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.

[Diagnosis and follow-up of 2 cases of pediatric nephrogenic syndrome of inappropriate antidiuresis resulting from activating mutation in AVPR2 and literature review].

Objective: To analyze the clinical and genetic features, as well as the treatment outcomes of two boys with nephrogenic syndrome of inappropriate antidiuresis (NSIAD) caused by gain-of-function mutations in the V2 vasopressin receptor gene (AVPR2). Methods: The clinical manifestations, genetic testing, therapeutic interventions and the outcomes of two boys with NSIAD hospitalized in the Department of Endocrinology, Beijing Children's Hospital in April 2019 were reported. A literature search with "Nephrogenic syndrome of inappropriate antidiuresis" and "AVPR2 gene" as keywords was conducted at the China national knowledge infrastructure (CNKI), the Wanfang Data Knowledge Service Platform, PubMed and Springer Link up to May 2020. Relevant published articles were reviewed. Results: The two cases presented with chronic and severe hyponatremia with hypo-osmolality, inappropriately elevated urinary osmolality and urinary sodium levels. The onset age was 5.25-years and 2 months respectively. AVPR2 sequencing revealed a previously described hemizygous activating mutation (c.409C>T, p.R137C) in both of boys, each inherited the variant from their mother. Patient 1 limited fluid intake by himself in his daily life, intravenous and oral sodium supplementations showed no significant increase of serum sodium level. Oral furosemide increased the serum sodium level and maintained it within normal range. The serum sodium and potassium levels were in the normal range during the 1-year follow-up period with oral furosemide. The serum sodium level of Patient 2 increased with restricting fluid intake and with salt supplementation. However, after he experienced respiratory infection, the plasma sodium level decreased. Subsequently, oral anti-infection medicine and furosemide were applied. The serum sodium level increased two days later and remained at a normal range afterwards. The boy was 1 year old with normal growth. He stopped taking furosemide after 4 months while taking 1 gram of salt per day, the blood sodium level maintained at normal range. Literature search identified no reports in Chinese journals, whereas 50 publications were found in English journals. A total of 30 NSIAD probands were reported and 16 of those (53%) had childhood onset, most presented with seizures. The majority had a hotspot change at the nucleotide position of 409 in AVPR2. Nine cases had an amino acid change as R137C and five cases as R137L. Fluid restriction and oral urea intake were main treatment options, no report so far was found with oral furosemide treatment. Conclusions: NSIAD presented with hyponatremia without any other specific presentations. Genetic testing for variants in AVPR2 is helpful for early diagnosis and timely treatment. The first two cases of oral furosemide treatment were reported by the article which helped to maintain a normal serum sodium level after limiting fluid intake and supplementing sodium which showed limited effect.

Molecular characterization and expression of arginine vasotocin V1a2 receptor in Atlantic croaker brain: Potential mechanisms of its downregulation by PCB77.

The arginine vasotocin (AVT)-V1a receptor mediates critical reproductive behaviors of the nonapeptide vasotocin in the teleost brain. In this study, we report the molecular characterization of the AVT-V1a2 receptor and its messenger RNA (mRNA) and protein expressions in the Atlantic croaker brain after exposure to the planar polychlorinated biphenyl congener 3,3',4,4'-tetrachlorobiphenyl (PCB77). The full-length sequence of croaker AVT-V1a2 receptor complementary DNA (cDNA) is highly homologous to other teleost AVT-V1a2 receptor cDNAs. Double-labeled immunohistochemistry showed coexpression of AVT-V1a2 receptor and gonadotropin-releasing hormone-I (GnRH-I, a neuropeptide that regulates gonadotropin secretion) in hypothalamic neurons, thereby providing the anatomical basis for possible AVT modulation of croaker reproduction through alterations in GnRH-I secretion. AVT-V1a2 receptor mRNA and protein levels as well as GnRH-I mRNA levels were markedly decreased in hypothalamic tissues of croaker exposed to PCB77 (dose: 2 and 8 µg/g body weight for 4 weeks) compared with levels in untreated (control) fish. In contrast, hypothalamic cytochrome P450 1A (CYP1A, a monooxygenase enzyme) and interleukin-1ß (IL-1ß, a cytokine indicator of inflammation and response to neuronal damage) mRNA levels, and plasma protein carbonyl (PC, an indicator of reactive oxygen species) contents, important biomarkers of neural stress, were increased in PCB77-exposed fish compared with controls. Collectively, these results suggest that the downregulation of hypothalamic AVT-V1a2 receptor and GnRH-I transcripts due to PCB77 exposure is associated with induction of CYP1A, cellular inflammation and oxidative stress in Atlantic croaker, a marine teleost that inhabits estuaries along the US Atlantic coast and the Gulf of Mexico that are often contaminated with persistent organic pollutants such as PCBs.

