Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The cardiac responses of isolated frog (Rana tigrina) atria to peptide hormones were studied. 2. Calcitonin gene-related peptide (CGRP), arginine vasotocin (AVT), bovine parathyroid hormone fragment (bPTH-(1-34)) and oxytocin (OXY) produced dose-related positive chronotropic and inotropic responses; atrial natriuretic peptide (ANP) was negative chronotropic and inotropic; cholecystokinin (CCK), vasoactive intestinal peptide (VIP) were without effects. 3. The dose-related responses under bPTH-(1-34) stimulation but not CGRP or AVT were attenuated in the presence of ANP (300 ng/ml, approximately 0.98 x 10(-7) M). As expected ANP decreased the basal AR and AT responses of the isolated atria and the inhibitory effects were dose-dependent. 4. As shown previously, propranolol blocked the atrial tension stimulated by bPTH (1-34) but did not alter the cardiac responses to CGRP and AVT. 5. In the presence of beta-adrenergic blocker (propranolol 10(-7) M) or ANP (10(-7) M), the AR and AT changes under ISO stimulation in the frog were also decreased. 6. These cardiac changes suggest the cardiac inhibitory effects of ANP are related to beta-adrenoceptor activity and ANP might be a beta antagonist.
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PMID:Cardiac activity of some peptide hormones in the frog, Rana tigrina. 136 98

The hypothalamo-neurohypophyseal tract is known to contain the classical neurohypophyseal hormones vasopressin and oxytocin. Additionally, dynorphin, methionine- and leucine-enkephalin, cholecystokinin (CCK), corticotropin-releasing factor (CRF), and galanin are co-stored with vasopressin and/or oxytocin. Recent immunohistochemical studies have revealed the existence of a low to moderate number of substance P-, vasoactive intestinal peptide (VIP)-, neuropeptide Y (NPY)- and somatostatin-immunoreactive nerve fibers within the rat neurohypophysis. VIP-, substance P- and NPY-immunoreactive fibers were distributed throughout the organ, whereas somatostatin-immunoreactive fibers were present in the proximal part of the organ. The positive nerve endings were either large in size resembling classical nerve terminals related to perivascular spaces, or smaller similar to peptidergic fibers as described in the CNS. These results indicate that these neuropeptides may be either co-stored with the classical neurohypophyseal hormones or contained in another system of afferents to the organ. The probably distinct functional roles of these neuropeptides in the physiology of the neurohypophysis are discussed.
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PMID:Non-vasopressinergic, non-oxytocinergic neuropeptides in the rat hypothalamo-neurohypophyseal tract: experimental immunohistochemical studies. 138 83

The distribution of vasoactive intestinal peptide (VIP) was analysed in perikarya of the mink hypothalamus with immunohistochemistry and, surprisingly, a large population of magnocellular VIP-immunoreactive neurons was present in the paraventricular and supraoptic nuclei as well as in accessory hypothalamic nuclei. From perikarya in the paraventricular as well as supraoptic nuclei, a large number of VIP immunoreactive nerve fibers was observed to enter the hypothalamo-neurohypophysial tract. Within the median eminence, a high density of VIP-immunoreactive nerve fibers was present in the external and internal zones. Fibers in the external zone of the median eminence were endowed with varicosities and perivascular terminals, while fibers in the internal zone were smooth and without terminal specializations. From the internal zone of the median eminence, fibers coursed via the infundibular stalk to terminate in perivascularly situated terminals in the neurohypophysis. In addition, a substantial number of small VIP-immunoreactive perikarya was observed within the suprachiasmatic nucleus. These perikarya were immunoreactive to neither vasopressin nor neurophysin. To elucidate the co-existence of VIP-immunoreactivity with vasopressin, oxytocin or neurophysin, a sequential double immunoperoxidase procedure to localize antigens with diaminobenzidine and benzidine dihydrochloride as chromagens was performed. From these experiments it was evident that VIP in nearly all magnocellular hypothalamo-neurohypophysial neurons co-existed with neurophysin. Based on a semi-quantitative estimate, half the VIP-immunoreactive magnocellular perikarya co-stored vasopressin, while another half co-stored oxytoxin. The present study describes the presence of a large population of VIP-containing neurons in the hypothalamo-neurohypophysial system of the mink. These findings raise evidence that within the mink, VIP may be involved in neurohypophysial physiology.
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PMID:Vasoactive intestinal peptide (VIP) in magnocellular neurons of the hypothalamo-neurohypophysial system of the mink (Mustela vision) is co-localized with vasopressin or oxytocin. 147 74

