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)

Oxytocin-induced contractions of isolated strips of oestradiol-treated rat myometrium were found to be affected by exposure to the diuretic frusemide. At a concentration of 20 microM. frusemide transiently increased the force of contraction over a period of approximately 10 min. After this time there was a progressive fall in contractile force. At a higher concentration of 200 microM, only the progressive fall in force was seen until contractions were completely abolished. Frusemide has been reported to increase the activity of cAMP-phosphodiesterase in tissue extracts from oestradiol-treated rat myometrium. Therefore, the changes in contraction due to exposure to frusemide may be a reflection of the changes in intracellular cAMP resulting from a stimulation of cAMP-phosphodiesterase activity. In support of this idea, addition of dibutyryl cAMP was found to partially restore contractions after frusemide treatment. These data suggest that frusemide may be a useful tool in the manipulation of tissue cAMP levels in order to determine the different roles of cAMP in the oestradiol-treated rat myometrium.
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PMID:The effect of frusemide on oxytocin-induced contractions of the rat myometrium. 781 57

The effects of growth hormone (GH) and prolactin (PRL) (1, 10, 100, 1000 or 10,000 ng/ml medium) on oxytocin, vasopressin, progesterone, cAMP and cGMP release by cultured bovine granulosa cells were studied. It was found that GH significantly stimulated oxytocin, vasopressin and cAMP but suppressed progesterone secretion. PRL tended to have the same pattern of action on nonapeptide, cAMP and steroid release, but its effect was not as great, with only a high supraphysiological dose (10,000 ng/ml) producing a statistically significant effect. No significant influence of GH on cGMP output was observed. Physiological doses of PRL (1, 10, 100 or 1000 ng/ml) significantly inhibited cGMP production whilst a high dose (10,000 ng/ml) resulted in stimulation. These observations suggested that GH may regulate ovarian oxytocin, vasopressin, progesterone and cAMP secretion. The effects of PRL on the release of these substances appeared to be non-specific, possibly resulting from its structural similarity to GH.
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PMID:Growth hormone and prolactin affect oxytocin, vasopressin, progesterone and cyclic nucleotide secretion by bovine granulosa cells in vitro. 783 85

The release of progesterone, estradiol-17 beta, oxytocin, arginine-vasopressin, cAMP, and cGMP by cultured granulosa cells isolated from porcine ovaries without and in the presence of melatonin (0.001, 0.01, 0.1, 1, 10, and 100 ng/ml medium) was analyzed. It was found that melatonin is able to inhibit progesterone and stimulate estradiol secretion. Melatonin treatments significantly inhibited oxytocin release. Some inhibition of vasopressin and cAMP and significant stimulation of cGMP also resulted from melatonin treatment. The present observations suggest a direct effect of melatonin on the steroid, nonapeptide hormone, and cyclic nucleotide release from porcine ovarian cells.
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PMID:Direct influence of melatonin on steroid, nonapeptide hormones, and cyclic nucleotide secretion by granulosa cells isolated from porcine ovaries. 789 82

Immediate-early genes, such as c-fos, couple extracellular signals to genetic changes in the cell. We have previously demonstrated that depolarization with 50 mM KCl increases Fos immunoreactivity in hypothalamic tyrosine hydroxylase (TH) and oxytocin immunoreactive (-ir) neurons in primary culture. This Fos activation occurs within 1.5-2 h in TH-ir cells. In the present study, we examined the effects of depolarization, glutamate receptor activation and adenylyl cyclase stimulation on Fos-ir to determine the possible mechanism(s) of Fos activation in TH-ir neurons. Hypothalamic cultures were treated with KCl, glutamate or forskolin, and Fos and TH were visualized immunocytochemically. Forskolin increased the percentage of Fos/TH-ir neurons in a dose-dependent manner, with a maximal stimulation of 53.4 +/- 4.5% Fos/TH-ir neurons at 30 microM forskolin. The dose-response curve for glutamate was steep, with a maximal stimulation of 24.8 +/- 2.1% Fos-ir neurons at 100 microM. 50 mM KCl resulted in 50.0 +/- 0.8% Fos/TH-ir neurons. Pretreatment with verapamil decreased KCl induced Fos-ir by 57%, glutamate by 65% and forskolin by 39%. Combined drug administration demonstrated significant additivity between forskolin and glutamate, and forskolin and KCl, however, no significant additivity was found with KCl and glutamate. The results are discussed in terms of cAMP and calcium mediation of the Fos response to these stimuli.
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PMID:Calcium and cAMP mediated stimulation of Fos in cultured hypothalamic tyrosine hydroxylase-immunoreactive neurons. 798 47

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

The genes for the alpha subunit of inhibin and for the nonapeptide hormone oxytocin are both expressed in the granulosa cells of the ruminant follicle as well as in the Sertoli cells of the ruminant testis. Northern hybridization of mRNA from both ovary and testis indicate that in both gonads the expression of the two genes is inversely regulated. In the luteinizing granulosa cells, in vitro as in vivo, the alpha-inhibin gene is down-regulated when the oxytocin gene is up-regulated. In the Sertoli cells of the bull and sheep testis, the situation is similar, with the alpha-inhibin gene being up-regulated in the prepubertal gonad and down-regulated concomitantly with an up-regulation of the oxytocin gene in early puberty. The gene for the bovine alpha-inhibin subunit was cloned and characterized. Assessment of transcriptional initiation by primer extension and ribonuclease protection assays showed that several different sites were used in both granulosa cells and testis. Transient transfection of primary bovine granulosa cells with alpha-inhibin/luciferase gene constructs indicated that a major promoter element resided in the region -178 to -245 respective to the methionine start codon of translation, a region that contains a cAMP response element. The ability of forskolin to up-regulate the transcription of transfected gene constructs also depended on the integrity of this region. In contrast, transfection of TM4 cells led to transcriptional initiation from an unusual site in the alpha-inhibin gene and to a lack of forskolin regulation. Comparison of the alpha-inhibin and oxytocin genes indicates that although both can be up-regulated by FSH or by forskolin within the same cells, different mechanisms of signal transduction are involved to explain the temporal differences in expression. Together the results indicate that a differentiation step occurring in Sertoli cells at early puberty and in granulosa cells at luteinization involves comparable regulation of genes through the sequential action of different cAMP-linked transcription factors.
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PMID:Structure of the alpha-inhibin gene and its regulation in the ruminant gonad: inverse relationship to oxytocin gene expression. 814 57

