V1a Receptor Research Articles

Upregulation of the hypothalamo-neurohypophysial system and activation of vasopressin neurones attenuates hyperalgesia in a neuropathic pain model rat

Arginine vasopressin (AVP) is a hypothalamic neurosecretory hormone well known as an antidiuretic, and recently reported to be involved in pain modulation. The expression kinetics of AVP and its potential involvement in the descending pain modulation system (DPMS) in neuropathic pain (NP) remains unclear. We investigated AVP expression and its effects on mechanical and thermal nociceptive thresholds using a unilateral spinal nerve ligation (SNL) model. All rats with SNL developed NP. Intensities of enhanced green fluorescent protein (eGFP) in the supraoptic and paraventricular nuclei, median eminence, and posterior pituitary were significantly increased at 7 and 14 days post-SNL in AVP-eGFP rats. In situ hybridisation histochemistry revealed significantly increased AVP mRNA expression at 14 days post-SNL compared with the sham control group. The chemogenetic activation of AVP neurones significantly attenuated mechanical and thermal hyperalgesia with elevated plasma AVP concentration. These analgesic effects were suppressed by pre-administration with V1a receptor antagonist. AVP neurones increased the neuronal activity of serotonergic dorsal raphe, noradrenergic locus coeruleus, and inhibitory interneurones in the spinal dorsal horn. These results suggest that the hypothalamo-neurohypophysial system of AVP is upregulated in NP and activated endogenous AVP exerts analgesic effects via the V1a receptors. AVP neurones may activate the DPMS.

Balovaptan vs Placebo for Social Communication in Childhood Autism Spectrum Disorder

There are no approved medications for the core symptoms of autism spectrum disorder (ASD), socialization and communication difficulties. To evaluate the efficacy and safety of balovaptan, an oral selective vasopressin 1a receptor antagonist, compared with placebo in children and adolescents with ASD. The aV1ation study was a randomized, double-blind, 24-week, parallel-group, placebo-controlled phase 2 trial. Between November 22, 2016, and September 3, 2019, individuals were screened and randomly assigned to treatment groups. The primary efficacy analysis population comprised participants taking age-adjusted balovaptan equivalent to a 10-mg adult dose and participants from the concurrently randomized placebo group. This multicenter trial took place across 41 sites in the US. Participants were aged 5 to 17 years with diagnosed ASD and an IQ of 70 or greater. Data were analyzed from April 8 to November 16, 2020. Participants were randomly assigned to daily 4-mg or 10-mg adult-equivalent balovaptan or placebo, until the 4-mg group was discontinued. The primary end point was change from baseline on the Vineland-II two-domain composite (2DC; socialization and communication domains) score at week 24. Between November 2016 and September 2019, a total of 599 individuals were screened and 339 participants were randomly assigned to receive 4-mg balovaptan adult-equivalent dose (91 [26.8%]), 10-mg balovaptan adult-equivalent dose (126 [37.2%]), or placebo (122 [36.0%]). Primary analysis included 86 participants assigned to receive 10-mg balovaptan adult-equivalent dose and 81 assigned to receive placebo (mean [SD] age, 12.1 [3.4] years; 139 male participants [83.2%]). No statistically significant differences were observed between the balovaptan and placebo groups in change from baseline on the Vineland-II 2DC score at week 24 (difference in adjusted least-squares mean, -0.16; 90% CI, -2.56 to 2.23; P = .91). No improvements for balovaptan vs placebo were observed at week 24 for any secondary end points. Balovaptan was well tolerated with no emerging safety concerns. Similar proportions of participants reported adverse events (balovaptan, 66 of 86 [76.7%] vs placebo, 61 of 81 [75.3%]) and serious adverse events (balovaptan, 1 of 86 [1.2%] vs placebo, 4 of 81 [4.9%]). In this randomized clinical trial, balovaptan did not demonstrate efficacy in improvement of socialization and communication in this population with pediatric ASD. Balovaptan was well tolerated in children 5 years or older. Further development of robust, sensitive, and objective outcome measures may help to improve future studies in the assessment of therapies targeting communication and socialization in pediatric ASD. ClinicalTrials.gov Identifier: NCT02901431.

Effect of Vasopressin V1a Receptor Blockade on Renal Osmoregulatory Function in L-Thyroxine-Induced Hyperthyroid Rats with Different Blood Vasopressin Levels

Effect of Vasopressin V1a Receptor Blockade on Renal Osmoregulatory Function in L-Thyroxine-Induced Hyperthyroid Rats with Different Blood Vasopressin Levels

PLCβ-Mediated Depletion of PIP2 and ATP-Sensitive K+ Channels Are Involved in Arginine Vasopressin-Induced Facilitation of Neuronal Excitability and LTP in the Dentate Gyrus.