Identification of a novel X-linked arginine-vasopressin receptor 2 mutation in nephrogenic diabetes insipidus: Case report and pedigree analysis.

INTRODUCTION: The clinical and genetic characteristics of nephrogenic diabetes insipidus (NDI) were described via assessing 2 cases of NDI patients from a Chinese family. PATIENT CONCERNS: Two patients who manifest polyuria and polydipsia were admitted to hospital for definite diagnosis. DIAGNOSIS: Water deprivation-vasopressin tests showed that the patients may possess renal-origin diabetes insipidus. All the levels of thyroid-stimulating hormone, luteinizing hormone, follicle stimulation hormone, adrenocorticotropic hormone, prolactin, and growth hormone in both patients were normal. These results were certified that both patients possess a nephropathy-type diabetes insipidus. B-mode ultrasonography and urinalysis test demonstrated that the patient's diabetes insipidus is unlikely to originate from renal organic disease. Remarkably, by nucleotide sequencing, we found a novel mutation c.414_418del in arginine-vasopressin receptor 2 (AVPR2) was related to the disease of NDI. INTERVENTIONS: Two patients were treated with oral hydrochlorothiazide and indomethacin. In addition, low salt diet and potassium supplementation throughout the patients' treatment. OUTCOMES: The clinical symptoms of 2 patients were significantly reduced after targeted therapy. CONCLUSION: A mutation in AVPR2 was discovered to be associated with NID. It provides a new target for molecular diagnosis of NDI, enabling families to undergo genetic counseling and obtain prenatal diagnoses.

Preclinical Efficacy of [V4 Q5 ]dDAVP, a Second Generation Vasopressin Analog, on Metastatic Spread and Tumor-Associated Angiogenesis in Colorectal Cancer.

PURPOSE: Control of metastatic spread of colorectal cancer (CRC) remains as a major therapeutic challenge. [V4 Q5 ]dDAVP is a vasopressin peptide analog with previously reported anticancer activity against carcinoma tumors. By acting as a selective agonist of arginine vasopressin type 2 membrane receptor (AVPR2) present in endothelial and tumor cells, [V4Q5]dDAVP is able to impair tumor aggressiveness and distant spread. Our aim was to evaluate the potential therapeutic benefits of [V4Q5]dDAVP on highly aggressive CRC disease using experimental models with translational relevance. MATERIALS AND METHODS: Murine CT-26 and human Colo-205 AVPR2-expressing CRC cell lines were used to test the preclinical efficacy of [V4Q5]dDAVP, both in vitro and in vivo. RESULTS: In syngeneic mice surgically implanted with CT-26 cells in the spleen, sustained intravenous treatment with [V4Q5]dDAVP (0.3 µg/kg) dramatically impaired metastatic progression to liver without overt signs of toxicity, and also reduced experimental lung colonization. The compound inhibited in vivo angiogenesis driven by Colo-205 cells in athymic mice, as well as in vitro endothelial cell migration and capillary tube formation. [V4Q5]dDAVP exerted AVPR2-dependent cytostatic activity in vitro (IC50 1.08 µM) and addition to 5-fluorouracil resulted in synergistic antiproliferative effects both in CT-26 and Colo-205 cells. CONCLUSION: The present preclinical study establishes for the first time the efficacy of [V4Q5]dDAVP on CRC. These encouraging. RESULTS: suggest that the novel second generation vasopressin analog could be used for the management of aggressive CRC as an adjuvant agent during surgery or to complement standard chemotherapy, limiting tumor angiogenesis and metastasis and thus protecting the patient from CRC recurrence.

