Relation between human vasopressin 1a gene variance, fat intake, and diabetes

Increased copeptin may reflect vasopressin-related metabolic changes after bariatric surgery

OBJECTIVE

Mechanisms underlying metabolic improvement following metabolic and bariatric surgery (MBS) may provide insight into novel therapies. Vasopressin improves body composition and protects against hypoglycemia. Associations of copeptin, a stable cleavage product of vasopressin, with BMI and insulin resistance suggest an adaptive increase in vasopressin to counteract metabolic disruption. To our knowledge, no study has investigated copeptin before and after MBS in humans. This study's aim was to investigate copeptin changes following MBS and associations with metabolic parameters.

METHODS

This was a 12-month longitudinal study of 64 youth (78% female; mean age 18.7 [SD 2.8] y) with obesity (mean BMI 45.6 [SD 6.8] kg/m2) undergoing MBS (n = 34) or nonsurgical (NS) lifestyle management (n = 30). Fasting copeptin, hemoglobin A1c (HbA1c), homeostatic model assessment for insulin resistance (HOMA-IR), body composition, and resting energy expenditure (REE) were assessed.

RESULTS

Over 12 months, copeptin increased more (time-by-treatment p = 0.017) whereas HbA1c and adiposity decreased more after MBS than NS (ps ≤ 0.036). Copeptin changes correlated negatively with percentage fat mass and REE changes (rho ≤ -0.29; ps ≤ 0.025) in the whole group, and they correlated positively with HbA1c and HOMA-IR (rho ≥ 0.41; false discovery rate-adjusted p = 0.05) and negatively with REE changes (rho = -0.55; false discovery rate-adjusted p = 0.036) in the MBS group.

CONCLUSIONS

Increases in copeptin after weight loss in MBS compared with NS were associated with lower REE and higher HbA1c/HOMA-IR values. Vasopressin may contribute to MBS-related metabolic modifications.

Intestinal butyric acid-mediated disruption of gut hormone secretion and lipid metabolism in vasopressin receptor-deficient mice

OBJECTIVES

Arginine vasopressin (AVP), known as an antidiuretic hormone, is also crucial in metabolic homeostasis. Although AVP receptor-deficient mice exhibit various abnormalities in glucose and lipid metabolism, the mechanism underlying these symptoms remains unclear. This study aimed to explore the involvement of the gut hormones including glucagon-like peptide-1 (GLP-1) and microbiota as essential mediators.

METHODS

We used the mouse GLP-1-secreting cell line, GLUTag, and performed live cell imaging to examine the contribution of V1a and V1b vasopressin receptors (V1aR and V1bR, respectively) to GLP-1 secretion. We next investigated the hormone dynamics of V1aR-deficient mice (V1aR-/- mice), V1bR-deficient mice (V1bR-/- mice), and V1aR/V1bR-double deficient mice (V1aR-/-V1bR-/-mice).

RESULTS

AVP induced the increase in intracellular Ca2+ levels and GLP-1 secretion from GLUTag cells in a V1aR and V1bR-dependent manner. AVP receptor-deficient mice, particularly V1aR-/-V1bR-/- mice, demonstrated impaired secretion of GLP-1 and peptide YY secreted by enteroendocrine L cells. V1aR-/-V1bR-/-mice also exhibited abnormal lipid accumulation in the brown adipose tissue and skeletal muscle. We discovered that V1aR-/-V1bR-/- mice showed increased Paneth cell-related gene expression in the small intestine, which was attributed to increased fecal butyric acid levels. Exposure to butyric acid reduced GLP-1 secretion in L cell line. Additionally, human Paneth cell-related gene expressions negatively correlated with that of V1 receptor genes.

CONCLUSIONS

The deficiency in V1 receptor genes may increase gut butyric acid levels and impair the function of L cells, thus dysregulating lipid homeostasis in the brown adipose tissue and skeletal muscle. This study highlights the importance of appropriate control of the gut microbiota and its metabolites, including butyric acid, for the optimum functioning of enteroendocrine cells.

The Interaction of Vasopressin with Hormones of the Hypothalamo-Pituitary-Adrenal Axis: The Significance for Therapeutic Strategies in Cardiovascular and Metabolic Diseases

A large body of evidence indicates that vasopressin (AVP) and steroid hormones are frequently secreted together and closely cooperate in the regulation of blood pressure, metabolism, water-electrolyte balance, and behavior, thereby securing survival and the comfort of life. Vasopressin cooperates with hormones of the hypothalamo-pituitary-adrenal axis (HPA) at several levels through regulation of the release of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and multiple steroid hormones, as well as through interactions with steroids in the target organs. These interactions are facilitated by positive and negative feedback between specific components of the HPA. Altogether, AVP and the HPA cooperate closely as a coordinated functional AVP-HPA system. It has been shown that cooperation between AVP and steroid hormones may be affected by cellular stress combined with hypoxia, and by metabolic, cardiovascular, and respiratory disorders; neurogenic stress; and inflammation. Growing evidence indicates that central and peripheral interactions between AVP and steroid hormones are reprogrammed in cardiovascular and metabolic diseases and that these rearrangements exert either beneficial or harmful effects. The present review highlights specific mechanisms of the interactions between AVP and steroids at cellular and systemic levels and analyses the consequences of the inappropriate cooperation of various components of the AVP-HPA system for the pathogenesis of cardiovascular and metabolic diseases.

Interplay of Angiotensin Peptides, Vasopressin, and Insulin in the Heart: Experimental and Clinical Evidence of Altered Interactions in Obesity and Diabetes Mellitus

The present review draws attention to the specific role of angiotensin peptides [angiotensin II (Ang II), angiotensin-(1-7) (Ang-(1-7)], vasopressin (AVP), and insulin in the regulation of the coronary blood flow and cardiac contractions. The interactions of angiotensin peptides, AVP, and insulin in the heart and in the brain are also discussed. The intracardiac production and the supply of angiotensin peptides and AVP from the systemic circulation enable their easy access to the coronary vessels and the cardiomyocytes. Coronary vessels and cardiomyocytes are furnished with AT1 receptors, AT2 receptors, Ang (1-7) receptors, vasopressin V1 receptors, and insulin receptor substrates. The presence of some of these molecules in the same cells creates good conditions for their interaction at the signaling level. The broad spectrum of actions allows for the engagement of angiotensin peptides, AVP, and insulin in the regulation of the most vital cardiac processes, including (1) cardiac tissue oxygenation, energy production, and metabolism; (2) the generation of the other cardiovascular compounds, such as nitric oxide, bradykinin (Bk), and endothelin; and (3) the regulation of cardiac work by the autonomic nervous system and the cardiovascular neurons of the brain. Multiple experimental studies and clinical observations show that the interactions of Ang II, Ang(1-7), AVP, and insulin in the heart and in the brain are markedly altered during heart failure, hypertension, obesity, and diabetes mellitus, especially when these diseases coexist. A survey of the literature presented in the review provides evidence for the belief that very individualized treatment, including interactions of angiotensins and vasopressin with insulin, should be applied in patients suffering from both the cardiovascular and metabolic diseases.

