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)

Vasotocin receptors were investigated in glomeruli and nephron segments microdissected from collagenase-treated kidneys of Rana ridibunda, using [d(CH2)5Tyr(Me)2,Thr4,Orn8,125I-Tyr-NH2(9)]vasotocin (125I-OVTA) as a radioligand. Specific 125I-OVTA binding sites were found only in glomeruli and not in all tubule segments tested. Glomerular receptors exhibited the following stereospecificity for recognition of vasotocin analogues: Tyr-NH2(9)-LA-V1a > 125I-OVTA > arginine vasotocin (AVT) > or = [d(CH2)5Tyr-(Me)2]AVP > OVTA > or = [Phe2,Orn8]VT > oxytocin (OT) > or = [d(CH2)5-Sar7]AVP > desGly9[d(CH2)5Tyr(Et)2]VAVP > or = [d(CH2)5Tyr(Et)2]VAVP > AVP > [1-desamino-8-D-arginine]vasopressin (DDAVP) > [Thr4,Gly7]OT. In addition, vasotocin enhanced [3H]inositol phosphate production in sieved glomeruli labeled with myo-[3H]inositol; the rank order of structural vasotocin analogues for stimulation of phosphoinositidase C was [Phe2,Orn8]VT > AVT > OT > AVP > DDAVP, whereas [Thr4,Gly7]OT was almost inactive, and the rank order of antagonists for inhibition of hormone-induced enzyme activation was Tyr-NH2(9)-LA-V1a > [d(CH2)5Tyr(Me)2]AVP = OVTA > [d(CH2)5Sar7]AVP > [d(CH2)5Tyr(Et)2]VAVP > or = desGly9[d(CH2)5Tyr(Et)2]VAVP. Results indicate that the 125I-OVTA-labeled binding sites detected in frog glomeruli reveal the pharmacological properties of mammalian V1b-pituitary vasopressin receptors and might be physiological vasotocin receptors involved in phosphoinositidase C stimulation.
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PMID:Frog glomerular vasotocin receptors resemble mammalian V1b receptors. 797 46

Oxytocin(OT) is considered to have several activities besides strongly inducing myometrial contraction by activating phosphatidilinositol-specific phospholipase C(PI-PLC). These include reconstructing the phospholipid constituents of the cell membrane and activating a variety of fatty acid producing systems. On the other hand, pregnancy-related steroid hormones which are produced by the fetus, placenta and mother are considered to be closely involved in the maintenance of pregnancy and the initiation of labor. In the present study with cultured myometrial cells, we examined what effect these steroid hormones might exert on the intramyometrial production of fatty acid by OT. Our results confirmed bi-phasic production of arachidonic acid(AA), linoleic acid(LA), palmitic acid(PA), and stearic acid(SA) by OT. Phase 1 was an increasing but transient phenomenon having its peak at 30 sec. It is considered to be derived from phosphatidylinositol bis-phosphate. Phase 2 was a persistent and increasing phenomenon which was initiated after 120 sec. It is considered to be mediated by Ca-dependent phospholipase. We also studied the effect of steroid hormones on the production of fatty acid. For AA, LA, and PA, we confirmed that dehydroepiandrosterone sulfate(DHAS) shortened the time taken in reaching the peak of Phase 1 to half of that of the control, and progesterone(P) extended the time 2-3 fold. These findings suggest that DHAS, P and F might modify the human myometrial construction mechanism as a factor which regulates the quantity and velocity of fatty acid production.
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PMID:[The effect of oxytocin on production of free fatty acid in primary human uterine myometrial cell culture]. 837 Oct 25

Gonadotropes synthesize and secrete LH and FSH under the control of GnRH, which acts via phosphoinositidase C (PIC)-linked G protein coupled receptors. Additionally, gonadotropin released from the pituitary is influenced by oxytocin, a peptide that has been shown to play a role in generation of the preovulatory LH surge. Although oxytocin receptors are present in the pituitary, studies have identified their presence on lactotropes but not on gonadotropes, raising the question of which cells act as the direct target of oxytocin in gonadotrope regulation. In this study, we examined effects of oxytocin on alphaT3-1 cells, a gonadotrope-derived cell line. Oxytocin, vasopressin, and vasotocin each stimulated accumulation of [3H]inositol phosphates in cells prelabeled with [3H]inositol, indicating activation of PIC. The rank order of potency (oxytocin > vasotocin > vasopressin) and sensitivity to inhibition by oxytocin and vasopressin receptor antagonists, revealed the effect to be mediated by oxytocin-selective receptors. Like other PIC activators, these nonapeptides caused biphasic (spike-plateau) increases in the cytosolic Ca2+. The spike response to oxytocin and GnRH were both retained in Ca2+-free medium, reflecting mobilization of intracellular Ca2+, and were comparably reduced by thapsigargin, implying mobilization of Ca2+ from a shared thapsigargin-sensitive intracellular pool. Brief stimulation with oxytocin, vasopressin, or vasotocin prevented subsequent Ca2+ responses to oxytocin, but not to GnRH, suggesting that the oxytocin receptor undergoes rapid homologous desensitization and reinforcing the interpretation that the nonapeptides act via the same receptor type. Oxytocin did not increase Ca2+ in cells stimulated with GnRH, whereas GnRH caused a spike Ca2+ increase even in the presence of oxytocin, implying that different mechanisms of desensitization (Ca2+ pool depletion and receptor uncoupling) are operating for two distinct PIC-coupled receptors in these cells. The demonstration that oxytocin acts directly via PIC-linked, oxytocin-selective receptors to increase cytosolic Ca2+ in a gonadotrope-derived cell line is consistent with the possibility that oxytocin has a comparable effect on nonimmortalized gonadotropes.
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PMID:Oxytocin receptor-mediated activation of phosphoinositidase C and elevation of cytosolic calcium in the gonadotrope-derived alphaT3-1 cell line. 911 4