Search

Although class A seven-transmembrane-helix (7TM) receptor hetero-oligomers have been proposed, information on the assembly and function of such higher-order hetero-oligomers is not available. Utilizing bioluminescence resonance energy transfer (BRET), bimolecular luminescence/fluorescence complementation (BiLC/BiFC) and BiLC/BiFC BRET in HEK293T cells, we provide evidence that chemokine (C-X-C motif) receptor 4 (CXCR4), atypical chemokine receptor 3 (ACKR3), α(1a)-adrenoceptor (α(1a)-AR), and arginine vasopressin receptor 1A (AVPR1A) form hetero-oligomers composed of 2-4 different protomers. We show that hetero-oligomerization per se and ligand binding to individual protomers regulate agonist-induced coupling to the signaling transducers of interacting receptor partners. Our findings support the concept that receptor hetero-oligomers form supramolecular machineries with molecular signaling properties distinct from the individual protomers. These findings provide a mechanism for the phenomenon of context-dependent receptor function.

What is known and objective Terlipressin has been shown to be effective in controlling variceal bleeding and decreasing associated mortality. Terlipressin is a synthetic analogue of vasopressin and is safer than arginine vasopressin; it induces selective vasoconstriction by stimulating the vasopressin V1 receptors that are predominantly located in the splanchnic tissues. However, severe hyponatraemia may occur during terlipressin treatment, resulting in neurological manifestations. Case summary We describe two patients who presented a marked decrease in serum sodium levels and developed obvious neurological manifestations after receiving terlipressin therapy. Although the two patients were given sodium supplementation, their serum sodium levels continually declined. After the discontinuation of terlipressin, their serum sodium levels rapidly recovered to normal limits, and the neurological manifestations subsequently disappeared in both patients. What is new and conclusion Some studies have reported hyponatraemia as a side effect of terlipressin; however, severe hyponatraemia with neurological manifestations has rarely been reported. We presented the cases of 2 patients with obvious neurological manifestations after receiving terlipressin therapy. Severe hyponatraemia may develop in patients treated with terlipressin, resulting in associated neurological symptoms. Therefore, the close monitoring of serum sodium is necessary.

Arginine-vasopressin (AVP) is believed to be positively correlated with the brain edema formation, but the underlying mechanism is still unclear. In this study, we explored the role of the V2 receptors antagonist tolvaptan on brain edema following intracerebral hemorrhage (ICH) with a rat model. Animals were randomly given tolvaptan or vehicle through oral gavage at 12 h, 36 h, and 60 h after ICH surgery. Brain swelling (%), brain water content(BWC), neurological scores, Evans blue fluorescence and blood-brain barrier (BBB) tight junction proteins were measured to evaluate the effect of tolvaptan in ICH. We found that tolvaptan alleviated the brain swelling (%), decreased the BWC growth, and attenuated the neurological deficits after ICH (p 0.05, vs vehicle). What's more, tolvaptan increased the expression of ZO-1 and occludin (p 0.05, vs vehicle), which might be attributed to the down-regulated effects of tolvaptan on MMP-9. These results provided evidence supporting the use of tolvaptan for ICH-induced brain edema. Large animal experiments are required to further explore the efficacy and mechanism of tolvaptan in ICH treatment.

The majority of studies examining the consequences of prenatal stress in rodent models analyze pups having been raised by their biological mother, i.e. the female which experienced stress during her pregnancy. To test whether pregnancy stress changes maternal behavior and thereby - in addition to stress exposure in utero – influences behavior and brain function of offspring, we implemented a fostering model, in which mouse pups that were not stressed in utero, are raised by dams which were exposed to stress during their pregnancy. We found that dams, which were stressed during pregnancy (PS foster dams), unexpectedly displayed slightly more active and passive light time nursing compared to unstressed dams (CON foster dams). Adult male offspring which were raised by a PS foster dam showed significantly less anxiety-like behavior compared to males raised by a CON foster dam, whereas adult female offspring which were raised by PS foster dams displayed increased depressive-like behavior as a tendency. Since the arginine vasopressin receptor 1a (AvpR1a) and the structurally related oxytocin receptor (OxtR) are both closely related to stress-responsiveness, anxiety and depression, mRNA expression of these genes were assessed in the hippocampus of adult male and female offspring. No significant differences in mRNA expression of both receptor types were observed, however, in female offspring of PS foster dams maternal licking/grooming correlated positively with AvpR1a and negatively with OxtR mRNA expression. These findings indicate that stress during pregnancy does not reduce, but slightly increase maternal behavior, which might lead to sex-specific behavioral outcomes and changes in hippocampal AvpR1a and OxtR mRNA expression in adult offspring.

Recently, we reported that the chemokine (C-X-C motif) receptor 4 (CXCR4) and atypical chemokine receptor 3 (ACKR3) heteromerize with α1A/B/D-adrenoceptors (ARs) and arginine vasopressin receptor 1A (AVPR1A) in recombinant systems and in rodent and human vascular smooth muscle cells (hVSMCs). In these studies, we observed that heteromerization between two receptor partners may depend on the presence and the expression levels of other partnering receptors. To test this hypothesis and to gain initial insight into the formation of these receptor heteromers in native cells, we utilized proximity ligation assays in hVSMCs to visualize receptor-receptor proximity and systematically studied how manipulation of the expression levels of individual protomers affect heteromerization patterns among other interacting receptor partners. We confirmed subtype-specific heteromerization between endogenously expressed α1A/B/D-ARs and detected that AVPR1A also heteromerizes with α1A/B/D-ARs. siRNA knockdown of CXCR4 and of ACKR3 resulted in a significant re-arrangement of the heteromerization patterns among α1-AR subtypes. Similarly, siRNA knockdown of AVPR1A significantly increased heteromerization signals for seven of the ten receptor pairs between CXCR4, ACKR3, and α1A/B/D-ARs. Our findings suggest plasticity of seven transmembrane helix (7TM) receptor heteromerization in native cells and could be explained by a supramolecular organization of these receptors within dynamic clusters in the plasma membrane. Because we previously observed that recombinant CXCR4, ACKR3, α1a-AR and AVPR1A form hetero-oligomeric complexes composed of 2–4 different protomers, which show signaling properties distinct from individual protomers, re-arrangements of receptor heteromerization patterns in native cells may contribute to the phenomenon of context-dependent GPCR signaling. Furthermore, these findings advise caution in the interpretation of functional consequences after 7TM receptor knockdown in experimental models. Alterations of the heteromerization patterns among other receptor partners may alter physiological and pathological responses, in particular in more complex systems, such as studies on the function of isolated organs or in in vivo experiments.

