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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Highly purified populations of guinea pig Leydig cells were incubated with a maximally stimulating dose of 100 ng/mL LH for 24 h in the presence of increasing concentrations of sodium ascorbate. Sample supernatants were extracted, concentrated under vacuum, and reconstituted with acidified absolute ethanol. Samples were analyzed for oxytocin using high-performance liquid chromatography with electrochemical detection and known concentrations of an authentic oxytocin standard. Leydig cells stimulated with 0, 25, and 50 microM ascorbate produced and secreted 40.1 +/- 1.23, 77.4 +/- 13.8, 74.2 +/- 26.3 pg of an oxytocin-like peptide, respectively, per 1 x 10(6) cells. These results indicate that guinea pig Leydig cells are capable of producing an oxytocin-like peptide de novo and that low concentrations of ascorbate stimulate the production of this peptide in Leydig cells cultured in vitro.
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PMID:HPLC determination of an oxytocin-like peptide produced by isolated guinea pig Leydig cells: stimulation by ascorbate. 145 39

Human granulosa cells synthesize and secrete the oxytocin hormone. We have already shown that oxytocin-Gly, the last post-translational maturation intermediate of pro-hormone, is largely secreted by cultured granulosa cells deprived of ascorbate (Plevrakis et al. (1990) J. Endocrinol. 124, R5-R8). Using a combination of high performance liquid chromatography and radioimmunoassay, the oxytocin-like material present in human granulosa cell extracts, in follicular fluid, in cultured granulosa cell supernatants and in corpora lutea extracts was identified. We have demonstrated the presence of oxytocin-Gly, oxytocin-Gly-Lys and oxytocin-Gly-Lys-Arg, the same post-translational maturation intermediates as those we identified in bovine corpus luteum secretory granules. Thus we conclude that post-translational maturation of pro-oxytocin/neurophysin in human ovary proceeds by the same proteolytic events as those we described in bovine post-pituitary gland and corpus luteum.
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PMID:COOH-terminally-extended processing forms of oxytocin in human ovary. 154 13

Corpora lutea (CL) of a number of species produce oxytocin (OXT). In the present experiments we studied basal, prostaglandin (PG) F2 alpha-stimulated and ascorbate-stimulated OXT release from individual bovine luteal cells utilizing the reverse hemolytic plaque assay (RHPA). Using a mixture of C- and N-terminus-specific antisera against OXT, we were able to demonstrate OXT plaque formation by individual luteal cells. CL consist of two steroidogenic cell types: large luteal cells (LLC), believed to derive from granulosa cells and to produce and secrete OXT, and small luteal cells (SLC), thought to derive from theca cells. To distinguish between these two cell types, we designated cells greater than 20 microns as LLC and those less than 20 microns as SLC. On the basis of this morphological parameter, OXT release from both LLC and SLC was demonstrable. After an incubation period of 15 h, 7% of both cell types formed OXT plaques. PGF 2 alpha and ascorbate increased the size of plaques surrounding both LLC and SLC to more than 200% and 240%, respectively (basal plaque size = 100%). The number of plaque-forming cells increased only slightly in the presence of either PGF 2 alpha or ascorbate in comparison to basal conditions. We suggest that the RHPA can be used to demonstrate peptide release from luteal cells. It is concluded that LLC may be subdivided into functional subclasses because less than 10% of bovine luteal cells release OXT. Known OXT secretagogues increased the amount of OXT released. It appears that not only LLC but also SLC secrete this peptide.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Demonstration of oxytocin release by bovine luteal cells utilizing the reverse hemolytic plaque assay. 161 14

Human granulosa cells were collected from preovulatory follicles during follicular puncture for in-vitro fertilization. They were cultured in serum-free medium supplemented with ascorbic acid. Using a combination of high-performance liquid chromatography and radioimmunoassay, the oxytocin material present in the cell extracts and secreted into the medium was identified. When cells were deprived of ascorbate, intermediary forms resulting of the post-translational processing of pro-oxytocin/neurophysin were detected. These data demonstrate that oxytocin biosynthesis occurs in human granulosa cells.
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PMID:Oxytocin biosynthesis in serum-free cultures of human granulosa cells. 231 14