Hippocampal gene expression patterns in oxytocin male knockout mice are related to impaired social interaction.

Social interaction between animals is crucial for the survival and life in groups. It is well demonstrated that oxytocin (OT) and vasopressin (AVP) play critical roles in the regulation of social behaviors in mammals, however, other neurotransmitters and hormones are involved in the brain circuitry related to these behaviors. The present study aimed to investigate the gene expression of neurotransmitter receptors in the brain of OT knockout (OTKO) male mice. In this study, we evaluated the expression levels of the OT receptor (Oxtr), AVP receptors 1a and 1b (Avpr1a; Avpr1b), dopamine receptor 2 (Drd2), and the estrogen receptors alpha and beta (Esr1; Esr2) genes in the hippocampus (HPC), olfactory bulb (OB), hypothalamus (HPT) and prefrontal cortex (PFC). AVP gene (Avp) expression was analyzed in the HPT. Gene expression results were discussed regarding to social interaction and sexual behavior findings. Additionally, we analyzed the influence of OT absence on the Avp mRNA expression levels in the HPT. RNA extraction and cDNAs synthesis followed by quantitative polymerase chain reaction were performed for gene expression determination. Results were calculated with the 2-ΔΔCt method. Our main finding was that HPC is more susceptible to gene expression changes due to the lack of OT. OTKOs exhibited decreased expression of Drd2 and Avpr1b, but increased expression of Oxtr in the HPC. In the PFC, Esr2 was increased. In the HPT, there was a reduced Avp expression in the OTKO group. No differences were detected in the OB and HPT. Despite these changes in gene expression, sexual behavior was not affected. However, OTKO showed higher social investigation and lower aggressive performance than wild-type mice. Our data highlight the importance of OT for proper gene expression of neurotransmitter receptors related to the regulation of social interaction in male mice.

Detection of activity-dependent vasopressin release from neuronal dendrites and axon terminals using sniffer cells.

Our understanding of neuropeptide function within neural networks would be improved by methods allowing dynamic detection of peptide release in living tissue. We examined the usefulness of sniffer cells as biosensors to detect endogenous vasopressin (VP) release in rat hypothalamic slices and from isolated neurohypophyses. Human embryonic kidney cells were transfected to express the human V1a VP receptor (V1aR) and the genetically encoded calcium indicator GCaMP6m. The V1aR couples to Gq11, thus VP binding to this receptor causes an increase in intracellular [Ca2+] that can be detected by a rise in GCaMP6 fluorescence. Dose-response analysis showed that VP sniffer cells report ambient VP levels >10 pM (EC50 = 2.6 nM), and this effect could be inhibited by the V1aR antagonist SR 49059. When placed over a coverslip coated with sniffer cells, electrical stimulation of the neurohypophysis provoked a reversible, reproducible, and dose-dependent increase in VP release using as few as 60 pulses delivered at 3 Hz. Suspended sniffer cells gently plated over a slice adhered to the preparation and allowed visualization of VP release in discrete regions. Electrical stimulation of VP neurons in the suprachiasmatic nucleus caused significant local release as well as VP secretion in distant target sites. Finally, action potentials evoked in a single magnocellular neurosecretory cell in the supraoptic nucleus provoked significant VP release from the somatodendritic compartment of the neuron. These results indicate that sniffer cells can be used for the study of VP secretion from various compartments of neurons in living tissue. NEW & NOTEWORTHY The specific functional roles of neuropeptides in neuronal networks are poorly understood due to the absence of methods allowing their real-time detection in living tissue. Here, we show that cultured "sniffer cells" can be engineered to detect endogenous release of vasopressin as an increase in fluorescence.

The behavioral and molecular evaluation of effects of social instability stress as a model of stress-related disorders in adult female rats.

