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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endocrine responses to the serotonin (5-HT) 5-HT1C/5-HT2 agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) were utilised to evaluate cocaine-induced alterations in postsynaptic 5-HT receptor function. Rats received cocaine HCl (0, 5 or 15 mg/kg i.p.) twice daily for 7 days. Effects of DOI (0, 0.5, 2 or 10 mg/kg i.p.) on plasma adrenocorticotropic hormone (ACTH), corticosterone, prolactin, oxytocin and renin concentrations were assessed 42 h after the final cocaine injection. DOI dose dependently increased the plasma concentrations of each hormone. Cocaine potentiated the DOI-induced elevations of plasma ACTH, corticosterone and prolactin concentrations. In contrast, the oxytocin response was reduced, and the renin response was unaltered by cocaine exposure. The data suggest that 5-HT2 receptor-mediated responses for ACTH, corticosterone and prolactin secretion become supersensitive following repeated cocaine. In contrast, the 5-HT2 receptor-mediated response for oxytocin secretion is subsensitive. The cocaine-induced changes in postsynaptic 5-HT receptor function are likely a consequence of deficits in the function of 5-HT nerve terminals, that we have documented previously.
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PMID:Repeated cocaine modifies the neuroendocrine responses to the 5-HT1C/5-HT2 receptor agonist DOI. 133 68

Serotonin (5-HT) receptor agonist-induced excessive grooming, penile erection and oxytocin secretion were studied in chronically cannulated freely moving rats. The 5-HT1C receptor agonist, m-chlorophenylpiperazine (m-CPP), which also binds to other 5-HT receptors, produced dose-dependent excessive grooming, penile erection and increases in circulating oxytocin concentrations. Maximal responses for excessive grooming and penile erection occurred at 0.3-0.6 mg/kg i.v. m-CPP. Higher doses (0.9-2.5 mg/kg i.v.) caused further increases in oxytocin concentrations, but attenuated both behavioral responses. All three responses to m-CPP (0.6 mg/kg) were attenuated by antagonists with high affinity for the 5-HT1C receptor site (mianserin, LY-53857 and metergoline), but not by the 5-HT2 receptor antagonist ketanserin. The 5-HT2/5-HT1C agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), increased plasma oxytocin concentrations only. After ketanserin pretreatment, DOI caused penile erection and diminished the oxytocin response. All responses to DOI were blocked completely by pretreatment with LY-53857 plus ketanserin. Excessive grooming and penile erection showed significant bimodal correlations with the oxytocin response. These data suggest that stimulation of 5-HT1C receptors induces excessive grooming, penile erection and increased oxytocin secretion. Stimulation of 5-HT2 receptors causes a further increase in plasma oxytocin concentration, but inhibits both behavioral responses.
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PMID:Effect of 5-HT1C and 5-HT2 receptor stimulation on excessive grooming, penile erection and plasma oxytocin concentrations. 147 65

A number of receptor subtypes mediate hormonal responses to serotonin (5-HT). To test the hypothesis that the hypothalamic paraventricular nucleus (PVN) mediates 5-HT1A and 5-HT2 receptor-mediated oxytocin, PRL, and corticosterone responses, we studied the effects of the 5-HT1A agonist ipsapirone and the 5-HT2A/2C agonist 1-(2,5-dimethoxy-4-iodophenyl)2-aminopropane (DOI) after surgical PVN lesions or sham operations. Chronically cannulated, conscious, freely moving, male Wistar rats were injected iv (1 mg/kg) shortly after (3-4 days) and 5 weeks after (35-37 days) the operations. In sham-operated rats, ipsapirone caused marked elevations in plasma PRL and corticosterone, but not oxytocin concentrations, whereas DOI increased plasma concentrations of all three hormones. Short term PVN lesions prevented ipsapirone-induced corticosterone and DOI-induced oxytocin responses. DOI-induced PRL and corticosterone responses were also markedly inhibited 3-4 days after lesioning, although small rises over the baseline values were still observed. The ipsapirone-induced PRL response was unaffected by the lesioning. Five weeks after PVN lesioning, partial recoveries were observed in ipsapirone- and DOI-induced corticosterone and DOI-induced oxytocin responses, whereas DOI-induced PRL responses remained suppressed. The present findings suggest that the PVN or neural pathways close to it mediate oxytocin, PRL, and corticosterone responses to the 5-HT2 receptor agonist DOI as well as corticosterone, but not PRL, responses to the 5-HT1A receptor agonist ipsapirone. The results after long term PVN lesioning show that the oxytocin and corticosterone responses may be partially restored with time after lesioning.
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PMID:Hypothalamic paraventricular nucleus lesions differentially affect serotonin-1A (5-HT1A) and 5-HT2 receptor agonist-induced oxytocin, prolactin, and corticosterone responses. 811 51

