damage to the health of patients.

First voided volume: A novel approach to characterize nocturia

AIMS

Nocturnal polyuria syndrome (NPS) denotes nocturnal polyuria (NP) in the absence of identifiable contributory factors. The trajectory of nocturnal urine production (NUP; typically expressed as ml/hour) may be useful in delineating between NP patients with versus without NPS, but changes in absolute urine volume, the directly measured substrate for behavioral and pharmacologic interventions targeting nocturnal urine production, have not been well characterized. This study compares the ratio of the first nocturnal voided volume (FNVV) to the nocturnal average voided volume (NAVV) in patients with versus without NPS.

METHODS

Secondary analysis of 24-h voiding diaries from male patients greater than or equal to 18 years of age with two or more nocturnal voids and NP using two different criteria for NP: NUP greater than or equal to 90 ml/h and nocturnal polyuria index (NPi) greater than or equal to 0.33. Patients with diabetes insipidus and CPAP-adherent obstructive sleep apnea (OSA) were excluded. Patients were divided into 2 groups: secondary NP (OSA, congestive heart failure, and chronic kidney disease) and NPS (absence of edema, diuretic use, and the aforementioned comorbidities). FNVV was defined as the volume of urine accompanying the first nocturic episode. NAVV was defined as nocturnal urine volume/(number of nocturnal voids + 1). The nocturnal urine trajectory ratio (NUTR) was defined as FNVV/NAVV.

RESULTS

At NUP greater than or equal to 90 ml/h, NUTR was significantly greater in patients with (n = 73) versus without (n = 28) NPS (1.10 [0.89-1.33] vs. 0.91 [0.55-1.15], p = .012). At NPi greater than or equal to 0.33, NUTR was likewise significantly greater in patients with (n = 92) versus without (n = 32) NPS (1.09 [0.90-1.33] vs. 0.91 [0.57-1.17], p = .010).

CONCLUSIONS

The volume of urine produced in the early hours of sleep is central to identification of NPS in patients with nocturia.

The Role of Apelin/Apelin Receptor in Energy Metabolism and Water Homeostasis: A Comprehensive Narrative Review

The apelin receptor (APJ) is a member of the family A of G-protein-coupled receptors (GPCRs) and is involved in range of physiological and pathological functions, including fluid homeostasis, anxiety, and depression, as well as cardiovascular and metabolic disorders. APJ was classically described as a monomeric transmembrane receptor that forms a ternary complex together with its ligand and associated G proteins. More recently, increasing evidence indicates that APJ may interact with other GPCRs to form heterodimers, which may selectively modulate distinct intracellular signal transduction pathways. Besides, the apelin/APJ system plays important roles in the physiology and pathophysiology of several organs, including regulation of blood pressure, cardiac contractility, angiogenesis, metabolic balance, and cell proliferation, apoptosis, or inflammation. Additionally, the apelin/APJ system is widely expressed in the central nervous system, especially in neurons and oligodendrocytes. This article reviews the role of apelin/APJ in energy metabolism and water homeostasis. Compared with the traditional diuretics, apelin exerts a positive inotropic effect on the heart, while increases water excretion. Therefore, drugs targeting apelin/APJ system undoubtedly provide more therapeutic options for patients with congestive heart failure accompanied with hyponatremia. To provide more precise guidance for the development of clinical drugs, further in-depth studies are warranted on the metabolism and signaling pathways associated with apelin/APJ system.

Detection of neuropeptides in vivo and open questions for current and upcoming fluorescent sensors for neuropeptides

During a stress response, various neuropeptides are secreted in a spatiotemporally coordinated way in the brain. For a precise understanding of peptide functions in a stress response, it is important to investigate when and where they are released, how they diffuse, and how they are broken down in the brain. In the past two decades, genetically encoded fluorescent calcium indicators have greatly advanced our knowledge of the functions of specific neuronal activity in regulation of behavioral changes and physiological responses during stress. In addition, various kinds of structural information on G-protein-coupled receptors (GPCRs) for neuropeptides have been revealed. Recently, genetically encoded fluorescent sensors have been developed for detection of neurotransmitters by making use of conformational changes induced by ligand binding. In this review, we summarize the recent and upcoming advances of techniques for detection of neuropeptides and then present several open questions that will be solved by application of recent or upcoming technical advances in detection of neuropeptides in vivo.

