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

The effect of several growth factors, protein and steroid hormones on follicle stimulating hormone (FSH)-stimulated and basal inhibin secretion by mature porcine granulosa cells (g-cells) in culture was examined in order to elucidate the putative role of growth factors and hormones in the regulation of inhibin secretion by porcine g-cells in vitro. Cells were incubated with the respective hormones over a timespan of 0-144 h and immunoreactive inhibin was measured with a radioimmunoassay against porcine inhibin. Epidermal growth factor (EGF) and human transforming growth factor type beta (TGF-beta) decreased basal and gonadotrophin-stimulated inhibin and progesterone in a dose-dependent manner. In the absence of insulin, insulin-like growth factor type I (IGF-I) caused a 4-fold enhancement of basal inhibin secretion, but inhibin secretion was elevated only to 20% above control in the presence of 500 nM insulin. Porcine platelet-derived growth factor (PDGF) had no significant effect on basal or FSH-induced inhibin secretion by g-cells. In addition, neither gonadotrophin-releasing hormone (GnRH) nor prolactin (PRL), arginine vasopressin (AVP) and oxytocin affected basal or FSH-stimulated inhibin release by porcine g-cells. Oestradiol caused a slight but significant (P less than 0.01) rise of basal inhibin production (158% of control) in the last 2 days of culture (96-144 h) and the effect of androstenedione on basal (158% of control) and FSH-stimulated (140% of control) inhibin release (P less than 0.01) was also only visible on Days 4-6 of culture. In contrast to androstenedione and oestradiol, progesterone did not show any effect during 6 days of culture in a dose range of 10(-5) to 10(-9) M. Like steroids, prostaglandin E2 (PGE2) had a stimulatory effect on basal inhibin production (250% of control) by porcine g-cells, visible on Days 3-6 of culture, but an inhibitory effect on FSH-stimulated release (less than 40% of control). Over all the experiments with different hormones and growth factors, tested in varying doses and over a time span of 0-144 h, there was a strong correlation between progesterone and inhibin secretion by g-cells (0-48 h = 0.78; 48-96 h = 0.92; 96-144 h = 0.92). These results suggest that EGF, TGF-beta, IGF-I, oestradiol and androstendione as well as PGE2 have para- and/or autocrine modulatory effects on basal and FSH-stimulated inhibin secretion by mature porcine g-cells in vitro and further demonstrate that the secretion of the proteohormone inhibin and the steroid progesterone are closely related.
 ...
PMID:Effects of growth factors and hormones on basal and FSH-stimulated inhibin production by porcine granulosa cells in vitro. 194 20

The influence of arginine vasotocin (AVT) on the interrenal secretion of the clawed toad (Xenopus laevis) was studied combining in vivo and in vitro experiments. In vivo: A single injection of 3 nmol AVT per 100 g body weight was given, and the concentrations of corticosterone and aldosterone in the serum were measured after 1, 3, 6, 12, and 24 hr. The serum levels of both steroids remained elevated over 6 hr and declined to normal levels within 12 hr. The increase of the aldosterone concentration was relatively stronger than that of corticosterone. In vitro: A perifusion system was used to study the influence of AVT concentrations ranging from 0.1 to 50 nM on the secretion rates of corticosterone and aldosterone. The response of the interrenals was dose dependent; corresponding to the in vivo results, the elevation rate was higher for aldosterone than for corticosterone. The effects of several nonapeptides were compared. AVT was most effective, followed by mesotocin and arginine vasopressin (AVP). Isotocin and oxytocin had less effect. The selective agonist of the mammalian V2 receptor (1-deamino-8-D-arginine)-vasopressin (DDAVP) did not stimulate the interrenals, while the V1 receptor-selective antagonist ((1-beta-mercapto-beta,beta-cyclopentamethylene propionic acid)-2-(O-methyl)-tyrosine)-AVP could not diminish the stimulation by AVT. Thus, the AVT receptor of the amphibian interrenal must be a special one and is different from the V1 and V2 types of mammals. In a comparison of the effects of AVT with other stimulators such as ACTH(1-28) or urotensin II, it was found that the sensitivity of the interrenals to AVT was similar to that of these peptides. The results indicate that AVT plays an important role in the osmomineral regulation of Xenopus laevis by acting on the corticosteroid secretion of the interrenals.
 ...
PMID:Neurohypophysial hormones and steroidogenesis in the interrenals of Xenopus laevis. 196 9