The study aimed to test the hypotheses that chronic social instability stress (CSIS) alters behavioral and physiological parameters and expression of selected genes important for stress response and social behaviors. Adult female Sprague-Dawley rats were subjected to the 4-week CSIS procedure, which involves unpredictable rotation between phases of isolation and overcrowding. Behavioral analyses (Experiment 1) were performed on the same rats before and after CSIS (n = 16) and physiological and biochemical measurements (Experiment 2) were made on further control (CON; n = 7) and stressed groups (CSIS; n = 8). Behaviors in the open field test (locomotor and exploratory activities) and elevated-plus maze (anxiety-related behaviors) indicated anxiety after CSIS. CSIS did not alter the physiological parameters measured, i.e. body weight gain, regularity of estrous cycles, and circulating concentrations of stress hormones and sex steroids. QRT-PCR analysis of mRNA expression levels was performed on amygdala, hippocampus, prefrontal cortex (PFC), and hypothalamus. The main finding is that CSIS alters the mRNA levels for the studied genes in a region-specific manner. Hence, expression of POMC (pro-opiomelanocortin), AVPR1a (arginine vasopressin receptor), and OXTR (oxytocin receptor) significantly increased in the amygdala following CSIS, while in PFC and/or hypothalamus, POMC, AVPR1a, AVPR1b, OXTR, and ERß (estrogen receptor beta) expression decreased. CSIS significantly reduced expression of CRH-R1 (corticotropin-releasing hormone receptor type 1) in the hippocampus. The directions of change in gene expression and the genes and regions affected indicate a molecular basis for the behavior changes. In conclusion, CSIS may be valuable for further analyzing the neurobiology of stress-related disorders in females.

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

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

The effect of starvation and re-feeding on vasotocinergic and isotocinergic pathways in immature gilthead sea bream (Sparus aurata).

This study describes the responses of the vasotocinergic and isotocinergic systems to food deprivation and re-feeding processes in immature gilthead sea bream (Sparus aurata). The animals were subjected to the following experimental treatments: (1) normal feeding (control), (2) food deprivation for 21 days; and (3) re-feeding for 7 days, beginning 14 days after starvation. The animals were sampled at 0, 7, 14 and 21 days from the beginning of the trial. The pituitary and plasma arginine vasotocin (AVT) and isotocin (IT) levels and the hypothalamic pro-vasotocin and pro-isotocin mRNA expression levels were measured. In addition, the mRNA levels of three receptors, avtr v1, avtr v2 and itr, were analyzed in target organs associated with (1) the integration and control of different physiological pathways related to stress and food intake (i.e., the hypothalamus), (2) hormonal release into the bloodstream (i.e., the pituitary), and (3) metabolism and its control (i.e., the liver). The metabolic parameters in the liver were also determined. The hepatosomatic index decreased, and hepatic metabolites were mobilized beginning in the early stages of starvation. Moreover, an over-compensation of these parameters occurred when the fish were re-fed after starvation. In terms of the vasotocinergic and isotocinergic systems, feed restriction induced a clear time-dependent regulation among metabolic organization, stress regulation and orexigenic processes in the mature hormone concentration and pro-peptide and receptor mRNA expression. Our results reveal the important role of the AVT/IT endocrine systems in the orchestration of fish physiology during starvation and re-feeding and indicate their involvement in both central and peripheral organs.

Therapeutic effects of Euphorbia Pekinensis and Glycyrrhiza glabra on Hepatocellular Carcinoma Ascites Partially Via Regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 Signal Axis.