Prostate cancer patients managed with androgen-deprivation therapy usually recur after a few years and the disease gradually becomes castration-resistant prostate cancer (CRPC). The role of tumor cell plasticity, including processes such as transdifferentiation and epithelial-mesenchymal transition, is pivotal in the development of androgen receptor (AR)-indifferent tumor variants (1). Cell plasticity may allow CRPC progression and metastasis by favoring reactivation of AR signaling as a result of different mechanisms of transcriptome reprogramming. Interestingly, dissection of such mechanisms can lead to the identification of novel vulnerabilities of aggressive tumor cells that can be targeted therapeutically. The recent work by Zhao et al. (2) identified the vasopressin receptor 1a (AVPR1a) as a critical effector in CRPC expressing the AR coactivator VAV3 and the constitutively active AR variant AR-V7. They demonstrated that ectopic expression of AVPR1a is capable of conferring castration resistance and agonist treatment with the receptor ligand, the natural hormone arginine vasopressin, activates ERK and CREB, signaling molecules known to promote prostate cancer progression. Interestingly, depletion of AVPR1a or inhibition by the selective AVPR1a antagonist relcovaptan resulted in decreased CRPC cell proliferation and reduced bone metastatic growth in vivo. We completely agree with the authors in the sense that AVPR1a can be a potential target for CRPC therapy. We believe that clinical trials with relcovaptan are warranted, particularly in patients with bone-metastatic disease for which therapeutic options are limited. However, we want to point out that these results could be revealing other untapped antitumor properties of the vasopressin system-related drugs against prostate cancer cells. Our team has reported that the vasopressin analog desmopressin, a selective agonist for the vasopressin receptor 2 (AVPR2), significantly reduced tumor cell growth and migration in AR-negative CRPC (3). In vitro exposure to desmopressin also induced a dramatic decrease of the neuroendocrine markers chromogranin and neuron-specific enolase in aggressive CRPC cells (3). In prostate cancer, neuroendocrine transdifferentiation is known to be related with transition toward AR-indifference and metastatic phenotype. Besides, recent studies in orthotopic and heterotopic models of CRPC in athymic nude mice demonstrated an enhanced efficacy of docetaxel in combination with desmopressin (4, 5). Agonist activation of AVPR2 present in various human cancer cell lines has been associated with triggering of antiproliferative signaling pathways involving canonical adenylate cyclase/cAMP/PKA axis activation. cAMP blocks the proliferation of many cell types, both normal and transformed, through multiple downstream effectors. It is known that increased cAMP levels inhibit the Raf/MAPK/ERK signaling pathway in a PKA-dependent manner, but this is not the only mitogenic pathway impaired by cAMP (6). Although cytostatic effect after AVPR2 stimulation is robust, the underlying mechanism is intriguing since AVPR2-mediated cell signaling may eventually lead to phosphorylation of hundreds of PKA substrates granting a complex and seemingly contradictory framework of signaling pathways as evidenced in immortalized epithelial cells after stimulation with desmopressin (7). In this sense, high cAMP levels and PKA activation may eventually lead to phosphorylation and activation of CREB. However, many factors contribute to final cell response. It is known that cAMP can either stimulate or inhibit tumor cell apoptosis, and PKA is able to mediate cAMP-promoted proapoptotic responses depending on the cell type and the cell context (8). In addition, it has been reported a crosstalk of cAMP/PKA that can inhibit RhoA-mediated signaling, thus affecting the aggressive behavior of CRPC cells (9). Taken together, it seems that CREB activation is not prominent after AVPR2 selective agonist action on cancer cells, being favored certain antiproliferative signals. In breast cancer cells expressing AVPR1a and AVPR2, natural vasopressin can activate both receptors but its affinity is higher for AVPR1a and the number of functional AVPR2 tends to be relatively low. Thus, vasopressin elicits AVPR1a-dependent proliferative signals mediated by ERK activation that clearly predominate over AVPR2-dependent antiproliferative signals (10). On the contrary, when AVPR1a is blocked by selective antagonists such as relcovaptan or tumor cells are exposed to specific AVPR2 agonists such as desmopressin, significant antiproliferative effects are achievable in hormone-resistant breast cancer cell lines (10, 11). Desmopressin also contributed to reduce aggressiveness of mammary tumors during chemotherapy in an immunocompetent mouse model (12). We have conducted a Phase 2 dose-escalation clinical trial of desmopressin as a perioperative adjuvant in patients with breast cancer (NCT01606072). Desmopressin appeared safe when administered in two slow infusions before and after surgery, and a rapid postoperative drop in circulating tumor cells was detected after treatment (13). In addition, we documented a reduced intraoperative bleeding associated to the well-known hemostatic effects of the compound (13). From a wider perspective, the stimulating article by Zhao et al. (2) ratifies the relevance of the vasopressin system for searching novel therapeutic targets in hormone-resistant cancer and particularly in CRPC (Figure 1; see also Supplementary Table 1 for preclinical data summary). In this context, repurposing of already-used drugs with a non-oncology primary purpose stands as an interesting strategy to offer effective therapeutic options to cancer patients, allowing faster development and reducing safety concerns (14). The selective AVPR1a antagonist relcovaptan is a small-molecule inhibitor that has been safely and effectively used in clinical trials for Raynaud syndrome, dysmenorrhea and preterm labor. The specific AVPR2 agonist desmopressin is a synthetic peptide compound that has been employed for decades as an antidiuretic in the treatment of diabetic insipidus and enuresis, and as a hemostatic agent for the management of bleeding disorders, with a history of good tolerability and clinical effectiveness. Both compounds constitute promising therapeutic approaches for CRPC that deserve clinical testing either alone or in combination, as well as concurrently with standard chemotherapy regimens. Fil: Ripoll, Giselle Vanina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pifano, Marina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Garona, Juan. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Background & Aims: Acetaminophen-related acute liver injury and liver failure (ALF) result from ingestion of supratherapeutic quantities of this analgesic, frequently in association with other forms of substance abuse including alcohol, opioids, and cocaine. Thus, overdosing represents a unique high-risk behavior associated with other forms of drug use disorder. Methods: We examined a series of 21 single nucleotide polymorphisms (SNPs) in 9 genes related to impulsivity and/or stress responsivity that may modify response to stress. Study subjects were 229 white patients admitted to tertiary care liver centers for ALF that was determined to be due to acetaminophen toxicity after careful review of historical and biochemical data. Identification of relevant SNPs used Sanger sequencing, TaqMan, or custom microarray. Association tests were carried out to compare genotype frequencies between patients and healthy white controls. Results: The mean age was 37 years, and 75.6% were female, with similar numbers classified as intentional overdose or unintentional (without suicidal intent, occurring for a period of several days, usually due to pain). There was concomitant alcohol abuse in 30%, opioid use in 33.6%, and use of other drugs of abuse in 30.6%. The genotype frequencies of 2 SNPs were found to be significantly different between the cases and controls, specifically SNP rs2282018 in the arginine vasopressin gene (AVP, odds ratio 1.64) and SNP rs11174811 in the AVP receptor 1A gene (AVPR1A, odds ratio 1.89), both of which have been previously linked to a drug use disorder diagnosis. Conclusions: Patients who develop acetaminophen-related ALF have increased frequency of gene variants that may cause altered stress responsivity, which has been shown to be associated with other unrelated substance use disorders. Keywords: Impulsivity, Stress Responsivity, Pituitary-Adrenal Axis, Overdose

Arginine vasopressin (AVP), also known as antidiuretic hormone, is a peptide endogenously secreted by the posterior pituitary in response to hyperosmolar plasma or systemic hypoperfusion states. When administered intravenously, it causes an intense peripheral vasoconstriction through stimulation of V1 receptors on the vascular smooth muscle. Patients in refractory shock associated with severe sepsis, cardiogenic or vasodilatory shock, or cardiopulmonary bypass have inappropriately low plasma levels of AVP ('relative vasopressin deficiency') and supersensitivity to exogenously-administered AVP. Low doses of AVP and its synthetic analog terlipressin can restore vasomotor tone in conditions that are resistant to catecholamines, with preservation of renal blood flow and urine output. They are also useful in the treatment of refractory arterial hypotension in patients chronically treated with renin-angiotensin system inhibitors, cardiac arrest, or bleeding esophageal varices. In the perioperative setting, they represent attractive adjunct vasopressors in advanced shock states that are unresponsive to conventional therapeutic strategies.