Arginine vasopressin (AVP) serves as a neuromodulator in the brain. The hippocampus is one of the major targets for AVP, as it has been demonstrated that the hippocampus receives vasopressinergic innervation and expresses AVP receptors. The dentate gyrus (DG) granule cells (GCs) serve as a gate governing the inflow of information to the hippocampus. High densities of AVP receptors are expressed in the DG GCs. However, the roles and the underlying cellular and molecular mechanisms of AVP in the DG GCs have not been determined. We addressed this question by recording from the DG GCs in rat hippocampal slices. Our results showed that application of AVP concentration-dependently evoked an inward holding current recorded from the DG GCs. AVP depolarized the DG GCs and increased their action potential firing frequency. The excitatory effects of AVP were mediated by activation of V1a receptors and required the function of phospholipase Cβ (PLCβ). Whereas intracellular Ca2+ release and protein kinase C activity were unnecessary, PLCβ-induced depletion of phosphatidylinositol 4,5-bisphosphate was involved in AVP-evoked excitation of the DG GCs. AVP excited the DG GCs by depression of the ATP-sensitive K+ channels, which were required for AVP-elicited facilitation of long-term potentiation at the perforant path–GC synapses. Our results may provide a cellular and molecular mechanism to explain the physiological functions of AVP, such as learning and memory, and pathologic disorders like anxiety.

Management of Decongestion in Acute Heart Failure: Time for a New Approach?

As the primary cause of hospitalization in acute heart failure (AHF) patients, congestion was responsible for a higher risk of mortality, rehospitalization, and renal dysfunction in AHF patients. Although loop diuretic was routinely used as the mainstay of AHF therapy, it is still ineffective to obtain the euvolemic state in most hospitalized AHF patients. Therefore, a higher loop diuretic dose was often required to increase the decongestion effect. However, consequently, it can cause several detrimental complications, including renal dysfunction, neurohormonal activation, hyponatremia, hypokalaemia, and reduced blood pressure, which eventually result in poor prognosis. Hence, the new approach may be proposed to optimize decongestion in acute phase, including the use of arginine vasopressin V2 receptor antagonist – Tolvaptan. As an additive therapy to loop diuretic in AHF patients, it can be considered due to its several beneficial effects, including greater decongestion effect, lowered worsening renal function incidence, counteract neurohormonal activation, neutralized hyponatraemic state, no alteration of potassium metabolism, stabilize the blood pressure, and reduced requirement of a higher dose of loop diuretic to achieve an equal or even greater decongestion effect compared to a high dose of loop diuretic alone. Tolvaptan provided favourable outcomes in several specific populations and was considered safe with several mild adverse effects. Several guidelines across countries have approved the use of Tolvaptan in AHF patients with or without hyponatremia. The initial dose of Tolvaptan was 7.5 to 15 mg and can be titrated up to 30 mg. However, further studies were still required to determine the timing dose and optimal dose of Tolvaptan in general and elderly populations with AHF, respectively.

Clinical Implication of Tolvaptan in Patients with Autosomal Dominant Polycystic Kidney Disease

Tolvaptan, a non-peptide arginine vasopressin V2 receptor antagonist, is a newly developed drug to reduce kidney volume and preserve kidney function in autosomal dominant polycystic kidney disease (ADPKD) patients. We aimed to evaluate the descriptive characteristics of patients according to the use of tolvaptan. Also, we tried to find the efficacy of tolvaptan on kidney volume and kidney function. We included patients with ADPKD who visited a tertiary hospital in South Korea during Sep. 2018 and Apr. 2022. The data was acquired from the Electric Medical Records system. A total of 64 patients were included in the study, and there were 33 (51.6%) patients taking tolvaptan during follow-up periods. During 17.8 ± 13.1 months of follow-up periods, estimated glomerular filtration rate (eGFR) changes were 89.4% compared to the baseline eGFR. Although the latest eGFR was lower in patients with tolvaptan (55.9 ± 24.7 mL/min/1.73 m2) than without tolvaptan (68.4 ± 35.1 mL/min/1.73 m2), there was no statistical significance (p = 0.108). We found that the mean change of height-adjusted total kidney volume (HtTKV) was -2.7% based on the baseline HtTKV in patients taking tolvaptan for more than 1-year. Although there was no statistical significance, the mean change of HtTKV was the highest in patients with 1E of Mayo classification (-4.3%). To anticipate the solid data on the efficacy of tolvaptan in the Asian population, more aggressive efforts are needed to search for suitable patients accompanied by appropriate monitoring over a more extended period. Keywords: Chronic kidney disease, Polycystic kidney, autosomal dominant, Tolvaptan