Four labelled ligands, [3H]arginine vasopressin ([3H]AVP), [3H]oxytocin ([3H]OT), [3H]d(CH2)5[Tyr(Me)2]AVP ([3H]VPA), and [125I]d(CH2)5[Tyr(Me)2-Thr4-Orn8-Tyr(NH2)9]OT([125I]OTA] and nine unlabelled analogues exhibiting enhanced selectivity for rat oxytocin (OT) and vasopressin (VP) receptors were used to characterize OT and VP receptors on myometrial membranes from non-pregnant and pregnant human uteri. On membranes from non-pregnant uteri, [3H]AVP, [3H]VPA, and [125I]OTA labelled with high affinity (Kd values: 3.2, 2 and 0.8 nM, respectively) a major and apparently homogeneous population of sites, the ligand selectivity of which resembled that of rat V1a VP receptors. On membranes from pregnant and non-pregnant uteri, [3H]OT labelled a single population of high-affinity sites that could be distinguished from VP receptors on the basis of ligand selectivity. Several analogues (in particular [125I]OTA) that are highly selective for rat OT receptors exhibited a much less pronounced selectivity for human OT receptors. Experiments with [3H]VPA allowed detection of VP receptors on myometrical membranes from pregnant uteri and confirmed that only OT but not VP receptors increase during pregnancy in humans.
 ...
PMID:Labelling of vasopressin and oxytocin receptors from the human uterus. 196 9

The status of the arginine vasopressin-neurophysin-II (AVP-NPII) gene was studied in three families with autosomal dominant neurohypophyseal diabetes insipidus (AD-NDI). Restriction fragments of genomic DNA containing AVP-NPII sequences from affected individuals were not detectably different in size from those of normal controls. Thus, these individuals with ADNDI do not have apparent large deletions, insertions, or rearrangements of an AVP-NPII allele. Four restriction fragment length polymorphisms were detected with a probe for the adjacent gene on chromosome 20, oxytocin-neurophysin-I (OT-NPI). Linkage studies in these three families between the restriction fragment length polymorphism haplotypes and ADNDI phenotype strongly suggest cosegregation. This indicates that the genetic locus for ADNDI maps within or near the AVP-NPII locus and suggests that a defective AVP-NPII allele may be the basis of ADNDI.
 ...
PMID:Molecular analysis of autosomal dominant neurohypophyseal diabetes insipidus. 196 69

The in vivo labeling of somatostatin-14, somatostatin-28, arginine vasopressin, and oxytocin was studied in rat hypothalamus after third ventricular administration of [35S]cysteine to streptozotocin-diabetic and normal rats. Immunoreactive somatostatin levels in hypothalamus were unaffected by diabetes, as was the incorporation of [35S]cysteine into hypothalamic somatostatin-14 and somatostatin-28. In contrast, immunoreactive vasopressin levels in hypothalamus and posterior pituitary (and oxytocin levels in posterior pituitary) were below normal in diabetic rats. Moreover, [35S]cysteine incorporation into hypothalamic vasopressin and oxytocin (probably mainly in the paraventricular nucleus because of its proximity to the third ventricular site of label injection) was significantly above normal. The increments in vasopressin and oxytocin labeling were reversed by insulin administration. In vivo cysteine specific activity and the labeling of acid-precipitable protein did not differ between normal and diabetic animals; effects of diabetes on vasopressin and oxytocin labeling were therefore not caused by simple differences in cysteine specific activity. These results suggest that diabetes 1) does not influence the production of somatostatin peptides in hypothalamus but 2) stimulates the synthesis of vasopressin and oxytocin. For vasopressin at least, the increase in synthesis may be a compensatory response to the known increase in its secretion that occurs in uncontrolled diabetes.
 ...
PMID:In vivo somatostatin, vasopressin, and oxytocin synthesis in diabetic rat hypothalamus. 197 Jul 6

The role of lysine-vasopressin and oxytocin, as well as of their analog and fragment (DGAVP, desglycinamide arginine vasopressin; PLG, prolyl-leucyl-glycyl-amine), microinjected into the ventral hippocampus, in the formation and extinction of active avoidance conditioned reflex, was investigated. It was established that the introduction of lysine-vasopressin, as well as of its analog, into the hippocampus promoted the improvement of the formation of the avoidance reaction, while an inhibitory effect was elicited in the period of extinction of the skill. The opposite effects on the active avoidance reaction were obtained with oxytocin and its fragments. It is hypothesized that the observed behavioral changes in the active avoidance reaction are associated with the influence of these peptides on the processes of learning and memory.
 ...
PMID:Influence of neurohypophyseal peptides on the formation of active avoidance conditioned reflex behavior. 197 96