To clarify unknown rationalities of herbaceous compatibility of Euphorbia Pekinensis (DJ) and Glycyrrhiza glabra (GC) acting on hepatocellular carcinoma (HCC) ascites, peritoneum transcriptomics profiling of 15 subjects, including normal control (Con), HCC ascites mouse model (Mod), DJ-alone, DJ/GC-synergy and DJ/GC-antagonism treatment groups were performed on OneArray platform, followed by differentially expressed genes (DEGs) screening. DEGs between Mod and Con groups were considered as HCC ascites-related genes, and those among different drug treatment and Mod groups were identified as DJ/GC-combination-related genes. Then, an interaction network of HCC ascites-related gene-DJ/GC combination-related gene-known therapeutic target gene for ascites was constructed. Based on nodes' degree, closeness, betweenness and k-coreness, the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis with highly network topological importance was demonstrated to be a candidate target of DJ/GC combination acting on HCC ascites. Importantly, both qPCR and western blot analyses verified this regulatory effects based on HCC ascites mice in vivo and M-1 collecting duct cells in vitro. Collectively, different combination designs of DJ and GC may lead to synergistic or antagonistic effects on HCC ascites partially via regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis, implying that global gene expression profiling combined with network analysis can offer an effective way to understand pharmacological mechanisms of traditional Chinese medicine prescriptions.

Diurnal regulation of hypothalamic kisspeptin is disrupted during mouse pregnancy.

Kisspeptin, the neuropeptide product of the Kiss1 gene, is critical in driving the hypothalamic-pituitary-gonadal (HPG) axis. Kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (Arc) of the hypothalamus mediate differential effects, with the Arc regulating negative feedback of sex steroids and the AVPV regulating positive feedback, vital for the preovulatory surge and gated under circadian control. We aimed to characterize hypothalamic Kiss1 and Kiss1r mRNA expression in nonpregnant and pregnant mice, and investigate potential circadian regulation. Anterior and posterior hypothalami were collected from C57BL/6J mice at diestrus, proestrus, and days 6, 10, 14, and 18 of pregnancy, at six time points across 24h, for real-time PCR analysis of gene expression. Analysis confirmed that Kiss1 mRNA expression in the AVPV increased at ZT13 during proestrus, with a luteinizing hormone surge observed thereafter. No diurnal regulation was seen at diestrus or at any stage of pregnancy. Anterior hypothalamic Avp mRNA expression exhibited no diurnal variation, but Avpr1a peaked at 12:00h during proestrus, possibly reflecting the circadian input from the suprachiasmatic nucleus to AVPV Kiss1 neurons. Rfrp (Npvf) expression in the posterior hypothalamus did not demonstrate diurnal variation at any stage. Clock genes Bmal1 and Rev-erbα were strongly diurnal, but there was little change between diestrus/proestrus and pregnancy. Our data indicate the absence of the circadian input to Kiss1 in pregnancy, despite high gestational estradiol levels and normal clock gene expression, and may suggest a disruption of a kisspeptin-specific diurnal rhythm that operates in the nonpregnant state.

Arginine Vasopressin and Arginine Vasopressin Receptor 1b Involved in Electroacupuncture-Attenuated Hypothalamic-Pituitary-Adrenal Axis Hyperactivity in Hepatectomy Rats.

OBJECTIVE: The study aims to know the effect of electroacupuncture (EA) in maintenance of the homeostasis of the neuroendocrine system in hepatectomy rats and the involvement of arginine vasopressin (AVP) signaling in hypothalamus after EA was observed. MATERIALS AND METHODS: Rats were randomly assigned to four groups, including the intact group, model group, sham-EA group, and EA group. EA was given during the perioperative period at the Zusanli (ST36) and Sanyinjiao (SP6) points after hepatectomy. The serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels were detected via radioimmunoassay. The expression of AVP, arginine vasopressin receptor 1a (AVPR1a), arginine vasopressin receptor 1b (AVPR1b), and glucocorticoid receptor (GR) was detected by Western blot after surgery. RESULTS: Compared with the intact group, the ACTH and CORT levels in the serum of model group were increased, whereas the ACTH and CORT levels were decreased in the EA group compared with the model group. Moreover, AVP and AVPR1b protein levels in the pituitary gland were increased in the model group and decreased in the EA group. Further, a distinct increase in the AVP and AVPR1a protein levels was observed in the model group, whereas they were significantly decreased in the EA group. Blockade of AVPR1b by nelivaptan reduced the increase of ACTH and CORT. D [Leu(4) , Lys(8) ] vasopressin can inhibit the effect of EA in rectification of the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. CONCLUSIONS: EA application at ST36 and SP6 can ameliorate the hyperactivity of the HPA axis via AVP signaling during the perioperative period.