Genomic Signatures of Positive Selection in Human Populations of the OXT, OXTR, AVP, AVPR1A and AVR1B Gene Variants Related to the Regulation of Psychoemotional Response

The neurobiological systems of maintenance and control of behavioral responses result from natural selection. We have analyzed the selection signatures for single nucleotide variants (SNV) of the genes of oxytocin (OXT, OXTR) and vasopressin (AVP, AVPR1A, AVPR1B) systems, which are associated with the regulation of social and emotional behavior in distinct populations. The analysis was performed using original WGS (whole genome sequencing) data on Eastern Slavs (SlEast), as well as publicly available data from the 1000 Genomes Project on GBR, FIN, IBR, PUR, BEB, CHB, and ACB populations (the latter were taken as reference). To identify selection signatures, we rated the integrated haplotype scores (iHS), the numbers of segregating sites by length (nSl), and the integrated haplotype homozygosity pooled (iHH12) measures; the fixation index Fst was implemented to assess genetic differentiation between populations. We revealed that the strongest genetic differentiation of populations was found with respect to the AVPR1B gene, with the greatest differentiation observed in GRB (Fst = 0.316) and CHB (Fst = 0.325) in comparison to ACB. Also, high Fst values were found for SNVs of the AVPR1B gene rs28499431, rs33940624, rs28477649, rs3883899, and rs28452187 in most of the populations. Selection signatures have also been identified in the AVP, AVPR1A, OXT, and OXTR genes. Our analysis shows that the OXT, OXTR, AVP, AVPR1A, and AVPR1B genes were subject to positive selection in a population-specific process, which was likely contributing to the diversity of adaptive emotional response types and social function realizations.

Rethinking Vasopressin: New Insights into Vasopressin Signaling and Its Implications

Vasopressin is a highly conserved peptide hormone that has been traditionally associated with water homeostasis. There is accumulating evidence in both humans and animal models that vasopressin is implicated in the regulation of metabolism. This review focuses on the effects that vasopressin exerts on the regulation of glucose and fatty acids with a particular emphasis on the potential repercussions of metabolic dysregulation in kidney disease.

Vaptans or voluntary increased hydration to protect the kidney: how do they compare?

The adverse effects of vasopressin (AVP) in diverse forms of chronic kidney disease have been well described. They depend on the antidiuretic action of AVP mediated by V2 receptors (V2R). Tolvaptan, a selective V2R antagonist, is now largely used for the treatment of patients with autosomal dominant polycystic kidney disease. Another way to reduce the adverse effects of AVP is to reduce endogenous AVP secretion by a voluntary increase in fluid intake. These two approaches differ in several ways, including the level of thirst and AVP. With voluntary increased drinking, plasma osmolality will decline and so will AVP secretion. Thus, not only will V2R-mediated effects be reduced, but also those mediated by V1a and V1b receptors (V1aR and V1bR). In contrast, selective V2R antagonism will induce a loss of fluid that will stimulate AVP secretion and thus increase AVP's influence on V1a and V1b receptors. V1aR is expressed in the luminal side of the collecting duct (CD) and in inner medullary interstitial cells, and their activation induces the production of prostaglandins, mostly prostaglandin E2 (PGE2). Intrarenal PGE2 has been shown to reduce sodium and water reabsorption in the CD and increase blood flow in the renal medulla, both effects contributing to increase sodium and water excretion and reduce urine-concentrating activity. Conversely, non-steroidal anti-inflammatory drugs have been shown to induce significant water and sodium retention and potentiate the antidiuretic effects of AVP. Thus, during V2R antagonism, V1aR-mediated actions may be responsible for part of the diuresis observed with this drug. These V1aR-dependent effects do not take place with a voluntary increase in fluid intake. In summary, while both strategies may have beneficial effects, the information reviewed here leads us to assume that pharmacological V2R antagonism, with resulting stimulation of V1aR and increased PGE2 production, may provide greater benefit than voluntary high water intake. The influence of tolvaptan on the PGE2 excretion rate and the possibility to use somewhat lower tolvaptan doses than presently prescribed remain to be evaluated.

Kidney collecting duct cells make vasopressin in response to NaCl-induced hypertonicity

Vasopressin has traditionally been thought to be produced by the neurohypophyseal system and then released into the circulation where it regulates water homeostasis. The questions of whether vasopressin could be produced outside of the brain and if the kidney could be a source of vasopressin are raised by the syndrome of inappropriate antidiuretic hormone secretion (vasopressin). We found that mouse and human kidneys expressed vasopressin mRNA. Using an antibody that detects preprovasopressin, we found that immunoreactive preprovasopressin protein was found in mouse and human kidneys. Moreover, we found that murine collecting duct cells made biologically active vasopressin, which increased in response to NaCl-mediated hypertonicity, and that water restriction increased the abundance of kidney-derived vasopressin mRNA and protein expression in mouse kidneys. Thus, we provide evidence of biologically active production of kidney-derived vasopressin in kidney tubular epithelial cells.

Psoriasis and Cardiometabolic Diseases: Shared Genetic and Molecular Pathways

A convincing deal of evidence supports the fact that severe psoriasis is associated with cardiovascular diseases. However, the precise underlying mechanisms linking psoriasis and cardiovascular diseases are not well defined. Psoriasis shares common pathophysiologic mechanisms with atherosclerosis and cardiovascular (CV) risk factors. In particular, polymorphism in the IL-23R and IL-23 genes, as well as other genes involved in lipid and fatty-acid metabolism, renin-angiotensin system and endothelial function, have been described in patients with psoriasis and with cardiovascular risk factors. Moreover, systemic inflammation in patients with psoriasis, including elevated serum proinflammatory cytokines (e.g., TNF-α, IL-17, and IL-23) may contribute to an increased risk of atherosclerosis, hypertension, alteration of serum lipid composition, and insulin resistance. The nonlinear and intricate interplay among various factors, impacting the molecular pathways in different cell types, probably contributes to the development of psoriasis and cardiovascular disease (CVD). Future research should, therefore, aim to fully unravel shared and differential molecular pathways underpinning the association between psoriasis and CVD.

Weight-reducing, lipid-lowering and antidiabetic activities of a novel arginine vasopressin analogue acting at the V1a and V1b receptors in high-fat-fed mice

AIM

To assess the beneficial metabolic effects of the nonapeptide hormone, arginine vasopressin (AVP), on metabolism.

MATERIALS AND METHODS

We exchanged amino acids at position 3 and 8 of AVP, namely phenylalanine and arginine, with those of oxytocin, to generate novel analogues with altered receptor selectivity. Secondary modification by N-terminal acetylation was used to impart stability to circulating endopeptidases. Analogues were screened for degradation, bioactivity in rodent/human clonal beta cells and primary murine islets, together with evaluation of receptor activation profile.

RESULTS

Analogue Ac3IV, which lacked effects at the V2 receptors responsible for modulation of fluid balance, was selected as the lead compound for assessment of antidiabetic efficacy in high-fat-fed mice. Twice-daily administration of Ac3IV, or the gold standard control exendin-4, for 22 days, reduced energy intake as well as body weight and fat content. Both interventions decreased circulating glucose levels, enhanced insulin sensitivity, and substantially improved glucose tolerance and related insulin secretion in response to an intraperitoneal or oral glucose challenge. The peptides decreased total- and increased HDL-cholesterol, but only Ac3IV decreased LDL-cholesterol, triglyceride and non-fasting glucagon concentrations. Elevations of islet and beta-cell areas were partially reversed, accompanied by suppressed islet cell proliferation, decreased beta-cell apoptosis and, in the case of exendin-4, also decreased alpha-cell apoptosis.

CONCLUSION

AVP-based therapies that exclusively target V1a and V1b receptors may have significant therapeutic potential for the treatment of obesity and related diabetes, and merit further clinical exploration.