Bovine granulosa cells secrete oxytocin when cultured in a serum-supplemented medium. The time-course of secretion is similar to that in the early corpus luteum in vivo, with a delay of 1 to 2 days followed by a peak and decline over the first 5 days of culture. We have investigated the basis of this time-course in vitro and studied the temporal characteristics of the stimulatory actions of ascorbic acid and adrenaline on this process. Cells cultured on stirred microcarriers showed a similar pattern of secretion of oxytocin to those cultured on conventional flat plates, despite continuing and rapid mitosis. This indicated that the secretion profile in conventional culture was not an artifact related to the cessation of mitosis. Furthermore, secretion of oxytocin and progesterone by cells on microcarriers was stimulated without a corresponding change in mitotic rate, showing that the secretion per cell had been increased. In conventional culture, addition of ascorbic acid to culture media (0.5 mmol/l) increased the secretion of oxytocin (up to 4.5-fold) but only if ascorbic acid was present during the first day of culture. The cells showed a progressive refractoriness to stimulation after 12 h. Since the time-course of secretion was unaltered by treatment, this resulted in a delay of 1 to 2 days before the action of the ascorbate was seen. The secretion of progesterone was similarly affected but with less stimulation and less consistency. In contrast, cells treated with adrenaline (10 mumol/l) secreted more oxytocin on the day of treatment and did so at any time during culture provided that there was sufficient basal secretion of hormone. Adrenaline also failed to alter the time-course of secretion but treated cells showed a persistent response, maintaining enhanced secretion for up to 3 days after the adrenaline had been removed. Ascorbate and adrenaline were highly synergistic in their effects, provided that the ascorbate was present from the start of culture; the response to adrenaline strongly reflected the degree of ascorbate stimulation. We conclude that granulosa cells secrete oxytocin according to an inherent time-schedule and that there is a limited period during which they can respond to ascorbate. Since ascorbate is required for the biosynthesis of oxytocin, this suggests that the availability of ascorbate during corpus luteum formation may determine the amount of oxytocin which can be released subsequently in response to catecholamines.
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PMID:The time-course of oxytocin secretion from cultured bovine granulosa cells, stimulated by ascorbate and catecholamines. 335 20

Experiments were performed with cultured bovine granulosa cells to examine the relationship between the secretions of oxytocin and progesterone and to determine whether progesterone could be responsible for the progressive refractoriness of these cells to stimulation by ascorbic acid. Aminoglutethimide suppressed progesterone secretion by 95% but it neither reduced oxytocin secretion nor restored the cellular response to delayed ascorbate treatment. Addition of a high concentration of progesterone to the culture medium also failed to affect oxytocin secretion, its stimulation by ascorbate, or the endogenous secretion of the steroid. It is concluded that oxytocin and progesterone can be independently secreted and that progesterone regulates neither its own secretion nor that of oxytocin.
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PMID:Ovarian oxytocin and progesterone are secreted independently of one another. 337 42

Bovine granulosa cells were exposed in vitro to various adrenal steroids (cortisol, cortisone, corticosterone, aldosterone; 1 mumol/l), in the presence and absence of stimulation by ascorbic acid (0.5 mmol/l), to determine the possible effects of these hormones on ovarian oxytocin and progesterone secretion. Only cortisol produced a consistent stimulation of the cells; the response was dose-related over the range 0.01 to 1.0 mumol/l and was greatly enhanced in the presence of ascorbate. The secretion of oxytocin was stimulated to a greater extent and with more consistency than was that of progesterone. Although the secretion of oxytocin could be stimulated by cortisol on the day of treatment, the cells also showed a delayed and persistent response to exposure earlier in the culture. It is concluded that cortisol may directly stimulate the secretion of ovarian oxytocin in the cow and that granulosa cells may respond in such a way as to smooth out the effects of short-term fluctuations in cortisol concentration.
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PMID:Enhanced secretion of oxytocin from bovine granulosa cells treated with adrenal steroids. 341 79

The effects of catecholamines and ascorbic acid on cultured bovine granulosa cells have been examined to assess their possible role in the initiation and maintenance of luteal oxytocin secretion. The actions of these agents have also been compared with the previously reported ability of follicular theca tissue to enhance oxytocin secretion. Using granulosa cells cultured in serum-supplemented medium, we observed a highly significant enhancement of oxytocin secretion in the presence of adrenaline and noradrenaline, particularly over the concentration range 1-10 mumol/l. This effect was accompanied by smaller and less consistent changes in progesterone secretion and did not involve any change in the time-course of oxytocin secretion. Acetylcholine was without effect. Ascorbic acid stimulated oxytocin secretion when used alone over a range of concentrations, but was also able to synergize with adrenaline. Lactic acid was ineffective. The stimulation of oxytocin secretion by adrenaline could be blocked by equimolar propranolol, but the stimulation of progesterone was not blocked. Propranolol had a variable effect on the ability of theca tissue to stimulate oxytocin secretion by granulosa cells but the results also suggested the presence of some beta-agonistic activity in the culture medium. We conclude, first, that catecholamines may be involved in the regulation of ovarian oxytocin secretion, secondly, that ascorbate may regulate oxytocin secretion through its involvement in the biosynthesis of oxytocin but also through interaction with catecholamines and, thirdly, that the stimulatory action of theca tissue probably does not involve the action of beta-agonists.
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PMID:Catecholamines and ascorbic acid as stimulators of bovine ovarian oxytocin secretion. 366 32

