Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although the role of serotonin (5HT) in the regulation of anterior pituitary hormone secretion is well documented, the involvement of specific 5HT receptor subtypes in this action is not yet fully elucidated. In the present work we attempted to determine the neuroendocrine role of the 5HT1A receptor subtype. This was chosen mainly because highly selective pharmacological tools are available for that subtype. 8-Hydroxy-2-(di-n-propylamino)tetralin (8OHDPAT) and ipsapirone were injected iv in conscious, freely moving male rats cannulated in the jugular vein. For the sake of comparison, a 5HT receptor agonist with preference for the 5HT1B and 5HT1C receptor subtypes 1-(m-trifluoromethyl-phenyl)piperazine (TFMPP) was also administered. Plasma PRL, ACTH, and beta-endorphin levels increased in a dose-dependent manner after 8-OHDPAT (0.01-1 mg/kg) or ipsapirone (0.5-7.5 mg/kg) injection. Maximal effects were obtained between 7-15 min. Only the highest dose of 1-(m-trifluoromethyl-phenyl)piperazine (5 mg/kg) resulted in the same response. In contrast, none of the drugs used affected plasma GH, TSH, or LH levels at any dose tested. The results indicate that 5HT1A receptors are involved in the regulation of PRL as well as ACTH and beta-endorphin secretion. 8OHDPAT was almost 40 times more potent than ipsapirone. The maximal effects of the two drugs on PRL release were comparable. In contrast, ipsapirone behaved as a partial agonist only on ACTH and beta-endorphin secretion, thus suggesting that different neuronal targets are involved in the stimulation of the three hormones by 5HT.
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PMID:Changes in anterior pituitary hormone levels after serotonin 1A receptor stimulation. 216 13

Experimental evidence suggests that serotonin (5HT) is excitatory to the hypothalamic-pituitary-adrenal axis and that this effect involves activation of both hypothalamic corticotropin-releasing hormone (CRH) and pituitary ACTH secretion. The present study was undertaken to examine the mechanism by which 5HT stimulates the central component of the HPA axis. To accomplish this we employed an in vitro rat hypothalamic organ culture system in which CRH secretion from single explanted hypothalami was measured by specific radioimmunoassay (IR-rCRH). All experiments were performed after an overnight (15-18 hr) preincubation. Serotonin stimulated IR-rCRH secretion in a dose-dependent fashion. The response was bell-shaped and the peak effect was observed at the concentration of 10(-9) M. The stimulatory effect of 10(-9) M 5HT was antagonized by the 5HT1 and 5HT2 receptor metergoline and by the selective 5HT2 receptor antagonists ketanserin and ritanserin. The muscarinic antagonist atropine, the nicotinic antagonist hexamethonium and the alpha-adrenergic receptor antagonist phentolamine, on the other hand, did not inhibit 5HT-induced IR-rCRH secretion. The specific 5HT2 receptor agonist 1-(2,5-dimethoxy-4-iodo-phenyl)-2-aminopropane (DOI) stimulated IR-rCRH secretion in a dose-dependent fashion. The response was bell-shaped with peak of effect reached at the concentration of 10(-9) M. We also tested the ability of the 5HT agonist meta-chlorophenylpiperazine (m-CPP) and of the selective 5HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) to cause CRH secretion. Although both m-CPP and 8-OH-DPAT stimulated IR-rCRH secretion in a dose-dependent fashion, several differences were observed when their effect was compared to that of 5HT. These included a different shape of the dose-response curve, a lower maximal stimulatory effect and a different maximal stimulatory concentration. These findings suggest that serotonin stimulates CRH secretion by explanted rat hypothalami and that this effect appears to be mediated mainly through a 5HT2 receptor mechanism.
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PMID:Effects of serotonergic agonists and antagonists on corticotropin-releasing hormone secretion by explanted rat hypothalami. 278 1