Arginine vasopressin: Direct and indirect action on metabolism

From its identification and isolation in 1954, arginine vasopressin (AVP) has attracted attention, not only for its peripheral functions such as vasoconstriction and reabsorption of water from kidney, but also for its central effects. As there is now considerable evidence that AVP plays a crucial role in feeding behavior and energy balance, it has become a promising therapeutic target for treating obesity or other obesity-related metabolic disorders. However, the underlying mechanisms for AVP regulation of these central processes still remain largely unknown. In this review, we will provide a brief overview of the current knowledge concerning how AVP controls energy balance and feeding behavior, focusing on physiological aspects including the relationship between AVP, circadian rhythmicity, and glucocorticoids.

Pituitary Dysfunction as a Cause of Cardiovascular Disease

The hypothalamic-pituitary axis is responsible for the neuroendocrine control of several organ systems. The anterior pituitary directly affects the functions of the thyroid gland, the adrenal glands, and gonads, and regulates growth and milk production. The posterior hypophysis, through nerve connections with the hypothalamic nuclei, releases vasopressin and oxytocin responsible for water balance and social bonding, sexual reproduction and childbirth, respectively. Pituitary gland hormonal excess or deficiency results in dysregulation of metabolic pathways and mechanisms that are important for the homeostasis of the organism and are associated with increased morbidity and mortality. Cardiovascular (CV) disorders are common in pituitary disease and have a significant impact on survival. Hormonal imbalance is associated with CV complications either through direct effects on the heart structure and function and vasculature or indirectly by altering the metabolic profile. Optimal endocrine control can prevent or reverse CV defects and preserve survival and quality of life. In this review, we discuss the effects of pituitary hormone excess and deficiency on the CV system. Specifically, we assess the impact of Somatotroph, Corticotroph, Gonadotroph, and Lactotroph anterior pituitary axes on the CV system. The effect of posterior pituitary function on the CV system is also explored.

A Journey through the Early Evidence Linking Hydration to Metabolic Health

The idea that water intake or hydration may play an intrinsic, independent role in modulating metabolic disease risk is relatively recent. Here, we outline the journey from early experimental works to more recent evidence linking water and hydration to metabolic health. It has been known for decades that individuals with existing metabolic dysfunction experience challenges to body water balance and have elevated arginine vasopressin (AVP), <underline>a key</underline> hormone regulating body fluid homeostasis. Later, intervention studies demonstrated that altering fluid balance in these individuals could worsen their condition, suggesting that hydration played a role in modulating glycemic control. More recently, observational and interventional studies in healthy individuals have implicated the hydration-vasopressin axis in the pathophysiology of metabolic diseases. Individuals with higher AVP (or its surrogate, copeptin) are at higher risk for developing type 2 diabetes and components of the metabolic syndrome, an association that remains even when controlling for known risk factors. Supporting preclinical work also suggests a causal role for AVP in metabolic dysfunction. It is known that individuals who habitually drink less fluids tend to have higher circulating AVP, which may be lowered by increasing water intake. In the short term, water supplementation in habitual low drinkers with high copeptin may reduce fasting glucose or glucagon, generating a proof of concept for the role of water supplementation in reducing incident metabolic disease. A large randomized trial is ongoing to determine whether water supplementation for 1 year in subjects with low water intake can meaningfully reduce fasting glucose, risk of new-onset diabetes, and other cardiometabolic risk factors.

The influence of post-infarct heart failure and high fat diet on the expression of apelin APJ and vasopressin V1a and V1b receptors

Vasopressin and apelin are reciprocally regulated hormones which are implicated in the pathophysiology of heart failure and the regulation of metabolism; however, little is known about their interactions under pathological conditions. In this study, we determined how post-infarct heart failure (HF) and a high fat diet (HFD) affect expression of the apelin APJ receptor (APJR) and the V1a (V1aR) and V1b (V1bR) vasopressin receptors in the hypothalamus, the heart, and the retroperitoneal adipose tissue. We performed experiments in male 4-week-old Sprague Dawley rats. The animals received either a normal fat diet (NFD) or a HFD for 8 weeks, then they underwent left coronary artery ligation to induce HF or sham surgery (SO), followed by 4 weeks of NFD or HFD. The HF rats showed higher plasma concentration of NT-proBNP and copeptin. The HF reduced the APJR mRNA expression in the hypothalamus. The APJR and V1aR protein levels in the hypothalamus were regulated both by HF and HFD, while the V1bR protein level in the hypothalamus was mainly influenced by HF. APJR mRNA expression in the heart was significantly higher in rats on HFD, and HFD affected the reduction of the APJR protein level in the right ventricle. The regulation of APJR, V1aR and V1bR expression in the heart and the retroperitoneal adipose tissue were affected by both HF and HFD. Our study demonstrates that HF and HFD cause significant changes in the expression of APJR, V1aR and V1bR, which may have an important influence on the cardiovascular system and metabolism.

Oxytocin and Vasopressin Systems in Obesity and Metabolic Health: Mechanisms and Perspectives

PURPOSE OF REVIEW

The neurohypophysial endocrine system is identified here as a potential target for therapeutic interventions toward improving obesity-related metabolic dysfunction, given its coinciding pleiotropic effects on psychological, neurological and metabolic systems that are disrupted in obesity.

RECENT FINDINGS

Copeptin, the C-terminal portion of the precursor of arginine-vasopressin, is positively associated with body mass index and risk of type 2 diabetes. Plasma oxytocin is decreased in obesity and several other conditions of abnormal glucose homeostasis. Recent data also show non-classical tissues, such as myocytes, hepatocytes and β-cells, exhibit responses to oxytocin and vasopressin receptor binding that may contribute to alterations in metabolic function. The modulation of anorexigenic and orexigenic pathways appears to be the dominant mechanism underlying the effects of oxytocin and vasopressin on body weight regulation; however, there are apparent limitations associated with their use in direct pharmacological applications. A clearer picture of their wider physiological effects is needed before either system can be considered for therapeutic use.

Copeptin relates to a fatty liver and measures of obesity in a South African population with mixed ethnicities

PURPOSE

Elevated copeptin, a vasopressin marker, is linked to metabolic disease, and obese rats with low-vasopressin concentration had a decreased risk of liver steatosis. We here investigated the association between copeptin and nonalcoholic fatty liver disease (NAFLD) and possible differences in copeptin concentration between ethnicities.

METHODS

In this cross-sectional study of 361 South Africans (n = 172 African black, 189 = Caucasian) with a mean age of 45 years and 45% men, plasma copeptin was measured and associated with NAFLD according to a validated fatty liver index accounting for measures of BMI, waist, triglycerides, and gamma-glutamyltransferase.

RESULTS

There was no significant difference in copeptin concentrations between ethnicities after age and gender adjustment (p = 0.24). Increasing copeptin tertile levels were significantly associated with obesity, overweight, and abdominal obesity, respectively, after multivariate adjustment for age, gender, ethnicity, and high HOMA-IR (p = 0.02 for all). Individuals in the second and third copeptin tertile had an increased odds (95% CI) of NAFLD of 1.77 (1.04-3.02) and 2.97 (1.74-5.06), respectively, compared to the bottom tertile (p < 0.001). The association between increasing copeptin tertile and NAFLD remained significant after adjustment for age, gender, ethnicity, high HOMA-IR, self-reported current alcohol intake, and statin treatment (p = 0.01).

CONCLUSIONS

Elevated plasma copeptin is independently associated with NAFLD in a population with mixed ethnicities, pointing at the pharmacologically modifiable vasopressin system as a new mechanism behind NAFLD.