Data are presented to show that vasoactive intestinal peptide (VIP) is synthesized and secreted by the hypothalamus and anterior pituitary and that it participates in the regulation of pituitary functions. Immunoreactive VIP in the hypothalamus and pituitary is increased following estrogen treatment and adrenalectomy and is reduced in hyperprolactinemic states. The level of VIP mRNA in the hypothalamus is increased during lactation and sexual maturation, while that in the anterior pituitary shows a sexual dimorphism and is increased with estrogen treatment and hypothyroidism. All these findings suggest a physiological regulation of hypothalamic and pituitary VIP gene expression in relation to its potential role as a neuroendocrine hormone. Furthermore, VIP stimulates prolactin (PRL) release at concentrations attainable in the hypophyseal-portal blood. Passive immunoneutralization studies with anti-VIP antisera suggest that endogenous VIP acts at multiple loci in the hypothalamic-pituitary axis to regulate PRL secretion, interacting possibly with other regulators of PRL secretion such as estrogen, serotonin, cholecystokinin, prostaglandins, galanin and oxytocin. Regarding other pituitary functions, although VIP has been shown to release growth hormone, ACTH, and vasopressin in vivo and in vitro, the physiological significance of these findings remains to be determined.
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PMID:Vasoactive intestinal peptide in the hypothalamus and pituitary. 190 91

The intrinsic innervation of the human uterine artery was investigated histochemically, and the motor responses to some of the demonstrated peptides and other humoral factors were studied on isolated vascular preparations. There were nerves with specific immunoreactivities for tyrosine hydroxylase, dopamine beta-hydroxylase, neuropeptide-Y (NPY), vasoactive intestinal peptide (VIP) and peptide histidine methionine, and enzymatic reactivity for acetylcholine esterase. The most effective stimulator of smooth muscle contractility was arginine vasopressin followed in order by oxytocin, noradrenaline together with NPY, noradrenaline alone and dopamine. No effect was seen with acetylcholine and tyrosine, and VIP caused inconsistent relaxation of contractile activity induced by PGF2 alpha. These results suggest that the uterine blood flow is regulated by complex interactions of factors, some occurring in nerve terminals and some being circulating humoral factors.
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PMID:Innervation of the human uterine artery and contractile responses to neuropeptides. 201 Jan 12

In female rats the mating stimulus induces a bimodal pattern of PRL secretion. A surge of PRL occurs at approximately 0300 h, called the nocturnal surge (N). Another surge occurs at 1700 h on the same day, called the diurnal surge (D). By lowering dopaminergic tone pharmacologically, we have recently demonstrated the existence of an endogenous rhythm stimulatory to PRL secretion in female rats. The periods of this stimulatory influence coincide with the periods of the N and D surges of PRL that occur in mated rats. In addition, we have shown that the 0300 h component of this endogenous rhythm is regulated by oxytocin (OT) and vasoactive intestinal peptide (VIP), and the 1700 h component is regulated by OT and serotonin (5-HT). In this study, we investigated the roles of OT, VIP, and 5-HT in controlling the N and D surges of PRL in ovariectomized (OVX) rats receiving a physiological dopamine-lowering stimulus, copulomimetic stimulation. Blood samples were obtained the day before the experiments between 1700 and 1900 h to verify that the rats used were having surges of PRL in response to cervical stimulation (CS). The role of OT was studied by infusing the OT antagonist 1-deamino-2-D-Trp4-Val8-Orn-OT (OT-A; 0.5 micrograms/kg.min) beginning at either 0100 or 1500 h and continuing for 5 h on day 2 after the last CS. Serial blood samples were obtained immediately before infusion and 60, 90, 120, 150, 180, 240, and 300 min after the start of infusion. The samples overlapped either the N or D surge of PRL. All rats used in these studies demonstrated D surges of PRL the day before the experiment. Saline infusion had no effect on either the N or D surge of PRL in OVX-CS rats. However, infusion of OT-A completely blocked both the N and D surges of PRL. The role of VIP was studied by infusing the VIP antagonist [4-D-Cl-Phe6-Leu17]VIP (VIP-A; 01 micrograms/kg.min) beginning at either 0100 or 1500 h and continuing for 5 h. VIP-A completely blocked both the N and D surges of PRL. To study the role of 5-HT, rats received an acute treatment with p-chlorophenylalanine (PCPA; 250 mg/kg, sc) at either 0100 or 1500 h, and blood samples were taken as before. PCPA had no effect on the N surge of PRL.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Oxytocin, vasoactive-intestinal peptide, and serotonin regulate the mating-induced surges of prolactin secretion in the rat. 213 24

