V1a Receptor Research Articles

Efficacy and safety of balovaptan for posttraumatic stress disorder: A randomized, placebo-controlled trial.

Posttraumatic stress disorder (PTSD) has a significant impact on quality of life and affects more than 13 million individuals in the United States, with limited treatments available. EXUVIA (NCT05401565) was a Phase 2, randomized, placebo-controlled, double-blind trial, conducted across eight sites in the United States. The study aimed to assess the efficacy, safety, and pharmacokinetics of balovaptan, a highly selective vasopressin 1a receptor antagonist, in adults with PTSD. Between August 2022 and October 2023, a total of 57 adult participants (aged 18-60 years) were screened, and 29 participants were randomly allocated (1:1) to receive either balovaptan (13/29 [44.8%]) or placebo (16/29 [55.2%]). No meaningful differences were observed for balovaptan (-17.2 [± 10.7]) versus placebo (-15.6 [± 10.7]) as measured by the primary endpoint of change from baseline at Week 12 in Clinician-Administered PTSD Scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition total symptom severity score. No meaningful differences for balovaptan versus placebo were observed at Week 12 for any secondary endpoints. Balovaptan was well tolerated with no new safety findings. The number of participants with at least one adverse event of any intensity was 9/13 (69.2%) in the balovaptan group and 7/16 (43.8%) in the placebo group. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Implication of vasopressin receptor genes (AVPR1A and AVPR1B) in the susceptibility to polycystic ovary syndrome

BackgroundPolycystic ovary syndrome (PCOS) is a complex heterogenous disorder manifesting with various reproductive, endocrine, and metabolic derangements such as insulin resistance and hyperglycemia. The arginine vasopressin peptide (AVP), also called or antidiuretic hormone (ADH), modulates metabolic functions such as glucose hemostasis, insulin sensitivity, and lipid metabolism via binding to two central and peripheral receptors (AVPR1A and AVPR1B). In the present study, we aimed to detect whether the AVPR1A and AVPR1B genes confer risk for PCOS.MethodsIn peninsular Italian families, we tested 7 variants in the AVPR1B gene and 2 variants in the AVPR1A gene via Pseudomarker for linkage and linkage joint to association (i.e.., linkage disequilibrium) with PCOS.ResultsWe identified two risk variants in each gene, significantly associated with the risk of PCOS.ConclusionTo the best of our knowledge, this is the first study to report risk variants in AVPR1A and AVPR1B genes in association with PCOS. However, replication in other ethnic groups as well as functional studies are needed to confirm these results.

Female patients exhibit altered vasopressin-induced coronary microvascular contractile response and molecular signaling following cardiac surgery

BackgroundEmerging data suggest women have worse outcomes than men following cardioplegia and cardiopulmonary bypass (CP/CPB). Altered coronary microvascular function affecting myocardial perfusion may contribute, but human translational studies are lacking. MethodsViable coronary microvessels (<200 μ m) were dissected from human atrial samples collected before and after CP/CPB from a subset of 108 patients enrolled. Ex vivo contractile responses to vasopressin were assessed using video microscopy. RNA deep-sequencing and immunoblotting were used to quantify gene and protein expression, respectively. ResultsCoronary microvessels exhibited increased vasopressin-induced contractile responses post-CP/CPB in males and females (p ​< ​0.0001). Females exhibited a decrease in microvascular contractile response versus males pre- (p ​= ​0.1) and post-CP/CPB (p ​= ​0.09) which approached significance. Myocardial vasopressin 1a receptor levels were increased in females versus males (p ​= ​0.001). Vasopressin-induced vasoconstriction predicted postoperative cardiac index. ConclusionsImpaired coronary microvascular contractile responses in females jeopardizing myocardial perfusion may underlie worse outcomes following cardiac surgery.

Stress enhances aggression in male rats with genetic stress hyper-reactivity.