Hydration, Arginine Vasopressin, and Glucoregulatory Health in Humans: A Critical Perspective

Glucoregulatory diseases, such as type 2 diabetes are currently a key public health priority. Public health messages have started to include the addition of water in their dietary guidelines. Such guidelines however are not based on causal evidence pertaining to the health effects of increased water intake, but rather more heavily based upon non-causal or mechanistic data. One line of thinking linking fluid intake and health is that hypohydration induces elevated blood concentrations of arginine vasopressin (AVP). Research in the 1970s and 1980s implicated AVP in glucoregulation, supported by observational evidence. This important area of research subsequently appeared to stop until the 21st century during which interest in hypertonic saline infusion studies, animal AVP receptor knockout models, dietary and genetic associations, and human interventions manipulating hydration status have resurged. This narrative review briefly describes and critically evaluates the usefulness of the current AVP-glucoregulatory research. We offer suggestions on how to test the independent glucoregulatory effects of body water changes compared to elevated circulating AVP concentrations, such as investigating hydration manipulations using 3,4-Methylenedioxymethamphetamine. Whilst much research is still needed before making firm conclusions, the current evidence suggests that although AVP may be partially implicated in glucoregulation, more ecologically valid models using human participants suggests this effect might be independent of the hydration status. The key implication of this hypothesis if confirmed in future research is that manipulating the hydration status to reduce circulating AVP concentrations may not be an effective method to improve glucoregulatory health.

Water Intake, Water Balance, and the Elusive Daily Water Requirement

Water is essential for metabolism, substrate transport across membranes, cellular homeostasis, temperature regulation, and circulatory function. Although nutritional and physiological research teams and professional organizations have described the daily total water intakes (TWI, L/24h) and Adequate Intakes (AI) of children, women, and men, there is no widespread consensus regarding the human water requirements of different demographic groups. These requirements remain undefined because of the dynamic complexity inherent in the human water regulatory network, which involves the central nervous system and several organ systems, as well as large inter-individual differences. The present review analyzes published evidence that is relevant to these issues and presents a novel approach to assessing the daily water requirements of individuals in all sex and life-stage groups, as an alternative to AI values based on survey data. This empirical method focuses on the intensity of a specific neuroendocrine response (e.g., plasma arginine vasopressin (AVP) concentration) employed by the brain to regulate total body water volume and concentration. We consider this autonomically-controlled neuroendocrine response to be an inherent hydration biomarker and one means by which the brain maintains good health and optimal function. We also propose that this individualized method defines the elusive state of euhydration (i.e., water balance) and distinguishes it from hypohydration. Using plasma AVP concentration to analyze multiple published data sets that included both men and women, we determined that a mild neuroendocrine defense of body water commences when TWI is ˂1.8 L/24h, that 19⁻71% of adults in various countries consume less than this TWI each day, and consuming less than the 24-h water AI may influence the risk of dysfunctional metabolism and chronic diseases.

Water intake keeps type 2 diabetes away? Focus on copeptin

INTRODUCTION

In both diabetic subjects and animal models high levels of vasopressin (AVP) have beendetected. The relationship between AVP and glucose metabolism is mediated through several direct andindirect effects and most of them are still unknown.

METHODS

We have reviewed 100 manuscripts retrieved from Cochrane Library, Embase and Pubmeddatabases in order to highlight a possible relationship between copeptin and type 2 diabetes and to provideinsights on the molecular mechanism that could explain this association.

RESULTS AND CONCLUSIONS

AVP potentiates CRH action at pituitary level resulting in an increased ACTH secretion and in turn in an increased cortisol secretion that escapes the negative feedback loop. Further, AVP regulates insulin and glucagon secretion through V1b receptor and promotes hepatic glycogenolysis and gluconeogenesis through V1a receptor. In addition to worsen glucose metabolism, AVP has been reported to have a role in the pathogenesis of diabetic complications such as cardiovascular diseases, kidney and ocular complications. Due to the very low concentration of AVP in the blood, the small size and poor stability, the assay of AVP is very difficult to perform. Thus, copeptin, the stable C-terminal portion of the prepro-vasopressin peptide has been identified as an easier assay to be measured and that mirrors AVP activity. Although there are promising evidence that copeptin could be involved in the pathogenesis of type 2 diabetes, further studies need to demonstrate the importance of copeptin as clinical marker to predict glucose metabolism derangements.

Acute effects of salt on blood pressure are mediated by serum osmolality

It is classically thought that it is the amount of salt that is critical for driving acute blood pressure responses. However, recent studies suggest that blood pressure responses, at least acutely, may relate to changes in serum osmolality. Here, we test the hypothesis that acute blood pressure responses to salt can be altered by concomitant water loading. Ten healthy patients free of any disease and medication underwent 4 interventions each a week apart in which they took 300 mL of lentil soup with no salt (visit 1), lentil soup with 3 g salt (visit 2), or lentil soup with 3 g salt and 500 mL water (visit 3) or 750 mL water (visit 4). At each visit, hourly blood measurements and blood pressure measurements (baseline, 1st, 2nd, 3rd, and 4th hour) were performed and plasma osmolarity, sodium and copeptin levels were measured. Patients receiving the 3 g salt showed a 6 mOsm/L change in osmolality with a 2.5 mmol/L change in plasma sodium and 10 mm Hg rise in systolic blood pressure at 2 hours. When the same patients drank salty soup with water, the changes in plasma osmolarity, plasma sodium, and blood pressure were prevented. The ability to raise blood pressure acutely with salt appears dependent on changes in plasma osmolality rather than the amount of salt. Our findings suggest that concurrent intake of water must be considered when evaluating the role of salt in blood pressure.

Improving Metabolic Health Through Precision Dietetics in Mice

The incidence of diet-induced metabolic disease has soared over the last half-century, despite national efforts to improve health through universal dietary recommendations. Studies comparing dietary patterns of populations with health outcomes have historically provided the basis for healthy diet recommendations. However, evidence that population-level diet responses are reliable indicators of responses across individuals is lacking. This study investigated how genetic differences influence health responses to several popular diets in mice, which are similar to humans in genetic composition and the propensity to develop metabolic disease, but enable precise genetic and environmental control. We designed four human-comparable mouse diets that are representative of those eaten by historical human populations. Across four genetically distinct inbred mouse strains, we compared the American diet's impact on metabolic health to three alternative diets (Mediterranean, Japanese, and Maasai/ketogenic). Furthermore, we investigated metabolomic and epigenetic alterations associated with diet response. Health effects of the diets were highly dependent on genetic background, demonstrating that individualized diet strategies improve health outcomes in mice. If similar genetic-dependent diet responses exist in humans, then a personalized, or "precision dietetics," approach to dietary recommendations may yield better health outcomes than the traditional one-size-fits-all approach.

Vasopressin and metabolic disorders: translation from experimental models to clinical use

Vasopressin has many physiological actions in addition to its well-defined role in the control of fluid homeostasis and urine concentration. An increasing body of evidence suggests that the vasopressin-hydration axis plays a role in glucose homeostasis. This review summarizes the knowledge accumulated over the last decades about the influence of vasopressin in the short-term regulation of glycaemia. It describes the possible role of this hormone through activation of V1a and V1b receptors on liver and pancreas functions and on the hypothalamic-pituitary-adrenal axis. Moreover, we report recent in vivo studies demonstrating the role of vasopressin in the long-term regulation of glycaemia. Indeed, V1a- or double-V1aV1b-receptor knockout mice display significant changes in the glucose and lipid metabolism. In rats, sustained high V1aR activation increases basal glycaemia and aggravates glucose intolerance in obese rats. Finally, the translation from animal findings to human was evidenced by epidemiological and genetic studies that showed that high vasopressin level is a risk factor for hyperglycaemia, metabolic disorders and diabetes.

