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 myometrial contractile responses to synthetic 1-0-octadecyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (platelet-activating factor, PAF) and to oxytocin were evaluated in vitro on uterine (lower segment) strips obtained from pregnant women at term (39th week), undergoing elective cesarean section. Contractility was measured isometrically in an isolated organ bath using a superfusion technique. PAF in a concentration range between 5 and 100 nM as well as oxytocin (0.1-10 mU/ml) induced a dose-dependent contraction which could be categorized in two patterns, depending on whether spontaneous activity was present. In resting strips, oxytocin induced a prompt (0.5-1 min) development of active tension, followed by a prolonged (6-18 min), slow contraction and a final relaxation. However, at variance with oxytocin, PAF-induced contractions were rhythmic (3-8/hr), and characterized by a prompt (0.5-2 min) development of tension, followed by a brief (0.5-2 min) plateau, and a final, rapid relaxation. In spontaneously active strips, both stimuli induced a marked potentiation of the contractile activity. PAF response was dependent on both cyclooxygenase- and lipoxygenase-derived products as inferred from the abrogating effects of indomethacin and FPL 55712. A receptor-mediated mechanism of action was inferred from the occurrence of specific desensitization to PAF (but not to oxytocin), and from the blocking effect of CV 3988, a specific PAF receptor antagonist. The present study indicates that PAF stimulates the contraction of human myometrium in vitro and suggests that this mediator may have a role in labor.
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PMID:Platelet-activating factor contracts human myometrium in vitro. 379 21

High concentrations of PGF2 alpha and PGE2 are produced by the uterus during the early postpartum period in cows and may play an important role in both placental separation and uterine involution. In the present study, we have examined the hormonal and intracellular control mechanisms involved in PGF2 alpha and PGE2 secretion by caruncular and allantochorionic tissue in vitro. Tissue explants, obtained about 6 hr postpartum from cows that delivered normally (NFM, n = 10) or cows with retained fetal membranes (RFM, n = 4), were incubated for 6 hr and PGF2 alpha and PGE2 concentrations in the medium were determined by radioimmunoassay. Addition of oxytocin (100 microU/ml), platelet activating factor (PAF, 100 ng/ml) and epidermal growth factor (EGF, 100 ng/ml) had no effect on secretion of PGF2 alpha from the caruncle, but oxytocin and PAF did stimulate PGE2. There was no difference between groups of cows. All three substances stimulated PGF2 alpha from the allantochorion of NFM, but not RFM, cows and stimulated PGE2 secretion from the allantochorion of both groups of cows. Incubation of the tissues with cholera toxin (100 ng/ml), dibutyryl cyclic adenosine 3',5'-monophosphate (dibutyryl cAMP, 1 mM), calcium ionophore A23187 (5 microM) or phorbol ester 12-myristate-13 acetate (PMA, 100 nM) showed that PGF2 alpha secretion is essentially via the calcium-protein kinase C effector pathway. However, calcium-protein kinase C and cAMP second messenger systems appear to be involved in the secretion of PGE2. Prostaglandin secretion was sensitive to cycloheximide in both caruncular and allantochorionic tissues, suggesting that protein synthesis may be involved. In conclusion, these data show that in vitro PGF2 alpha secretion can be modulated by the agonists used only in allantochorion and is essentially via the calcium-protein kinase C effector pathway. PGE2 secretion can be modified in both caruncular and allantochorion tissues and involves both inositol triphosphate-diacylglycerol and cAMP second messenger systems.
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PMID:Control of in vitro prostaglandin F2 alpha and E2 synthesis by caruncular and allantochorionic tissues from cows that calved normally and those with retained fetal membranes. 804 99

Secretion of progesterone in vitro by mature day 8 ovine corpora lutea (CL) of the estrous cycle was increased linearly by ovine LH (1, 10 and 100 ng/ml) or prostaglandin E2 (PGE2) 1, 10 and 100 ng/ml) in a dose dependent manner (P < or = 0.05). Progesterone secretion in vitro by 88-90 day ovine CL of pregnancy was not affected P > or = 0.05 by LH (1, 10 and 100 ng/ml) while prostaglandin E1 (PGE1) 1, 10 and 100 ng/ml) increased (P < or = 0.05) secretion of progesterone in a dose dependent manner and PGE2 (1, 10 and 100 ng/ml) increased (P < or = 0.05) secretion of progesterone only at the 100 ng/ml dose. Day 8 ovine CL of the estrous cycle did not secrete (P > or = 0.05) detectable quantities of prostaglandin F2 alpha (PGF2 alpha) or prostaglandin E (PGE) while 88-90 day ovine CL of pregnancy secrete PGE (P < or = 0.05) but not PGF2 alpha (P > or = 0.05). Regulation of PGE secretion by 88-90 day ovine CL of pregnancy may be via pregnancy specific protein B (PSPB), which increased (P < or = 0.05) PGE and progesterone but not PGF2 alpha (P > or = 0.05) secretion. Secretion of progesterone by CL of 88-90 days of pregnancy was not affected by IGF1, IGF2, PAF-16, PAF-18, oxytocin, PGI2, PGD2 or leukotriene C4 (P > or = 0.05). It is concluded that PGE1 or PGE2 but not LH regulates secretion of progesterone in vitro by 88-90 day ovine CL of pregnancy. In addition, it is concluded that 88-90 day ovine CL of pregnancy secretes it's own luteotropin, which is PGE. Secretion of PGE by ovine CL of pregnancy may be regulated by PSPB.
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PMID:PGE1 or PGE2 not LH regulates secretion of progesterone in vitro by the 88-90 day ovine corpus luteum of pregnancy. 924 73