The current study investigated stress-induced aggressive behavior in the resident-intruder test in males of the genetically stress hyper-reactive Wistar Kyoto More Immobile (WMI), and the nearly isogenic, control Wistar Kyoto Less Immobile (WLI) strains. Tests were carried out against same-age intruders during adolescence, and same-age and juvenile intruders in adulthood. In adolescence and adulthood, prior acute restraint stress decreased social interactions and decreased aggressive behaviors of adolescents and adult WLIs. However, prior stress precipitated aggression in the adult WMI males toward both same-age, and juvenile intruders compared with control WMIs and WLIs. Trunk blood levels of testosterone and androstenedione increased in stressed WLIs, but not in WMIs, suggesting no direct role of androgens in the increased aggression of WMIs. Expressions of aggression-relevant genes showed patterns commensurate with being causative in aggressive behavior. The methyl-CpG binding protein 2 was lower in the frontal cortex of control WMIs, and in the amygdala of stressed WMIs compared with their respective WLIs. Frontal cortex expression of vasopressin receptor 1a and serotonin transporter increased, solely in WMI males after stress. As behaviors were the same toward same-age and non-threatening juvenile intruders, the stress-induced increase in confrontational behavior of the adult WMI male was not because of enhanced fear or anxiety. These results suggest that genetic stress hyper-reactivity is a risk factor for stress-induced increases in aggression in males. Additionally, as known aggression-related genes showed expression patterns paralleling aggressive behavior, this model system could identify novel molecular pathways leading to stress-enhanced aggression.

Associations of the AVPR1A RS1 Microsatellite Locus with the Level of Hormones of the Anterior Pituitary Gland and Personality Traits.

The arginine vasopressin receptor gene (AVPR1A) is one of the genes affecting mental processes. The aim of this study was to search for associations of microsatellite locus RS1, which is related to the AVPR1A expression level, with the level of hormones of the anterior pituitary gland and personality traits. The study sample included Yakut men aged 18-26years (n = 121). The analysis of RS1 locus was carried out using the PCR method and sequencing of the primary nucleotide sequence. Serum hormonal levels of thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin were determined by the time-resolved fluorescence immunoassay (DELFIA), plasma adrenocorticotropic hormone (ACTH) levels were determined by enzyme-linked immunosorbent assay (ELISA). In the Yakut population "short" (S) alleles of the AVPR1A RS1 locus containing ≤ 10 repeats (63%) and the corresponding SS genotypes (44.6%) were more frequent, while individuals with "long" (LL) and "heterozygous" (SL) genotypes accounted for 18.2 and 37.2%, respectively. The range of concentrations of ACTH and TSH in the group of SS genotype carriers was significantly lower than that observed in the group of LL genotype carriers (p = 0.042 and p = 0.048, respectively); the LH level was significantly higher (p = 0.029). The trend towards higher neuroticism in SS genotype carriers compared to the individuals with LL genotypes (p = 0.05) is revealed. The results obtained indicate the modulating effect of genetic variants of the AVPR1A gene on the level of anterior pituitary hormones, which could slightly affect the level of neuroticism in humans.

Activation of arginine vasopressin receptor 1a reduces inhibitory synaptic currents at reciprocal synapses in the mouse accessory olfactory bulb.

Central arginine vasopressin (AVP) facilitates social recognition and modulates many complex social behaviors in mammals that, in many cases, recognize each other based on olfactory and/or pheromonal signals. AVP neurons are present in the accessory olfactory bulb (AOB), which is the first relay in the vomeronasal system and has been demonstrated to be a critical site for mating-induced mate recognition (olfactory memory) in female mice. The transmission of information from the AOB to higher centers is controlled by the dendrodendritic recurrent inhibition, i.e., inhibitory postsynaptic currents (IPSCs) generated in mitral cells by recurrent dendrodendritic inhibitory inputs from granule cells. These reports suggest that AVP might play an important role in regulating dendrodendritic inhibition in the AOB. To test this hypothesis, we examined the effects of extracellularly applied AVP on synaptic responses measured from mitral and granule cells in slice preparations from 23--36-day-old Balb/c mice. To evoke dendrodendritic inhibition in a mitral cell, depolarizing voltages of -70 to 0 mV (10 ms duration) were applied to a mitral cell using a conventional whole-cell configuration. We found that AVP significantly reduced the IPSCs. The suppressive effects of AVP on the IPSCs was diminished by an antagonist for vasopressin receptor 1a (V1aR) (Manning compound), but not by an antagonist for vasopressin receptor 1b (SSR149415). An agonist for V1aRs [(Phe2)OVT] mimicked the action of AVP on IPSCs. Additionally, AVP significantly suppressed voltage-activated currents in granule cells without affecting the magnitude of the response of mitral cells to gamma-aminobutyric acid (GABA). The present results suggest that V1aRs play a role in reciprocal transmission between mitral cells and granule cells in the mouse AOB by reducing GABAergic transmission through a presynaptic mechanism in granule cells.