To test the hypothesis that the mechanisms of 5-HT1 and 5-HT2 receptor-mediated hormonal responses are different, we compared the effects of hypothalamic paraventricular nucleus (PVN) lesions on the ACTH/corticosterone, prolactin and oxytocin responses to the 5-HT1A agonist ipsapirone (1 and 2 mg/kg), the 5-HT2C agonist m-chlorophenylpiperazine (m-CPP, 0.6 mg/kg), which also binds to other 5-HT receptors with lower affinity, and the 5-HT2A/2C agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI, 1 mg/kg) in chronically cannulated, freely moving male rats. Pharmacological characterization using antagonists with different affinity for 5-HT2A and 5-HT2C receptors revealed that DOI's responses were mediated mainly by 5-HT2A receptors and m-CPP's responses were almost exclusively mediated by 5-HT2C receptors. ACTH/corticosterone responses to ipsapirone, DOI and m-CPP were almost completely blocked after PVN lesions. Prolactin responses were significantly different in lesioned rats only after DOI and m-CPP challenges. Oxytocin responses to ipsapirone and DOI, but not m-CPP were markedly attenuated after PVN lesions. The present findings suggest that the PVN, or neural pathways close to it, mediate corticosterone and in some cases prolactin and oxytocin responses to selective stimulation of 5-HT1A, 5-HT2A, or 5-HT2C receptors.
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PMID:Role of the hypothalamic paraventricular nucleus in 5-HT1A, 5-HT2A and 5-HT2C receptor-mediated oxytocin, prolactin and ACTH/corticosterone responses. 878 18

The neurotransmitter serotonin (5-HT) stimulates the secretion of vasopressin and oxytocin, and 5-HT is involved in the mediation of the vasopressin and oxytocin response to stress. In male Wistar rats, we investigated the 5-HT receptors involved in the 5-HT-induced increase of mRNA expression of vasopressin and oxytocin in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). The 5-HT precursor, 5-hydroxytryptophan, injected in combination with the 5-HT reuptake inhibitor, fluoxetine, increased oxytocin mRNA expression in the PVN, and the concentration of vasopressin and oxytocin in plasma, whereas mRNA in the SON was not affected. Intracerebroventricular infusion of 5-HT agonists selective for the 5-HT1A, 5-HT1B, 5-HT2A and 5-HT2C receptor increased oxytocin mRNA in the SON and PVN. Infusion of agonists selective for the 5-HT2A + 2C receptor increased vasopressin mRNA in the PVN, whereas none of the 5-HT agonists affected vasopressin mRNA in the SON. All the 5-HT agonists infused increased peripheral oxytocin concentration and vasopressin was increased by stimulation of the 5-HT2A, 5-HT2C and 5-HT3 receptor. Intracerebroventricular infusion of 100 nmol 5-HT increased the extracellular hypothalamic concentration of vasopressin as measured by microdialysis in the PVN. To evaluate the involvement of hypothalamic-pituitary system in the 5-hydroxytryptophan and fluoxetine-induced vasopressin secretion, rats were immunoneutralized with a specific anti-corticotropin-releasing hormone antiserum. This treatment reduced plasma vasopressin and oxytocin responses. We conclude that stimulation with 5-hydroxytryptophan or 5-HT agonists increases mRNA expression of oxytocin in the PVN and the SON via stimulation of at least 5-HT1A, 5-HT1B, 5-HT2A and 5-HT2C receptors. Vasopressin mRNA in the PVN was increased only via the 5-HT2 receptor, whereas vasopressin mRNA in the SON does not seem to be affected by 5-HT stimulation. Corticotropin-releasing hormone appears to be partly involved in the mediation of 5-HT induced vasopressin and oxytocin secretion.
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PMID:Serotonin stimulates hypothalamic mRNA expression and local release of neurohypophysial peptides. 1271 7

Various childhood mood disorders are being treated with serotonin selective reuptake inhibitors (SSRIs) such as fluoxetine (Prozac(R)), yet limited data are available on their effects on serotonergic systems prior to maturation. This study investigated the effects of chronic fluoxetine treatment on 5-HT2A serotonin receptor-mediated neuroendocrine responses in young male rats. Prepubescent male rats were treated with saline or fluoxetine (10 mg/kg/day, i.p.) for 14 days, a treatment regimen producing maximal changes in postsynaptic 5-HT2A function in adults. Eighteen hours post-treatment, the rats received saline or increasing doses (0.5, 2.0, or 5.0 mg/kg, i.p.) of the 5-HT2 receptor agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl ((+/-)-DOI). Trunk blood was obtained to determine changes in oxytocin, ACTH, corticosterone, and renin responses. Fluoxetine produced a small ( approximately 6%) but significant reduction in body weight gain, but no changes were observed in basal hormone levels. In both saline- and fluoxetine-treated rats, (+/-)-DOI increased plasma oxytocin levels in a dose-dependent manner. However, the magnitude of the oxytocin responses to all doses of (+/-)-DOI were markedly attenuated ( approximately 50%) in the fluoxetine-treated rats, indicating a functional reduction in the E(max) of 5-HT(2A) receptor-mediated oxytocin responses. In contrast, fluoxetine did not alter the (+/-)-DOI-induced increases in plasma ACTH, corticosterone, or renin. These data provide the first demonstration of selective neuroadaptive responses in 55-HT2A serotonin receptor function due to prepubescent treatment with fluoxetine. These data may be clinically relevant with respect to the use of selective serotonin reuptake inhibitors in children and adolescents.
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PMID:Fluoxetine treatment of prepubescent rats produces a selective functional reduction in the 5-HT2A receptor-mediated stimulation of oxytocin. 1608 47

