Arginine Vasopressin Deficiency Research Articles

Degradation of Mutant Protein Aggregates within the Endoplasmic Reticulum of Vasopressin Neurons.

SummaryMisfolded or unfolded proteins in the ER are said to be degraded only after translocation or isolation from the ER. Here, we describe a mechanism by which mutant proteins are degraded within the ER. Aggregates of mutant arginine vasopressin (AVP) precursor were confined to ER-associated compartments (ERACs) connected to the ER in AVP neurons of a mouse model of familial neurohypophysial diabetes insipidus. The ERACs were enclosed by membranes, an ER chaperone and marker protein of phagophores and autophagosomes were expressed around the aggregates, and lysosomes fused with the ERACs. Moreover, lysosome-related molecules were present within the ERACs, and aggregate degradation within the ERACs was dependent on autophagic-lysosomal activity. Thus, we demonstrate that protein aggregates can be degraded by autophagic-lysosomal machinery within specialized compartments of the ER.

Central Diabetes Insipidus in a Patient with Stiff Person Syndrome

Background: Central diabetes insipidus (CDI) is a rare hypothalamic-pituitary disease due to the deficiency of arginine vasopressin (AVP) synthesis of which more than one third of etiologies are unidentified. Autoimmunity is associated with one third of patients with apparently idiopathic CDI. The most common antibody detected in auto immune CDI is autoantibodies to AVP-secreting cells (AVPcAb). Stiff-person syndrome (SPS) is a rare neurological disorder with features of an autoimmune disease. It is characterized by fluctuating muscle rigidity in the trunk and limbs and a heightened sensitivity to stimuli. It is well known that SPS is associated with multiple auto immune endocrinopathy including auto immune diabetes and auto immune thyroid disease. The association between SPS and CDI is not well documented in the literature. Case information: We report a case of 51 year old female who developed CDI while being treated for SPS unmasked by high dose steroids. Result: Anti amphiphysin is the only antibody detected in our patient. Animal studies showed a high expression of amphiphysin in anterior and posterior pituitary gland, data in human are still vague .One theory is that anti-amphiphysin antibodies attack the amphiphysin molecules in the AVP secreting cells and inhibit release of AVP. Conclusion: This antibody could hint towards the autoimmune cause of CDI.

Low arginine vasopressin levels in patients with diabetes insipidus are not associated with anaemia.

Arginine vasopressin (AVP) is released upon osmotic stimulation or hypovolaemia in order to maintain water balance. A recent study showed a role of AVP in haematopoiesis by stimulating red blood cell precursors, suggesting a higher risk of anaemia in patients with AVP deficiency. The objective was to explore the effect of low AVP levels in patients with central diabetes insipidus (cDI) and primary polydipsia (PP) on haemoglobin and the prevalence of anaemia. A total of 164 patients with either cDI (70, 43%) or PP (94, 57%) and 30 healthy volunteers from two prospective diagnostic studies performed in Switzerland, Germany and Brazil were studied. A standardized clinical and biochemical (eg copeptin, full blood count) assessment was performed. Haemoglobin and haematocrit levels and prevalence of anaemia (defined as haemoglobin values of <120g/L in women and <130g/L in men) were analysed. Mean copeptin values were 2.63pmol/L (±1.08) and 3.91pmol/L (±4.28) in patients with cDI and PP and 24.76pmol/L (±5.75) in healthy volunteers, P=.02. The prevalence of anaemia was low in all participants with 7.1%, 2.2% and 10% in cDI, PP and in healthy volunteers, P=.15. Mean haemoglobin values were similar in all groups: 139g/L (±15.85), 140g/L (±13.16) and 139g/L (±13.05) in patients with cDI, PP and healthy volunteers, P=.90, as were mean haematocrit values with 41% in all groups (P=.85). Chronic low AVP levels in patients with cDI and PP do not affect haemoglobin levels and prevalence of anaemia.