Vasopressin regulates social play behavior in sex-specific ways through glutamate modulation in the lateral septum.

Understanding the neural basis of social play in juvenile rats may ultimately help restore social play deficits in autistic children. We previously found that administration of a vasopressin (AVP) V1a receptor (V1aR) antagonist into the lateral septum (LS) increased social play behavior in male juvenile rats and decreased it in females. Here, we demonstrate that glutamate, but not GABA, is involved in this sex-specific regulation. First, we found a sex difference in extracellular LS glutamate/GABA ratio (lower in females) that was eliminated by V1aR antagonist infusion in the LS that caused an increase in glutamate release in females only. Second, infusion of the glutamate receptor agonist L-glutamic acid into the LS mimicked the V1aR antagonist-induced decrease in female social play while preventing the increase in male social play. Third, infusion of the glutamate receptor antagonists AP-5 and CNQX into the LS prevented the V1aR antagonist-induced decrease in female social play. Fourth, there were no sex differences in extracellular GABA release in the LS upon either V1aR antagonist infusion or in social play expression upon infusion of the GABA-A receptor agonist muscimol into the LS, suggesting that GABA is not involved in the sex-specific regulation of social play by the LS-AVP system. Last, we found no sex differences in the type (GAD1/2, somatostatin, calbindin 1, Sox9) of V1aR-expressing LS cells, suggesting other cellular mechanisms mediating the sex-specific effects on glutamate release in the LS by the LS-AVP system. In conclusion, we demonstrate that the LS-AVP system regulates social play sex-specifically via glutamatergic neurotransmission. These findings have relevance for potential sex-specific effects of AVP-based treatment of social deficits in children.

The modulation of social and non-social behavior by arginine vasotocin in the common waxbill, Estrilda astrild

The influence of the neuropeptide arginine vasotocin (AVT) has been demonstrated across various species, on an ample range of behaviors, yet the results appear to be highly species-specific. In this study, we aimed to test how AVT influences both social and non-social behaviors in the common waxbill Estrilda astrild, a highly social estrildid finch. Through a within-subject design study, we experimentally manipulated AVT pathways through muscular injections of both an agonist and an antagonist of AVT at different dosages, and performed competition over food tests to assess behavioral changes. Our observations reveal a decrease in birds' movements with both low and high dosages of AVT. Additionally, the higher AVT dosage led to a significant decrease in birds' feeding, aggressive behavior, and allopreening. Conversely, the lower AVT dosage increased the duration of allopreening, which is a proxy for affiliation. The use of Manning Compound, a V1a antagonist, did not produce any changes in behavior, however, the absence of affinity studies for this compound in birds makes it difficult to interpret these results. It is plausible that in common waxbills, AVT V1b or V1a receptors may be involved in regulating movement, feeding, aggressive behavior, and allopreening, rather than V2 AVT receptors.

Update on Tolvaptan for the Treatment of Refractory Ascites in Liver Cirrhosis

Ascites is the most prevalent complication of decompensated cirrhosis, and approximately 5%-10% of cirrhotic ascites will develop into refractory ascites (RA). With complicated pathogenesis, obscure treatment strategies and poor prognosis, it is still a challenge for physicians to manage RA properly. Tolvaptan (TLV) is a new type of non-peptide selective arginine vasopressin V2 receptor antagonist targeting at suppressing renal water reabsorption, promoting free water excretion and raising blood sodium levels, which provides a new option for the treatment of RA in liver cirrhosis. In this review, we summarized the mechanisms of TLV's effect and described its efficacy, safety and predictive factors of response in treating RA, intending to provide a supplement for clinical application of tolvaptan in the management of RA.

