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

Effects of nonapeptide hormones and some of their chemical analogues on progesterone and testosterone production by culture of porcine granulosa cells have been investigated. Oxytocin (0.01-10 IU/ml), arginine-8-vasopressin (0.01-10 micrograms/ml), arginine-8-vasotocin (0.01-10 micrograms/ml) and, in a lesser degree, 2-0-methyl-tyrosine (deamino-1-karba)-oxytocin (0.01-10 micrograms/ml, but no 1-deamino-8-vasopressin (0.01-10 micrograms/ml) stimulated a progesterone surge. Testosterone production was significantly stimulated by oxytocin and inhibited by vasopressin or vasotocin additions. 2-0-methyl-tyrosine (deamino-1-karba)-oxytocin or 1-deamino-8-vasopressin had little or no effect on testosterone secretion. The present results suggest the existence of a direct influence of nonapeptide hormones on porcine ovarian progestagen and androgen production.
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PMID:The influence of oxytocin, vasopressin and their analogues on progesterone and testosterone production by porcine granulosa cells in vitro. 144 77

Postnatal development of the supraoptic nucleus (SON) in the pig hypothalamus was studied morphometrically. The volume of the SON increased from 6.2 +/- 0.45 (S.E.M.) mm3 at 7 weeks postnatally to 18.5 +/- 1.35 mm3 at 2.5 years of age. A sex difference was found at the development point when the SON volume increased, with earlier SON enlargement in males. This sex difference was 30% at 30 weeks and 50% at 1 year of age. At 2.5 years of age no difference in volume was apparent between the sexes. The number of SON neurones was similar for all age groups concerned (43,500 +/- 1475), except for the 2.5-year-old females where 40% more were found (55,500 +/- 3285). No significant difference was found in neurone number between gonadectomized and sham-operated animals, but the operation caused a 30% reduction in the number of neurones and SON volume. Testosterone supplementation following gonadectomy, during the first 4 weeks postnatally, resulted in sexual dimorphism, the males having more SON neurones than the females. The volume showed only a trend in the same direction. Testosterone supplementation at other ages did not result in any difference when compared with controls. The results of this study show that the postnatal development of the SON of the pig is sexually dimorphic, and that it continues after puberty in females. In contrast to the vasopressin- and oxytocin-containing nucleus, the development of the SON was not influenced by gonadectomy and only slightly by gonadal steroids.
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PMID:The supraoptic nucleus in the pig hypothalamus: postnatal development and the effect of gonadal steroids. 150 Aug 41

The aims of the present study were to determine whether Leydig cells in vitro synthesize oxytocin, and whether LH modulates the secretion of oxytocin by Leydig cells. Highly purified adult Leydig cells were prepared from adult rats and cultured for 3 days in the presence or absence of 0.1 ng/ml ovine LH, and media were changed daily. The total amount of oxytocin present in the culture was estimated by RIA of cell extracts before culture (day 0) and at the end of day 3 of culture and in media on days 1-3. The content of immunoreactive oxytocin in cell extracts on day 0 (3.4 +/- 1.2 pg/10(6) cells) was significantly lower than the total amount that had been released into the medium and was present in the cell extracts at the end of day 3 (+LH, 27.8 +/- 3.3; -LH, 16.5 +/- 2.7 pg/10(6) cells), suggesting that Leydig cells are able to synthesize and secrete oxytocin. This hypothesis was supported by the observation that oxytocin release into the medium was significantly reduced during a 3-h treatment of Leydig cells with the protein synthesis inhibitor cycloheximide (5 micrograms/ml for 3 h). The role of LH in regulating testosterone production by Leydig cells is well defined, but whether LH also regulates oxytocin is unknown. Therefore, the effects of LH on oxytocin and testosterone production by Leydig cells were compared. The production of both hormones was stimulated by increasing doses of LH (0.001-100 ng/ml), but no further rise in oxytocin release could be elicited with amounts of LH greater than 0.1 ng/ml. Testosterone production, however, continued to increase with doses of LH up to 100 ng/ml. Furthermore, the two hormones differed in the rate of their responses to both 3- and 12-h exposures to LH; testosterone secretion increased more rapidly than that of oxytocin. These data provide direct evidence that adult Leydig cells produce immunoreactive oxytocin, and that their production of this peptide is regulated by LH.
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PMID:Luteinizing hormone differentially regulates the secretion of testicular oxytocin and testosterone by purified adult rat Leydig cells in vitro. 173 15