Associations Between Vocal Symptoms and Genetic Variants in the Oxytocin Receptor and Arginine Vasopressin 1A Receptor Gene

PURPOSE

Oxytocin and arginine vasopressin are associated with different aspects of the stress response. As stress is regarded as a risk factor for vocal symptoms, we wanted to explore the association between the oxytocin receptor gene (OXTR) and arginine vasopressin 1A receptor gene (AVPR1A) single-nucleotide polymorphisms (SNPs) and vocal symptoms. We also wanted to explore whether such effects might be mediated by cortisol because oxytocin and vasopressin are associated with cortisol levels.

METHOD

A population-based sample (N = 657) of Finnish twins (born 1961-1989) completed a web questionnaire on the occurrence of vocal symptoms. A total of 170 participants submitted saliva samples for hormone analysis. A total of 20 OXTR and AVPR1A SNPs were analyzed.

RESULTS

Three OXTR polymorphisms (rs2270465, rs2268493, rs7632287) and 2 AVPR1A polymorphisms (rs1587097, rs1042615) showed nominal effects (p < .05) on vocal symptoms, of which 1 (rs1587097) remained significant after correcting for multiple testing (p = .003). We found potential mediation of the effect of the OXTR rs2268493 polymorphism on vocal symptoms through levels of cortisol.

CONCLUSIONS

The associations between variants of OXTR and AVPR1A and vocal symptoms indicate that oxytocin and vasopressin might influence vocal symptoms. The effect of oxytocin seems to be partly mediated through cortisol actions.

Circadian Metabolomics in Time and Space

Circadian rhythms are widely known to govern human health and disease, but specific pathogenic mechanisms linking circadian disruption to metabolic diseases are just beginning to come to light. This is thanks in part to the development and application of various "omics"-based tools in biology and medicine. Current high-throughput technologies allow for the simultaneous monitoring of multiple dynamic cellular events over time, ranging from gene expression to metabolite abundance and sub-cellular localization. These fundamental temporal and spatial perspectives have allowed for a more comprehensive understanding of how various dynamic cellular events and biochemical processes are related in health and disease. With advances in technology, metabolomics has become a more routine "omics" approach for studying metabolism, and "circadian metabolomics" (i.e., studying the 24-h metabolome) has recently been undertaken by several groups. To date, circadian metabolomes have been reported for human serum, saliva, breath, and urine, as well as tissues from several species under specific disease or mutagenesis conditions. Importantly, these studies have consistently revealed that 24-h rhythms are prevalent in almost every tissue and metabolic pathway. Furthermore, these circadian rhythms in tissue metabolism are ultimately linked to and directed by internal 24-h biological clocks. In this review, we will attempt to put these data-rich circadian metabolomics experiments into perspective to find out what they can tell us about metabolic health and disease, and what additional biomarker potential they may reveal.

Short article: Impact of genetic variation in the vasopressin 1a receptor on the development of organ failure in patients admitted for acute decompensation of liver cirrhosis

BACKGROUND

Vasopressin receptor-mediated vasoconstriction is considered to be involved in the pathogenesis of organ failure in acute-on-chronic liver failure (ACLF).

PATIENTS AND METHODS

We studied the association between six single nucleotide polymorphisms (SNPs) of the vasopressin 1a receptor gene and the development of organ failure in 826 patients admitted for acute decompensation of liver cirrhosis (n=641) or ACLF (n=185).

RESULTS

No associations were found for SNPs with the presence of circulatory or renal failure. A C>T mutation in SNP rs7308855 and a T>A mutation in SNP rs7298346 showed an association with the presence of coagulation failure in the entire population (n=61, P=0.024 and 0.060, respectively) and in the subgroup of patients with ACLF (n=44, P=0.081 and 0.056, respectively).

CONCLUSION

Genetic variation in the vasopressin 1a receptor was found not to be associated with circulatory or renal failure, but with the presence of coagulation failure in patients with acute decompensation of liver cirrhosis and ACLF.

Extracting Genes Involved in Disease from a Connected Network of Perturbed Biological Processes

Metabolic disorders such as obesity and diabetes are nowadays regarded as diseases affecting majority of population. These diseases develop gradually over time in an individual. Recently, systematic experiments tracking disease progression are conducted giving a high-throughput complex data. There is a pressing need for developing methods to analyze this complex data to capture the disease mechanism at molecular level. Diseases usually develop through perturbations of biological processes in an organism. In this study, we have tried to capture the interlinking between different biological processes that work together to regulate the disease phenotype. Here, we have considered a temporal microarray data from an experiment conducted to study obesity and diabetes in mice. We have analyzed the data to obtain perturbed biological processes and developed methods to establish link between these perturbed biological processes. We have derived a mathematical formula to score genes and identified a significant set of genes regulating such a complex process network. The methods developed in our study are also applicable to a broad array of data types.

Acute and chronic hyperglycemic effects of vasopressin in normal rats: involvement of V1A receptors

Recent epidemiological studies have revealed novel relationships between low water intake or high vasopressin (AVP) and the risk of hyperglycemia and diabetes. AVP V_1A and V_1B receptors (R) are expressed in the liver and pancreatic islets, respectively. The present study was designed to determine the impact of different levels of circulating AVP on glucose homeostasis in normal Sprague-Dawley rats, as well as the respective roles of V_1AR and V_1BR. We showed that acute injection of AVP induces a dose-dependent increase in glycemia. Pretreatment with a selective V_1AR antagonist, but not a V_1BR antagonist, dose-dependently prevented the rise in glycemia. V_1BR antagonism did not modify the hyperinsulinemic response, resulting from AVP-induced hyperglycemia, but enhanced the fall in glucagonemia. Acute administration of selective V_1AR or V_1BR agonists confirmed the involvement of V_1AR in the hyperglycemic effect of AVP. In chronic experiments, AVP levels were altered in both directions. Sustained AVP infusion through implantable minipumps induced a time-dependent increase in fasting glycemia, whereas lowering endogenous AVP by increasing water intake had no effect. After 4 wk of AVP infusion, the rise in glycemia amounted to 1.1 mmol/l (P < 0.01) without significant change in insulinemia. This effect was attenuated by cotreatment with a V_1AR antagonist. Similar results were observed in lean Zucker rats. These findings demonstrate for the first time a causal link between chronic high AVP and hyperglycemia through V_1AR activation and, thus, provide a pathophysiological explanation for the relationship observed in human cohorts between the AVP-hydration axis and the risk of diabetes.

Serum levels of copeptin are associated with type 2 diabetes and diabetic complications in Chinese population

PURPOSE

The aim of this study was to investigate copeptin levels in serum, and assess their associations with type 2 diabetes (T2DM) and diabetic complications.

METHODS

In this post hoc analysis, serum levels of copeptin were tested in 306 patients with T2DM. Clinical information including diabetic retinopathy (DR) and diabetic nephropathy (DN) were collected. The relation of serum copeptin with DR and DN were investigated with the use of logistic regression models according to equal quartiles of the distributions of serum copeptin.

