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)

The medial preoptic nucleus (MPN) is a sexually dimorphic complex with three major subdivisions. The cell-dense central (MPNc) and medial (MPNm) subdivisions are larger in male rats, while the cell-sparse lateral subdivision (MPNl) occupies a majority of the nucleus in females. In the present study we evaluated the distribution of possible monoaminergic and peptidergic cells and fibers within the MPN, as well as in adjacent regions of the medial preoptic area of the adult male rat. For this, we used an indirect immunohistochemical method with antisera to serotonin (5HT), dopamine beta-hydroxylase (DBH), tyrosine hydroxylase (TH), neuropeptide Y (NPY), cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP), substance P (SP), neurotensin (NT), corticotropin-releasing factor (CRF), luteotropin-releasing hormone (LRH), somatostatin (SS), thyrotropin-releasing hormone (TRH), oxytocin (OXY), vasopressin (VAS), adrenocorticotropic hormone (1-24; ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), leucine-enkephalin (L-ENK), and calcitonin gene-related peptide (CGRP). The results suggest that cell bodies and/or fibers crossreacting with all of these putative neurotransmitters are differentially distributed within the MPN. Within the MPNm, the densest plexuses of fibers were stained with antisera to SP and NPY, while moderate densities of fibers were stained with anti-DBH, SS, CCK, CGRP, ACTH, and alpha-MSH, and only a few fibers were stained with anti-5HT, TH, NT, VAS, and L-ENK. Moderate numbers of SP- and L-ENK-immunoreactive cell bodies, and a few SS-, NT-, CRF-, and TRH-stained cell bodies were also found within the MPNm. The MPNc contained a dense plexus of CCK-immunoreactive fibers, as well as a few CRF-immunoreactive fibers. Both fiber types were localized almost exclusively to this subdivision, while most of the others studied here appeared to avoid it selectively. This suggests that there are relatively few inputs to the MPNc, and that they tend to avoid other parts of the nucleus, although moderate densities of DBH- and NPY-immunoreactive fibers were found in both the MPNm and MPNc. The MPNc contained several CCK-immunoreactive cell bodies as well as a moderate number of TRH-stained cell bodies. Both cell types were nearly completely localized to the MPNc. The major inputs to the MPNl studied here appear to be stained with antisera to 5HT and L-ENK, although moderate numbers of NT- and CRF- immunoreactive fibers were also found in this part of the nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Neurotransmitter specificity of cells and fibers in the medial preoptic nucleus: an immunohistochemical study in the rat. 242 28

Neurohypophysial hormones stimulate gonadotrophin release from dispersed rat anterior pituitary cells in vitro, acting through receptors distinct from those which mediate the secretory response to gonadotrophin-releasing hormone (GnRH). The LH response to oxytocin was not affected by the presence of the phosphodiesterase inhibitor, methyl isobutylxanthine, but was diminished in the absence of extracellular calcium and was progressively increased as the calcium concentration in the medium was raised to normal. In addition, the calcium channel antagonist, nifedipine, suppressed oxytocin-stimulated secretion of LH. It is likely that the mechanisms of LH release induced by GnRH and neurohypophysial hormones are similar, although stimulation of gonadotrophin secretion is mediated by separate receptor systems. Oxytocin was more active than vasopressin in releasing LH, but less active in releasing ACTH. The highly selective oxytocin agonist, [Thr4,Gly7]oxytocin, elicited concentration-dependent secretion of LH but had little effect on corticotrophin secretion. The neurohypophysial hormone antagonist analogues, [d(CH2)5Tyr(Me)2]vasopressin, [d(CH2)5Tyr(Me)2,Orn8]vasotocin and [d(CH2)5D-Tyr(Et)2Val4,Cit8]vasopressin, inhibited the LH response to both oxytocin and vasopressin. However, [d(CH2)5Tyr(Me)2]vasopressin was much less effective in inhibiting the ACTH response to the neurohypophysial hormones, and [d(CH2)5Tyr-(Me)2,Orn8]vasotocin and [d(CH2)5D-Tyr(Et)2,Val4,Cit8]vasopressin exhibited no inhibitory activity against ACTH release. Thus, agonist and antagonist analogues of neurohypophysial hormones display divergent activities with regard to LH and ACTH responses, and the neuropeptide receptor mediating gonadotroph activation is clearly different from that on the corticotroph. Whereas the corticotroph receptor is a vasopressin-type receptor an oxytocin-type receptor is responsible for gonadotrophin release by neurohypophysial hormones.
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PMID:Gonadotrophin-releasing activity of neurohypophysial hormones: II. The pituitary oxytocin receptor mediating gonadotrophin release differs from that of corticotrophs. 247 64