We have studied the effects of gonadectomy and testoterone supplementation on the development of the vasopressin- and oxytocin-containing nucleus (VON) of the pig hypothalamus that shows a decrease in neuron number during the first weeks postnatally, followed by an increase during puberty. Neonatal gonadectomy caused a 2.5-fold increase in VON volume and neuron number in males and 3-fold in females at the age of 16 weeks, the onset of puberty. However, the difference between gonadectomized and nongonadectomized animals disappeared after puberty (38 weeks). Testosterone replacement from 16 weeks onwards induced a decrease in neuron number and volume of the VON. The present study indicates that the development of the VON is influenced by gonadal steroids although it seems improbable that these hormones affect the VON directly.
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PMID:Influence of gonadectomy and testosterone supplementation on the postnatal development of the vasopressin and oxytocin-containing nucleus of the pig hypothalamus. 178 44

Penile erection and yawning induced by the intracerebroventricular (ICV) injection of oxytocin (10-1000 ng) was studied in hypophysectomized rats and in rats neonatally treated with monosodium glutamate (MSG), a treatment that depletes hypothalamic opiomelanocorticotropin-derived peptides without altering their pituitary and circulating concentration. Oxytocin effect was strongly reduced by hypophysectomy, but not by neonatal MSG. Testosterone replacement (50 micrograms/kg/day for 23 days) partially reversed the effect of hypophysectomy on penile erection, but not on yawning. The present results suggest that oxytocin does not induce penile erection and yawning by releasing an ACTH-derived peptide from hypothalamic opiomelanotropinergic neurons, and that the pituitary gland exerts a permissive role on the expression of the above behavioural responses induced by oxytocin.
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PMID:Oxytocin-induced penile erection and yawning in male rats: effect of neonatal monosodium glutamate and hypophysectomy. 249 89

There is considerable disagreement in the literature on changes in the hypothalamo-neurohypophyseal system (HNS) with aging: some reports support HNS degeneration, whereas others claim an activation of this system in senescence. In order to study age-related changes in vasopressin (VP) and oxytocin (OT) excretion in relation to water metabolism, six young (4 months) and 12 aged (34 months) male Brown-Norway rats were placed in metabolism cages. Since plasma testosterone levels have been reported to affect HNS activity and to decline progressively with age, half of the aged animals were given subcutaneous testosterone implants. Urine volume and water intake were significantly increased in aged animals, while urine osmolality was significantly reduced. These changes could not be attributed to diminished VP secretion, since 24-h urinary excretion of this peptide was elevated in the aged animals. In addition, 24-h OT excretion was elevated in the aged animals, indicating an overall activation of the HNS in senescence. VP excretion was significantly correlated with urine osmolality, urine volume and urinary VP concentration. No significant differences were observed between testosterone- and sham-implanted aged rats. It is concluded that the moderate polyuria/polydipsia in the senescent Brown-Norway rat is probably due to renal changes and is accompanied by a compensatory rise in both VP and OT secretion. Testosterone does not affect these changes.
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PMID:Vasopressin and oxytocin excretion in the Brown-Norway rat in relation to aging, water metabolism and testosterone. 321 21