We investigated the role of histamine (HA) in the neuroendocrine regulation of PRL secretion in conscious male rats. Blood samples were obtained by decapitation of the animals at 0 min. Intracerebroventricular infusion of HA (34-540 nmol at -15 min) stimulated PRL secretion dose dependently with an ED50 of approximately 135 nmol. Inhibition of neuronal HA synthesis by the specific histidine decarboxylase-inhibitor (S)alpha-fluoro-methylhistidine (alpha FMH; 100 mumol/kg ip at -6 h or 400 mumol/kg ip at -20 h and -6 h) caused a 50% reduction (P less than 0.01) in the PRL response to 5 min of restraint stress. Inhibition of neuronal HA metabolism by the specific histamine-methyltransferase-inhibitor SKF-91488 (400 and 800 nmol icv at -20 min) augmented the restraint stress-induced PRL release 26% and 37%, respectively (P less than 0.05). The two enzyme inhibitors had no or only modest effect on the basal PRL secretion. Pretreatment with a specific antiserum (0.5 ml) to arginine vasopressin (AVP) or an AVP antagonist (25 nmol) administered iv at -20 min inhibited the PRL response to HA (270 nmol icv) 80% and 45%, respectively (P less than 0.01) and inhibited the PRL response to restraint stress 70% (P less than 0.01). In contrast, pretreatment with a specific oxytocin (OT) antagonist (50 nmol) had no effect on the HA- or stress-induced PRL release. The AVP antiserum showed less than 0.0003% cross-reactivity with OT, and radiolabeled OT did not bind to serial dilutions of plasma from rats treated with the AVP antiserum. The AVP antiserum or the AVP antagonist almost prevented the PRL release induced by iv infusion of 800 pmol AVP or a posterior pituitary extract. Infusion of AVP (24-800 pmol iv at -15 min) stimulated PRL secretion dose dependently. However, the dose of AVP (800 pmol) required to induce an increase in plasma PRL similar to that obtained by HA-stimulation, led to a rise in plasma AVP which was approximately 1000-fold higher than that induced by HA, which increased plasma AVP 2-fold. Restraint stress had no effect on the plasma AVP level. We conclude that neuronal HA participates in the mediation of the PRL response to stress and that the stress- and HA-induced release of PRL may involve AVP, whereas an involvement of OT seems unlikely.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Mediation of the stress-induced prolactin release by hypothalamic histaminergic neurons and the possible involvement of vasopressin in this response. 198 13

A number of structurally novel cyclic hexapeptides have been characterized as potent and selective oxytocin (OT) antagonists in vitro. As a representative of this class of compounds, L-366,948 [[cyclo(L-prolyl-D-2-naphthylalanyl-L-isoleucyl-D-pipecolyl- L-pipecolyl-D- histidyl)]] exhibited a high binding affinity (Ki, low nanomolar) for OT receptors in rat (uterus and mammary) and primate (pregnant rhesus and human myometrium) tissue with a several hundred-fold binding selectivity vs. rat arginine vasopressin (AVP)-V1 (liver) and AVP-V2 (kidney medulla) receptors. In functional assays, L-366,948 was a pure OT antagonist, blocking both OT-stimulated contraction of the isolated rat uterus (pA2, 8.5) and phosphatidylinositol turnover in uterine slices (IC50, 40 vs. 3 nM OT), with no evidence of partial agonist activity. L-366,948 was comparatively weak as an antagonist of AVP-induced contraction of the isolated rat tail artery (AVP-V1 receptor) and AVP-stimulated adenylate cyclase (AVP-V2 receptor) activity in rat kidney medulla and did not influence prostaglandin F2 alpha- or bradykinin-induced contractions of the isolated rat uterus. L-366,948 and related compounds described in this report represent new experimental tools for the study of the pharmacology and physiology of OT.
 ...
PMID:In vitro pharmacological profile of a novel structural class of oxytocin antagonists. 198 61

Two cyclic hexapeptides unrelated in chemical structure to oxytocin (OT) were shown in vivo to be antagonists of the contractile action of OT on the uterus. In anesthetized rats challenged with OT (1 micrograms/kg) administered as an i.v. bolus, L-366,682 [cyclo-(L-Pro-D-Trp-L-Ile-D-pipecolic acid-L-pipecolic acid-D-His)] and L-366,948 (D-2-naphthyl-alanine in place of D-Trp) were equipotent with AD50 values of about 100 micrograms/kg i.v. At doses of L-366,682 or L-366,948 causing approximately 90 to 95% block (approximately the AD95 dose) of OT, the duration of action of the antagonists exceeded 145 min. Both compounds exhibited selectivity in the rat, as a dose of either at 300 micrograms/kg i.v. shifted the dose-response for OT-induced uterine contraction to the right by approximately 5-fold but did not affect the dose-response to prostaglandin F2 alpha. Furthermore, neither compound, at a dose of 3 mg/kg i.v., antagonized the action of arginine vasopressin acting at V-1 (pressor effect in pithed rats) or V-2 (antidiuretic) receptors. In conscious, freely moving, pregnant rhesus monkeys, L-366,948 or L-366,682 given i.v. or s.c. were effective antagonists of uterine contractions elicited by an infusion of OT. OT- or arginine vasopressin-like agonist activity was not observed in any of the in vivo models. It is concluded that L-366,682 and L-366,948 act in vivo as reasonably potent, long-acting and selective antagonists at OT receptors in the rat and rhesus uterus.
 ...
PMID:Antagonism of oxytocin in rats and pregnant rhesus monkeys by the novel cyclic hexapeptides, L-366,682 and L-366,948. 200 82

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.
 ...
PMID:Innervation of the human uterine artery and contractile responses to neuropeptides. 201 Jan 12


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>