Furosemide increased the hydrosmotic water flow in the frog urinary bladder and promoted the ADH-like effect of inhibitors of phosphodiesterase cAMP, potentiated hydrosmotic effects of theophylline and serosal osmotic hypertonicity but failed to change the effect of pituitrin. Fur reversibly suppressed oxytocin-induced contractions in the rat myometrium, inhibited the activity of the frog urinary bladder PDE cAMP, whereas the activity of the enzyme from the rat medulla and myometrium was activated by saluretic. Incubation of the myometrium strips in Fur resulted in a decrease in the cAMP content of the tissue. The cAMP seems to play an important role both in the myometrium smooth muscle relaxation and in the oxytocin-activated contractions.
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PMID:[The mechanisms of the effect of furosemide on the water permeability of the frog bladder and on oxytocin-stimulated contractions of the rat uterus]. 816 67

Granulosa cells were isolated from ovaries (without pre-ovulatory follicles or corpora lutea) of cycling gilts slaughtered at 8 months of age. They were cultured in the presence or absence of exogenous porcine prolactin (1, 10, 1,000, 10,000, or 100,000 pmol/ml medium). The secretion of estrogen, cAMP and oxytocin into the incubation medium was analysed by radioimmunoassay. It was found that prolactin (10, 1,000, 10,000 and 100,000 pmol/ml) inhibited estrogen secretion (p < 0.001) and stimulated cAMP output (p < 0.001, p < 0.001, not significant, and p < 0.01, respectively). Small doses of prolactin (1 and 10 pmol/ml) decreased (p < 0.001, p < 0.05), whilst high doses (1,000, 10,000 and 100,000 pmol/ml) increased (p < 0.001) oxytocin secretion by granulosa cell culture. The data suggest a direct action of prolactin on porcine ovarian cyclic nucleotides, steroid and nonapeptide hormone release.
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PMID:Effects of prolactin on estrogen, cAMP and oxytocin secretion by porcine granulosa cells in vitro. 817 13

Previous reports have suggested that gonadotropins, estradiol, and prostaglandin F2 alpha (PGF2 alpha) have varying effects on progesterone and oxytocin synthesis or secretion in cultured granulosa and luteal cells collected at different stages of the estrous cycle. The experiments reported here were designed to investigate whether effects of these agonists on secretion of hormones and their coupling to second messenger systems changed around the time of ovulation. Granulosa cells and Day 2 luteal cells of the ewe were cultured for three days and then treated for 30 min with varying doses of PGF2 alpha, LH, or estradiol. LH increased intracellular cAMP at both stages, but granulosa cells were more responsive in terms of both minimum effective dose (10 compared with 100 ng/ml) and degree of stimulation. LH caused no change in intracellular inositol phosphate levels. Both granulosa and early luteal cells responded to LH treatment by an increase in progesterone output in a dose-responsive fashion. PGF2 alpha increased inositol phosphate accumulation in cells collected at both stages of the cycle. All doses tested (10(-6)-10(-8) M) stimulated the release of oxytocin into the culture medium from both granulosa and luteal cells. Progesterone secretion was also increased, but only at the highest dose (10(-6) M). Estradiol treatment (10(-6) M) did not affect either the inositol phosphate or cAMP second messenger systems, but it did inhibit the secretion of oxytocin from granulosa cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Acute effects of prostaglandin F2 alpha, luteinizing hormone, and estradiol on second messenger systems and on the secretion of oxytocin and progesterone from granulosa and early luteal cells of the ewe. 819 57

The initiation of human parturition remains an enigma but is thought to involve a number of hormonal signals such as oxytocin and prostaglandins. One other possible signal is placentally derived corticotropin-releasing hormone (CRH). We have recently reported that the human myometrium expresses a specific receptor for CRH which changes to a high affinity state prior to term. In view of this we sought to determine whether this receptor is functionally linked to some of the known modulators of myometrial function. Myometrial membranes were prepared by differential centrifugation from either pregnant (caesarian section) or non-pregnant (hysterectomy) myometrium. For binding studies the membranes were incubated with radiolabelled oCRH at 22 degrees C for 2 h. For second messenger studies they were incubated at 37 degrees C for 10 or 30 min with either 0.5 mM ATP and 10 mM theophylline (cAMP) or 0.05 mM arachidonic acid or 0.5 mM linoleic acid (PGE2). When increasing concentrations of membranes were incubated with radiolabelled oCRH an interesting phenomenon was observed. In non-pregnant membranes the binding reached a plateau, whereas in membranes prepared from pregnant myometrium, the binding decreased at concentrations above 130 micrograms/ml. Possible explanations for this phenomenon include an inhibitor which prevents ligand-receptor binding or an enzyme which destroys the receptor binding region of the ligand. Incubation of both types of membranes with GTP or its analogue, GppNHp, resulted in a dose-dependent inhibition of specific binding suggesting that the myometrial CRH receptor is linked to a G regulatory protein.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The human myometrial CRH receptor: G proteins and second messengers. 820 32


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