Effect of pre-meal water intake on the serum levels of Copeptin, glycemic control, lipid profile and anthropometric indices in patients with type 2 diabetes mellitus: a randomized, controlled trial

Background

Water pre-load affects insulin secretion by altering the level of copeptin (C-terminal component of the arginine vasopressin hormone (AVP)) and preventing obesity by reducing food intake.

Aims

The present randomized controlled trial (RCT) aimed to investigate the effects of pre-meal water intake on type 2 diabetes Mellitus (T2DM).

Materials and methods

In this study, 40 patients with T2DM were randomly assigned to two intervention groups for 8 weeks; a) drinking 1 liter of water per day before each main meal (PW group)., and b) no water consumption before any meal (NPW group). At the beginning and at the end of the study, blood samples were taken to assess glycemic indices, lipid profile, copeptin and anthropometric indices.

Results

Pre-meal water intake was associated with lower energy intake, BMI, waist circumference (WC) and greater weight loss, in compared with the controls (P < 0.0001) after 8 weeks. At the end of the trial, the concentrations of fasting blood sugar (FBS) (P < 0.0001), triglyceride (TG) (P < 0.05), low-density lipoprotein cholesterol (LDL-C) (P < 0.05) and copeptin (P < 0.05) were significantly reduced following water drinking before meals.

Conclusion

To sum up, the present study revealed that pre-meal water intake is associated with lower BMI, body weight, WC, FBS, TG, LDL-C and copeptin levels in patients with T2DM.

Birth elicits a conserved neuroendocrine response with implications for perinatal osmoregulation and neuronal cell death

Long-standing clinical findings report a dramatic surge of vasopressin in umbilical cord blood of the human neonate, but the neural underpinnings and function(s) of this phenomenon remain obscure. We studied neural activation in perinatal mice and rats, and found that birth triggers activation of the suprachiasmatic, supraoptic, and paraventricular nuclei of the hypothalamus. This was seen whether mice were born vaginally or via Cesarean section (C-section), and when birth timing was experimentally manipulated. Neuronal phenotyping showed that the activated neurons were predominantly vasopressinergic, and vasopressin mRNA increased fivefold in the hypothalamus during the 2–3 days before birth. Copeptin, a surrogate marker of vasopressin, was elevated 30-to 50-fold in plasma of perinatal mice, with higher levels after a vaginal than a C-section birth. We also found an acute decrease in plasma osmolality after a vaginal, but not C-section birth, suggesting that the difference in vasopressin release between birth modes is functionally meaningful. When vasopressin was administered centrally to newborns, we found an ~ 50% reduction in neuronal cell death in specific brain areas. Collectively, our results identify a conserved neuroendocrine response to birth that is sensitive to birth mode, and influences peripheral physiology and neurodevelopment.

Fluid management: An update for perioperative practitioners

An interprofessional team approach is required to achieve optimum fluid balance for patients during the perioperative period. Incorrect management of fluid assessment and monitoring is associated with adverse outcomes. The scientific understanding of perioperative fluid balance has improved over recent years leading to changes in clinical practice with regard to volume and choice of intravenous fluid. It is important that perioperative practitioners have an understanding of intravenous fluid, fluid compartmentalisation, fluid mechanics and intravascular fluid control mechanisms. Optimum fluid status not only shortens hospital stay but also reduces the incidence of postoperative nausea and vomiting and complication profiles. This article aims to provide perioperative practitioners with a comprehensive overview of fluid management. It will cover important issues surrounding physiological control of fluid balance, choice of intravenous fluid therapy, methods to monitor intravascular volume and factors which influence delivery.