Olfaction plays an important role in social recognition in most mammals. Central arginine vasopressin (AVP) plays a role in this olfaction-based recognition. The high level of expression of AVP receptors in the accessory olfactory bulb (AOB) at the first relay of the vomeronasal system highlights the importance of AVP signaling at this stage. We therefore analyzed the effects of AVP on the synaptic plasticity of glutamatergic transmission from mitral cells to granule cells in AOB slices from male mice. To monitor the strength of the glutamatergic transmission, we measured the maximal initial slope of the lateral olfactory tract-evoked field potential, which represents the granule cell response to mitral cell activation. AVP paired with 100-Hz stimulation that only produced short-term potentiation enhanced the induction of long-term potentiation (LTP) in a dose-dependent manner. AVP-paired LTP was blocked by the selective AVP receptor 1a (AVPR1a) antagonist, d(CH2)5[Tyr(Me)2]AVP (Manning compound), but not by the AVPR1b antagonist SSR149415, and it was mimicked by the selective AVPR1a agonist [Phe2, Ile3, Orn8]-vasopressin. We further examined the effect of AVP on the reciprocal transmission between mitral and granule cells by stimulating a mitral cell and recording the evoked inhibitory postsynaptic currents (IPSCs) from the same cell using conventional whole-cell patch-clamp techniques. AVP reduced the reciprocal IPSCs triggered by endogenous glutamate release from the excited mitral cell. These results suggest that AVP promotes the induction of LTP at the mitral-to-granule cell synapse via the activation of AVPR1a through an as-yet-to-be-determined mechanism in the AOB of male mice.

Oxytocin (OXT) is known to play an important role in trust, whereas the involvement of other peptide hormones has not been evaluated. In this study, we focused on microsatellite polymorphisms in the intron of the arginine-vasopressin receptor 1a (AVPR1a) gene and examined whether the association between the repeat lengths in the intron of AVPR1a is associated with trust and reciprocity in humans. Four-hundred and thirty-three participants played the trust game, answered the attitudinal trust question, and their buccal cells were collected. Results showed that men with a short form of AVPR1a tend to send more money to the opponent, even if there is a possibility of being betrayed by the opponent. Additionally, people with a short form of AVPR1a tended to return money to the opponent who trusts them. However, attitudinal trust was not associated with AVPR1a. These results indicate that arginine-vasopressin receptor 1a plays an important role in trust and reciprocal behaviors.

We aimed to study the relationship between rs11174811 and rs3803107 single nucleotide polymorphisms (SNPs) in miRNA target sites of the 3′ UTR in the arginine vasopressin receptor 1a gene (AVPR1A) and the risk of hypertension in the Chinese Han population. The genotypes at rs11174811 and rs3803107 were analyzed by direct sequencing in 425 Chinese Han patients with hypertension and 425 healthy subjects. AVPR1A expression was investigated by transfecting miR-526b, miR-375, and miR-186 mimics into human umbilical vein endothelial cells (HUVECs) containing AVPR1A rs11174811 CC, CA/AA and AVPR1A rs3803107 GG, GA/AA genotypes. The A alleles of rs11174811 (adjusted OR = 1.424, 95% CI: 1.231–1.599, P

Castration-resistant prostate cancer (CRPC) recurs after androgen deprivation therapy (ADT) and is incurable. Reactivation of androgen receptor (AR) signaling in the low androgen environment of ADT drives CRPC. This AR activity occurs through a variety of mechanisms, including up-regulation of AR coactivators such as VAV3 and expression of constitutively active AR variants such as the clinically relevant AR-V7. AR-V7 lacks a ligand-binding domain and is linked to poor prognosis. We previously showed that VAV3 enhances AR-V7 activity to drive CRPC progression. Gene expression profiling after depletion of either VAV3 or AR-V7 in CRPC cells revealed arginine vasopressin receptor 1a (AVPR1A) as the most commonly down-regulated gene, indicating that this G protein–coupled receptor may be critical for CRPC. Analysis of publicly available human PC datasets showed that AVPR1A has a higher copy number and increased amounts of mRNA in advanced PC. Depletion of AVPR1A in CRPC cells resulted in decreased cell proliferation and reduced cyclin A. In contrast, androgen-dependent PC, AR-negative PC, or nontumorigenic prostate epithelial cells, which have undetectable AVPR1A mRNA, were minimally affected by AVPR1A depletion. Ectopic expression of AVPR1A in androgen-dependent PC cells conferred castration resistance in vitro and in vivo. Furthermore, treatment of CRPC cells with the AVPR1A ligand, arginine vasopressin (AVP), activated ERK and CREB, known promoters of PC progression. A clinically safe and selective AVPR1A antagonist, relcovaptan, prevented CRPC emergence and decreased CRPC orthotopic and bone metastatic growth in mouse models. Based on these preclinical findings, repurposing AVPR1A antagonists is a promising therapeutic approach for CRPC.

Converging evidence from both human and animal studies has highlighted the pervasive role of the neuropeptide arginine vasopressin (AVP), which is mediated by arginine vasopressin receptor 1A (AVPR1A), in both social and nonsocial learning and memory. However, the effect of genetic variants in AVPR1A on verbal learning and memory is unknown. The hippocampus is a heterogeneous structure that consists of several anatomically and functionally distinct subfields, and it is the principal target structure for the memory-enhancing effect of AVP. We tested the hypothesis that genetic variants in the RS3 and RS1 repeat polymorphisms may influence verbal learning and memory performance evaluated by the California Verbal Learning Test-II (CVLT-II) by modulating the gray matter volume (GMV) and resting-state functional connectivity (rsFC) of whole hippocampus and its subfields in a large cohort of young healthy subjects (n = 1001). Using a short/long classification scheme for the repeat length of RS3 and RS1, we found that the individuals carrying more short alleles of RS3-RS1 haplotypes had poorer learning and memory performance compared to that of those carrying more long alleles. We also revealed that individuals carrying more short alleles exhibited a significantly smaller GMV in the left cornu ammonis (CA)2/3 and weaker rsFC of the left CA2/3-bilateral thalamic (primarily in medial prefrontal subfields) compared to those carrying more long alleles. Furthermore, multiple mediation analysis confirmed that these two hippocampal imaging measures jointly and fully mediated the relationship between the genetic variants in AVPR1A RS3-RS1 haplotypes and the individual differences in verbal learning and memory performance. Our results suggest that genetic variants in AVPR1A RS3-RS1 haplotypes may affect verbal learning and memory performance in part by modulating the left hippocampal CA2/3 structure and its rsFC with the thalamus.

We examined the extent to which the arginine vasopressin receptor 1a (AVPR1a) and dopamine receptor D4 (DRD4) were related to sensitive maternal behavior directly or indirectly via maternal social cognition. Participants were 207 (105 European-American and 102 African-American) mothers and their children (52% females). Sensitive maternal behavior was rated and aggregated across a series of tasks when infants were 6 months, 1 year and 2 years old. At 6 months, mothers were interviewed about their empathy, attributions about infant behavior and beliefs about crying to assess their parenting-related social cognition. Mothers with long alleles for AVPR1a and DRD4 engaged in more mother-oriented social cognition (i.e. negative attributions and beliefs about their infants' crying, s = 0.13, P < 0.05 and s = 0.16, P < 0.05, respectively), which in turn predicted less sensitive maternal behavior (s = -0.23, P < 0.01). Both indirect effects were statistically significant independent of one another and covariates [95% confidence interval (CI): -0.22, -0.03 and s = -0.03 for AVPR; 95% CI: -0.20, -0.03 and s = -0.04 for DRD4]. There were no significant direct effects of AVPR1a or DRD4 on maternal sensitivity (s = 0.02, P = .73 and s = -0.10, P = .57, respectively). The results did not vary for African-American and European-American mothers (??2 = 18.76, ?df = 16, P = 0.28). Results support the view that one mechanism by which maternal genes are associated with parental behavior is via social cognition.