Arginine vasopressin activates serotonergic neurons in the dorsal raphe nucleus during neonatal development in vitro and in vivo

Birth stress is a risk factor for psychiatric disorders and associated with exaggerated release of the stress hormone arginine vasopressin (AVP) into circulation and in the brain. In perinatal hippocampus, AVP activates GABAergic interneurons which leads to suppression of spontaneous network events and suggests a protective function of AVP on cortical networks during birth. However, the role of AVP in developing subcortical networks is not known. Here we tested the effect of AVP on the dorsal raphe nucleus (DRN) 5-hydroxytryptamine (5-HT, serotonin) system in male and female neonatal rats, since early 5-HT homeostasis is critical for the development of cortical brain regions and emotional behaviors. We show that AVP is strongly excitatory in neonatal DRN: it increases excitatory synaptic inputs of 5-HT neurons via V1A receptors in vitro and promotes their action potential firing through a combination of its effect on glutamatergic synaptic transmission and a direct effect on the excitability of these neurons. Furthermore, we identified two major firing patterns of neonatal 5-HT neurons in vivo, tonic regular firing and low frequency oscillations of regular spike trains and confirmed that these neurons are also activated by AVP in vivo. Finally, we show that the sparse vasopressinergic innervation in neonatal DRN originates exclusively from cell groups in medial amygdala and bed nucleus of stria terminalis. Hyperactivation of the neonatal 5-HT system by AVP during birth stress may impact its own functional development and affect the maturation of cortical target regions, which may increase the risk for psychiatric conditions later on.

Ionic mechanisms involved in arginine vasopressin-mediated excitation of auditory cortical and thalamic neurons

The axons containing arginine vasopressin (AVP) from the hypothalamus innervate a variety of structures including the cerebral cortex, thalamus, hippocampus and amygdala. A plethora amount of evidence indicates that activation of the V1a subtype of the vasopressin receptors facilitates anxiety-like and fear responses. As an essential structure involved in fear and anxiety responses, the amygdala, especially the lateral nucleus of amygdala (LA), receives glutamatergic innervations from the auditory cortex and auditory thalamus where high density of V1a receptors have been detected. However, the roles and mechanisms of AVP in these two important areas have not been determined, which prevents the understanding of the mechanisms whereby V1a activation augments anxiety and fear responses. Here, we used coronal brain slices and studied the effects of AVP on neuronal activities of the auditory cortical and thalamic neurons. Our results indicate that activation of V1a receptors excited both auditory cortical and thalamic neurons. In the auditory cortical neurons, AVP increased neuronal excitability by depressing multiple subtypes of inwardly rectifying K+ (Kir) channels including the Kir2 subfamily, the ATP-sensitive K+ channels and the G protein-gated inwardly rectifying K+ (GIRK) channels, whereas activation of V1a receptors excited the auditory thalamic neurons by depressing the Kir2 subfamily of the Kir channels as well as activating the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and a persistent Na+ channel. Our results may help explain the roles of V1a receptors in facilitating fear and anxiety responses.Categories: Cell Physiology.

Arginine vasopressin in mood disorders: A potential biomarker of disease pathology and a target for pharmacologic intervention.

Vasopressin or arginine-vasopressin (AVP) is a neuropeptide molecule known for its antidiuretic effects and serves to regulate plasma osmolality and blood pressure. The existing literature suggests that AVP plays a multifaceted-though less well-known-role in the central nervous system (CNS), particularly in relation to the pathophysiology and treatment of mood disorders. Animal models have demonstrated that AVP is implicated in regulating social cognition, affiliative and prosocial behaviors, and aggression, often in conjunction with oxytocin. In humans, AVP is implicated in mood disorders through its effects on the hypothalamic-pituitary-adrenal (HPA) axis as well as on the serotoninergic and glutamatergic systems. Measuring plasma AVP has yielded interesting but mixed results in mood and stress-related disorders. Recent advances have led to the development of copeptin as a stable and reliable surrogate biomarker for AVP. Another interesting but relatively unexplored issue is the interaction between the osmoregulatory system and mood disorder pathophysiology, given that psychotropic medications often cause dysregulation of AVP receptor expression or signaling that can subsequently lead to clinical syndromes like syndrome of inappropriate diuresis and diabetes insipidus. Finally, pharmaceutical trials of agents that act on V1a and V1b receptor antagonists are still underway. This narrative review summarizes: (1) the neurobiology of the vasopressinergic system in the CNS; (2) the interaction between AVP and the monoaminergic and glutamatergic pathways in the pathophysiology and treatment of mood disorders; (3) the iatrogenic AVP dysregulation caused by psychotropic medications; and (4) the pharmaceutical development of AVP receptor antagonists for the treatment of mood disorders.