RESULTS

We found that serum copeptin levels were significantly higher in diabetes as compared to normal controls [9.4(IQR, 7.4-12.5) pmol/L vs. 4.1(IQR, 2.5-6.2) pmol/L; P<0.0001]. In multivariate analysis, there was an increased risk of T2DM associated with copeptin levels (OR 1.312, 95% CI: 1.204-1.403; P<0.0001) after adjusting for possible confounders. After adjustment for possible confounders, serum copeptin levels were positively associated with the DR (odds ratio [OR], 1.117; 95% confidence interval [CI], 1.072-1.241; P<0.001) and DN (OR, 1.259; 95% CI, 1.198-1.323; P<0.001). Compared with the first quartile of serum copeptin levels, the ORs for DR and DN were as follows: second quartile, 1.19 (95% CI, 0.94-1.51, P=0.12) and 1.37 (95% CI, 0.78-2.37, P=0.28); third quartile, 1.61 (95% CI, 1.18-2.43, P=0.005) and 2.12 (95% CI, 1.32-3.27, P=0.003); fourth quartile, 2.83 (95% CI, 2.04-4.93; P<0.001) and 3.48 (95% CI, 1.77-7.03; P<0.001), respectively.

CONCLUSIONS

Using a post-hoc analysis our data show that elevated serum levels of copeptin are associated with type 2 diabetes and diabetic complications in Chinese population, suggesting a potential role of the AVP system (copeptin) in the pathophysiology of diabetes.

Vasopressin-induced Ca(2+) signals in human adipose-derived stem cells

Intracellular Ca(2+) signals are essential for stem cell differentiation due to their ability to control signaling pathways involved in this process. Arginine vasopression (AVP) is a neurohypophyseal hormone that increases intracellular Ca(2+) concentration during adipogenesis via V1a receptors, Gq-proteins and the PLC-IP3 pathway in human adipose-derived stromal/stem cells (hASCs). These Ca(2+) signals originate through calcium release from pools within the endoplasmic reticulum and the extracellular space. AVP supplementation to the adipogenic media inhibits adipogenesis and key adipocyte marker genes. This review focuses on the intersection between AVP, Ca(2+) signals and ASC differentiation.

Genetic vasopressin 1b receptor variance in overweight and diabetes mellitus

OBJECTIVE

Recently, imbalance in the vasopressin (AVP) system, measured as elevated levels of copeptin (the C-terminal part of the AVP pro-hormone) in plasma, was linked to the development of abdominal obesity and diabetes mellitus (DM). Here, we aim to investigate if the genetic variation of the human AVP receptor 1b gene (AVPR1B) is associated with measures of obesity and DM.

DESIGN

Malmö Diet and Cancer study (MDC) is a population-based prospective cohort examined 1991-1996.

METHODS

Four tag single nucleotide polymorphisms (SNPs: rs35810727, rs28373064, rs35439639, rs35608965) of AVPR1B were genotyped in the cardiovascular cohort (n=6103) of MDC (MDC-CC) and associated with measures of obesity and DM. Significant SNPs were replicated in another 24 344 MDC individuals (MDC replication cohort).

RESULTS

In MDC-CC, the major allele of rs35810727 was associated with elevated BMI (β-coefficient ± s.e.m.; 0.30 ± 0.14, P=0.03) and waist (0.78 ± 0.36, P=0.03) after age and gender adjustment. The association with BMI was replicated in the MDC replication cohort (0.21 ± 0.07, P=0.003), whereas that with waist was not significant. In MDC-CC there was no association between the major allele of rs35810727 and DM, but in the complete MDC cohort (n=30 447) the major allele of rs35810727 was associated with DM (OR (95% CI); 1.10 (1.00-1.20), P=0.04).

CONCLUSIONS

Genetic variance of AVPR1B contributes to overweight. Furthermore, our data indicate a link between AVPR1B variance and DM development. Our data point at a relationship between the disturbance of the pharmacologically modifiable AVP system and the body weight regulation.

Effect of increased water intake on plasma copeptin in patients with chronic kidney disease: results from a pilot randomised controlled trial

OBJECTIVES

Increased water intake may have a beneficial effect on the kidney through suppression of plasma vasopressin. We examined the effect of increased water intake on plasma copeptin (a marker of vasopressin) over 6 weeks in patients with chronic kidney disease.

DESIGN

Secondary analysis of a randomised controlled parallel-group pilot trial.

SETTING

Canada, 2012-2013.

PARTICIPANTS

28 patients with stage 3 chronic kidney disease randomised (2:1) to a hydration (n=17) or control group (n=11).

INTERVENTION

The hydration group was coached to increase water intake by up to 1.5 L/day for 6 weeks. The control group was asked to maintain regular water intake.

MEASURES AND OUTCOMES

Participants provided blood and 24 h urine samples at baseline and 6 weeks. Change in plasma copeptin was compared within and between study groups.

RESULTS

Participants were 64% male with a mean age of 62 years and an estimated glomerular filtration rate of 40 mL/min/1.73 m(2). Between baseline and 6 weeks, 24 h urine volume increased by 0.7 L/day in the hydration group, rising from 2.3 to 3.0 L/day (p=0.01), while decreasing by 0.3 L/day among controls, from 2.0 to 1.7 L/day (p=0.07); between-group difference: 0.9 L/day (95% CI 0.37 to 1.46; p=0.002). In the hydration group, median copeptin decreased by 3.6 pmol/L, from 15.0 to 10.8 pmol/L (p=0.005), while remaining stable among controls at 19 pmol/L (p=0.76; p=0.19 for the between-group difference in median change); the between-group difference in mean change was 5.4 pmol/L (95% CI -1.2 to 12.0; p=0.11).

CONCLUSIONS

Adults with stage 3 chronic kidney disease can be successfully randomised to drink approximately 1 L more per day than controls. This increased water intake caused a significant decrease in plasma copeptin concentration. Our larger 12-month trial will examine whether increased water intake can slow renal decline in patients with chronic kidney disease.

TRIAL REGISTRATION NUMBER

NCT01753466.

Protein- and diabetes-induced glomerular hyperfiltration: role of glucagon, vasopressin, and urea

A single protein-rich meal (or an infusion of amino acids) is known to increase the glomerular filtration rate (GFR) for a few hours, a phenomenon known as “hyperfiltration.” It is important to understand the factors that initiate this upregulation because it becomes maladaptive in the long term. Several mediators and paracrine factors have been shown to participate in this upregulation, but they are not directly triggered by protein intake. Here, we explain how a rise in glucagon and in vasopressin secretion, directly induced by protein ingestion, might be the initial factors triggering the hepatic and renal events leading to an increase in the GFR. Their effects include metabolic actions in the liver and stimulation of sodium chloride reabsorption in the thick ascending limb. Glucagon is not only a glucoregulatory hormone. It is also important for the excretion of nitrogen end products by stimulating both urea synthesis in the liver (along with gluconeogenesis from amino acids) and urea excretion by the kidney. Vasopressin allows the concentration of nitrogenous end products (urea, ammonia, etc.) and other protein-associated wastes in a hyperosmotic urine, thus allowing a very significant water economy characteristic of all terrestrial mammals. No hyperfiltration occurs in the absence of one or the other hormone. Experimental results suggest that the combined actions of these two hormones, along with the complex intrarenal handling of urea, lead to alter the composition of the tubular fluid at the macula densa and to reduce the intensity of the signal activating the tubuloglomerular feedback control of GFR, thus allowing GFR to raise. Altogether, glucagon, vasopressin, and urea contribute to set up the best compromise between efficient urea excretion and water economy.