The protective effect of vasopressin deficiency in liver fibrosis in rats with chronic portocaval anastomosis

Liver fibrosis occur in liver diseases and its complications is cause of the increased rate of human mortality. The disease is characterized by the gradual accumulation of scar tissue in the liver parenchyma with decrease in metabolic capacity and liver failure. It is known that arginine vasopressin (AVP) participate in the regulation of the immune responses, including the scarring. However, the effect of how AVP regulates this process is not clear. Here we study the role of the AVP deficiency induced by the neurointermediate pituitary lobectomy (NIL) in rats with chronic anastomosis portocaval (APC) model (sixteen weeks). Groups of young male Wistar rats of 8–10 each were prepared: Sham operated (SHAM), APC, LNI and APC+NIL. Blood, plasma and serum biochemical variables were assessed: prothrombin time (TP), blood NH3, transaminases (TGO and TGP), bilirubins and γ‐Glutamyl Transpeptidase (GGT). Liver histological slides were stained with H‐E, Masson, Sirius Red and PAS. Results showed that in the APC group: the TP, NH3, TGO and TGP, bilirubins and GGT were significantly increased, whereas serum glucose levels, cholesterol, triglycerides, albumin, total proteins and the liver glycogen content where significantly augmented. Comparisons between SHAM and NIL groups did not shown significant differences in all these variables. As compared with the APC, the APC+NIL group developed a significant improvement in all these variables. The liver histopathology showed that the APC group developed a significant increase in fibrosis septa, inflammatory infiltrates and diminution of the glycogen content. The NIL group we do not have available data yet. In the NIL+APC group histology data showed a significant liver regeneration; less fibrosis, disappearance of inflammatory infiltrates and liver glycogen restoration.ConclusionsResults indicate the AVP play a role in liver fibrosis (demonstrated by the AVP deficiency). Results also suggest that AVP antagonists may be used for liver fibrosis treatment.Support or Funding InformationUniversidad Autónoma de Aguascalientes PIFF14‐1 andCONACYT 221262. México

The role of arginine vasopressin deficiency in the regulation of the kidney fibrosis

It is known that arginine vasopressin (AVP) participate in the regulation of the immune responses, including the scarring. However, the effect of how AVP regulates this process is not clear. Here we describe the impact of AVP deficiency induced by neurointermediate pituitary lobectomy (NIL) or blocking the V1a‐V2 AVP receptors with conivaptan (CON) on the kidney fibrosis (KF), induced by unilateral ureteral ligature (UUL). Groups of 5 Wistar male rats were prepared: Control Intact (CI), UUL, NIL, NIL+UUL, UUL+NIL and UUL+CON. The NIL group was operated 6 weeks before sacrifice. In the NIL+UUL group NIL was performed 3 weeks before UUL and sacrificed 3 weeks after. In the UUL+CON (3mg/kg/day/SC/3 weeks before sacrifice) the UUL was done 6 weeks before sacrifice. KF was evaluated in histological slides stained with H‐E, Masson and Sirius red. Results showed that UUL induced hydronephrosis, severe kidney fibrosis and loss of histological architecture, whose severity was related to each experimental condition: In the UUL severe fibrosis occurred in the ilium, pelvis, periglomerular, intraglomerular, intraluminal tubules and interstitial kidney areas. In comparison with the CI, NIL group showed normal kidney histology, whereas that, in comparison with the UUL the NIL+UUL group developed significant less histological alterations and less kidney fibrosis. In the UUL+NIL group (NIL surgery performed 3 weeks after UUL and sacrificed 3 weeks later), although histological changes and fibrosis were apparent, these were significantly less severe as compared with the UUL group. In comparison with the NIL+UUL group, the UUL+CON animals developed less severe fibrosis and less histopathological changes. Conclusions. Results showed that kidney fibrosis may be controlled by AVP deficiency or blocking the V1a‐V2 AVP receptors (CON) indicating a major role of AVP on the fibrotic process. Results also suggests that conivaptan may be used for kidney fibrosis treatment.Support or Funding InformationUniversidad Autónoma de Aguascalientes PIFF14‐1 and CONACYT 221262. México

Mutation in the vasopressin gene eliminates the sex difference in social reinforcement in adolescent rats