Discovery and evaluation of a novel 18F-labeled vasopressin 1a receptor PET ligand with peripheral binding specificity

The arginine-vasopressin (AVP) hormone plays a pivotal role in regulating various physiological processes, such as hormone secretion, cardiovascular modulation, and social behavior. Recent studies have highlighted the V1a receptor as a promising therapeutic target. In-depth insights into V1a receptor-related pathologies, attained through in vivo imaging and quantification in both peripheral organs and the central nervous system (CNS), could significantly advance the development of effective V1a inhibitors. To address this need, we develop a novel V1a-targeted positron emission tomography (PET) ligand, [18F]V1A-2303 ([18F]8), which demonstrates favorable in vitro binding affinity and selectivity for the V1a receptor. Specific tracer binding in peripheral tissues was also confirmed through rigorous cell uptake studies, autoradiography, biodistribution assessments. Furthermore, [18F]8 was employed in PET imaging and arterial blood sampling studies in healthy rhesus monkeys to assess its brain permeability and specificity, whole-body distribution, and kinetic properties. Our research indicated [18F]8 as a valuable tool for noninvasively studying V1a receptors in peripheral organs, and as a foundational element for the development of next-generation, brain-penetrant ligands specifically designed for the CNS.

Chemokine receptor hetero-oligomers regulate monocyte chemotaxis.

It is known that stress influences immune cell function. The underlying molecular mechanisms are unclear. We recently reported that many chemokine receptors (CRs) heteromerize with α1-adrenoceptors (α1-ARs) through which CRs are regulated. Here, we show that arginine vasopressin receptor 1A (AVPR1A) heteromerizes with all human CRs, except chemokine (C-X-C motif) receptor (CXCR)1, in recombinant systems and that such heteromers are detectable in THP-1 cells and human monocytes. We demonstrate that ligand-free AVPR1A differentially regulates the efficacy of CR partners to mediate chemotaxis and that AVPR1A ligands disrupt AVPR1A:CR heteromers, which enhances chemokine (C-C motif) receptor (CCR)1-mediated chemotaxis and inhibits CCR2-, CCR8-, and CXCR4-mediated chemotaxis. Using bioluminescence resonance energy transfer to monitor G protein activation and CRISPR/Cas9 gene-edited THP-1 cells lacking AVPR1A or α1B-AR, we show that CRs that share the propensity to heteromerize with α1B/D-ARs and AVPR1A exist and function within interdependent hetero-oligomeric complexes through which the efficacy of CRs to mediate chemotaxis is controlled. Our findings suggest that hetero-oligomers composed of CRs, α1B/D-ARs, and AVPR1A may enable stress hormones to regulate immune cell trafficking.

#1636 Treatment of Tolvaptan related polyuria with bendroflumethiazide for ADPKD: Does it really work?