Translational and therapeutic potential of oxytocin as an anti-obesity strategy: Insights from rodents, nonhuman primates and humans

The fact that more than 78 million adults in the US are considered overweight or obese highlights the need to develop new, effective strategies to treat obesity and its associated complications, including type 2 diabetes, kidney disease and cardiovascular disease. While the neurohypophyseal peptide oxytocin (OT) is well recognized for its peripheral effects to stimulate uterine contraction during parturition and milk ejection during lactation, release of OT within the brain is implicated in prosocial behaviors and in the regulation of energy balance. Previous findings indicate that chronic administration of OT decreases food intake and weight gain or elicits weight loss in diet-induced obese (DIO) mice and rats. Furthermore, chronic systemic treatment with OT largely reproduces the effects of central administration to reduce weight gain in DIO and genetically obese rodents at doses that do not appear to result in tolerance. These findings have now been recently extended to more translational models of obesity showing that chronic subcutaneous or intranasal OT treatment is sufficient to elicit body weight loss in DIO nonhuman primates and pre-diabetic obese humans. This review assesses the potential use of OT as a therapeutic strategy for treatment of obesity in rodents, nonhuman primates, and humans, and identifies potential mechanisms that mediate this effect.

Arginine vasopressin inhibits adipogenesis in human adipose-derived stem cells

Intracellular Ca(2+) signaling is important for stem cell differentiation and there is evidence it may coordinate the process. Arginine vasopressin (AVP) is a neuropeptide hormone secreted mostly from the posterior pituitary gland and increases Ca(2+) signals mainly via V1 receptors. However, the role of AVP in adipogenesis of human adipose-derived stem cells (hASCs) is unknown. In this study, we identified the V1a receptor gene in hASCs and demonstrated that AVP stimulation increased intracellular Ca(2+) concentration during adipogenesis. This effect was mediated via V1a receptors, Gq-proteins and the PLC-IP3 pathway. These Ca(2+) signals were due to endoplasmic reticulum release and influx from the extracellular space. Furthermore, AVP supplementation to the adipogenic medium decreased the number of adipocytes and adipocyte marker genes during differentiation. The effect of AVP on adipocyte formation was reversed by the V1a receptor blocker V2255. These findings suggested that AVP may function to inhibit adipocyte differentiation.

Vasopressin and hydration play a major role in the development of glucose intolerance and hepatic steatosis in obese rats

AIMS/HYPOTHESIS

High plasma copeptin, a marker of vasopressin (VP) secretion, has been shown to be associated with the metabolic syndrome and development of type 2 diabetes in humans. The present study was designed to determine the long-term influence of plasma VP concentration in a rodent model prone to metabolic dysfunction.

METHODS

Obese Zucker rats and their lean counterparts were submitted for 4 weeks to one of three protocols inducing different levels of VP. Circulating VP was either reduced by increasing the daily water intake (low-VP), or increased by a chronic i.p. infusion of VP (high-VP). The control rats had normal VP levels that depended on their own regulation of water intake and VP secretion.

RESULTS

Compared with controls with normal VP, lean rats with high-VP had a higher fasting glycaemia after 4 weeks. In obese rats, high-VP promoted hyperinsulinaemia, glucose intolerance, assessed by glucose and insulin tolerance tests, and an impaired response to a pyruvate challenge. Conversely, treatment with a selective arginine vasopressin receptor 1A (V1aR) antagonist reduced glucose intolerance. Low-VP obese rats had unchanged glucose tolerance but exhibited a drastic decrease in liver steatosis compared with control obese rats, associated with low hepatic triacylglycerol and cholesterol content, and reduced expression of hepatic lipogenic genes. These effects were independent of changes in body adiposity, and plasma sodium and osmolality did not differ among groups.

CONCLUSION/INTERPRETATION

These findings show a causal relationship between the VP-hydration axis and the metabolic risk. Therapeutic perspectives include diet recommendations regarding hydration, but also potential pharmacological interventions targeting the VP V1aR.

A review of the nonpressor and nonantidiuretic actions of the hormone vasopressin

The pressor and antidiuretic actions of arginine vasopressin (AVP) have been well documented. This review focuses on the less widely appreciated actions of AVP which also have important physiologic functions and when better understood may provide important insights into common disease states. These actions include effects on pain perception and bone structure as well as important relationships to the varied components of metabolic syndrome. These include effects on blood glucose, lipid levels, and blood pressure. AVP may also play a role in the progression of chronic kidney disease and effect physiologic changes relating to aging, abnormal social behavior, and cognitive function. Important cellular responses including cell proliferation, inflammation, and control of infection and their relationship to AVP are described. Finally, the effects of AVP on hemostasis and the hypothalamic-pituitary-adrenal axis are noted. The goal of this summary of the various actions of AVP is to direct attention to the potential benefits of research in these underemphasized areas of importance.

Plasma copeptin is associated with type 2 diabetes in men but not in women in the population-based KORA F4 study

Elevated plasma CT-pro-vasopressin (copeptin) has been described as biomarkers for type 2 diabetes (T2D) and the metabolic syndrome (MetS), which, however, was not confirmed by all studies. Here, we analyzed the association of copeptin with T2D, MetS and MetS components in the population-based KORA F4 study. Plasma copeptin concentrations were analyzed in 1,554 study participants. We used fractional polynomial selection procedures to check for nonlinearity of the associations between copeptin and T2D and HbA1c, respectively. In logistic regression models, we investigated associations between copeptin and T2D, MetS and its components according to IDF criteria. In the fractional polynomial approach, linear models fitted best for copeptin. In multivariable adjusted models, copeptin as a continuous variable was associated with T2D and HbA1c only in men (OR = 1.38 per standard deviation, 95 % CI 1.13-1.70 for T2D). Comparing the top quartile Q4 versus Q1-3, elevated copeptin was associated with T2D (OR 2.70, 95 % CI 1.60-4.59) in men but not in women (OR 0.98, 95 % CI 0.52-1.83). Copeptin was not significantly associated with MetS, central obesity, triglycerides and reduced HDL cholesterol. A significant association with copeptin was observed for hypertension in women (OR 1.59, 95 % CI 1.08-2.33) and glucose dysfunction according to IDF criteria in men (OR 1.63, 95 % CI 1.14-2.34). In the KORA F4 study, copeptin was significantly associated with T2D only in men, whereas hypertension was associated with copeptin in women. No other components of the MetS were related to elevated copeptin.

Identification of a missense variant in LNPEP that confers psoriasis risk

Psoriasis is a chronic inflammatory disease with a complex genetic architecture. To further advance gene discovery, we extended our genome-wide association study data set of 1,139 cases and 2,234 controls and replicated two independent cohorts of 7,200 cases and 10,491 controls. We identified the missense variant rs2303138 (p.Ala763Thr) within the LNPEP gene associated with psoriasis (Pcombined=1.83 × 10(-13), odds ratio=1.16) and validated four previously reported genes: IL28RA, NFKBIA, TRAF3IP2, and CARD14 (9.74 × 10(-11)P9.37 × 10(-5)), which confirmed the involvement of the nuclear factor-κB signaling pathway in psoriasis pathogenesis. LNPEP, also named insulin-responsive aminopeptidase, was identified as an angiotensin IV receptor. Protein function prediction suggested that this missense variant of LNPEP was most likely deleterious. Expression analysis showed that LNPEP was significantly downregulated in psoriatic lesions compared with the control skin (P=1.44 × 10(-6)) and uninvolved patient skin (P=2.95 × 10(-4)). Pathway analysis indicated that LNPEP was involved in the renin-angiotensin system, which also has a key role in cardiovascular disease and diabetes. These results provided genetic evidence that psoriasis might share common mechanisms with hypertension and diabetes, which was consistent with clinical observations. Our study identified a genetic susceptibility factor and provided genetic evidence of insight into psoriasis pathogenesis with the involvement of the renin-angiotensin system pathway.