Human thymic epithelial cells (TEC) were grown in culture and confirmed to be keratin positive (98-100%) and epidermal growth factor (EGF) responsive. Bovine pituitary extracts (BPE) stimulated the proliferation of TEC. The proliferation of TEC was confirmed by cell counts and radioautography. The BPE was active as measured by tritiated thymidine incorporation in the absence of serum and in the absence of EGF. Individual anterior pituitary hormones (growth hormone, prolactin, ACTH, FSH, LH, TSH) and posterior pituitary hormones (vasopressin and oxytocin) were inactive alone to stimulate TEC proliferation. The effect of EGF but not BPE was blocked by an antibody to EGF suggesting that the active component of BPE is not EGF. Purification of the factor is in progress. The observations suggest that this pituitary-derived factor(s) may regulate thymic function in vivo.
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PMID:A pituitary factor induces thymic epithelial cell proliferation in vitro. 247 91

Penile erection and yawning induced by the intracerebroventricular (ICV) injection of oxytocin (10-1000 ng) was studied in hypophysectomized rats and in rats neonatally treated with monosodium glutamate (MSG), a treatment that depletes hypothalamic opiomelanocorticotropin-derived peptides without altering their pituitary and circulating concentration. Oxytocin effect was strongly reduced by hypophysectomy, but not by neonatal MSG. Testosterone replacement (50 micrograms/kg/day for 23 days) partially reversed the effect of hypophysectomy on penile erection, but not on yawning. The present results suggest that oxytocin does not induce penile erection and yawning by releasing an ACTH-derived peptide from hypothalamic opiomelanotropinergic neurons, and that the pituitary gland exerts a permissive role on the expression of the above behavioural responses induced by oxytocin.
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PMID:Oxytocin-induced penile erection and yawning in male rats: effect of neonatal monosodium glutamate and hypophysectomy. 249 89

Both oxytocin (OXY) and arginine vasopressin (AVP) enhance the effects of corticotropin-releasing factor on ACTH release by the pituitary. One of these, AVP, plays a role in the control of fluid balance and responses to hypoxemic stress in the fetal sheep. To determine the possibility that OXY also participates in fetal neuroendocrine events, OXY-containing neuronal structures must first be demonstrated within the fetal endocrine hypothalamus. OXY-immunoreactive elements were examined in fetal sheep hypothalami late in gestation and compared to AVP-containing structures using immunocytochemical procedures. Six fetal sheep ranging from 126 to 144 days gestational age were delivered via cesarian section from timed pregnant Rambouillet-Columbia ewes and killed by an overdose of anesthesia. The fetal head was perfused via bilateral carotid catheters and processed for immunocytochemical localization of OXY or AVP using the avidin-biotin complex procedure. At all fetal ages examined, OXY- and AVP-containing neurons were found within the paraventricular nuclei (PVN), supraoptic nuclei (SON) and accessory magnocellular hypothalamic nuclei. OXY-containing neurons were found principally in the SON and PVN. They were generally less numerous and less intensely stained than the AVP neurons. In the SON, they concentrated along the dorsal borders of the nucleus above the AVP neurons. In PVN, clusters of OXY cells were located along the dorsal and lateral borders of the nucleus surrounding the AVP neurons; in the periventricular division, they were intermingled with the AVP neurons. Small numbers of OXY axons were located in the external zone of the median eminence; whereas most OXY axons extended into the hypothalamo-neurohypophyseal tract and posterior lobe of the pituitary. A few of the OXY axons in the pituitary stalk were diverted to the pars intermedia. Likewise, some of the OXY fibers from the external zone of the median eminence entered the pars tuberalis but were rarely found in the distal lobe of the pituitary. In contrast, AVP axons richly innervated the external zone of the median eminence, and neural lobe. Like OXY, AVP axons from the median eminence and the pituitary stalk sent projections to the adenohypophysis. AVP fibers in the pars distalis frequently contacted corticotropes and were more numerous than OXY fibers in this region. These data provide anatomical evidence that OXY and AVP may directly regulate the fetal adenohypophysis. Of these two neuropeptides, AVP predominates anatomically.
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PMID:Neuropeptide cells and fibers in the hypothalamus and pituitary of the fetal sheep: comparison of oxytocin and arginine vasopressin. 251 63