In the present study, we examined denervation-induced changes in the sensitivity of hypothalamic postsynaptic serotonin1A (5-HT1A) receptor function with respect to changes in the dose-dependent elevation in plasma hormones [adrenocorticotropic hormone (ACTH), corticosterone, prolactin, oxytocin, prolactin, renin and vasopressin] by the 5-HT1A agonist 8-hydroxy-2-(dipropylamino)tetralin (8-OH-DPAT). Rats received intracerebroventricular (i.c.v.) injections of the serotonin neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) or vehicle (0.1% ascorbate in saline) 3 weeks before challenge with increasing doses of 8-OH-DPAT (0, 10, 50 or 200 micrograms/kg s.c.). The effectiveness of 5,7-DHT-induced destruction of serotonergic neurons was confirmed by a 93% reduction in [3H]paroxetine-labeled 5-HT uptake sites in the hypothalamus. No changes in basal levels of ACTH, corticosterone, oxytocin, prolactin, renin and vasopressin were observed in rats that received i.c.v. 5,7-DHT injections. The dose-response curves for 8-OH-DPAT-induced elevations of plasma corticosterone and prolactin levels were shifted to the left in rats treated with 5,7-DHT, whereas no significant difference in the ACTH dose-response curve was observed between rats treated with vehicle and rats treated with 5,7-DHT. In contrast, the maximal oxytocin response to 8-OH-DPAT was attenuated in rats treated with 5,7-DHT. A 5,7-DHT-induced decline in the synthesis of oxytocin could explain this phenomenon. Although 8-OH-DPAT did not increase plasma levels of renin or vasopressin in rats treated with vehicle, 8-OH-DPAT produced an elevation (75%) in plasma renin concentration but not in vasopressin levels in rats that received i.c.v. injections of 5,7-DHT. No change was observed in [3H]8-OH-DPAT labeled 5-HT1A receptors in the hypothalamus. In summary, denervation of hypothalamic serotonergic nerve terminals produces supersensitivity of some neuroendocrine responses to 8-OH-DPAT independent of changes in the density of hypothalamic 5-HT1A receptors.
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PMID:Alterations in 8-hydroxy-2-(dipropylamino)tetralin-induced neuroendocrine responses after 5,7-dihydroxytryptamine-induced denervation of serotonergic neurons. 965 67

The development of a multicellular spheroid comprising bovine endometrial epithelial cells (BEE) and bovine endometrial stromal cells (BES) is described in this study. The BES were cultured to confluence in medium with L -ascorbic acid phosphate magnesium salt n -hydrate (AsA-P) which stimulates collagen synthesis in BES. The BEE were co-cultured on a BES cell-sheet for 24h before detachment of the cell-sheet to generate a hetero-spheroid. After EDTA treatment and agitating with pipette, the floating cell-sheet shrank and became an aggregated cell mass in a few days; it finally formed a round-shaped hetero-spheroid composed of BES and BEE. Histological examination found that hetero-spheroids were covered with BEE on the outer layer. When cell viability was examined with TUNEL (terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling), no positive signal was detected in the spheroid for up to 10 days. Immunofluorescence observations showed that spheroids contained abundant extracellular matrices, including type-I, -III, -IV collagen, fibronectin, and laminin. PGF(2alpha) produced by hetero-spheroids in response to oxytocin was significantly higher than those produced by monolayer cultured BEE (P< 0.05). MMPs were not detected in media from spheroids cultured for 5 days after detachment of the cell sheet. These results indicate that bovine endometrial cells have the capacity to regenerate as a multicellular spheroid after treatment with ascorbate in vitro. The spheroid displays an endometrium-mimic feature. Thus, we conclude that spheroids formed by BES and BEE are a useful in vitro model of bovine endometrium.
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PMID:A three-dimensional cell culture model for bovine endometrium: regeneration of a multicellular spheroid using ascorbate. 1256 53


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