The central control of the micturition is dependent on cortical areas and other ascending and descending pathways in the brain stem. The descendent pathways from the pons to the urinary bladder (UB) can be direct or indirect through medullary neurons (MN). Chemical stimulation with l-glutamate of MN known for their involvement in cardiovascular regulation evokes changes in pelvic nerves activities, which innervate the urinary bladder. Different neurotransmitters have been found in medullary areas; nevertheless, their involvement in UB control is few understood. We focused to investigate if cholinergic activation of neurons in the medulla oblongata changes the urinary bladder activity. Carbachol (cholinergic agonist) or atropine (cholinergic antagonist) was injected into the 4thV in anesthetized female Wistar rats and the intravesical pressure (IP), mean arterial pressure (MAP), heart rate (HR) and renal conductance (RC) were recorded for 30 min. Carbachol injection into the 4thV increased IP with peak response at 30 min after carbachol and yielded no changes in MAP, HR and RC. Atropine injection into the 4thV decreased IP and elicited no changes in MAP, HR and RC. Plasma vasopressin levels evaluated by ELISA kit assay increased after carbachol into the 4th V. Intravenous blockade of V1 receptors prior to carbachol into the 4thV abolished the increase in IP evoked by carbachol. Therefore, our findings suggest that cholinergic activation of neurons in the medulla oblongata by carbachol injections into the 4thV increases IP due to plasma vasopressin release, which acts in V1 receptors in the UB.

Modified constraint-induced movement therapy is an effective treatment for neurological and motor impairments in patients with stroke by increasing the use of their affected limb and limiting the contralateral limb. However, the molecular mechanism underlying its efficacy remains unclear. In this study, a middle cerebral artery occlusion (MCAO) rat model was produced by the suture method. Rats received modified constraint-induced movement therapy 1 hour a day for 14 consecutive days, starting from the 7th day after middle cerebral artery occlusion. Day 1 of treatment lasted for 10 minutes at 2 r/min, day 2 for 20 minutes at 2 r/min, and from day 3 onward for 20 minutes at 4 r/min. CatWalk gait analysis, adhesive removal test, and Y-maze test were used to investigate motor function, sensory function as well as cognitive function in rodent animals from the 1st day before MCAO to the 21st day after MCAO. On the 21st day after MCAO, the neurotransmitter receptor-related genes from both contralateral and ipsilateral hippocampi were tested by micro-array and then verified by western blot assay. The glutamate related receptor was shown by transmission electron microscopy and the glutamate content was determined by high-performance liquid chromatography. The results of behavior tests showed that modified constraint-induced movement therapy promoted motor and sensory functional recovery in the middle cerebral artery-occluded rats, but had no effect on cognitive function. The modified constraint-induced movement therapy upregulated the expression of glutamate ionotropic receptor AMPA type subunit 3 (Gria3) in the hippocampus and downregulated the expression of the beta3-adrenergic receptor gene Adrb3 and arginine vasopressin receptor 1A, Avpr1a in the middle cerebral artery-occluded rats. In the ipsilateral hippocampus, only Adra2a was downregulated, and there was no significant change in Gria3. Transmission electron microscopy revealed a denser distribution the more distribution of postsynaptic glutamate receptor 2/3, which is an α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor, within 240 nm of the postsynaptic density in the contralateral cornu ammonis 3 region. The size and distribution of the synaptic vesicles within 100 nm of the presynaptic active zone were unchanged. Western blot analysis showed that modified constraint-induced movement therapy also increased the expression of glutamate receptor 2/3 and brain-derived neurotrophic factor in the hippocampus of rats with middle cerebral artery occlusion, but had no effect on Synapsin I levels. Besides, we also found modified constraint-induced movement therapy effectively reduced glutamate content in the contralateral hippocampus. This study demonstrated that modified constraint-induced movement therapy is an effective rehabilitation therapy in middle cerebral artery-occluded rats, and suggests that these positive effects occur via the upregulation of the postsynaptic membrane α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor expression. This study was approved by the Institutional Animal Care and Use Committee of Fudan University, China (approval No. 201802173S) on March 3, 2018.

PURPOSE: Stress contributes to many psychiatric disorders; however, responsivity to stressors can vary depending on previous or current stress exposure. Relatively innocuous heterotypic (differing in type) stressors can summate to result in exaggerated neuronal and behavioral responses. Here we investigated the ability of prior high dietary sodium chloride (salt) intake, a dehydrating osmotic stressor, to enhance neuronal and behavioral responses of mice to an acute psychogenic swim stress (SS). Further, we evaluated the contribution of the osmo-regulatory stress-related neuropeptide arginine vasopressin (VP) in the hypothalamic paraventricular nucleus (PVN), one of only a few brain regions that synthesize VP. The purpose of this study was to determine the impact of high dietary salt intake on responsivity to heterotypic stress and the potential contribution of VPergic-mediated neuronal activity on high salt-induced stress modulation, thereby providing insight into how dietary (homeostatic) and environmental (psychogenic) stressors might interact to facilitate psychiatric disorder vulnerability. APPROACH: Salt loading (SL) with 4% saline for 7 days was used to dehydrate and osmotically stress mice prior to exposure to an acute SS. Fluid intake and hematological measurements were taken to quantify osmotic dehydration, and serum corticosterone levels were measured to index stress axis activation. Immunohistochemistry (IHC) was used to stain for the immediate early gene product c-Fos to quantify effects of SL on SS-induced activation of neurons in the PVN and extended amygdala – brain regions that are synaptically connected and implicated in responding to osmotic stress and in modulation of SS behavior, respectively. Lastly, the role of VPergic PVN neurons and VP type 1 receptor (V1R) activity in the amygdala in mediating effects of SL on SS behavior was evaluated by quantifying c-Fos activation of VPergic PVN neurons and, in functional experiments, by nano-injecting the V1R selective antagonist dGly[Phaa1,d-tyr(et), Lys, Arg]-VP bilaterally into the amygdala prior to the SS. FINDINGS: SL increased serum osmolality (P < 0.01), which positively correlated with time spent mobile during, and time spent grooming after a SS (P < 0.01, P < 0.01), and SL increased serum corticosterone levels (P < 0.01). SL alone increased c-Fos immunoreactivity among PVN neurons (P = 0.02), including VP positive neurons (P < 0.01). SL increased SS-induced c-Fos activation of PVN neurons as well (P

Arginine vasopressin (AVP) is the predominant hormone regulating urine concentration. Its primary role is to increase water reabsorption from the connecting tubule through the collecting duct. AVP is produced in the hypothalamus, stored in the posterior pituitary, and released as a result of stimulation of osmoreceptors or baroreceptors. Normal circulating levels of AVP approximate 1 pM in humans and rodents. There are three subtypes of the vasopressin receptor (V1a, V1b, and V2). In general, V1 receptors are coupled to phosphoinositide-3-kinase (PI-3K) signaling and calcium release, while V2 receptors are coupled both to the generation of cyclic AMP and mobilization of intracellular calcium. In addition to water, AVP regulates renal chloride, bicarbonate, and potassium reabsorption via specific transporters, exchangers, and channels. Vasopressin actions in the kidney have also been shown to regulate glomerular filtration rate, renal blood flow, nitric oxide generation, and blood pressure in human animal model systems.

ELABELA (ELA) is a novel hormone consisting of 32 amino acid peptides found in humans as well as other vertebrates and is considered to play an important role in the circulatory system through the apelin receptor (APJ). However, whether ELA also acts in the central nervous system remains unknown. Here, we show that ELA functions as an anorexigenic hormone in adult mouse brain. An intracerebroventricular injection of ELA reduces food intake and activates arginine vasopressin (AVP) and corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus (PVN), a hypothalamic region that regulates food intake. Cytosolic calcium ([Ca]i) measurement shows that ELA dose dependently increases [Ca]i in single AVP and CRH-immunoreactive neurons isolated from the PVN. Our data suggest that ELA functions as an anorexigenic hormone through activation of AVP and CRH neurons in the PVN.