Oxytocin, vasopressin, cortisol and testosterone levels in the plasma were measured by radioimmunoassay in intact male goats as well as in prepubertally castrated goats injected daily, for 2 weeks, with oil vehicle and then, for 4 weeks, with testosterone propionate in oil to study the influence of gonadal steroids on posterior pituitary hormones. Packed cell volume, plasma osmolality and sodium concentration were also measured in all blood samples. Plasma levels of oxytocin, vasopressin and cortisol were similar in the intact and oil-injected castrated goats. Testosterone treatment significantly increased plasma levels of oxytocin (P less than 0.01) in castrated goats but the increased levels were similar to those seen in the intact goats at the same time of year. Plasma levels of cortisol and vasopressin were unaffected by testosterone propionate treatment, whereas packed cell volume was significantly decreased (P less than 0.01). Testosterone treatment of castrated male goats appears not to have any action on pituitary hormones and oxytocin increases in the spring in both intact and castrated male goats.
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PMID:Plasma vasopressin and oxytocin levels in intact goats and in castrated goats given testosterone. 338 35

In male rats, two-week orchidectomy induced a significant increase in the pituitary content of oxytocin-immunoreactivity and a significant fall in its hypothalamic concentration, without detectable changes in plasma. Testosterone replacement therapy in castrated animals abolished the stimulant effect of orchidectomy on pituitary accumulation of oxytocin. The present study demonstrates an inhibitory effect of testicular androgens on oxytocin release. These results and previous observations suggest that the neurohypophysial hormone oxytocin may play a role in male reproductive system.
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PMID:The effects of orchidectomy and testosterone replacement therapy on plasma and brain oxytocin in normal rats. 367 99

Recently we reported that castration of rats eliminates vasopressin immunoreactivity in the lateral septum and other areas that appear to receive vasopressin innervation from the bed nucleus of the stria terminalis. Testosterone treatment counteracts this effect of castration. In the present study, we investigated whether this action of testosterone depends on its androgenic or estrogenic metabolites by treating long-term castrated rats with estradiol (E) and/or 5 alpha-dihydrotestosterone (DHT) or testosterone. The brains were then processed for immunocytochemistry or radioimmunoassay. DHT did not increase vasopressin staining in the lateral septum, although it fully restored the size of the seminal vesicles. E did restore the original fiber density, but individual fibers stained more weakly than in sham-operated males. Only treatment with both E and DHT fully restored the vasopressin innervation. This pattern was also reflected in the radioimmunoassay data. The vasopressin content of the lateral septum decreased about 90% after castration but was fully restored by either testosterone or E + DHT treatment. E alone, however, was only half as effective as E + DHT. The treatments had no effect on the oxytocin content of the septum, or on the vasopressin or oxytocin content of the dorsal vagal complex. The results suggest that E mediates most of the effects of testosterone on the vasopressin innervation of the lateral septum. DHT enhances the response to E but has little effect on its own.
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PMID:Effects of androgens and estrogens on the vasopressin and oxytocin innervation of the adult rat brain. 382 65

Testosterone (100 nM to 40 microM) antagonized the effect of aldosterone (10 nM) on Na+ transport in the toad bladder measured in vitro as short-circuit current (SCC). Half-maximal inhibition occurred at an antagonist-agonist molar ratio of 150:1. The antagonist action of testosterone was reversed by addition of more aldosterone. The antagonism was specific in the sense that testosterone (20 microM) did not inhibit the response of the SCC to oxytocin (50 mU/ml). By itself, testosterone (up to 20 microM) had no agonist activity on base-line SCC. Finally, testosterone (500 nM to 20 microM) specifically displaced [3H]aldosterone (5 nm) from its cytoplasmic and nuclear binding sites in bladders incubated in vitro at 25 or 0 degrees C and labeled at steady state. There was a significant linear correlation between the effect of testosterone on the aldosterone-dependent SCC and its effect on [3H]aldosterone binding sites in the cytoplasm and in the nucleus. We conclude that 1) testosterone is a specific competitive antagonist of aldosterone, and 2) [3H]aldosterone nuclear and cytoplasmic binding sites could be mineralocorticoid receptors, mediating the action of aldosterone on Na+ transport.
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PMID:Testosterone: a specific competitive antagonist of aldosterone in the toad bladder. 677 25


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