Ether and restraint stress-induced peripheral plasma corticotropin releasing hormone (CRH), arginine vasopressin (AVP), oxytocin (OXY) and adrenocorticotropin (ACTH) levels were measured by radioimmunoassays. Plasma CRH, AVP, OXY and ACTH rose to approximately twice the level of control rats 2 min after the onset of a 1-min exposure to ether. Plasma CRH rose further 5 min after the onset of ether stress, while plasma AVP and OXY returned to the baseline levels at 5 min. Plasma CRH, OXY and ACTH showed significant elevation 2 min after the onset of restraint stress, while plasma AVP did not show a significant change. Plasma OXY and ACTH rose further 5 min after the onset of restraint stress, whereas plasma CRH returned to baseline levels. CRH and OXY concentrations in the hypothalamic median eminence decreased 5 min after the onset of ether exposure and restraint, while the AVP concentration did not differ from control levels. The results, including the discrepancy between plasma CRH and ACTH 5 min after stress, suggest that CRH in the peripheral plasma is derived from both hypothalamic and extrahypothalamic tissues. The levels of stress-induced CRH in the peripheral plasma were sufficient to stimulate ACTH release. These results suggest that ether and restraint stress elevate plasma CRH shortly after the onset of the stress, and that this elevation in the plasma CRH level is at least partly responsible for stress-induced ACTH secretion.
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PMID:Effect of acute ether or restraint stress on plasma corticotropin-releasing hormone, vasopressin and oxytocin levels in the rat. 254 72

Variability in gold bead distribution between individual cells was demonstrated in both pituitary melanotrophic cells immunocytochemically reacted for ACTH and in neurohypophysial terminals reacted for oxytocin-neurophysin. Gold beads were confined to the secretory granules compartment of both tissues. Density of gold beads in melanotrophic cells reacted for ACTH varied from 100-480 gold beads/microns 2. A much narrower range of gold beads distribution (460-900 gold beads/microns 2) was observed in axons of the neurohypophysis reacted with anti-oxytocin-neurophysin. These results indicate that the labeling density varies from cell to cell (as well as axon terminals) within morphologically homogeneous populations. Thus, it may reflect certain physiological differences between cells. A suggestion is being made that mean gold bead density coefficient of variation should be calculated by comparison between individual cells.
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PMID:Variability in gold bead density in cells. Quantitative immunocytochemistry. 254 83

Oxytocin may function as a hypothalamic releasing hormone for prolactin and ACTH secretion in the rat. In the present study we have investigated the properties of putative oxytocin receptors in the rat adenohypophysis by radioligand-binding assay. A novel oxytocin receptor antagonist [1-(beta-mercapto-beta,beta-cyclopentamethylene propionic acid),2-(ortho-methyl)-Tyr2-Thr4-Orn8-Tyr9-NH2]-vasotocin (OTA) was radioiodinated by the iodogen method to a specific activity of 0.6 nCi/fmol. The radioiodinated derivative 125I-labelled OTA (125I-OTA) was reacted with membrane suspensions prepared from the uterus or adenohypophysis of female rats which were (a) ovariectomized for 7 days, (b) ovariectomized and treated with 5 micrograms oestradiol-17 beta 48 h before death or (c) implanted with a piece of silicone elastomer tubing containing 50 mg diethylstilboestrol (DES) 5 days before death. In uterine as well as the pituitary membrane suspensions, the radioligand was bound reversibly and with high affinity (dissociation constants 0.2 +/- 0.1 and 0.1 +/- 0.01 nmol/l respectively; mean +/- S.E.M., n = 3) to a single class of sites with limited binding capacity, which varied with the type of pretreatment. Oestradiol-17 beta increased the binding capacity fivefold in the uterus in ovariectomized rats, but only very low specific radioligand binding was found in pituitary preparations from the same animals. Treatment with DES markedly increased the number of receptors in both the uterus and the adenohypophysis. Studies with several agonist and antagonist analogues revealed no difference in the ligand specificity of the uterine and adenohypophysial sites binding 125I-OTA, indicating that they are the same species of receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of oxytocin receptors in rat adenohypophysis using a radioiodinated receptor antagonist peptide. 254 59