High plasma copeptin, a marker of vasopressin (VP) secretion, has been shown to be associated with the metabolic syndrome and development of type 2 diabetes in humans. The present study was designed to determine the long-term influence of plasma VP concentration in a rodent model prone to metabolic dysfunction. Obese Zucker rats and their lean counterparts were submitted for 4 weeks to one of three protocols inducing different levels of VP. Circulating VP was either reduced by increasing the daily water intake (low-VP), or increased by a chronic i.p. infusion of VP (high-VP). The control rats had normal VP levels that depended on their own regulation of water intake and VP secretion. Compared with controls with normal VP, lean rats with high-VP had a higher fasting glycaemia after 4 weeks. In obese rats, high-VP promoted hyperinsulinaemia, glucose intolerance, assessed by glucose and insulin tolerance tests, and an impaired response to a pyruvate challenge. Conversely, treatment with a selective arginine vasopressin receptor 1A (V1aR) antagonist reduced glucose intolerance. Low-VP obese rats had unchanged glucose tolerance but exhibited a drastic decrease in liver steatosis compared with control obese rats, associated with low hepatic triacylglycerol and cholesterol content, and reduced expression of hepatic lipogenic genes. These effects were independent of changes in body adiposity, and plasma sodium and osmolality did not differ among groups. These findings show a causal relationship between the VP–hydration axis and the metabolic risk. Therapeutic perspectives include diet recommendations regarding hydration, but also potential pharmacological interventions targeting the VP V1aR.

Empathy is the ability to recognize and share in the emotions of others. It can be considered a multifaceted concept with cognitive and emotional aspects. Little is known regarding the underlying neurochemistry of empathy and in the current study we used a neurogenetic approach to explore possible brain neurotransmitter pathways contributing to cognitive and emotional empathy. Both the oxytocin receptor (OXTR) and the arginine vasopressin receptor 1a (AVPR1a) genes contribute to social cognition in both animals and humans and hence are prominent candidates for contributing to empathy. The following research examined the associations between polymorphisms in these two genes and individual differences in emotional and cognitive empathy in a sample of 367 young adults. Intriguingly, we found that emotional empathy was associated solely with OXTR, whereas cognitive empathy was associated solely with AVPR1a. Moreover, no interaction was observed between the two genes and measures of empathy. The current findings contribute to our understanding of the distinct neurogenetic pathways involved in cognitive and emotional empathy and underscore the pervasive role of both oxytocin and vasopressin in modulating human emotions.

Both negative and positive social experiences during sensitive life phases profoundly shape brain and behaviour. Current research is therefore increasingly focusing on mechanisms mediating the interaction between varying life experiences and the epigenome. Here, male mice grew up under either adverse or beneficial conditions until adulthood, when they were subdivided into groups exposed to situations that either matched or mismatched previous conditions. It was investigated whether the resulting four life histories were associated with changes in anxiety-like behaviour, gene expression of selected genes involved in anxiety and stress circuits, and arginine vasopressin receptor 1a (Avpr1a) gene methylation. Varying experiences during life significantly modulated (1) anxiety-like behaviour; (2) hippocampal gene expression of Avpr1a, serotonin receptor 1a (Htr1a), monoamine oxidase A (Maoa), myelin basic protein (Mbp), glucocorticoid receptor (Nr3c1), growth hormone (Gh); and (3) hippocampal DNA methylation within the Avpr1a gene. Notably, mice experiencing early beneficial and later adverse conditions showed a most pronounced downregulation of Avpr1a expression, accompanied by low anxiety-like behaviour. This decrease in Avpr1a expression may have been, in part, a consequence of increased methylation in the Avpr1a gene. In summary, this study highlights the impact of interactive social experiences throughout life on the hippocampal epigenotype and associated behaviour.

Vasopressin also known as Anti Diuretic hormone acting through V2 receptor is the primary physiologic determinant of the rate of free water excretion. In the last decade, knowledge of vasopressin receptors has increased significantly. Multiple vasopressin receptor antagonists have been developed with differences in their specificity to V2:V1 receptors. These agents have applications in conditions of hypervolemic and euvolemic hyponatremia like the syndrome of inappropriate antidiuretic hormone secretion, congestive heart failure, cirrhosis and perhaps in brain edema following traumatic brain injury. Although V2 receptor antagonist may have a proven role in certain condition, only few drugs are currently available and its use still remains limited.

Chronic mild stress (CMS) and myocardial infarction (MI) induce anhedonia, which is one of the symptoms of depression. The purpose of this study was to determine the role of the central V1 vasopressin receptors (V1R) in post-CMS and post-MI anhedonia. To this end, we investigated the effect of blockage the central V1R [28days of intracerebroventricular (ICV) infusion of V1 receptors antagonist (V1RANT)] on CMS-induced and the post-infarct anhedonia. The experiments were conducted on conscious MI or sham-operated (SO) rats that were either exposed to CMS for 20days or remained at rest. The sucrose/water intake ratio (S/W) was measured to determine hedonic behavior. Seven days after MI, the S/W was reduced. This effect was no longer present 37days after the infarction and was also absent in the SO rats. Exposure to CMS reduced the S/W in SO rats also. In the CMS-exposed MI rats, the S/W was similar to that in the CMS-exposed SO rats. ICV administration of V1RANT abolished reductions in the S/W in the CMS-exposed MI rats, however, it did not influence S/W in the SO rats exposed to CMS and in the MI and SO rats not exposed to CMS. We conclude that: (1) myocardial infarction and chronic stressing cause anhedonia, (2) myocardial infarction-induced anhedonia appears to be transient, (3) myocardial infarction does not potentiate CMS-induced anhedonia, and (4) CMS-induced anhedonia critically depends on the stimulation of the central V1 receptors.

International audience; : In many species males display alternative reproductive tactics (ARTs). While males of different tactics differ behaviorally in the field, it is often not known whether these behavioral differences would also occur under standardized laboratory conditions, nor how ARTs are regulated by the brain. In the present study we kept male African striped mice (Rhabdomys pumilio) in captivity either in family groups or solitary, to mimic ARTs observed in the field. This allowed us to study these males behaviorally under standardized conditions, to replicate physiological findings from the field, and to study the expression of the arginine vasopressin 1a receptor (AVPR1a) in their brains. Changes in either peptide release or receptor expression (or both) might regulate ARTs with differential timelines, with peptide secretion being faster than receptor expression. As observed in the field, family living males had higher corticosterone but lower testosterone levels than singly housed males. Surprisingly, singly housed males were less aggressive while at the same time having higher testosterone levels. We found no differences in AVPR1a expression. In a previous study it was shown that singly housed males have higher levels of AVP stored in their brain, which potentially could be secreted when the social situation changes, for example to establish social bonds. Our study on AVPR1a suggests the hypothesis that, given that the receptor distribution and expression of singly housed males do not differ from that of family-living males, the brains of singly-housed males have a similar capacity to be responsive to AVP when given the chance to interact socially.