Large multicenter randomized trials in autism: key insights gained from the balovaptan clinical development program

BackgroundAutism spectrum disorder (ASD) is a common and heterogeneous neurodevelopmental condition that is characterized by the core symptoms of social communication difficulties and restricted and repetitive behaviors. At present, there is an unmet medical need for therapies to ameliorate these core symptoms in order to improve quality of life of autistic individuals. However, several challenges are currently faced by the ASD community relating to the development of pharmacotherapies, namely in the conduct of clinical trials. Balovaptan is a V1a receptor antagonist that has been investigated to improve social communication difficulties in individuals with ASD. In this viewpoint, we draw upon our recent first-hand experiences of the balovaptan clinical development program to describe current challenges of ASD trials.Discussion pointsThe balovaptan trials were conducted in a wide age range of individuals with ASD with the added complexities associated with international trials. When summarizing all three randomized trials of balovaptan, a placebo response was observed across several outcome measures. Placebo response was predicted by greater baseline symptom severity, online recruitment of participants, and less experienced or non-academic trial sites. We also highlight challenges relating to selection of outcome measures in ASD, the impact of baseline characteristics, and the role of expectation bias in influencing trial results.ConclusionTaken together, the balovaptan clinical development program has advanced our understanding of the key challenges facing ASD treatment research. The insights gained can be used to inform and improve the design of future clinical trials with the collective aim of developing efficacious therapies to support individuals with ASD.

Social Interactions Increase Activation of Vasopressin-Responsive Neurons in the Dorsal Raphe

Social interactions play an important role in our daily lives and can profoundly impact our health for better and worse. To better understand the neural circuitry underlying social behavior, we focused on neural circuits involving vasopressin neurons of the bed nucleus of the stria terminalis (BNST) and serotonin neurons of the dorsal raphe (DR). Previous research shows that BNST vasopressin neurons are activated in male mice by interaction with a female and that vasopressin indirectly excites serotonin neurons. In our studies, we tested the hypothesis that specific social interactions would also activate neurons in the DR, specifically vasopressin 1A receptor (Avpr1a)-expressing neurons, which may be direct targets of the BNST vasopressin neurons. Using in separate experiments immunohistochemistry and in situ hybridization, we found that male and female subjects exposed to a female conspecific show activation in the DR, and the activated neurons include populations of Avpr1a-expressing and other non-serotonergic, non-Avpr1a neurons in roughly equal numbers. Avpr1a neurons in the DR constitute a largely undocumented neuron population. Electrophysiological data suggest that most DR Avpr1a neurons behave like fast spiking interneurons found in other brain regions. Examination of RNAseq and in situ hybridization data suggests that there are glutamatergic, GABAergic, and serotonergic subtypes of Avpr1a neurons in the DR. Together our data support a model in which a subset of vasopressin-responsive interneurons in the DR may relay stimulus specific social signals from the forebrain BNST to the serotonergic DR system, which could help direct prosocial stimulus specific behavioral responses.

CRISPR-Cas9 editing of the arginine–vasopressin V1a receptor produces paradoxical changes in social behavior in Syrian hamsters

Studies from a variety of species indicate that arginine–vasopressin (AVP) and its V1a receptor (Avpr1a) play a critical role in the regulation of a range of social behaviors by their actions in the social behavior neural network. To further investigate the role of AVPRs in social behavior, we performed CRISPR-Cas9–mediated editing at the Avpr1a gene via pronuclear microinjections in Syrian hamsters (Mesocricetus auratus), a species used extensively in behavioral neuroendocrinology because they produce a rich suite of social behaviors. Using this germ-line gene-editing approach, we generated a stable line of hamsters with a frame-shift mutation in the Avpr1a gene resulting in the null expression of functional Avpr1as. Avpr1a knockout (KO) hamsters exhibited a complete lack of Avpr1a-specific autoradiographic binding throughout the brain, behavioral insensitivity to centrally administered AVP, and no pressor response to a peripherally injected Avpr1a-specific agonist, thus confirming the absence of functional Avpr1as in the brain and periphery. Contradictory to expectations, Avpr1a KO hamsters exhibited substantially higher levels of conspecific social communication (i.e., odor-stimulated flank marking) than their wild-type (WT) littermates. Furthermore, sex differences in aggression were absent, as both male and female KOs exhibited more aggression toward same-sex conspecifics than did their WT littermates. Taken together, these data emphasize the importance of comparative studies employing gene-editing approaches and suggest the startling possibility that Avpr1a-specific modulation of the social behavior neural network may be more inhibitory than permissive.