Abstract Background and Aims Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease worldwide and accounts for 10% of patients on renal replacement therapy. Currently, the arginine vasopressin (AVP) V2 receptor antagonist Tolvaptan is the only available treatment for ADPKD which slows cyst formation and thus the progression of kidney disease by inducing AVP resistance. However, its aquaretic side effects can be debilitating and is the most common reason for medication discontinuation. Thiazides such as bendroflumethiazide are natriuresis-promoting diuretics through their action on the sodium-chloride channel in the distal convoluted tubule that are widely used to treat polyuria in inherited AVP deficiency or resistance. However, there is limited information about their effect in patients treated with Tolvaptan. The aim of this observational study is to review the impact on patients’ quality of life by using a low dose bendroflumethiazide with Tolvaptan in patients with ADPKD who are suffering from Tolvaptan induced aquaretic side effects. Method Details of all patients with ADPKD who are on Tolvaptan with or without bendroflumethiazide who are currently attending the polycystic kidney disease (PKD) clinic at Royal Free London NHS Foundation Trust were obtained, and their medications reviewed. Patients who have previously been or were currently on bendroflumethiazide to enable them to continue Tolvaptan therapy were identified. Information about the impact of bendroflumethiazide on their quality of life and their aquaretic side effects were obtained via phone call. If they discontinued bendroflumethiazide, the reason for this was explored. In addition, eGFR, sodium, potassium, and calcium at the time of bendroflumethiazide initiation as well as at three, six, nine and twelve months post bendroflumethiazide initiation were obtained. Results Out of 136 patients receiving Tolvaptan for treatment of ADPKD at our centre, eight (5.8%) were prescribed bendroflumethiazide for treatment of their aquaretic side effects from Tolvaptan. Two of these eight patients (25%) stopped bendroflumethiazide due to adverse reactions. The remaining six patients (75%) remained on the medication, and all reported significant subjective improvement in their symptoms of polyuria, nocturia and in their overall quality of life. Two of the six patients (33.3%) that remained on bendroflumethiazide had also subsequently increased their Tolvaptan dose. No electrolyte disturbances were noted after initiation of bendroflumethiazide. Conclusion Using bendroflumethiazide appears to improve the quality of life through reduction of polyuria and nocturia in patients suffering from Tolvaptan-induced aquaretic side effects with some patients subsequently able to increase their Tolvaptan dose by taking bendroflumethiazide which might result in augmented therapeutic benefit of Tolvaptan. Further placebo-controlled randomised studies with longitudinal will be needed to determine the true benefit-disbenefit balance of thiazide therapy in patients taking tolvaptan, especially to determine whether there is a negative effect on efficacy of tolvaptan on the underlying ADPKD. However, based on our small observational study, the number of patients needed to determine whether bendroflumethiazide improves the tolerability and medication adherence in patients who are debilitated by the aquaretic side effects of Tolvaptan would be small.

Sex differences in the structure and function of the vasopressin system in the ventral pallidum are associated with the sex-specific regulation of social play behavior in juvenile rats

Vasopressin (AVP) regulates various social behaviors, often in sex-specific ways, including social play behavior, a rewarding behavior displayed primarily by juveniles. Here, we examined whether and how AVP acting in the brain's reward system regulates social play behavior in juvenile rats. Specifically, we focused on AVP signaling in the ventral pallidum (VP), a brain region that is a part of the reward system. First, we examined the organization of the VP-AVP system in juvenile rats and found sex differences, with higher density of both AVP-immunoreactive fibers and AVP V1a receptor (V1aR) binding in males compared to females while females show a greater number of V1aR-expressing cells compared to males. We further found that, in both sexes, V1aR-expressing cells co-express a GABA marker to a much greater extent (approx. 10 times) than a marker for glutamate. Next, we examined the functional involvement of V1aR-expressing VP cells in social play behavior. We found that exposure to social play enhanced the proportion of activated V1aR-expressing VP cells in males only. Finally, we showed that infusion of a specific V1aR antagonist into the VP increased social play behaviors in juvenile male rats while decreasing these behaviors in juvenile female rats. Overall, these findings reveal structural and functional sex differences in the AVP-V1aR system in the VP that are associated with the sex-specific regulation of social play behavior.

Characterization of oxytocin and vasopressin receptors in the Southern giant pouched rat and comparison to other rodents.

Vasopressin and oxytocin are well known and evolutionarily ancient modulators of social behavior. The distribution and relative densities of vasopressin and oxytocin receptors are known to modulate the sensitivity to these signaling molecules. Comparative work is needed to determine which neural networks have been conserved and modified over evolutionary time, and which social behaviors are commonly modulated by nonapeptide signaling. To this end, we used receptor autoradiography to determine the distribution of vasopressin 1a and oxytocin receptors in the Southern giant pouched rat (Cricetomys ansorgei) brain, and to assess the relative densities of these receptors in specific brain regions. We then compared the relative receptor pattern to 23 other species of rodents using a multivariate ANOVA. Pouched rat receptor patterns were strikingly similar to hamsters and voles overall, despite the variation in social organization among species. Uniquely, the pouched rat had dense vasopressin 1a receptor binding in the caudate-putamen (i.e., striatum), an area that might impact affiliative behavior in this species. In contrast, the pouched rat had relatively little oxytocin receptor binding in much of the anterior forebrain. Notably, however, oxytocin receptor binding demonstrated extremely dense binding in the bed nucleus of the stria terminalis, which is associated with the modulation of several social behaviors and a central hub of the social decision-making network. Examination of the nonapeptide system has the potential to reveal insights into species-specific behaviors and general themes in the modulation of social behavior.