Introduction: A correlation between AVPR1A promoter polymorphisms and prepulse inhibition (PPI) of startle reflexes has been described in healthy adults. Many children with nocturnal enuresis (NE) have a reduced PPI and treatment with desamino arginine vasopressin (dDAVP), a ligand of the arginine vasopressin receptor 1A (AVPR1A), and both improve clanical symptoms and significantly increase PPI. Methods: In 17 children (median 9.1 years, range 6.4-17.3) with NE, promoter repeats within the RS1 and RS3 regions of AVPR1A were quantified and correlated to PPI (native and age-adjusted). Results: No direct correlation was found between the number of promoter repeats at RS1 and PPI (correlation coefficient—0.240, p = 0.346) or RS3 and PPI (correlation coefficient—0.0192, p = 0.936), with no change through age-adjustment of PPI. The different RS3 length subgroups did not show differences in PPI, nor did differentiation of NE according to clinical subtype or treatment response to dDAVP show differences in the number of promoter repeats. Conclusion: The missing reproducibility of the correlation between AVPR1A promoter polymorphisms and PPI in a group with wide range of PPI suggests a more complex interaction. Therefore, further investigations are needed to analyze this very plausible interaction. Conditions with a reduced PPI, such as enuresis, schizophrenia or autism, are particularly interesting for this research.

The aim of this study was to analyze whether arginine vasopressin (AVP) may be considered a modulator of intestinal motility. In this view, we evaluated, in vitro, the effects induced by exogenous administration of AVP on the contractility of mouse distal colon, the subtype(s) of receptor(s) activated and the action mechanism. Isometric recordings were performed on longitudinal and circular muscle strips of mouse distal colon. AVP (0.001 nM-100 nM) caused concentration-dependent contractile effects only on the longitudinal muscle, antagonized by the V1 receptor antagonist, V-1880. AVP-induced effect was not modified by tetrodotoxin, atropine and indomethacin. Contractile response to AVP was reduced in Ca(2+)-free solution or in the presence of nifedipine, and it was abolished by depletion of calcium intracellular stores after repetitive addition of carbachol in calcium-free medium with addition of cyclopiazonic acid. U-73122, an inhibitor of the phospholipase C, effectively antagonized AVP effects, whilst it was not affected by an adenylyl cyclase inhibitor. Oxytocin induced an excitatory effect in the longitudinal muscle of distal colon at very high concentrations, effect antagonized by V-1880. The results of this study shown that AVP, via activation of V1 receptors, is able to modulate positively contractile activity of longitudinal muscle of mouse distal colon, independently by enteric nerve activation and prostaglandin synthesis. Contractile response is achieved by increase in cytoplasmatic Ca(2+) concentration via extracellular Ca(2+) influx from L-type Ca(2+) channels and via Ca(2+) release from intracellular stores through phospholipase C pathway. No modulation has been observed on the contractility of the circular muscle.

During pregnancy, females undergo several physiologically driven changes that facilitate adaptive behaviours and prepare the mother to care for her developing offspring. The nonapeptide hormone oxytocin is best recognised for its involvement in mammalian pregnancy and has been tightly associated with maternal care, in addition to its roles in pregnancy, parturition and lactation. A closely-related nonapeptide hormone, arganine vasopressin, has received considerably less attention for its role in pregnancy, although it has recently been implicated in modulating maternal care and aggression. In the present study, we examined the expression patterns of receptors for oxytocin (OXTR) and vasopressin (V1aR) over the course of pregnancy, ranging from non-mated virgin to immediately postpartum female prairie voles (Microtus ochrogaster). Unexpectedly, we found that OXTR was highly stable in all measured structures in the forebrain. V1aR was also stable throughout most of the brain. Two exceptions to this were found in the ventral pallidum (VPall) and the paraventricular nucleus of the hypothalamus (PVN); both significantly correlated with the length of time that females were pregnant. Changes in the PVN may reflect functional feedback in vasopressin release, or preparatory changes for ensuing maternal behaviour. The results also indicate an unappreciated role for VPall V1aR in pregnancy, which may relate to the function of the VPall in hedonic ‘liking’ and motivational ‘wanting.’ Taken together, our data indicate that, with a few compelling exceptions, nonapeptide dynamics during prairie vole pregnancy are largely limited to changes in the synthesis and release of oxytocin and vasopressin, and not the receptors to which they bind.

The peptide hormone arginine vasopressin (AVP) plays a critical role in regulating salt and water transport in the mammalian kidney. Recent studies have also demonstrated that AVP can promote cell survival in neuronal cells through V1 receptors. The current study addresses whether AVP can inhibit apoptosis in kidney collecting duct cells via V2 receptors and also explores the downstream signaling pathways regulating this phenomenon. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling analysis and caspase cleavage assays demonstrated that 1-desamino-8-d-arginine vasopressin (dDAVP) inhibited apoptosis induced by various agents (staurosporine, actinomycin D, and cycloheximide) in cultured mouse cortical collecting duct cells (mpkCCD). Incubation with dDAVP also inhibited apoptosis induced by the phosphatidylinositol 3-kinase (PI3K) pathway inhibitor LY294002, suggesting that the antiapoptotic effects of dDAVP are largely independent of PI3K signaling. The V2 receptor antagonist SR121463 completely abolished the antiapoptotic effects of dDAVP. In addition, incubation with 8-cpt-cAMP, a cell-permeable analog of cAMP, reproduced the antiapoptotic effects of dDAVP. Both dDAVP and 8-cpt-cAMP increased phosphorylation of proapoptotic Bcl-2 family members Bad and Bok. Bad phosphorylation at Ser-112 and Ser-155 is known to inhibit its proapoptotic activity. Preincubation with H89 blocked dDAVP-induced phosphorylation of both Bad and Bok, suggesting dependence on protein kinase A (PKA). This study provides evidence that AVP can inhibit apoptosis through the V2 receptor and downstream cAMP-mediated pathways in mammalian kidney. The antiapoptotic action of AVP may be relevant to a number of physiological and pathophysiological conditions including osmotic tolerance in the inner medulla, escape from AVP-induced antidiuresis, and polycystic kidney disease.

Arginine-vasopressin (AVP) V1 receptors are known to mediate brain edema formation after traumatic brain injury (TBI). So far, however, AVP V1 receptors were only inhibited by genetic deletion or prior to trauma. Therefore, the current study aimed to determine the therapeutic window of AVP V1 receptor antagonization after TBI. Male C57BL/6 mice (n = 7 per group) were subjected to controlled cortical impact (CCI), and 500 ng of a selective peptide V1 receptor antagonist (V1880) were applied by intracerebroventricular injection 5 min, and 1, 3, and 6 h thereafter. After 24 h, brain water content (BWC), intracranial pressure (ICP), and secondary contusion expansion volume were assessed. Neurological function was assessed daily for 7 days after trauma. Inhibition of AVP V1 receptors within 1 h after TBI significantly reduced BWC from 81.6 ± 0.7 to 80.6 ± 0.7% (mean ± SD; p