Effects of maternal chlorpyrifos diet on social investigation and brain neuroendocrine markers in the offspring - a mouse study.

BACKGROUND: Chlorpyrifos (CPF) is one of the most widely used organophosphate pesticides worldwide. Epidemiological studies on pregnant women and their children suggest a link between in utero CPF exposure and delay in psychomotor and cognitive maturation. A large number of studies in animal models have shown adverse effects of CPF on developing brain and more recently on endocrine targets. Our aim was to determine if developmental exposure to CPF affects social responsiveness and associated molecular neuroendocrine markers at adulthood. METHOD: Pregnant CD1 outbred mice were fed from gestational day 15 to lactation day 14 with either a CPF-added (equivalent to 6 mg/kg/bw/day during pregnancy) or a standard diet. We then assessed in the offspring the long-term effects of CPF exposure on locomotion, social recognition performances and gene expression levels of selected neurondocrine markers in amygdala and hypothalamus. RESULTS: No sign of CPF systemic toxicity was detected. CPF induced behavioral alterations in adult offspring of both sexes: CPF-exposed males displayed enhanced investigative response to unfamiliar social stimuli, whereas CPF-exposed females showed a delayed onset of social investigation and lack of reaction to social novelty. In parallel, molecular effects of CPF were sex dimorphic: in males CPF increased expression of estrogen receptor beta in hypothalamus and decreased oxytocin expression in amygdala; CPF increased vasopressin 1a receptor expression in amygdala in both sexes. CONCLUSIONS: These data indicate that developmental CPF affects mouse social behavior and interferes with development of sex-dimorphic neuroendocrine pathways with potential disruptive effects on neuroendocrine axes homeostasis. The route of exposure selected in our study corresponds to relevant human exposure scenarios, our data thus supports the view that neuroendocrine effects, especially in susceptible time windows, should deserve more attention in risk assessment of OP insecticides.

Arginine vasopressin inhibits adipogenesis in human adipose-derived stem cells.

Intracellular Ca(2+) signaling is important for stem cell differentiation and there is evidence it may coordinate the process. Arginine vasopressin (AVP) is a neuropeptide hormone secreted mostly from the posterior pituitary gland and increases Ca(2+) signals mainly via V1 receptors. However, the role of AVP in adipogenesis of human adipose-derived stem cells (hASCs) is unknown. In this study, we identified the V1a receptor gene in hASCs and demonstrated that AVP stimulation increased intracellular Ca(2+) concentration during adipogenesis. This effect was mediated via V1a receptors, Gq-proteins and the PLC-IP3 pathway. These Ca(2+) signals were due to endoplasmic reticulum release and influx from the extracellular space. Furthermore, AVP supplementation to the adipogenic medium decreased the number of adipocytes and adipocyte marker genes during differentiation. The effect of AVP on adipocyte formation was reversed by the V1a receptor blocker V2255. These findings suggested that AVP may function to inhibit adipocyte differentiation.

Cortisol modulates vasotocinergic and isotocinergic pathways in the gilthead sea bream.