Systemic and local administration of vasopressin differently affect hemodynamic and respiratory parameters in normotensive and hypertensive rats

IntroductionUpregulation of vasopressinergic system and increased chemoreflex activity contribute to essential hypertension. Vasopressin (AVP) V1a receptors (V1aRs) were found in the brain stem structures involved in the control of breathing and in the carotid bodies (CBs). It has also been shown that in normotensive rats intravenous (i.v.) and local (intra‐carotid, i.a.) AVP administration results in different hemodynamic and respiratory response.PurposeWe aimed at finding out how systemic (i.v.) and local (i.a.) administration of AVP affects cardiorespiratory system via V1aRs in normo‐ and hypertensive rats and if V1aRs are expressed in CBs in spontaneously hypertensive (SHR) and normotensive Wistar‐Kyoto (WKY) rats.MethodsThe study was performed on urethane‐anesthetized adult male WKY (n=7) and SHR rats (n=7). Animals were implanted with vascular catheters into femoral vein (i.v. infusions), femoral artery (hemodynamic parameters) and external carotid artery (local infusions), as well as the tracheal tube (respiratory parameters) and subcutaneous ECG electrodes. After obtaining baseline parameters, the arterial chemoreflex was triggered with i.v. administration of potassium cyanide (KCN) (30 μg/100 μL). Bolus of AVP was given i.v. (10 ng/100 μL) and i.a. (5 ng/50 μL). After stabilization of hemodynamic and respiratory parameters, V1a receptor was blocked by administration of V1aR antagonist (d(CH2)51,Tyr(Me)2,Arg8)‐Vasopressin; 5 μg/100 μL) and AVP and KCN infusions were repeated. After measurements, carotid bodies (CBs) were collected and immunostained for V1aRs and visualized with confocal microscopy.ResultsResting mean arterial blood pressure (MABP), heart rate (HR) and minute ventilation (MV) were significantly higher in SHR rats than in WKY control. In both groups hemodynamic and respiratory response to pharmacological trigger of the reflex occurred, however increase in MABP and MV were significantly greater in SHR than in WKY rats. Intravenous AVP administration caused an increase in MABP, but ventilatory inhibition only in SHR rats. Intra‐arterial AVP infusion caused a modest increase in MABP in both groups, but inhibition of ventilation only in SHR rats. Blockade of V1aR abolished the effects of both systemic and local AVP administration. Furthermore, V1aR antagonist decreased the pressor component of the chemoreflex, however it did not influence ventilatory response. Immunostaining revealed V1aRs in CBs in both groups.ConclusionsOur findings show that enhanced cardiorespiratory responses to activation of arterial chemoreflex and augmented pressor and ventilatory effects of systemic and local administrations of AVP are present in hypertensive rats and depend on V1aRs. Presence of V1aRs in CBs suggests that AVP may control cardiorespiratory system via arterial chemoreceptors.

The Impact of Avpr1a Expression and Host-Microbiome Interactions on Visceral Hypersensitivity

Visceral hypersensitivity (VH) is commonly cited as a major driver of chronic abdominal pain in "functional" gastrointestinal disorders (e.g., irritable bowel syndrome) where persistent and/or recurrent abdominal pain is the primary unifying symptom regardless of any alterations in bowel habits. The complexity of VH is in part influenced by genetic factors and individual differences in gut microbiome composition, yet specific mechanisms that generate VH remain incompletely understood. Correspondingly, current treatments to primarily focus on symptom management rather than targeting physiological mechanisms responsible for generating VH. We have begun to examine the role of genetic susceptibility and microbiome response dynamics in VH development using a preclinical model of intracolonic zymosan (ZYM) administration in which there are strain differences to VH susceptibility. Preliminary data reveals differential susceptibility between ZYM-induced VH in two closely related C57BL/6 sub strains, one from Taconic Biosciences (C57BL/6NTac) and the other from Jackson Laboratory (C57BL/6J). We have identified a VH candidate gene that encodes the arginine-vasopressin receptor 1A (AVPR1A) protein. We have further observed dynamic strain differences in the location and composition of the gut microbiome in response to ZYM corresponding to VH susceptibility. Ongoing studies are focused on teasing apart the potential bidirectional relationship(s) between genetic susceptibility and host-microbiome interactions in the etiology of VH. Identifying underlying mechanisms that drive VH would provide novel targets for pharmacological intervention and decrease reliance on opioids, which are prescribed at a significantly higher rate to patients who report abdominal pain with no accompanying structural disease. Grant support from R21 NS104789/NS/NINDS (KMB), R03 NS096454/NS/NINDS (KMB), Rita Allen Foundation Award in Pain (KMB), P20GM103418 (EEY and KMB), and a K-INBRE recruitment startup package.

