Peripheral Blood Mononuclear Cell Oxytocin and Vasopressin Receptor Expression Positively Correlates with Social and Behavioral Function in Children with Autism.

The peptide hormone oxytocin is an established regulator of social function in mammals, and dysregulated oxytocin signaling is implicated in autism spectrum disorder (ASD). Several clinical trials examining the effects of intranasal oxytocin for improving social and behavioral function in ASD have had mixed or inclusive outcomes. The heterogeneity in clinical trials outcomes may reflect large inter-individual expression variations of the oxytocin and/or vasopressin receptor genes OXTR and AVPR1A, respectively. To explore this hypothesis we examined the expression of both genes in peripheral blood mononuclear cells (PBMC) from ASD children, their non-ASD siblings, and age-matched neurotypical children aged 3 to 16 years of age as well as datamined published ASD datasets. Both genes were found to have large inter-individual variations. Higher OXTR and AVPR1A expression was associated with lower Aberrant Behavior Checklist (ABC) scores. OXTR expression was associated with less severe behavior and higher adaptive behavior on additional standardized measures. Combining the sum expression levels OXTR, AVPR1A, and IGF1 yielded the strongest correlation with ABC scores. We propose that future clinical trials in ASD children with oxytocin, oxytocin mimetics and additional tentative therapeutics should assess the prognostic value of their PBMC mRNA expression of OXTR, AVPR1A, and IGF1.

Arginine vasopressin antagonism in heart failure: Current status and possible new directions.

Modulating neurohormonal imbalance is the cornerstone of successful therapy in patients with chronic heart failure with reduced ejection fraction (HFrEF). Plasma arginine vasopressin (AVP) levels are elevated in HFrEF and may contribute to disease progression by excess signaling at either the V1a or V2 receptors. The effects of V1a receptor antagonism are almost completely unexplored, but V1a signaling is closely related to that for angiotensin II and blocking that receptor deserves further study. Interfering with V2 signaling causes free water diuresis and improves congestion without worsening renal function when added to loop diuretics but alone did not improve outcomes when carried into the post-acute phase in one large study. Outcomes in chronic HFrEF are quite good while outcomes in acute HF remain poor. Therefore, further study of V2 or combined V1/V2 blockade of the effects of AVP would most likely yield positive results in patients with acute HF, perhaps especially as alternative, not adjunctive therapy to loop diuretics.

Prognostic Value of Copeptin in Chronic Kidney Disease: From General Population to End-Stage Renal Disease.

Arginine vasopressin (AVP), also known as antidiuretic hormone (ADH), is released in response to osmotic and non-osmotic stimuli and plays a key role in many physiologic and pathologic processes. The main function of AVP is the control of fluid homeostasis by inducing water conservation by the kidney, but it also stimulates arteriolar vasoconstriction and the release of adrenocorticotropic hormone (ACTH). These actions are mediated by different AVP receptors located on various target cells. Produced in hypothalamus from a larger precursor, pre-proAVP, AVP is produced in equimolar amounts to copeptin, a glycopeptide with yet unknown biologic function. Copeptin remains stable in plasma and its circulating concentrations correlate directly with those of AVP. Because AVP is unstable in isolated plasma or serum and its half-life is short, copeptin has become an easily measured surrogate marker reflecting vasopressin concentration. Recently, associations between high circulating copeptin and decline in glomerular filtration rate as well as greater risk of new-onset chronic kidney disease (CKD) have been reported. In addition, copeptin has been shown to be associated with increased risk of complications such as myocardial infarction, heart failure, diabetes mellitus and metabolic syndrome. In this brief review, studies on the prognostic value of copeptin measurement in the general population and in CKD are presented and discussed.

L-Carnitine Ameliorates the Decrease of Aquaporin 2 Levels in Rats with Cisplatin-Induced Kidney Injury.

BACKGROUND: It has been found that L-carnitine ameliorated cisplatin-induced acute kidney injury (AKI) in rats. However, the detailed role of L-carnitine in improving the renal urinary concentration function in cisplatin-induced AKI is not fully understood. METHODS: In this study, 30 Sprague-Dawley rats were divided randomly into 5 groups: control, cisplatin (CIS), L-carnitine (CAR), L-carnitine plus cisplatin (CAR + CIS), and cisplatin plus L-carnitine (CIS + CAR) groups. Cisplatin (7 mg/kg) and L-carnitine (300 mg/kg) were injected intraperitoneally. Urine (24 h) and blood samples were collected to analyze renal urinary concentrating function. Immunoblotting, confocal laser microscopy, and enzyme-linked immunosorbent assays were used to assess the level and localization of the water channel aquaporin (AQP) 2, and levels of stimulatory G protein α subunit (GSα protein), arginine vasopressin (AVP) receptor 2, adenylyl cyclase and serum AVP. RESULTS: Renal urinary concentrating function was improved by L-carnitine in rats with cisplatin-induced AKI. AQP2 expression, which decreased after cisplatin treatment, was improved by L-carnitine in different regions of the kidney. Moreover, our data indicated that L-carnitine could increase AQP2 accumulation at the apical plasma membranes of the renal-collecting ducts. Finally, intervention with L-carnitine effectively improved the expression of AQP2 upstream signaling proteins, such as GSα protein, adenylyl cyclase, and serum AVP levels in rats with cisplatin-induced AKI. CONCLUSION: L-carnitine resolves the cisplatin-induced urinary concentration defect, which may occur by increasing AVP/cyclic adenosine monophosphate/AQP2 levels, indicating the potential use of L-carnitine to ameliorate the renal urinary concentration effect in cancer patients treated with cisplatin.