In the present study, we assessed the responses of the vasotocinergic and isotocinergic systems to chronic stress induced by cortisol administration in the gilthead sea bream (Sparus aurata). Pituitary and plasma arginine vasotocin (AVT) and isotocin (IT) levels, as well as hypothalamic pro-vasotocin (pro-VT) and pro-isotocin (pro-IT) mRNA expression levels, were analysed. In addition, the mRNA levels of three receptors, AVTR type V1a2, AVTR type V2 and ITR, were analysed in several target organs associated with the following physiological processes: (i) integration and control (hypothalamus), (ii) metabolism and its control (liver and hypothalamus), (iii) osmoregulation (gills) and (iv) stress response (head kidney). Specimens were injected intraperitoneally with slow-release implants (5 µL g(-1) body mass) containing coconut oil alone (control group) or with cortisol (50 µg g(-1) body mass; cortisol group). Both AVT and IT synthesis and release were correlated with plasma cortisol values, suggesting a potential interaction between both hormonal systems and cortisol administration. Our results suggest that the activation of hepatic metabolism as well as the hypothalamic control of metabolic processes provide the energy necessary to overcome stress, which could be partly mediated by AVTRs and ITR. Upregulation of branchial AVT and IT receptor expression following cortisol treatment suggests an involvement of the vasotocinergic and isotocinergic systems in the regulation of ion channels/transporters during stressful situations. Finally, changes in AVT and IT receptor mRNA expression in the head kidney suggest these nonapeptides participate in feedback mechanisms that regulate the synthesis/release of cortisol. Our results indicate a relationship between cortisol and both the vasotocinergic and isotocinergic systems during simulated chronic stress in S. aurata.

Sclederma of Poria cocos exerts its diuretic effect via suppression of renal aquaporin-2 expression in rats with chronic heart failure.

ETHNOPHARMACOLOGICAL RELEVANCE: Sclederma of Poria cocos (Hoelen) has been used as a diuretic in traditional Asian medicine. However, the underlying mechanism by which Sclederma of Poria cocos (hoelen) exerts its diuretic effect has not been well identified. The aim of the present study was to evaluate the effects of Sclederma of Poria cocos (hoelen) in rats with chronic heart failure (CHF) induced by acute myocardial infarction and to investigate the underlying mechanisms. MATERIALS AND METHODS: An aqueous extract of Sclederma of Poria cocos (hoelen) (2.4 g/kg/d, 1.2 g/kg/d or 0.6 g/kg/d) or furosemide (20 mg/kg/d) was administered orally to male Sprague-Dawley rats starting on the day of coronary ligation. The urine output of all rats was quantified and collected every day for 1 or 4 weeks. The expression of aquaporin-2 (AQP2) was examined after treatment for 1 or 4 weeks. RESULTS: Urinary output increased significantly and urinary osmolality decreased after oral administration of Sclederma of Poria cocos (hoelen) for both 1 and 4 weeks. Sclederma of Poria cocos (hoelen) caused less electrolyte disorder than furosemide. Furthermore, Sclederma of Poria cocos (hoelen) reduced the levels of plasma BNP in CHF rats, whereas furosemide had no effect. Importantly, both mRNA and protein expression of AQP2 were down-regulated and urinary excretion of AQP2 was decreased after administration of Sclederma of Poria cocos (hoelen) to CHF rats. Similarly, Sclederma of Poria cocos (hoelen) reduced plasma arginine vasopressin (AVP) level and down-regulated vasopressin type 2 receptor (V2R) mRNA expression. CONCLUSIONS: Sclederma of Poria cocos (hoelen) exerts its diuretic effect and improves cardiac function in CHF rats via the AVP-V2R-AQP2 axis.

Variations in the expression of vasotocin and isotocin receptor genes in the gilthead sea bream Sparus aurata during different osmotic challenges.

The dynamic changes in mRNA expression levels for vasotocin (AVT) and isotocin (IT) receptor gene levels were assessed in a time-course response study in immature male specimens of the gilthead sea bream (Sparus aurata) submitted to hyper- (55‰ salinity) and hypo-osmotic (5‰ salinity) challenges. Two different cDNAs for the AVT receptor and one for the IT receptor (V1a2-type and V2-type AVTR, and ITR, respectively) were cloned by screening an S. aurata brain cDNA library. Genes for these receptors were expressed differentially and is nearly ubiquitously in 26 of the examined tissues. In the gills, both environmental salinity challenges up-regulated AVTR V1a2-type gene expression concomitantly with mRNA expression protein activity of Na(+), K(+)-ATPase gene expression and protein, whereas the AVTR V2-type and cystic fibrosis transmembrane conductance regulator (CFTR) mRNA levels were associated with mRNAs environmental salinity, indicating a possible connection between AVTRs and these transporters. In kidney, AVTR V1a2-type gene expression peaked rapidly and lasted only a short time (12-24h) in response to both osmotic challenges. In contrast, AVTR V2-type mRNA levels were enhanced in specimens exposed to hyperosmotic conditions, whereas they decreased under hypoosmotic environments, suggesting an antidiuretic role related to the vasoconstriction function. In the hypothalamus, only the expression of the AVTR V2-type gene was enhanced at 7 and 14 days under both experimental conditions. In the liver, both AVTRs had increased mRNA levels, with the upregulation of their AVTR V2-type gene increasing faster than the V1a2-type. The ITR gene was not sensitive to variations of external salinity in any of the analyzed tissues. Our results demonstrate the involvement of the vasotocinergic, but not the isotocinergic, pathway as well as the hypothalamic function, in the adjustments of both osmoregulatory and metabolic processes after osmotic challenges.