The neuropeptide, arginine vasopressin (AVP), is thought to contribute to sex differences in normative and pathological social development by regulating social motivation. Recent studies using Brattleboro rats that have a mutation in the Avp gene, however, have suggested that AVP impacts adolescent social behaviors of males and females in a similar manner through actions on behavioral state (i.e., arousal). In the present study, we made use of a recently developed operant conditioning paradigm to test whether the chronic, lifelong AVP deficiency caused by the Brattleboro mutation impacts the reinforcement value of social stimuli during adolescence. Operant responding for access to a familiar conspecific was assessed in male and female adolescent wild type (WT; normal AVP), heterozygous Brattleboro (HET), and homozygous Brattleboro (HOM) rats. Following the social reinforcement test, rats were tested in the same operant paradigm except that the social reinforcer was replaced with a light reinforcer to determine whether effects of the Brattleboro mutation were specific to social stimuli or a general characteristic of operant conditioning. WT males directed a greater proportion of their responding toward the social and light stimuli than WT females; only males exhibited a preference for these reinforcers over unreinforced ports. The sex difference in social reinforcement was absent in HOM rats, whereas the sex difference in light reinforcement was present in all genotypes. These data indicate that adolescent males are more sensitive to the reinforcing properties of social and light stimuli, and that the sex difference in social, but not light, reinforcement depends upon normal levels of AVP. These findings support the hypothesis that AVP plays a critical role in sex differences in social development by acting on factors that influence social motivation.

Central Diabetes Insipidus in a Patient with Stiff Person Syndrome

Background: Central diabetes insipidus (CDI) is a rare hypothalamic-pituitary disease due to the deficiency of arginine vasopressin (AVP) synthesis of which more than one third of etiologies are unidentified. Autoimmunity is associated with one third of patients with apparently idiopathic CDI. The most common antibody detected in auto immune CDI is autoantibodies to AVP-secreting cells (AVPcAb). Stiff-person syndrome (SPS) is a rare neurological disorder with features of an autoimmune disease. It is characterized by fluctuating muscle rigidity in the trunk and limbs and a heightened sensitivity to stimuli. It is well known that SPS is associated with multiple auto immune endocrinopathy including auto immune diabetes and auto immune thyroid disease. The association between SPS and CDI is not well documented in the literature. Case information: We report a case of 51 year old female who developed CDI while being treated for SPS unmasked by high dose steroids. Result: Anti amphiphysin is the only antibody detected in our patient. Animal studies showed a high expression of amphiphysin in anterior and posterior pituitary gland, data in human are still vague .One theory is that anti-amphiphysin antibodies attack the amphiphysin molecules in the AVP secreting cells and inhibit release of AVP. Conclusion: This antibody could hint towards the autoimmune cause of CDI.

Vasopressin therapy in cardiac surgery.

Arginine vasopressin (AVP) is a naturally occurring peptide with diverse effects mediated through selective V1 and V2 receptors. About 10% of patients undergoing cardiopulmonary bypass develop postoperative vasodilatory shock requiring high-dose catecholamines. We sought to examine the role of AVP therapy in cardiac surgery. A search of Medline was conducted through September 2018 using key words and medical subject headings (MeSH) relating to AVP, copeptin, and cardiac surgery. A systematic review was performed on articles as they pertained to AVP for use as a vasopressor after cardiovascular surgery complicated by vasodilatory shock. A relative or absolute deficiency of Arginine vasopressin is associated with vasodilatory shock after cardiopulmonary bypass. Physiologic replacement with exogenous Arginine vasopressin results in significant increases in systemic vascular resistance and mean arterial pressure with decreased requirements of catecholamines. At doses of <0.1 U/min Arginine vasopressin is safe with very few adverse effects. Post-cardiopulmonary bypass vasodilatory shock is largely due to a relative deficiency of Arginine vasopressin. Exogenous administration of low-dose Arginine vasopressin alone or in combination with traditional catecholamines is a safe and effective way to manage this type of vasodilatory shock.

FGF-21 levels in polyuria-polydipsia syndrome.