Bryophyllum pinnatum Inhibits Oxytocin and Vasopressin Signaling in Myometrial Cells.

The medicinal plant Bryophyllum pinnatum was previously shown to block oxytocin (OT)-induced signals in myometrial cells, consistent with its tocolytic effect observed in patients. OT activates not only OT receptors but also V1A receptors, two receptors with high receptor homology that are both expressed in the myometrium and play a crucial role in myometrial contraction signaling. We aimed to study the molecular pharmacology of B. pinnatum herbal preparations using specific receptor ligands, the human myometrial cell line hTERT-C3, and cell lines expressing recombinant human OT and V1A receptors.We found that press juice from B. pinnatum (BPJ) inhibits both OT- and vasopressin (AVP)-induced intracellular calcium increases in hTERT-C3 myometrial cells. In additional assays performed with cells expressing recombinant receptors, BPJ also inhibited OT and V1A receptor-mediated signals with a similar potency (IC50 about 0.5 mg/mL). We further studied endogenous OT- and AVP-sensitive receptors in hTERT-C3 cells and found that OT and AVP stimulated those receptors with similar potency (EC50 of ~ 1 nM), suggesting expression of both receptor subtypes. This interpretation was corroborated by the antagonist potencies of atosiban and relcovaptan that we found. However, using qPCR, we almost exclusively found expression of OT receptors suggesting a pharmacological difference between recombinant OT receptors and native receptors expressed in hTERT-C3 cells.In conclusion, we show that B. pinnatum inhibits both OT and AVP signaling, which may point beyond its tocolytic effects to other indications involving a disbalance in the vasopressinergic system.

Intraperitoneal administration of arginine vasotocin (AVT) induces anorexigenic and anxiogenic actions via the brain V1a receptor-signaling pathway in the tiger puffer, Takifugu rubripes

Arginine vasotocin (AVT) is produced mainly in the hypothalamus and as a neurohypophyseal hormone peripherally regulates water-mineral balance in sub-mammals. In addition, AVT-containing neurons innervate several areas of the brain, and AVT also acts centrally as both an anorexigenic and anxiogenic factor in goldfish. However, it is unclear whether these central effects operate in fish in general. In the present study, therefore, we investigated AVT-like immunoreactivity in the brain of the tiger puffer, a cultured fish with a high market value in Japan and also a representative marine teleost species, focusing particularly on whether AVT affects food intake and psychomotor activity. AVT-like immunoreactivity was distributed higher in the ventral region of the telencephalon, the hypothalamus and midbrain. Intraperitoneal (IP) administration of AVT at 100 pmol g−1 body weight (BW) increased the immunoreactivity of phosphorylated ribosomal proteinS6 (RPS6), a neuronal activation marker, in the telencephalon and diencephalon, decreased food consumption and enhanced thigmotaxis. AVT-induced anorexigenic and anxiogenic actions were blocked by IP co-injection of a V1a receptor (V1aR) antagonist, Manning compound (MC) at 300 pmol g−1 BW. These results suggest that AVT acts as an anorexigenic and anxiogenic factor via the V1aR-signaling pathway in the tiger puffer brain.

A vasopressin circuit that modulates mouse social investigation and anxiety-like behavior in a sex-specific manner

One of the largest sex differences in brain neurochemistry is the expression of the neuropeptide arginine vasopressin (AVP) within the vertebrate brain, with males having more AVP cells in the bed nucleus of the stria terminalis (BNST) than females. Despite the long-standing implication of AVP in social and anxiety-like behaviors, the circuitry underlying AVP's control of these behaviors is still not well defined. Using optogenetic approaches, we show that inhibiting AVP BNST cells reduces social investigation in males, but not in females, whereas stimulating these cells increases social investigation in both sexes, but more so in males. These cells may facilitate male social investigation through their projections to the lateral septum (LS), an area with the highest density of sexually differentiated AVP innervation in the brain, as optogenetic stimulation of BNST AVP → LS increased social investigation and anxiety-like behavior in males but not in females; the same stimulation also caused a biphasic response of LS cells ex vivo. Blocking the vasopressin 1a receptor (V1aR) in the LS eliminated all these responses. Together, these findings establish a sexually differentiated role for BNST AVP cells in the control of social investigation and anxiety-like behavior, likely mediated by their projections to the LS.