The roles of 5-hydroxytryptaminergic (5HT) neurons and receptor subtypes in mediating the effects of stress on the activity of periventricular hypophysial dopaminergic (PHDA) neurons and the secretion of alpha-melanocyte-stimulating hormone (alpha MSH) were examined in female rats. Periventricular hypophysial dopaminergic neuronal activity was estimated by measuring concentrations of 3,4-dihydroxyphenylacetic acid in the intermediate lobe of the pituitary. Brief exposure to diethylether followed by 30 min of supine restraint decreased intermediate lobe 3,4-dihydroxyphenylacetic acid concentrations and increased plasma concentrations of alpha MSH. These stress-induced effects were not observed in animals in which 5HT neurons had been previously destroyed by 5,7-dihydroxytryptamine or inhibited by the administration of the 5HT1A receptor agonist 8-hydroxy-2-(di-n-propyl-amino)-tetralin. Pretreatment of rats with the 5HT2 receptor antagonist MDL-11,939 blocked the inhibitory effects of stress on intermediate lobe 3,4-dihydroxyphenylacetic acid concentrations and the corresponding increase in plasma alpha MSH concentrations, whereas the 5HT3 receptor antagonist ondansetron was without effect. These results reveal that 5HT neurons, acting via 5HT2 receptors, mediate the inhibitory effects of stress on periventricular hypophysial dopaminergic neurons and the consequent increase in secretion of alpha MSH.
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PMID:5HT2 receptors mediate the effects of stress on the activity of periventricular hypophysial dopaminergic neurons and the secretion of alpha-melanocyte-stimulating hormone. 838 38

In male Wistar rats the effect of adrenalectomy on pituitary activation by the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), was studied. Rats were injected intravenously with 8-OH-DPAT (0.10 mg/kg) in their home cages. Blood samples were withdrawn from freely moving cannulated rats for determination of plasma adrenaline and plasma adrenocorticotropin hormone (ACTH). Adrenalectomized rats showed almost no measurable amounts of plasma adrenaline, but these animals had elevated baseline plasma (ACTH levels as compared to sham-operated rats. 8-OH-DPAT treatment led to a large plasma adrenaline response in the sham-operated animals, which was abolished after adrenalectomy. The plasma ACTH response to 8-OH-DPAT was significantly diminished in the adrenalectomized rats as compared to sham animals. This blunted ACTH response in adrenalectomized rats, however, was still considerable in magnitude. The present data thus indicate that the plasma ACTH response to 8-OH-DPAT is due to at least two different mechanisms. First, via 5-HT1A receptor-mediated adrenaline release, which may consequently stimulate the pituitary. Second, a direct action of 8-OH-DPAT on hypothalamic 5HT1A receptors is assumed, independent of peripheral adrenaline release.
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PMID:Adrenaline release by the 5-HT1A receptor agonist 8-OH-DPAT is partly responsible for pituitary activation. 887 52

5-Hydroxytryptamine-1A (5-HT1A) receptor agonists, including flesinoxan, reduce anxiety and activate the hypothalamus-pituitary-adrenal (HPA) axis under basal conditions. In order to investigate the underlying neural mechanisms we investigated immunoreactivity for the immediate early gene protein product Fos (Fos-ir) in rat brains 1 h after flesinoxan treatment (0.0, 0.3 or 3.0 mg/kg p.o.). Typically, 5-HT1A receptor-containing brain areas, such as the dorsal raphe nuclei, hippocampus, septum, diagonal band and the cortical and basomedial amygdala, do not show Fos-ir. Apparently, binding of flesinoxan at the 5-HT1A receptor does not directly lead to activation of c-fos in the cell, probably due to its negative coupling to adenylate cyclase. However, in typically non-5HT1A receptor-containing brain areas Fos-ir is increased due to flesinoxan treatment, as in the paraventricular nucleus of the hypothalamus (PVN), the dorsolateral part of the bed nucleus of the stria terminalis (BNSTdl) and the central amygdala (CeA). Flesinoxan-treated rats also exhibited higher plasma corticosterone levels than vehicle-treated animals, which suggests the involvement of corticotropin-releasing hormone (CRH) or vasopressin in the hypothalamus. After double immunolabelling (Fos/CRH or Fos/vasopressin), every CRH neuron detected in the PVN also contained Fos. Moreover, a significant correlation existed between the number of Fos-ir neurons in the PVN and the plasma corticosterone level. Hardly any Fos/vasopressin double labelling was visible in the PVN. Accordingly, flesinoxan exerts its activating effects on the HPA axis via CRH neurons in the PVN. These effects are trans-synaptically mediated by other brain areas, such as the CeA and BNSTdl, which also show increased Fos-ir.
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PMID:5-HT1A receptor agonist flesinoxan enhances Fos immunoreactivity in rat central amygdala, bed nucleus of the stria terminalis and hypothalamus. 895 98