Oxytocin (OT) has been shown to play a role in the control of physiological PRL release and has been demonstrated to have a direct effect on the pituitary to stimulate PRL secretion. Administration of OT into the third ventricle, however, lowers PRL levels. This reduction could be mediated by either an inhibition of the release of endogenous OT into the hypohysial portal circulation or via an alteration in the release of some other PRL releasing (PRF) or PRL release-inhibiting (PIF) factor. In order to determine if centrally administered OT lowers PRL levels by increasing secretion of dopamine (DA) into the portal circulation, endogenous dopaminergic tone was blocked by injection of the DA antagonist domperidone (DOM). Subcutaneous administration of DOM resulted in elevated PRL levels which could be further augmented by iv infusion of OT (at 0.01 or 0.1 microgram OT/kg.min) or partially, but significantly, reduced by pretreatment with anti-OT antiserum (0.75 ml) indicating that under conditions of DA blockade, OT (which has little PRF activity during conditions of normal dopaminergic tone) can stimulate PRL secretion by a direct pituitary action. Treatment with DOM did not prevent, however, the reduction in PRL levels produced by central administration of OT (2 micrograms). This suggests that the effect of OT to alter PRL secretion when administered into the third ventricle was not mediated via an increase in DA release into the portal circulation. Furthermore, central administration of the OT antagonist CAV-259 (1-deamino-2-D-Trp-4-Val-8-Orn-OT) after DOM treatment resulted in a significant increase in PRL secretion indicating that endogenous levels of OT within the hypothalamus inhibit PRL secretion through a nondopaminergic mechanism. This stimulatory effect of the OT antagonist was not blocked by pretreatment with anti-OT antiserum (iv) which had been demonstrated previously to reduce the PRL surges in lactating mothers and steroid-primed ovariectomized rats, as well as to block the increase in PRL secretion seen after central administration of vasoactive intestinal peptide (VIP). Thus the central effect of OT to alter PRL secretion was probably not due to a change in the release of OT into the portal circulation. Intravenous administration of a VIP antagonist (D-4-Cl-6-Phe-17-Leu-VIP, previously demonstrated to be capable of reducing the PRL surge seen in lactating mothers) into DOM-treated rats does not alter PRL levels but blocks the ability of central administration of the OT antagonist CAV-259 to increase PRL levels under these conditions.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Interactions of dopaminergic and peptidergic factors in the control of prolactin release. 229 69

Two nuclei, termed here the medial hypothalamic nucleus and the lateral hypothalamic retinorecipient nucleus, are possible homologs of the mammalian suprachiasmatic nucleus. As the mammalian suprachiasmatic nucleus is characterized by a dense concentration of vasoactive intestinal peptide (VIP)- and neurophysin (NP)-immunoreactive neurons and an absence of acetylcholinesterase (AChE) staining, we decided to examine these factors in the ring dove hypothalamus. Neither the medial hypothalamic nucleus nor the lateral hypothalamic retinorecipient nucleus contained either VIP- or NP-like immunoreactive neurons. The lateral hypothalamic retinorecipient nucleus stained darkly for AChE. Although there was some overlap in the distribution of VIP- and NP-like immunoreactive neurons, a clustering of both types into a well defined nucleus was not observed. Therefore, an avian homolog to the mammalian suprachiasmatic nucleus must differ in its chemoarchitecture from that of mammalian species described to date.
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PMID:Distribution of vasoactive intestinal peptide-like and neurophysin-like immunoreactive neurons and acetylcholinesterase staining in the ring dove hypothalamus with emphasis on the question of an avian suprachiasmatic nucleus. 233 26