The pathomechanism of primary polydipsia is poorly understood. Recent animal data reported a connection between fibroblast growth factor 21 (FGF-21) and elevated fluid intake independently of hormonal control by the hormone arginine-vasopressin (AVP) and osmotic stimulation. We therefore compared circulating FGF-21 levels in patients with primary polydipsia to patients with AVP deficiency (central diabetes insipidus) and healthy volunteers. In this prospective cohort study, we analyzed FGF-21 levels of 20 patients with primary polydipsia, 20 patients with central diabetes insipidus and 20 healthy volunteers before and after stimulation with hypertonic saline infusion targeting a plasma sodium level ≥150 mmol/L. The primary outcome was the difference in FGF-21 levels between the three groups. Baseline characteristics were similar between the groups except for patients with central diabetes insipidus being heavier. There was no difference in baseline FGF-21 levels between patients with primary polydipsia and healthy volunteers (122 pg/mL (52,277) vs 193 pg/mL (48,301), but higher levels in patients with central diabetes insipidus were observed (306 pg/mL (114,484); P = 0.037). However, this was not confirmed in a multivariate linear regression analysis after adjusting for age, sex, BMI and smoking status. Osmotic stimulation did not affect FGF-21 levels in either group (difference to baseline: primary polydipsia −23 pg/mL (−43, 22); central diabetes insipidus 17 pg/mL (−76, 88); healthy volunteers −6 pg/mL (−68, 22); P = 0.45). To conclude, FGF-21 levels are not increased in patients with primary polydipsia as compared to central diabetes insipidus or healthy volunteers. FGF-21 therefore does not seem to be causal of elevated fluid intake in these patients.

Investigation of social, affective, and locomotor behavior of adolescent Brattleboro rats reveals a link between vasopressin's actions on arousal and social behavior

Arginine vasopressin (AVP) has recently been implicated in juvenile and adolescent social development. How AVP influences social development, however, is not understood. Adolescent homozygous Brattleboro rats (Hom), which lack AVP due to a mutation in the Avp gene, exhibit fewer active social behaviors (e.g., social play) but more passive social behaviors (e.g., huddling) than their wild type and heterozygous (Het) littermates, raising the possibility that AVP impacts social development through an arousal mechanism. Here, we test whether the atypical social phenotype of adolescent Hom rats is associated with altered behavioral arousal, social approach, or affective behaviors and whether Brattleboro mothers impact these behavioral phenotypes. Male and female Het and Hom adolescents born to Het or Hom mothers were tested in social interaction, open field, novelty-seeking, social approach, and marble burying tests. As reported previously, Hom rats played less and emitted fewer 50 kHz ultrasonic vocalizations while huddling more than their Het littermates. No genotype differences were detected in novelty seeking or social approach, nor were consistent differences found between offspring from Het and Hom mothers. However, Hom rats were less active in the open field and buried fewer marbles than Het rats indicating a hypoaroused, low anxiety phenotype. Open field activity correlated with levels of social play indicating that the effects of the Brattleboro mutation on arousal and social behavior are linked. These data demonstrate that chronic AVP deficiency impacts behavioral arousal during adolescence and support the hypothesis that AVP influences adolescent social development, in part, through its regulation of arousal.

Effects of Arginine Vasopressin (AVP) Deficiency, Conivaptan and Desmopressin on Clinical Symptoms and Blood Cytokine Levels in Rats with Experimental Autoimmune Encephalomyelitis

IntroductionThe experimental autoimmune encephalomyelitis (EAE), the rat paradigm for the human multiple sclerosis (MS), are autoimmune diseases mediated by Th1 and Th17 cells and responsible of the nervous system demyelination and progressive paralysis. It is know that lymphocytes possess AVP receptors and that EAE increases AVP serum levels along the disease. Neurointermediate pituitary lobectomy (NIL) in rats causes AVP and oxytocin permanent low serum levels and decreased humoral and cell‐mediated immune responses. Nevertheless the role of AVP as a direct immune regulatory factor has not been well clarified.ObjectiveTo investigate the effects of AVP deficiency (by NIL), and the treatment with desmopressin (DP, a synthetic analog of AVP) and conivaptan (CNV, an AVP V1a‐V2 receptor antagonist) on the clinical symptoms of EAE, and to determine the serum levels of Interleukine‐2 (IL‐2), IL‐4, IL‐6, IL‐10, IL‐17A, INF‐γ and TNF‐α in the experimental groups.MethodsGroups of female Lewis rats were divided in: (1) Intact control (Control) (2) Control+EAE, (3) Sham‐operated (SHAM), (4) Control+CNV, (5) NIL and (6) NIL+DP. Except the Control the remaining groups were immunized for EAE three weeks post‐NIL. DP and CNV administrations started 3 days before EAE immunizations. Serum cytokines were analyzed by flow cytometry and EAE clinical symptoms were evaluated by a conventional numerical scale.ResultsEAE clinical symptoms, INF‐γ, TNF‐α, and the IL‐2, IL‐6 and IL‐17A were significantly decreased in both NIL and CNV groups, whereas the IL‐4 and IL‐10 increased in the CNV group. In NIL+DP group we found a significant increase in TNF‐α, whereas the IL‐4 was significantly decreased.Conclusions1) The present clinical and molecular findings demonstrate that AVP deficiency and the block of the AVP receptors decreased immune response, and that DP restores the susceptibility of the NIL animals to develop EAE. 2) The results strongly support that acting directly on the AVP receptors, AVP plays an important immuneregulatory role in the generation and maintenance of the immune‐competence, 3) AVP receptors may be therapeutic targets in the treatment of the human MS.Support or Funding InformationSupported by UAA‐PIFF14‐1 and CONACYT‐221262 (AQS). México.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Hypopituitarism is associated with lower oxytocin concentrations and reduced empathic ability