Inverse Neurovascular Coupling Contributes to Vasopressin Neuronal Activation in Response to Systemic Homeostatic Challenge

Neurovascular coupling (NVC), the process that links neuronal activity to cerebral blood flow changes, has been mainly studied in superficial brain areas, namely the neocortex. Still, whether the conventional, rapid and spatially restricted NVC response can be generalized to deeper, and functionally diverse brain regions remains unknown. The hypothalamic supraoptic nucleus (SON) is a deep brain region with unique cytoarchitectural properties including a high vascularization. Paradoxically, the dense vascular network is not required to maintain its metabolic demand. This mismatch in metabolic supply and demand suggests that the SON vasculature may serve additional functions beyond the delivery of energy substrates. To address this important gap in our knowledge, we set up the objective to implement a novel experimental approach to enable in vivo, real‐time two‐photon imaging from the ventral surface of the brain to monitor SON NVC responses to a systemic homeostatic challenge. Using this approach in anaesthetized male and female transgenic rats expressing GFP driven by the vasopressin (VP) promoter (VP‐GFP rats), we found that a systemic hypertonic saline (HTS) infusion evoked a gradual and linear increase in the firing rate of VP neurons (p < 0.0001; n = 4). Rather than resulting in a classical vasodilatory NVC, the increased VP neuronal activity was accompanied by a significant intraparenchymal arteriole (but not venule) vasoconstriction (one‐way RM ANOVA; p < 0.0001; n = 13 vessels from 5 rats). This “inverse” NVC was prevented when a VP V1a receptor antagonist was locally delivered within the SON (one‐way RM ANOVA; p < 0.0001; n = 4 vessels from 4 rats). The HTS infusion also significantly decreased RBC velocity in SON capillaries (one‐way RM ANOVA; p < 0.0001; n = 17 vessels from 6 rats) indicative of a decreased SON blood flow. The salt‐induced inverse NVC response resulted in a rapid and progressive decrease in SON pO2 (one‐way RM ANOVA; p < 0.002; n = 6 rats), along with an increased expression of the hypoxia inducible factor (HIF)‐1a mRNA (p < 0.001; one‐sample t test n = 6 rats). Finally, we show that a hypoxic SON microenvironment significantly increased the firing activity of VP neurons in ex vivo slices (p < 0.02; paired t test; n = 14 cells from 10 rats). Taken together, we show that the salt‐induced inverse NVC in the SON results in a hypoxia‐mediated positive feedback mechanism, which we propose contributes to sustain the activity of VP neurons in response to a systemic homeostatic challenge.

Ac3IV, a V1a and V1b receptor selective vasopressin analogue, protects against hydrocortisone-induced changes in pancreatic islet cell lineage

The Avpr1a (V1a) and Avpr1b (V1b) receptor selective, vasopressin (AVP) analogue, Ac3IV has been shown to improve metabolism and pancreatic islet structure in diabetes and insulin resistance. The present study further investigates these actions by assessing the ability of Ac3IV to protect against pancreatic islet architectural disturbances induced by hydrocortisone (HC) treatment in transgenic Ins1Cre/+;Rosa26-eYFP mice, that possess beta-cell lineage tracing capabilities. HC intervention increased (p < 0.001) energy intake but reduced (p < 0.01) body weight gain, with no impact of Ac3IV. All HC mice had reduced (p < 0.05) circulating glucose, but plasma insulin and glucagon concentrations remained unchanged. However, HC mice presented with increased (p < 0.001) pancreatic insulin content, which was further augmented by Ac3IV. In addition, Ac3IV treatment countered HC-induced increases in islet-, beta- and alpha-cell areas (p < 0.01), as well as promoting islet number towards control levels. This was accompanied by reduced (p < 0.05) beta-cell growth, but enhanced (p < 0.001) alpha-cell proliferation. There were no changes in islet cell apoptotic rates in any of the groups of HC mice, but co-expression of CK19 with insulin in pancreatic ductal cells was reduced by Ac3IV. Assessment of beta-cell lineage revealed that Ac3IV partially protected against HC-mediated de-differentiation of mature beta-cells, whilst also decreasing (p < 0.01) beta- to alpha-cell transdifferentiation. Our data indicate that sustained activation of V1a and V1b receptors exerts positive islet cell transition effects to help retain beta-cell identity in HC mice.