The aim of the thesis was to investigate in male Wistar rats, the involvement of serotonin (5-HT) and 5-HT receptors in the regulation of the gene expression of hypothalamic hormones and in the secretion of the pituitary gland hormones prolactin (PRL), adrenocorticotropic hormone (ACTH), vasopressin (AVP) and oxytocin in basal and stress conditions. Furthermore, to study the significance of some distinctive central nuclei in these processes, and the metabolism of 5-HT in the hypothalamus and the dorsal raphe nucleus (DRN). The experiments were focused on (1) determination of involved neurons and nuclei (2) the hypothalamic level and (3) the pituitary gland level of regulation. The studies were typically performed in vivo but some studies were performed in vitro. Stereotactically neurotoxic lesion with 5,7-dihydroxy-5-HT in the dorsal raphe nucleus (DRN) or the hypothalamic paraventricular nucleus (PVN) reduced the ACTH and AVP response to stress, indicating an importance of these structures for this response. In situ hybridization on rat brain slices with oligopeptides showed an increase of corticotropin releasing hormone (CRH) mRNA in the PVN and proopiomelanocortin in the anterior pituitary lobe upon stimulation of the 5-HT1A, 5-HT1B, 5-HT2A and 5-HT2C receptors. Stimulation of 5-HT2A+2C receptors increased AVP mRNA in the PVN but not in the supraoptic nucleus (SON), whereas the level of oxytocin (OT) mRNA was increased both in the SON and the PVN and this effect was in addition mediated via 5-HT1A+1B receptors. Serotonin infused directly into the PVN by microdialysis stimulated local release of AVP. CRH was found to have a major role but not a complete responsibility in the 5-HT-induced release of ACTH, since immunoneutralisation of CRH inhibited the POMC gene expression and the ACTH response and since 5-HT and 5-HT antagonists were able to modulate the ACTH release from anterior pituitary gland cells in vitro. Through the years of investigation, the classification of the 7 main groups of 5-HT receptors (5-HT1 - 5-HT7) has changed due to molecular biological characterisation of the receptors and new receptors have been identified. With a battery of 5-HT agonists and antagonists several pharmacological experiments were performed with systemically or central administration of compounds and radioimmuno assay of plasma for pituitary gland hormone levels. Specific substances were not available for all 5-HT receptors and subreceptors thus some conclusions are a based on combination of experiments. The 5-HT induced PRL response is mediated via 5-HT1A, 5-HT2A, 5-HT2C and 5-HT3 receptors. In addition an involvement of 5-HT1B, 5-HT5 or 5-HT7 receptors seem possible. The ACTH response to 5-HT is mediated via 5-HT1A, 5-HT1B, 5-HT2A and 5-HT2C receptors and an involvement of the 5-HT4, 5-HT5 and 5-HT7 receptors is proposed. Peripheral secretion of AVP upon stimulation with 5-HT is mediated via 5-HT2C, 5-HT4 and 5-HT7 receptors but not 5-HT1A receptors. The secretion of OT is primarily mediated via 5-HT1A, 5-HT2C and 5-HT4 receptors and probably also 5-HT1B, 5-HT2A, 5-HT5A and 5-HT7 receptors. Physical and psychological stress activates hippocampal and hypothalamic 5-HT neurons. In contrast to other stress factors, restraint stress increases the content of 5-HT in the DRN but do not increase the metabolism of 5-HT and does not induce changes in hypothalamic levels of 5-HT. Large variations are found in the literature with different kinds of stress, different measurements and different time schedules. Restraint or ether stress induced secretion of PRL involves 5-HT2 and 5-HT3 receptors, whereas the ACTH secretion is mediated via 5-HT1A, 5-HT2A and 5-HT2C receptors. In the present study restraint stress increased AVP secretion, but opposite findings has reported possibly due to differences in the stress procedure. The 5-HT2, 5-HT3 and 5-HT4 receptor is involved in the AVP response to restraint whereas the OT response involves the 5-HT1A and the 5-HT2 receptor. The 5-HT2 receptor is involved in the OT response to dehydration or haemorrhage, whereas the AVP responses to these stressors probably do not involve 5-HT. It can be concluded that 5-HT is involved in basal and stress-induced regulation of PRL, ACTH, AVP and oxytocin mainly via the 5-HT2A+2C receptors but other receptors are also important but differs from hormone to hormone. Serotonin affect the secretion of CRH and ACTH both at the hypothalamic, pituitary portal and pituitary gland level, and possibly also at the adrenal level.
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PMID:Studies on the neuroendocrine role of serotonin. 1820 78