Fructose stimulates vasopressin in humans and can be generated endogenously by activation of the polyol pathway with hyperosmolarity. We hypothesized that fructose metabolism in the hypothalamus might partly control vasopressin responses after acute dehydration. Wild-type and fructokinase-knockout mice were deprived of water for 24 h. The supraoptic nucleus was evaluated for vasopressin and markers of the aldose reductase-fructokinase pathway. The posterior pituitary vasopressin and serum copeptin levels were examined. Hypothalamic explants were evaluated for vasopressin secretion in response to exogenous fructose. Water restriction increased serum and urine osmolality and serum copeptin in both groups of mice, although the increase in copeptin in wild-type mice was larger than that in fructokinase-knockout mice. Water-restricted, wild-type mice showed an increase in vasopressin and aldose reductase mRNA, sorbitol, fructose and uric acid in the supraoptic nucleus. In contrast, fructokinase-knockout mice showed no change in vasopressin or aldose reductase mRNA, and no changes in sorbitol or uric acid, although fructose levels increased. With water restriction, vasopressin in the pituitary of wild-type mice was significantly less than that of fructokinase-knockout mice, indicating that fructokinase-driven vasopressin secretion overrode synthesis. Fructose increased vasopressin release in hypothalamic explants that was not observed in fructokinase-knockout mice. In situ hybridization documented fructokinase mRNA in the supraoptic nucleus, paraventricular nucleus and suprachiasmatic nucleus. Acute dehydration activates the aldose reductase-fructokinase pathway in the hypothalamus and partly drives the vasopressin response. Exogenous fructose increases vasopressin release in hypothalamic explants dependent on fructokinase. Nevertheless, circulating vasopressin is maintained and urinary concentrating is not impaired. NEW & NOTEWORTHY This study increases our understanding of the mechanisms leading to vasopressin release under conditions of water restriction (acute dehydration). Specifically, these studies suggest that the aldose reductase-fructokinase pathways may be involved in vasopressin synthesis in the hypothalamus and secretion by the pituitary in response to acute dehydration. Nevertheless, mice undergoing water restriction remain capable of maintaining sufficient vasopressin (copeptin) levels to allow normal urinary concentration. Further studies of the aldose reductase-fructokinase system in vasopressin regulation appear indicated.

Neuroplastic changes in the amygdala account for emotional-affective aspects of pain and involve neuropeptides such as calcitonin gene-related peptide and corticotropin-releasing factor. Another neuropeptide system, central arginine vasopressin, has been implicated in neuropsychiatric disorders, but its role in pain-related emotional expression and neuroplasticity remains to be determined. Here, we tested the hypothesis that arginine vasopressin in the amygdala contributes to pain-related emotional-affective responses, using stereotaxic applications of arginine vasopressin and antagonists for G-protein coupled vasopressin V1A and oxytocin receptors in adult male Sprague-Dawley rats. In normal animals, arginine vasopressin increased audible and ultrasonic vocalizations and anxiety-like behavior (decreased open-arm preference in the elevated plus maze). The facilitatory effects were blocked by a selective V1A antagonist (SR 49059, Relcovaptan) but not by an oxytocin receptor antagonist (L-371,257). L-371,257 had some facilitatory effects on vocalizations. Arginine vasopressin had no effect in arthritic rats (kaolin/carrageenan knee joint pain model). SR 49059 inhibited vocalizations and anxiety-like behavior (elevated plus maze) in arthritic, but not normal, rats and conveyed anxiolytic properties to arginine vasopressin. Arginine vasopressin, SR 49059, and L-371,257 had no significant effects on spinal reflexes. We interpret the data to suggest that arginine vasopressin through V1A in the amygdala contributes to emotional-affective aspects of pain (arthritis model), whereas oxytocin receptors may mediate some inhibitory effects of the vasopressin system.

Vasopressin, a nonapeptide, signaling both as hormone in the blood and neuromodulator/neurotransmitter in the brain is considered to be causally involved in the pathological changes underlying anxiety and depression. In the present review we summarize experimental data obtained with Brattleboro rats as a model of congenital vasopressin-deficiency to test the hypothesis that central vasopressin signaling contributes to anxiety- and depression-like behavior. Male, female and lactating rats were studied. We focused on the paraventricular nucleus of the hypothalamus (PVN) and the septum, two brain areas in which vasopressin is proposed to control the endocrine and behavioral stress response, respectively. The presented data support the hypothesis that the behavioral changes seen in these rats are brought about by an altered vasopressin signaling at the brain level. Whereas vasopressin synthesized and released within the hypothalamus is primarily involved in endocrine regulation, vasopressin signaling in other brain areas may contribute to anxiety- and depression-like behavioral parameters. Further studies in this context might focus particularly on the interplay between extra-hypothalamic brain areas such as the septum and the medial amygdala.

Summary In a rat model, the baroreceptor reflex can be assessed by graded infusions of either phenylephrine or sodium nitroprusside with continuous hemodynamic monitoring. Microinjection of the cholinergic agonist carbachol (CCh) into the posterior hypothalamic nucleus (PHN) evokes an increase in mean arterial pressure and a change in heart rate. Lower doses of CCh evoke only tachycardia, whereas middle and higher doses evoke a biphasic change in heart rate of tachycardia followed by bradycardia. The bradycardia following the microinjection of CCh into the PHN can be attenuated by the previous administration of the vasopressin V1 receptor antagonist [d(CH2)5Tyr(Me)] arginine vasopressin (AVPX). Circulating arginine vasopressin (AVP) has been shown to increase the sensitivity of the baroreceptor reflex by stimulating vasopressin V1 receptors in the area postrema. The attenuation by AVPX of the bradycardia that results following the high doses of CCh suggests that AVP is released into the circulation following stimulation of cholinergic systems within the PHN. Thus, microinjection of a high dose of CCh (11 nmol) into the PHN alters the sensitivity of the baroreceptor reflex by increasing peripheral levels of AVP.

There is extensive evidence in animal studies, particularly in vole species (Microtus), that oxytocin (OT) receptor and arginine-vasopressin (AVP) receptor 1a is critical for the regulation of maternal and paternal behavior, respectively. Human studies have gained insight into the relationship between both hormone receptor gene variants and behavior, but not between the variants and the underlying brain activity. To study this, we investigated the association between neural activation of the anterior prefrontal cortex (APFC) in mothers and fathers in response to their child smiling video stimuli to induce the positive affect related to attachment with their child, and genetic variants of OT receptor (OXTR) and AVP receptor 1A (AVPR1A). Overall, 43 mothers and 41 fathers participated, and each parent's child smiling was video recorded. Participants were then genotyped and underwent near-infrared spectroscopy to measure neural activation of the APFC while observing their own child smiling compared with an unfamiliar child. We found that the right inferior APFC was activated in response to child video stimuli in mothers and differential hemispheric activation of the inferior APFC in OXTR rs2254298-G/G mothers compared with -A carrier mothers, but not in fathers. Furthermore, we found a difference in the left inferior APFC activation between AVPR1A RS3-non-334 and -334 carrier fathers, but not mothers. Our results indicate a sex-dependent association between the genetic variants and the inferior APFC activations of maternal and paternal positive affect, analogous to the results reported in voles.

Background: Vasopressin type 2 receptor (V 2 R) is a G-protein-coupled receptor (GPCRs) located in nephrons mediating water reabsorption in kidneys. Vasopressin acts at these receptors to enhance water reabsorption in the kidneys while by acting on V1 receptors in blood vessels increases blood pressure. To study V 2 R better, it must be produced in high quantities. Objectives: The current study aimed to optimize expression of V 2 R in Escherichia coli. Materials and Methods: In this investigation, V 2 R gene was cloned in E. coli. The recombinant plasmid pEt15b/V 2 R (rpET-BL21) was transformed into competent E. coli strain BL21 (DE3) cells. Overnight culture of the transformed bacteria was induced by the addition of isopropyl-thio-β-D-galactoside (IPTG). The effects of different IPTG concentrations, temperatures and sampling times on the expression of V 2 R were examined. Samples were analyzed by SDS-PAGE. Results: The maximum amount of protein production was obtained by the addition of 0.75 mM IPTG at 37°C after three hours. The most important factor was harvesting time with P value < 0.0001. In statistical analysis of data, the normal plot shows the normality of distribution of the studentized data. Conclusions: Full factorial design experimental approach helped to identify the critical culture condition parameters in heterologous expression of V 2 R. It would allow studying the parameters affecting the function of this protein in future experiments.