We have examined the actions and interactions of arginine vasopressin (AVP), angiotensin-II (AII), and oxytocin (OT) on the ACTH secretory response of dispersed rat anterior pituitary cells in a microperifusion system. There was a dose-dependent ACTH secretory response to a 3-min perifusion of AII which reached its maximum 10 sec after the cells were exposed to AII and fell rapidly to baseline within 2 min, despite continued infusion of AII. This brief spike type of pattern is similar to that produced by AVP, but different from the sustained plateau response induced by CRF. The threshold stimulating concentration of AII was about 10(-9) M; the maximally stimulating concentration was not defined, but was 10(-6) M or more. The initial ACTH response to OT was similar, but fell to a plateau 2 min after the cells were exposed to OT and remained constant until perifusion with OT was stopped, after which it fell rapidly to baseline. The threshold stimulating concentration of OT was 10(-8) M; the maximally stimulating concentration was not defined, but was 10(-6) M or more. The ACTH secretory response to 10(-8) M AII was greatly diminished when cells were exposed to 10(-6) AVP or 10(-6) M OT before AII infusion. However, prior exposure to AII had no effect on the magnitude of the ACTH secretory response to either AVP or OT. The effects of simultaneous perifusion of AII and AVP and of AII and OT were additive. When AVP and OT were perifused sequentially, the ACTH secretory response to the peptide that was infused second was completely abolished. Furthermore, the combination of AVP and OT stimulated no greater response than either agent alone. When cells were perifused with the combination of 10(-7) M OT and 10(-7)- to 10(-5)-M concentrations of two potent AVP V1 receptor antagonists, [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-(O-methyl)tyrosine]-Arg8-vasopressin and [1-deaminopenicillamine-2-(O-methyl)tyrosine]-Arg8-vasopressin, both phases of the response to OT were progressively and almost completely inhibited. The initial spike phase was inhibited at lower antagonist concentrations than the sustained plateau phase.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Kinetic actions and interactions of arginine vasopressin, angiotensin-II, and oxytocin on adrenocorticotropin secretion by rat anterior pituitary cells in the microperifusion system. 255 32

Glucocorticoid feedback inhibition at the level of the brain is extremely complex, involving feedback at both hypothalamic and suprahypothalamic levels. The hippocampus has been implicated as a suprahypothalamic mediator of such feedback, based on numerous lesion, stimulation, and steroid implantation studies. These reports, however, predated the isolation and characterization of CRF and recognition of the multifactorial control of ACTH release. Thus, it is not clear which hypothalamic ACTH secretagogues are under inhibitory control of the hippocampus. To answer this, we measured hypophysialportal concentrations of CRF, arginine vasopressin, and oxytocin in rats with fornix transections, which disrupt hippocampal communication with the hypothalamus. Hypophysial-portal blood was collected in rats exposed to either low or high circulating corticosterone concentrations in the presence or absence of the coincident stressor of hypotension. We observed that fornix transection produced hypersecretion of all three secretagogues. However, the pattern of hypersecretion differed for each as follows: 1) fornix transection did not affect either initial CRF secretion or the magnitude of the stress response, but made rats resistant to a high feedback signal during stress; 2) fornix transection led to initial arginine vasopressin hypersecretion, which remained sensitive to a high feedback signal; and 3) fornix transection led to initial oxytocin hypersecretion as well as resistance to a high corticosterone feedback signal during hypotension.
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PMID:Elevation of hypophysial portal concentrations of adrenocorticotropin secretagogues after fornix transection. 255 30


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