Hypertension in mice with transgenic activation of the brain renin-angiotensin system is vasopressin dependent.

An indispensable role for the brain renin-angiotensin system (RAS) has been documented in most experimental animal models of hypertension. To identify the specific efferent pathway activated by the brain RAS that mediates hypertension, we examined the hypothesis that elevated arginine vasopressin (AVP) release is necessary for hypertension in a double-transgenic model of brain-specific RAS hyperactivity (the "sRA" mouse model). sRA mice experience elevated brain RAS activity due to human angiotensinogen expression plus neuron-specific human renin expression. Total daily loss of the 4-kDa AVP prosegment (copeptin) into urine was grossly elevated (≥8-fold). Immunohistochemical staining for AVP was increased in the supraoptic nucleus of sRA mice (~2-fold), but no quantitative difference in the paraventricular nucleus was observed. Chronic subcutaneous infusion of a nonselective AVP receptor antagonist conivaptan (YM-087, Vaprisol, 22 ng/h) or the V(2)-selective antagonist tolvaptan (OPC-41061, 22 ng/h) resulted in normalization of the baseline (~15 mmHg) hypertension in sRA mice. Abdominal aortas and second-order mesenteric arteries displayed AVP-specific desensitization, with minor or no changes in responses to phenylephrine and endothelin-1. Mesenteric arteries exhibited substantial reductions in V(1A) receptor mRNA, but no significant changes in V(2) receptor expression in kidney were observed. Chronic tolvaptan infusion also normalized the (5 mmol/l) hyponatremia of sRA mice. Together, these data support a major role for vasopressin in the hypertension of mice with brain-specific hyperactivity of the RAS and suggest a primary role of V(2) receptors.

Exposure to chronic isolation modulates receptors mRNAs for oxytocin and vasopressin in the hypothalamus and heart.

The goal of our study was to explore the effect of social isolation stress of varying durations on the plasma oxytocin (OT), messenger ribonucleic acid (mRNA) for oxytocin receptor (OTR), plasma arginine vasopressin (AVP) and mRNA for V1a receptor of AVP (V1aR) expression in the hypothalamus and heart of socially monogamous female and male prairie voles (Microtus ochrogaster). Continuous isolation for 4 weeks (chronic isolation) increased plasma OT level in females, but not in males. One hour of isolation every day for 4 weeks (repeated isolation) was followed by a significant increase in plasma AVP level. Chronic isolation, but not repeated isolation, significantly decreased OTR mRNA in the hypothalamus and heart in both sexes. Chronic isolation significantly decreased cardiac V1aR mRNA, but no effect on hypothalamic V1aR mRNA expression. We did not find a gender difference within repeated social isolation groups. The results of the present study reveal that although chronic social isolation can down-regulate gene expression for the OTR in both sexes, the release of the OT peptide was increased after chronic isolation only in females, possibly somewhat protecting females from the negative consequences of isolation. In both sexes repeated, but not chronic, isolation increased plasma AVP, which could be permissive for mobilization and thus adaptive in response to a repeated stressor. The differential effects of isolation on OT and AVP systems may help in understanding mechanisms through social interactions can be protective against emotional and cardiovascular disorders.