PurposeCentral diabetes insipidus is characterised by arginine vasopressin deficiency. Oxytocin is structurally related to vasopressin and is synthesised in the same hypothalamic nuclei, thus we hypothesised that patients with acquired central diabetes insipidus and anterior hypopituitarism would display an oxytocin deficiency. Moreover, psychological research has demonstrated that oxytocin influences social and emotional behaviours, particularly empathic behaviour. We therefore further hypothesised that central diabetes insipidus patients would perform worse on empathy-related tasks, compared to age-matched and gender-matched clinical control (clinical control-isolated anterior hypopituitarism) and healthy control groups.MethodFifty-six participants (age 46.54 ± 16.30 yrs; central diabetes insipidus: n = 20, 8 males; clinical control: n = 15, 6 males; healthy control: n = 20, 7 males) provided two saliva samples which were analysed for oxytocin and completed two empathy tasks.ResultsHypopituitary patients (both central diabetes insipidus and clinical control groups) had significantly lower oxytocin concentrations compared to healthy control participants. Hypopituitary patients also performed significantly worse on both the reading the mind in the eyes task and the facial expression recognition task compared to healthy control participants. Regression analyses further revealed that central diabetes insipidus patients’ oxytocin concentrations significantly predicted their performance on easy items of the reading the mind in the eyes task.ConclusionsHypopituitarism may therefore be associated with reduced oxytocin concentrations and impaired empathic ability. While further studies are needed to replicate these findings, our data suggest that oxytocin replacement may offer a therapeutic approach to improve psychological well-being in patients with hypopituitarism.

Liver cirrhosis reversion is improved in hamsters with a neurointermediate pituitary lobectomy

Regulating mechanisms of fibrosis is an important goal in the treatment of fibrosis and liver cirrhosis. The role of arginine vasopressin (AVP) in promoting fibrosis in several organs has been well documented. However, the result of an AVP deficiency during liver fibrosis has not been reported. We herein study the effects of an AVP deficiency, which was induced by neurointermediate pituitary lobectomy (NIL), on liver cirrhosis and liver cirrhosis reversion. Hamsters were intact (control) or underwent CCl4-induced cirrhosis, the latter animals divided into four groups: Cirrhotic, NIL-cirrhotic, Cirrhotic-reversion (R) and NIL-cirrhotic-R. Liver function, liver histopathology (including the fibrosis area and collagen types) and liver expression of MMP-13 and TIMP-2 were assessed. Results show that the AVP deficiency decreased the levels of alkaline phosphatase in serum and the expression of type I collagen and TIMP-2, and increased type III collagen deposition, MMP-13 expression and the size of regeneration nodules in NIL-cirrhotic and NIL-cirrhotic-R animals. A significantly greater recovery was found in the NIL-cirrhotic-R than the Cirrhotic-R group. We conclude that an AVP deficiency participates importantly in hamster liver regeneration by: 1) prompting the fibroblasts to produce type III collagen deposit, 2) influencing the activity of AP from bile duct cells, and 3) inhibiting TIMP-2 expression while favoring the fibrolytic activity of MMP-13.

Endocrine Considerations of the Pediatric Organ Donor.