Contrasting central and systemic effects of arginine-vasopressin on urinary marking behavior as a social signal in male mice

Arginine-vasopressin (AVP) is a neurohypophyseal peptide that plays a critical role in the regulation of social behavior in mammals. Neuronal AVP regulates male-specific social signaling processes, such as exocrine urinary scent deposition and marking behavior in mice. In the periphery, AVP is transported to the portal bloodstream and acts as an antidiuretic hormone. These AVP dynamics imply that the central role of AVP in the stimulation of urinary marking is dissociated with the peripheral role of AVP in the retention of osmotic conditions. Using male BALB/c mice as subjects, peripheral injection of AVP decreased urinary marking and urination. In contrast, a central infusion of AVP facilitated urinary marking with no effect on urination, while an antagonist of the AVP 1a receptor inhibited marking. Centrally AVP-injected mice also exhibited typical behaviors, such as hiccough/sneeze-like reactions and flash scratching, particularly when confronted with a stimulus mouse through a wire mesh screen. Significant expression of these typical reactions in these mice resulted in the disruption of marking deposition. Further analysis of AVP synthesis illustrated that AVP levels increased in the midbrain but not in the circulation immediately after the test, particularly when confronted with a stimulus mouse. The central AVP regulates urinary marking and other typical behaviors in a dose- and situation-dependent manner. The sequential process implies that centrally synthesized AVP may be secreted into the circulation following immediate neuronal processes, and then peripheral AVP acts as an antidiuretic hormone on urinary marking behavior.

Placebo effects and participant heterogeneity in clinical trials of autism spectrum disorder

In The Lancet Psychiatry, Suma Jacob and colleagues report the largest randomised controlled trial so far published of pharmacological treatment for autistic adults. 1 Jacob S Veenstra-Vander Weele J Murphy D et al. Efficacy and safety of balovaptan for socialisation and communication difficulties in autistic adults in North America and Europe: a phase 3, randomised, placebo-controlled trial. Lancet Psychiatry. 2022; (published online Feb 10.)https://doi.org/10.1016/S2215-0366(21)00429-6 Google Scholar This phase 3 multicentre trial (V1aduct) tested the efficacy and safety of balovaptan, a selective brain-penetrant receptor antagonist of the vasopressin 1a (V1a) receptor, on social adaptive behaviour, as measured by the Vineland-II two-domain composite (2DC) score, a composite of the Vineland-II socialisation and communication domains. The trial was discontinued following futility analyses after 50% of participants completed the week 24 follow-up visit, which found least-squares mean changes in Vineland-II 2DC scores of 2·91 (SE 1·52) in the balovaptan group (n=79) and 4·75 (1·60) in the placebo group (n=71), with an estimated treatment difference of −1·84 (95% CI −5·15 to 1·48). Efficacy and safety of balovaptan for socialisation and communication difficulties in autistic adults in North America and Europe: a phase 3, randomised, placebo-controlled trialBalovaptan did not improve social communication in autistic adults. This study provides insights into challenges facing autism spectrum disorder trials, including the considerable placebo response and the selection of appropriate outcome measures. Full-Text PDF

Efficacy and safety of balovaptan for socialisation and communication difficulties in autistic adults in North America and Europe: a phase 3, randomised, placebo-controlled trial