1. Membrane currents were recorded from voltage clamped Xenopus laevis oocytes, still surrounded by follicular cells, theca and enveloping inner ovarian epithelia (ovarian follicles). 2. Superfusing follicles with frog Ringer solution containing E-series prostaglandins (PGE1 or PGE2) or oxytocin (0.5-2 microM) generated slow membrane currents arising from an increase in membrane conductance to K+. 3. Follicles taken from different frogs varied greatly in responsiveness to PGE and oxytocin. For example, enclosed oocytes with good sensitivity to prostaglandins responded to 1 nM-PGE, whereas follicles from some frogs failed to respond at 5 microM. 4. Oocytes with good responsiveness to PGE also produced K+ currents to PGA1, PGA2, PGB1, 11-deoxy-PGE1 and 11-beta-PGE2, whereas PGF2 alpha, PGI2, PGD2 and 8-iso-PGE1 generally failed to elicit membrane currents. 5. Responses to PGE and oxytocin were mimicked by the adenylate cyclase activator forskolin or by intraoocyte pressure injection of cyclic nucleotides. Responses were potentiated by the phosphodiesterase inhibitors theophylline and 3-isobutyl-1-methylxanthine (IBMX). In IBMX (0.5 mM), human atrial natriuretic factor (ANF) (10-60 nM) elicited a similar K+ conductance. This all implied that cyclic nucleotides played a role in the receptor-channel coupling mechanism of these responses. 6. Defolliculating oocytes effectively abolished responses to prostaglandins, oxytocin and ANF, suggesting that the currents arise in follicular cells. 7. The responses of PGE, oxytocin and ANF thus resembled currents elicited by catecholamines, adenosine, gonadotrophins and vasoactive intestinal peptide (VIP). However, PGE, oxytocin and ANF responses were not blocked by catecholaminergic or purinergic antagonists. Moreover, when comparing follicles isolated from different frogs, the sensitivity to PGE and oxytocin varied independently of that to gonadotrophin or VIP. These experiments suggest that Xenopus ovarian follicles contain specific and distinct receptors for PGE, oxytocin and ANF. 8. Acetylcholine attenuated the cyclic nucleotide-mediated K+ responses, including currents elicited by PGE, oxytocin and ANF. Attenuation was not dependent on, or mimicked by, activation of the inositol phosphate-diacylglycerol messenger pathways located in the oocyte itself, nor was it appreciably blocked by loading follicle-enclosed oocytes with 0.1-1.5 mM-EGTA.
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PMID:Membrane currents elicited by prostaglandins, atrial natriuretic factor and oxytocin in follicle-enclosed Xenopus oocytes. 248 34

Ovariectomized rats, when transplanted with 4 anterior pituitaries (APs) to the kidney capsule for 2-3 weeks, had elevated plasma prolactin (PRL) levels (3.8-fold) and showed decreased in situ AP weights (0.62-fold) and PRL concentrations (0.63-fold). The concentrations of dopamine (DA) and oxytocin (OT) in pituitary portal plasma of hyperprolactinemic rats were increased 1.7- and 1.9-fold, respectively. However, the levels of vasoactive intestinal peptide (VIP) in pituitary portal plasma of these rats were decreased 0.31-fold. The secretion of DA, dihydroxyphenylalanine (DOPA) and OT from fetal hypothalamic cells in primary culture was increased, whereas VIP secretion from these cells was reduced in a dose-dependent fashion following PRL treatment. These data are the first in vivo and in vitro demonstration of a stimulatory action of PRL on OT release and an inhibitory action of PRL on VIP release. Furthermore, these data suggest that a subtle imbalance between the secretion of the PRL-inhibiting factor (DA) and the PRL-releasing factors (VIP and OT) during elevated systemic levels of PRL is responsible for decreased lactotrophic function.
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PMID:Evidence for prolactin feedback actions on hypothalamic oxytocin, vasoactive intestinal peptide and dopamine secretion. 249 58


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