Patients determined to be neurologically deceased exhibit potentially harmful changes in various endocrine pathways due to disruptions of the body's neurohormonal control mechanisms. These deviations from endocrine homeostasis lead to hemodynamic, metabolic, and immunologic aberrations that are associated with reduced graft procurement and function for the purposes of organ donation. Existing literature has attempted to describe the pathophysiology that associates disruptions in endocrine pathways with organ dysfunction, both to increase understanding and to identify strategies to support the donor. For example, diabetes insipidus due to arginine vasopressin deficiency is commonly encountered, and should be anticipated. The significance of abnormalities in other pathways such as those involving cortisol and thyroid hormone is less established; however, there is increasing support for treating potential organ donors with combined hormonal therapies. While there are published documents aimed at guiding management of organ donors in general, many controversies exist and pediatric-specific literature is scarce. This article aims to review several of the important endocrine-specific aspects of managing the neurologically deceased organ donor, with an emphasis on pediatrics where information is available.

Atypical Social Development in Vasopressin-Deficient Brattleboro Rats.

Over the past 3 decades, a large body of evidence has accumulated demonstrating that the neuropeptide arginine vasopressin (AVP) plays a critical role in regulating social behavior. The overwhelming majority of this evidence comes from adults, leaving a gap in our understanding of the role of AVP during development. Here, we investigated the effect of chronic AVP deficiency on a suite of juvenile social behaviors using Brattleboro rats, which lack AVP due to a mutation in the Avp gene. Social play behavior, huddling, social investigation & allogrooming, and ultrasonic vocalizations (USVs) of male and female rats homozygous for the Brattleboro mutation (Hom) were compared with their wild-type (WT) and heterozygous (Het) littermates during same-sex, same-genotype social interactions. Male and female Hom juveniles exhibited less social play than their Het and WT littermates throughout the rise, peak, and decline of the developmental profile of play. Hom juveniles also emitted fewer prosocial 50 kHz USVs, and spectrotemporal characteristics (call frequency and call duration) of individual call types differed from those of WT and Het juveniles. However, huddling behavior was increased in Hom juveniles, and social investigation and 22 kHz USVs did not differ across genotypes, demonstrating that not all social interactions were affected in the same manner. Collectively, these data suggest that the Avp gene plays a critical role in juvenile social development.

Central diabetes insipidus: clinical profile that suggests organicity in Peruvian children: Lima - Peru 2001-2013.

Central diabetes insipidus (CDI) is a heterogeneous disease caused by arginine vasopressin deficiency; its management implies a profound understanding of the pathophysiology and the clinical spectrum. The aim of the study was to describe the clinical characteristics that indicate organicity in children and adolescents with central diabetes insipidus treated at the Department of Endocrinology from The Child Health's Institute during 2001 to 2013. Cross-sectional, retrospective study. 79 cases of patients diagnosed with CDI (51 males and 28 females) from 1 month to 16 years of age were reviewed. For the descriptive analysis, measures of central tendency and dispersion were used; groups of organic and idiopathic CDI were compared using χ2-test and t-test. A p-value<0.05 was considered significant. The average age of patients was 8.1±4.2 years. Organic causes were intracranial tumors, 44 (55.7%), Langerhans cell histiocytosis (LCH), 11 (13.9%) and cerebral malformations in 7 (8.9%) patients, while the idiopathic group was 14 (17.7%) patients. Regarding clinical characteristics suggestive of organicity, headache (p=0.02) and visual disturbances (p=0.01) were found statistically significant. The anterior pituitary hormonal abnormalities were documented in 34 (52.3%) organic CDI patients. Furthermore, we did not find a significant difference in the average daily dose of desmopressin between patients with permanent vs. transitory CDI (0.81±0.65 vs. 0.59±0.62; p=0.363). The main clinical features suggestive of organicity in pediatric patients with central diabetes insipidus were headache and visual disturbances; furthermore, anterior pituitary hormonal abnormalities suggest an underlying organic etiology.

CT-proAVP IS NOT A GOOD PREDICTOR OF VASOPRESSOR NEED IN SEPTIC SHOCK.