There are no approved pharmacological therapies to support treatment of the core communication and socialisation difficulties associated with autism spectrum disorder in adults. We aimed to assess the efficacy, safety, and pharmacokinetics of balovaptan, a vasopressin 1a receptor antagonist, versus placebo in autistic adults. V1aduct was a phase 3, randomised, placebo-controlled, double-blind trial, conducted at 46 sites across six countries (the USA, the UK, France, Italy, Spain, and Canada). Eligible participants were aged 18 years or older with an intelligence quotient (IQ) of 70 or higher, and met the criteria for moderate-to-severe autism spectrum disorder (DSM-5 and Autism Diagnostic Observation Schedule). Participants were randomly allocated (1:1), with an independent interactive voice or web-based response system, to receive balovaptan (10 mg) or placebo daily for 24 weeks. Randomisation was stratified by an individual's baseline Vineland-II two-domain composite (2DC) score (<60 or ≥60), sex, region (North America or rest of world), and age (<25 years or ≥25 years). Participants, study site personnel, and the sponsor were masked to treatment assignment. The primary endpoint was change from baseline in Vineland-II 2DC score (the mean composite score across the Vineland-II socialisation and communication domains) at week 24. The primary analysis was done with ANCOVA in the intention-to-treat population. The V1aduct study was terminated for futility after around 50% of participants completed the week 24 visit. This trial is registered with ClinicalTrials.gov (NCT03504917). Between Aug 8, 2018, and July 1, 2020, 540 people were screened for eligibility, of whom 322 were allocated to receive balovaptan (164 [51%]) or placebo (158 [49%]). One participant from the balovaptan group was not treated before trial termination and was excluded from the analysis. 60 participants in the balovaptan group and 55 in the placebo group discontinued treatment before week 24. The sample consisted of 64 (20%) women and 257 (80%) men, with 260 (81%) participants from North America and 61 (19%) from Europe. At baseline, mean age was 27·6 years (SD 9·7) and mean IQ score was 104·8 (18·1). Two (1%) participants were American Indian or Alaska Native, eight (2%) were Asian, 15 (5%) were Black or African American, 283 (88%) were White, four (1%) were of multiple races, and nine (3%) were of unknown race. Mean baseline Vineland-II 2DC scores were 67·2 (SD 15·3) in the balovaptan group and 66·2 (17·7) in the placebo group. The interim futility analysis showed no improvement for balovaptan versus placebo in terms of Vineland-II 2DC score at week 24 compared with baseline, with a least-squares mean change of 2·91 (SE 1·52) in the balovaptan group (n=79) and 4·75 (1·60) in the placebo group (n=71; estimated treatment difference -1·84 [95% CI -5·15 to 1·48]). In the final analysis, mean change from baseline in Vineland-II 2DC score at week 24 was 4·56 (SD 10·85) in the balovaptan group (n=111) and 6·83 (12·18) in the placebo group (n=99). Balovaptan was well tolerated, with similar proportions of participants with at least one adverse event in the balovaptan group (98 [60%] of 163) and placebo group (104 [66%] of 158). The most common adverse events were nasopharyngitis (14 [9%] in the balovaptan group and 19 [12%] in the placebo group), diarrhoea (11 [7%] and 14 [9%]), upper respiratory tract infection (ten [6%] and nine [6%]), insomnia (five [3%] and eight [5%]), oropharyngeal pain (five [3%] and eight [5%]), and dizziness (two [1%] and ten [6%]). Serious adverse events were reported for two (1%) participants in the balovaptan group (one each of suicidal ideation and schizoaffective disorder), and five (3%) participants in the placebo group (one each of suicidal ideation, panic disorder, limb abscess, urosepsis, colitis [in the same participant with urosepsis], and death by suicide). No treatment-related deaths occurred. Balovaptan did not improve social communication in autistic adults. This study provides insights into challenges facing autism spectrum disorder trials, including the considerable placebo response and the selection of appropriate outcome measures. F Hoffmann-La Roche.

Role of linkage between cerebral activity and baroreflex control of heart rate via central vasopressin V1a receptors in food-deprived mice.

We previously reported that cerebral activation at the onset of voluntary locomotion suppressed baroreflex control of heart rate (HR) and increased arterial pressure via vasopressin V1a receptors in the brain. Here, we examined whether these responses were associated with food seeking, a motivated behavior, using free-moving wild type (WT, n = 10), V1a receptor knockout (KO, n = 9), and wild-type mice locally infused with a V1a receptor antagonist into the nucleus tractus solitarii (BLK, n = 10). For three consecutive days, mice were fed ad libitum (Fed), food deprived (FD), and refed (RF) under a dark/light cycle (1900/0700). Food was removed on day 2 and restored on day 3 at 1800. Throughout the protocol, cerebral activity was determined from the power density ratio of θ- to δ-wave band (θ/δ) by electroencephalogram every 4 s. Baroreflex was evaluated by the cross-correlation function [R(t)] between changes in HR and arterial pressure every 4 s. The cerebro-baroreflex linkage was then evaluated by the cross-correlation function between θ/δ and R(t). Behavior was recorded with CCD camera. We found that cerebro-baroreflex linkage, enhanced in WT at night after FD (P = 0.006), returned to Fed level after RF (P = 0.68). Similarly, food-seeking behavior increased after FD to a level twofold higher than during Fed (P < 0.001) and returned to Fed level after RF (P = 0.54). However, none of these changes occurred in KO or BLK (P > 0.11). Thus, the suppression of baroreflex control of HR linked with cerebral activation via central V1a receptors might play an important role at the onset of motivated behaviors, such as food seeking induced by FD.NEW & NOTEWORTHY Motivated behaviors, characterized by goal-directed and persistent movements, are indispensable for living. However, how cerebro-cardiovascular adjustment occurs during such behaviors remains unknown. By focusing on food-seeking behavior in a food-deprived condition using free-moving mice, we found that this condition enhanced the linkage between cerebral activation and suppression of baroreflex control of heart rate through central vasopressin V1a receptors, making it easier to start motivated behaviors by enhancing pressor response.

The Role of OXT, OXTR, AVP, and AVPR1a Gene Expression in the Course of Schizophrenia.