Novel mutations underlying nephrogenic diabetes insipidus in Arab families.

PURPOSE: Nephrogenic Diabetes Insipidus (NDI) is genetically heterogeneous and may be inherited in an X-linked or autosomal recessive manner. We aimed to investigate the molecular basis of NDI among Arab families. METHODS: Direct sequencing of coding regions for AQP2 and AVPR2 was used to identify underlying mutations. One large deletion required Southern blot analysis and a PCR-based strategy to identify deletion junctions. RESULTS: We identified two novel missense mutations (AQP2:p.Gly100Arg and p.Gly180Ser) in AQP2 and one novel missense mutation (AVPR2:p.Gly122Asp), one previously reported missense mutation (AVPR2:p.Arg137His) and one novel contiguous deletion (AVPR2:c.25 + 273_ARHGAP4o:2650-420del) affecting AVPR2. We also describe evidence of lyonization associated with the novel deletion. CONCLUSIONS: Two novel mutations were identified in each of AVPR2 and AQP2 underlying CNDI in Arab families. Identification of these mutations will facilitate early diagnosis of CNDI, counseling of families and provide opportunities for early intervention aimed at reducing morbidity. The presence of affected females and consanguinity, as is often observed in Arab communities should not be used to rule out AVPR2 as a candidate when considering diagnostic testing. Careful observation of phenotypic heterogeneity should be used in referring such families for both AQP2 and AVPR2 molecular genetic testing.

The therapeutic potential of vasopressin receptor antagonists in congestive heart failure.

Hospitalisation of patients presenting with deteriorating congestive heart failure is occurring with increasing frequency and is associated with significant morbidity and mortality. Diuretic use, the mainstay therapy for congestion, is associated with electrolyte abnormalities and deteriorating renal function. In a recent randomised study, tolvaptan, a novel vasopressin antagonist, in addition to standard therapy including diuretics, increased net fluid loss resulting in decreased body weight more effectively than standard therapy alone in patients hospitalised for heart failure. This desirable effect was achieved without adversely affecting blood pressure, heart rate, electrolyte levels, or renal function. Although tolvaptan did not reduce the rate of deteriorating heart failure after discharge, post hoc analysis suggested that mortality might be reduced in high-risk patients treated with tolvaptan. These results make an important contribution to heart failure research, and offer an insight into the future role of vasopressin antagonism in the treatment of congestive heart failure.

Soluble adhesion molecules in Gilles de la Tourette's syndrome.

To investigate the immune-mediated response in TS, and its relationship with streptococcal infection, we measured serum levels of soluble intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin in patients with TS, compared to healthy and diseased controls. Soluble VCAM-1 and sE-selectin were significantly elevated in children and adults with TS, and sVCAM-1 was higher among anti-basal ganglia antibodies (ABGA)-positive adults with TS. No correlation of adhesion molecule levels to clinical severity or anti-streptococcal antibodies was observed. Children with Sydenham's chorea and paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) showed an increased level of sICAM-1, but not sVCAM-1 and sE-selectin. These results provide initial evidence for a role of adhesion molecules and systemic inflammation in TS, and support the hypothesis of an ongoing immune-mediated process in this condition.

Further neuroendocrine evidence of enhanced vasopressin V3 receptor responses in melancholic depression.

BACKGROUND: In situations of chronic stress vasopressin plays an important role in regulating the hypothalamic-pituitary adrenal axis. The aim of the current study was to investigate the role of anterior pituitary vasopressin V3 receptors in maintaining the hypercortisolism seen in melancholic depression. METHOD: Fourteen patients with major depression and 14 age- and sex-matched healthy comparison subjects were recruited. Desmopressin (ddAVP) 10 microg was given intravenously and ACTH and cortisol release was monitored for 120 min. RESULTS: The mean +/- S.E.M. ACTH response in the depressives was 28.4 +/- 4.3 ng/l and in the healthy subjects was 18.8 +/- 4.9 ng/l (P = 0.04). The mean +/- S.E.M. cortisol response in the depressives was 261.8 +/- 46.5 nmol/l and in the healthy subjects was 107.3 +/- 26.1 nmol/l (P < 0.01). CONCLUSIONS: Patients with major depression have augmented ACTH and cortisol responses to desmopressin indicating enhanced V3 responsivity.