Septic shock features a high hospital mortality. Improving our ability to risk stratify these patients at admission may help better define management strategies and design studies. The primary objective of this study was to determine if patients dead or with sustained vasopressor need at day 7 had a relative arginine vasopressin (AVP) deficiency as compared with vasopressor-free patients at day 7. Another objective was to explore if plasma CT-proAVP (C terminal part of preprovasopressin) measured within 24 h of sepsis onset could predict patient severity. This was a prospective observational study in a medical and surgical intensive care unit. One hundred thirteen patients were included in this analysis: 102 patients with severe sepsis or septic shock and 11 nonseptic controls. The CT-proAVP was measured at three time points within the first week after sepsis onset. The CT-proAVP measured within 24 h of sepsis onset failed to predict vasopressor need. More importantly, CT-proAVP plasma levels in patients with a sustained need of vasopressors did not differ from vasopressor-free patients at days 1 and 2. The CT-proAVP was more elevated in septic shock as compared with severe sepsis or nonseptic patients. When analyzing 28-day mortality, nonsurvivors featured higher levels of the CT-proAVP compared with survivors. Patients with septic shock and sustained need of vasopressors do not seem to present a relative AVP deficiency. In sepsis, the subgroup of patients that may benefit from AVP supplementation still needs to be identified. Our study further confirms previous data on the ability of the CT-proAVP to predict patient severity in severe sepsis and septic shock.

What's new on the HPA axis?

The human body depends on an integrated neuro-endocrine response in order to adapt to external and internal stressors. In critical illness this stress response coordinates endocrine, neural, cardiovascular and immune systems with the aim to maximize survival chances. The hypothalamus–pituitary–adrenal (HPA) axis, which also includes elements producing the neurohypophysial hormone arginine–vasopressin (AVP), is one the key effectors within this system [1]. Relative HPA or AVP deficiency contributes to cardiovascular collapse in critically ill patients, leading to the rationale of therapy with these hormones in shock. Recent developments have implicated copeptin, a by-product of the AVP precursor, as a novel biomarker for early stages of critical illness that could influence clinical decision-making.

Effects of arginine vasopressin deficiency on innate immunity in the rat

Immune and vascular endothelial cells possess arginine vasopressin (AVP) receptors. AVP is an important stimulating/regulatory hormone in acquired immunity, whereas its role on innate immunity (INIM) is not well known. Neurointermediate pituitary lobectomy (NIL) in the rat causes permanent low AVP serum levels. Here, we investigate the AVP and INIM relationship in NIL rats (3 weeks after surgeries) subject to INIM tests: Phagocytic index (PI) (peritoneal macrophages (Mθ) erytrophagocytosis), and Skin Evans blue extravasation‐histamine doses‐response test. In the Study 1, NIL group was compared against Intact control (IC), sham operated (SHAM) and anterior pituitary lobectomysed (AL) groups. In the study 2, NIL group was compared against IC, NIL+desmopressin (a synthetic analog of AVP) and IC+conivaptan (antagonist of V1a‐V2 AVP receptors) groups. Results: Study 1 showed that as compared with the IC and AL groups, PI was significant decreased in NIL animals. In the Evans blue extravasation‐histamine test study, a significant and similar increases of skin edema histamine doses‐dependent occurred in NIL and IC+conivaptan groups, whereas no significant differences in IC and NIL+desmopressin groups were appreciated.ConclusionAVP plays an important role in phagocytic activity of the peritoneal Mθ and for the stabilization of the vascular endothelial cells permeability during histamine inflammation.Supported by UAA‐PIFF 14‐1. Universidad Autónoma de Aguascalientes, México and the Jarislowsky and Lloyd Carr‐Harris Foundations.

Adipsia increases risk of death in patients with central diabetes insipidus

Central diabetes insipidus (CDI) is caused by deficiency of arginine vasopressin, an antidiuretic hormone. Patients with CDI manifest polyuria which is usually compensated for by increases in water intake. However, some patients are not able to sense thirst due to the destruction of osmoreceptors in the hypothalamus. These adipsic CDI patients are easily dehydrated and the consequent dehydration could be life-threatening. The objective of this study was to investigate the prognosis of adipsic CDI patients. We have reviewed 149 patients with CDI in three hospitals using databases of the electronic medical recording systems, and examined whether adipsia could affect the morbidity and mortality in CDI patients with multivariable analyses. Twenty-three patients with CDI were adipsic while the remaining 126 patients were non-adipsic. The multivariate analyses showed that the incidence of serious infections which required hospitalization was significantly higher in the adipsic CDI patients compared to that in non-adipsic CDI patients (p <0.001). A total of 6 patients with CDI died during the follow-up (median duration; 60 months, range 1 to 132 months). Four of them were adipsic, three of whom died of infection. The statistical analyses revealed that the risk of death in adipsic CDI patients was significantly higher than in non-adipsic patients (p =0.007). It is thus suggested that adipsic CDI patients were susceptible to serious infections which could be the causes of death.