Schizophrenia is a serious and chronic mental illness, the symptoms of which usually appear for the first time in late adolescence or early adulthood. To date, much research has been conducted on the etiology of schizophrenia; however, it is still not fully understood. Oxytocin and vasopressin as neuromodulators that regulate social and emotional behavior are promising candidates for determining the vulnerability to schizophrenia. The aim of this study was to evaluate the expression of OXT, OXTR, AVP, and AVPR1a genes at the mRNA and protein levels in patients with schizophrenia. Due to the neurodegenerative nature of schizophrenia, the study group was divided into two subgroups, namely, G1 with a diagnosis that was made between 10 and 15 years after the onset of the illness, and G2 with a diagnosis made up to two years after the onset of the illness. Moreover, the relationship between the examined genes and the severity of schizophrenia symptoms, assessed using PANSS (Positive and Negative Syndrome Scale) and CDSS scales (Clinical Depression Scale for Schizophrenia) was evaluated. The analysis of the expression of the studied genes at the mRNA and protein levels showed statistically significant differences in the expression of all the investigated genes. OXT and AVPR1a gene expression at both the mRNA and protein levels were significantly lower in the schizophrenia group, and OXTR and AVP gene expression at both the mRNA and protein levels was higher in the schizophrenia subjects than in the controls. Furthermore, a significant correlation of OXT gene expression at the mRNA and protein levels with the severity of depressive symptoms in schizophrenia as assessed by CDSS was found.

Oxytocin Facilitates Allomaternal Behavior under Stress in Laboratory Mice.

Oxytocin (Oxt) controls reproductive physiology and various kinds of social behaviors, but the exact contribution of Oxt to different components of parental care still needs to be determined. Here, we illustrate the neuroanatomical relations of the parental nurturing-induced neuronal activation with magnocellular Oxt neurons and fibers in the medial preoptic area (MPOA), the brain region critical for parental and alloparental behaviors. We used genetically-targeted mouse lines for Oxt, Oxt receptor (Oxtr), vasopressin receptor 1a (Avpr1a), vasopressin receptor 1b (Avpr1b), and thyrotropin-releasing hormone (Trh) to systematically examine the role of Oxt-related signaling in pup-directed behaviors. The Oxtr-Avpr1a-Avpr1b triple knock-out (TKO), and Oxt-Trh-Avpr1a-Avpr1b quadruple KO (QKO) mice were grossly healthy and fertile, except for their complete deficiency in milk ejection and modest deficiency in parturition secondary to maternal loss of the Oxt or Oxtr gene. In our minimal stress conditions, pup-directed behaviors in TKO and QKO mothers and fathers, virgin females and males were essentially indistinguishable from those of their littermates with other genotypes. However, Oxtr KO virgin females did show decreased pup retrieval in the pup-exposure assay performed right after restraint stress. This stress vulnerability in the Oxtr KO was abolished by the additional Avpr1b KO. The general stress sensitivity, as measured by plasma cortisol elevation after restraint stress or by the behavioral performance in the open field (OF) and elevated plus maze (EPM), were not altered in the Oxtr KO but were reduced in the Avpr1b KO females, indicating that the balance of neurohypophysial hormones affects the outcome of pup-directed behaviors.

Blockade of vasopressin receptors reduces the threshold pressure of micturition reflex in female rats.

The mechanisms involved in urinary bladder control are not fully understood, but it is well accepted that a complex central network is involved in micturition control. The micturition reflex can be modulated by direct cortical influence through facilitatory and inhibitory mechanisms. In addition, humoral mechanisms are involved in the bladder control. Vasopressin increases bladder contraction and intravesical pressure. This study sought to investigate the effect of intravenous injections of vasopressin receptor antagonists on cystometric parameters in anesthetized female rats. Isoflurane anesthetized adult female Wistar rats underwent femoral artery and vein cannulation for arterial pressure (AP) and heart rate (HR) recordings, and infusion of drugs, respectively. The bladder was also cannulated for intravesical pressure (IP) recordings and infusion of saline (10 mL/h) for cystometric evaluation. After baseline AP, HR and IP recordings, saline (vehicle, 1 mL/kg), V1a (5 μg/kg) or V2 receptor antagonist (5 μg/kg) was injected i.v. and after 25 min the cystometry was carried out. Neither saline nor V1a or V2 receptor blockade evoked any change in AP, HR and IP. Nevertheless, during cystometry, the threshold pressure of the micturition reflex was significantly reduced in rats with V1a (to 19.30 ± 2.39 mmHg) and V2 receptor blockade (to 19.88 ± 2.49 mmHg) compared to the saline group (28.85 ± 2.06 mmHg, p = 0.014). No difference was observed in the other cystometric parameters. Therefore, the data suggest that blockade of V1a and V2 receptors reduces the threshold pressure of the micturition reflex and does not influence other cystometric parameters in anesthetized female Wistar rats.