The brain neuropeptide arginine-vasopressin (AVP) mediates a wide range of social behaviours via its V1a (V1aR) but also its V1b receptor (V1bR). With respect to maternal behaviour, V1bR are still less investigated, whereas V1aR have been shown repeatedly to trigger maternal behaviour, depending on the brain region. Here, we aimed to study the role of both V1aR and V1bR within the hypothalamic paraventricular nucleus (PVN), a major source of AVP, in maternal care (lactation day (LD) 1), maternal motivation in the pup retrieval test (LD 3) and anxiety-related behaviour on the elevated plus maze (EPM; LD 5) by acute local infusion of receptor subtype-specific antagonists for V1aR (d(CH2)5Tyr(Me)(2)AVP) or V1bR (SSR149415). Furthermore, we compared V1bR expression in the PVN of virgin versus lactating rats (LD 4). Our results demonstrate that within the PVN neither V1bR mRNA (qPCR) nor protein (Western Blot) content differed between virgin and lactating rats. Regarding behaviour, acute antagonism of V1aR, but not of V1bR, decreased the occurrence of nursing as well as anxiety-related behaviour as reflected by higher percentage of time spent on and of entries into the open arms of the EPM. Maternal motivation was not affected by any treatment. In summary, we demonstrate subtype-specific involvement of V1 receptors within the PVN in mediating various maternal behaviours. The lack of effects after V1bR blockade reveals that AVP acts mainly via V1aR in the PVN, at least in lactating rats, to mediate maternal care and anxiety.

In the mammalian peripartum period, the activity of both the brain oxytocin and vasopressin system is elevated as part of the physiological adaptations occurring in the mother. This is reflected by increased expression and intracerebral release of oxytocin and vasopressin, as well as increased neuropeptide receptor expression and binding. In this review we discuss the functional role of the brain oxytocin and vasopressin system in the context of maternal behavior, specifically maternal care and maternal aggression in rodents. In order to enable the identification of significant and peptide-specific contributions to the display of maternal behavior, various complementary animal models of maternal care and/or maternal aggression were studied, including rats selectively bred for differences in anxiety-related behavior (HAB and LAB dams), monitoring of local neuropeptide release during ongoing maternal behavior, and local pharmacological or genetic manipulations of the neuropeptide systems. The medial preoptic area was identified as a major site for oxytocin- and vasopressin-mediated maternal care. Furthermore, both oxytocin and vasopressin release and receptor activation in the central amygdala and the bed nucleus of the stria terminalis play an important role for maternal aggression. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

Oxytocin (OT) and arginine vasopressin (AVP), in their capacities as neuromodulators, are believed to play an important role in mood control, including regulation of the anxiety response. In the present study, the contributions of oxytocin and vasopressin receptor modulation to anxiety-like behaviors were examined in male Sprague-Dawley rats. The behavioral effects of the OT receptor agonist, carbetocin (intracerebroventricular, intravenous and intraperitoneal routes), the AVP receptor agonist desmopressin (intravenous route), and the OT/AVP1A receptor antagonist atosiban (intravenous route) were evaluated in the elevated plus maze. The benzodiazepine diazepam was included as a positive control. Central but not systemic administration of carbetocin produced pronounced anxiolytic-like behavioral changes comparable to those measured following systemic diazepam treatment. The anxiolytic efficacy of carbetocin was maintained following 10 days of once-daily treatment, contrasting with the effects of diazepam which were no longer distinguishable from saline treatment. Systemic administration of desmopressin produced anxiogenic-like effects whereas systemic atosiban produced anxiolytic-like effects. Co-administration of desmopressin with atosiban resulted in saline-like behavioral responses, implicating an AVP1A receptor mechanism in the anxiolytic and anxiogenic effects of these neuropeptides following systemic administration. A peripherally-mediated antidiuretic effect of desmopressin on water consumption was also demonstrated. These results highlight the potential therapeutic utility of AVP1A receptor blockade in the modulation of anxiety-related behaviors; AVP1A receptor blockade appears to be a more promising pharmacological target than does OT receptor activation following systemic drug administration.

The anterior olfactory nucleus (AON), a component of the main olfactory system, is a cortical region that processes olfactory information and acts as a relay between the main olfactory bulbs and higher brain regions such as the piriform cortex. Utilizing a transgenic rat in which an enhanced green fluorescent protein reporter gene is expressed in vasopressin neurones (eGFP-vasopressin), we have discovered a population of vasopressin neurones in the AON. These vasopressin neurones co-express vasopressin V1 receptors. They also co-express GABA and calbinin-D28k indicating that they are neurochemically different from the newly described vasopressin neurons in the main olfactory bulb. We utilized the immediate early gene product, early growth response protein 1 (Egr-1), to examine the functional role of these vasopressin neurons in processing social and non-social odours in the AON. Exposure of adult rats to a conspecific juvenile or a heterospecific predator odour leads to increases in Egr-1 expression in the AON in a subregion specific manner. However, only exposure to a juvenile increases Egr-1 expression in AON vasopressin neurons. These data suggest that vasopressin neurones in the AON may be selectively involved in the coding of social odour information.

The distribution of three types of arginine vasotocin (AVT) receptors in the brain and pituitary of the newt Cynops pyrrhogaster, namely, the V1a-, V2-, and V3/V1b-type receptors, was studied by means of in situ hybridization and immunohistochemistry. mRNA signals and immunoreactive cells for the V1a-type receptor were observed in the telencephalon (mitral layer of the olfactory bulb, dorsal and medial pallium, lateral and medial amygdala, bed nucleus of the decussation of the fasciculus telencephali, bed nucleus of the stria terminalis), diencephalon (anterior preoptic area, magnocellular preoptic nucleus, suprachiasmatic nucleus, ventral thalamus, dorsal and ventral hypothalamic nucleus), mesencephalon (tegmentum, interpeduncular nucleus), and medulla oblongata (median reticular formation, nucleus motorius tegmenti). Cells expressing the V2-type receptor were found in the telencephalon (medial pallium, lateral and medial amygdala, bed nucleus of the decussation of the fasciculus telencephali), and mesencephalon (tegmentum trigemini and facialis). In the paraphysis (possibly the main site of cerebrospinal fluid production), only V2-type receptor mRNA signal and immunoreactivity were detected. V3/V1b-type receptor mRNA was expressed in the diencephalon (dorsal hypothalamic nucleus, nucleus tuberculi posterioris), mesencephalon (tegmentum, interpeduncular nucleus), and medulla oblongata (raphe nucleus), whereas V3/V1b-type-receptor-like immunoreactivity was scarcely detectable in the entire brain. The V3/V1b-type receptor was predominantly expressed in the anterior pituitary. V3/V1b-type receptor and proopiomelanocortin mRNAs were co-localized in the distal lobe of the pituitary. This is the first report of the distribution of three types of AVT receptor in the brain and pituitary of non-mammalian vertebrates.

The ovarian hormone estradiol regulates the expression of arginine vasopressin gene and the release of arginine vasopressin by magnocellular hypothalamic neurons. Magnocellular neurons express estrogen receptor β and are contacted by afferent neurons that express estrogen receptor α. In this study we have assessed the effect of selective ligands for estrogen receptors to determine the subtype of estrogen receptor involved in the regulation of arginine vasopressin immunoreactivity in the supraoptic and paraventricular nuclei of ovariectomized rats. The volume fraction occupied by arginine vasopressin immunoreactive material was significantly increased in both nuclei in the animals treated with estradiol compared to the animals injected with vehicle. A similar result was obtained with an estrogen receptor α selective agonist. In contrast, the administration of an estrogen receptor β selective agonist did not significantly affect arginine vasopressin immunoreactivity. This finding suggests that estradiol may regulate arginine vasopressin levels on the supraoptic and paraventricular nuclei by acting on afferent neurons expressing estrogen receptor α. © 2010 Elsevier Ireland Ltd.