Vasopressin: a novel target for the prevention and retardation of kidney disease?

After several decades during which little attention was paid to vasopressin and/or urine concentration in clinical practice, interest in vasopressin has renewed with the availability of new, potent, orally active vasopressin-receptor antagonists--the vaptans--and with the results of epidemiological studies evaluating copeptin (a surrogate marker of vasopressin) in large population-based cohorts. Several experimental studies in rats and mice had previously shown that vasopressin, acting via vasopressin V2 antidiuretic receptors, contributes to the progression of chronic kidney disease; in particular, to autosomal dominant polycystic kidney disease. New epidemiological studies now suggest a role for vasopressin in the pathogenesis of diabetes mellitus and metabolic disorders via activation of hepatic V1a and/or pancreatic islet V1b receptors. The first part of this Review describes the adverse effects of vasopressin, as revealed by clinical and experimental studies in kidney diseases, hypertension, diabetes and the metabolic syndrome. The second part provides insights into vasopressin physiology and pathophysiology that may be relevant to the understanding of these adverse effects and that are linked to the excretion of concentrated nitrogen wastes and associated hyperfiltration. Collectively, the studies reviewed here suggest that more attention should be given to the vasopressin-thirst-urine concentration axis in clinical investigations and in patient care. Whether selective blockade of the different vasopressin receptors may provide therapeutic benefits beyond their present indication in hyponatraemia requires new clinical trials.

Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems

The neurohypophysial hormone arginine vasopressin (AVP) is essential for a wide range of physiological functions, including water reabsorption, cardiovascular homeostasis, hormone secretion, and social behavior. These and other actions of AVP are mediated by at least three distinct receptor subtypes: V1a, V1b, and V2. Although the antidiuretic action of AVP and V2 receptor in renal distal tubules and collecting ducts is relatively well understood, recent years have seen an increasing understanding of the physiological roles of V1a and V1b receptors. The V1a receptor is originally found in the vascular smooth muscle and the V1b receptor in the anterior pituitary. Deletion of V1a or V1b receptor genes in mice revealed that the contributions of these receptors extend far beyond cardiovascular or hormone-secreting functions. Together with extensively developed pharmacological tools, genetically altered rodent models have advanced the understanding of a variety of AVP systems. Our report reviews the findings in this important field by covering a wide range of research, from the molecular physiology of V1a and V1b receptors to studies on whole animals, including gene knockout/knockdown studies.

Copeptin, a marker of vasopressin, in abdominal obesity, diabetes and microalbuminuria: the prospective Malmö Diet and Cancer Study cardiovascular cohort

BACKGROUND

High plasma copeptin (copeptin), the C-terminal fragment of arginine vasopressin pro-hormone, has been associated with the metabolic syndrome (MetS), diabetes mellitus (DM) development and nephropathy. Here we tested whether elevated copeptin level is associated with later development of the MetS, its individual components and microalbuminuria.

METHODS

We analysed copeptin at baseline (1991-1994) in the population-based Malmö Diet and Cancer Study cardiovasular cohort and re-examined 2064 subjects 15.8 years later (mean age 72.8 years, 59% women) with oral glucose tolerance test and measurement of MetS and its individual components.

RESULTS

After age and sex adjustment, increasing quartiles of copeptin at baseline (the lowest quartile as reference) were associated with MetS (P for trend=0.008), incident abdominal obesity (P for trend=0.002), DM (P for trend=0.001) and microalbuminuria (P for trend=0.002). After additional adjustment for all the MetS components at baseline, increasing copeptin quartiles predicted incident abdominal obesity (odds ratios 1.55, 1.30 and 1.59; P for trend=0.04), DM (odds ratios 1.18, 1.32 and 1.46; P for trend=0.04) and microalbuminuria (odds ratios 1.05, 1.08 and 1.65; P for trend=0.02) but not MetS (P for trend=0.19) at the reexamination. Further, the relationship between copeptin and microalbuminuria was independent of baseline C-reactive protein, incident DM and incident hypertension.

CONCLUSION

Copeptin independently predicts DM and abdominal obesity but not the cluster of MetS. Apart from predicting DM and abdominal obesity, elevated copeptin signals increased risk of microalbuminuria. Interestingly, the association between copeptin and later microalbuminuria was independent of both prevalent and incident DM and hypertension. Our findings suggest a relationship between a dysregulated vasopressin system and cardiometabolic risk, which could have implications for risk assessment and novel preventive treatments.

Fatty acid interactions with genetic polymorphisms for cardiovascular disease

PURPOSE OF REVIEW

The number of studies investigating interactions between genes and nutrients for cardiovascular disease continues to grow, and holds tremendous potential for reducing disease risk at the level of the individual genotype. However, understanding the limitations and challenges of interaction studies, whether of observational or interventional design, is essential for critical evaluation of these studies.

RECENT FINDINGS

Nutrient-gene interactions for cardiovascular disease both parallel and extend nutrition studies, encompassing both traditional and novel cardiovascular risk factors. Fatty acid quality, lipid metabolism, inflammation, postprandial metabolism, fatty liver and macronutrient-gene interactions for obesity and metabolic syndrome represent a subset of the major areas of recent focus. With few exceptions, however, studies of gene-nutrient interactions are limited to a single population.

SUMMARY

Gene-nutrient research will continue to expand as genome-wide association studies uncover new sources of genetic variability associated with cardiovascular risk. However, in addition to investigation of newly discovered variants, continuing efforts must focus on the confirmation of previously reported genetic associations and interactions in additional populations.

Vasopressin V1a receptor polymorphism and interval walking training effects in middle-aged and older people

We assessed whether single nucleotide polymorphism rs1042615 of the vasopressin V1a receptor altered the indices of lifestyle-related diseases in middle-aged and older people (mean+/-SD: 64+/-7 years), and, if so, whether it also altered the effects of interval walking training (IWT). CC, CT, and TT carriers of rs1042615 (42, 118, and 64 men, respectively; 113, 263, and 154 women, respectively) performed IWT. We included 5 sets of 3-minute fast walking at > or =70% peak aerobic capacity for walking and 3-minute slow walking at 40% peak aerobic capacity per day for > or =4 days per week for 5 months. Before IWT, the body mass index and diastolic blood pressure (DBP) for men were 25.1+/-0.3 kg/m(2) (mean+/-SE) and 84+/-1 mm Hg in TT, higher than the 23.6+/-0.4 kg/m(2) and 78+/-1 mm Hg in CC, respectively (P<0.01), differences that disappeared after IWT despite similar training achievement between groups (P>0.6). After IWT, body mass index and DBP decreased in TT (-0.9+/-0.1 kg/m(2) and -5+/-1 mm Hg, respectively), more than in CC (-0.5+/-0.1 kg/m(2) and 1+/-1 mm Hg, respectively; P<0.05), with a greater decrease in low-density lipoprotein cholesterol in TT than CC carriers (P<0.01). The decreases in DBP and low-density lipoprotein cholesterol were still greater in TT carriers even after adjustment for their pretraining values. On the other hand, for women, these parameters before IWT and their changes after IWT were similar among CC, CT, and TT carriers. Thus, polymorphism rs1042615 of the V1a receptor altered body mass index and DBP in middle-aged and older men and the training-induced responses of DBP and low-density lipoprotein cholesterol, whereas women did not show any of these responses.