Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently controversial data has been obtained about the endocrine effects of the neurohypophyseal hormone oxytocin both in vitro and in vivo. We measured testosterone, prolactin, LH and FSH by specific radioimmunoassay in seven healthy adult males before, during and after intravenous infusion of either synthetic oxytocin (4IU/100 ml/120 min) or saline. The findings clearly demonstrate that in men oxytocin does not affect plasma prolactin, LH and FSH. Our results do not establish an effect of oxytocin on basal testosterone release in healthy male subjects.
 ...
PMID:The inability of oxytocin to influence the secretion of testosterone, prolactin, luteinizing and follicle-stimulating hormone in normal men. 310 64

The effect of insulin-like growth factor-I (IGF-I), epidermal growth factor (EGF), fibroblast growth factor (FGF) and nerve growth factor (NGF) on production of oxytocin and progesterone by cultured bovine granulosa and luteal cells was studied. Secretion of oxytocin was stimulated, in a dose-dependent manner, by IGF-I at 48 and 120 h of culture to levels much higher than those after stimulation with LH, FSH, EGF, FGF or NGF. A similar effect of IGF-I was observed for progesterone but, in contrast to oxytocin, secretion of progesterone was not increased by EGF, NGF or FGF. During primary culture, for 4 h, of dispersed bovine luteal cells obtained from corpora lutea between days 4 and 10 of the oestrous cycle, all the growth factors tested failed to stimulate secretion of oxytocin or progesterone. The data suggest the relevance of growth factors (especially IGF-I) for ovarian physiology and their possible importance for differentiation of follicles and luteinization.
 ...
PMID:Insulin-like growth factor-I stimulates oxytocin and progesterone production by bovine granulosa cells in culture. 325 17

The variety of peptides synthesized by the corpus luteum (relaxin, vasopressin, oxytocin and oxytocin-related neurophysin) and their possible intracellular effects are reviewed. After luteinization of the granulosa cells and in response to LH and FSH, the output of oxytocin is increased. In addition, insulin-like growth factor is a very potent stimulus of oxytocin secretion. Although luteal cells respond to gonadotrophins by increased production of progesterone, there is no further secretion of oxytocin. Oxytocin is localized in large luteal cells which seem not to be under the direct control of gonadotrophins. Synthesis of luteal oxytocin seems to occur during the early luteal phase according to measurements of oxytocin mRNA. Highest tissue concentrations and secretion under in-vitro conditions were observed during the mid-luteal phase, and so synthesis, storage and secretion are unlikely to occur concomitantly. Under in-vitro conditions, oxytocin is secreted concomitantly with neurophysin and progesterone, and there appears to be some form of communication between small and large luteal cells for the secretion of progesterone and oxytocin under in-vivo conditions. Evidence has been obtained that oxytocin may have local effects in the ovary by inhibition of secretion (synthesis ?) of progesterone, especially during the early luteal phase. A mechanism can be suggested whereby, under physiological conditions, oxytocin may delay the increase of progesterone by inhibition of progesterone secretion and therefore delay down regulation of its own receptor. This would prolong the life-span of the CL and the oestrous cycle. Exogenous progesterone given on Days 1-4 shortens the cycle to about 12 days. The best evidence that oxytocin may be involved in controlling luteolysis comes from immunization experiments in ewes and goats, but there is no clear evidence of this type for cattle. Basal concentrations of oxytocin at the end of the luteal phase may interact with oxytocin receptors after the inhibitory effect of progesterone in the uterus is reduced, thus initiating synthesis of PGF-2 alpha.
 ...
PMID:Luteal peptides and intercellular communication. 330 25

In Exp. I, blood samples were collected simultaneously from the posterior vena cava and jugular vein or aorta from 7 heifers every 5-20 min for 2-5 h. Concomitant pulsatile secretion of oxytocin and immunoreactive neurophysin I was detected in the vena cava, but not in the jugular vein or aorta. Concentrations of oxytocin and immunoreactive neurophysin increased earlier and were higher in the vena cava than in the jugular vein or aorta after the injection of a luteolytic dose of prostaglandin F-2 alpha analogue during the mid-luteal phase of the oestrous cycle, demonstrating its ovarian but not pituitary origin. In Exp. II, blood samples were collected from the jugular vein every 12 h during 1 week after oestrus. Follicular growth had been stimulated during the preceding oestrous cycle with PMSG (10 heifers and cows) or with FSH (5 animals); 6 heifers served as controls. There was a high correlation between the number of follicles or CL and the increase in oxytocin and immunoreactive neurophysin I. Although PMSG had a greater luteotrophic effect than did FSH on progesterone secretion, a similar stimulation of oxytocin and immunoreactive neurophysin I was not observed. It is concluded that immunoreactive neurophysin I and oxytocin are secreted from the ovary in concentrations dependent upon the number of corpora lutea (and of follicles) present. During the mid-luteal period the secretion occurs in a concomitant pulsatile fashion.
 ...
PMID:Evidence for the secretion of immunoreactive neurophysin I in addition to oxytocin from the ovary in cattle. 391 61

1. The epigastric adipose tissue of rabbits has been prepared so that the effects of close arterial injections and infusions on blood flow and release of free fatty acids (FFA) can be studied. The effects of pharmacologically active agents and hormone preparations have been investigated.2. Release of FFA was stimulated by synthetic adrenocorticotrophic hormone (ACTH), alpha and beta melanophore stimulating hormone (MSH), porcine growth hormone, glucagon, thyrotropic hormone (TSH) and luteotropic hormone (LTH). Single injections of fat-mobilizing agents produce a sustained rise in the release of FFA.3. Although pitressin caused release of FFA, synthetic vasopressin and oxytocin failed to do so. The FFA releasing activity of pitressin has therefore been attributed to a contaminant.4. Catecholamines were found not to stimulate release of FFA from this fat depot, but were found to increase plasma FFA when infused intravenously.5. Injections of acetylcholine, histamine, bradykinin, 5-hydroxytryptamine, synthetic arginine vasopressin, and lysine vasopressin, oxytocin, angiotensin and FSH did not stimulate release of FFA although marked effects on blood flow were produced.6. Injections of prostaglandin E(1) gave sustained increases in blood flow, and inhibited FFA release when stimulated by growth hormone.7. The mobilization of FFA is sometimes associated with an increased rate of blood flow.
 ...
PMID:The mobilization of free fatty acids from rabbit adipose tissue in situ. 430 78

This report concerns a review of the neuroendocrine effects of narcotic analgesics and endorphins. Acute administration of narcotic analgesics to rats increases the blood levels of ACTH, GH and prolactin, and decreases levels of LH and TSH, however, there is no general consensus regarding changes in serum FSH, ADH and oxytocin as induced by narcotics in rats. In humans, the narcotic analgesic increases in serum prolactin, decreases in serum LH and has no effect on the release of other known pituitary hormones. Endorphins mimic morphine regarding hormonal effects. Effects of naloxone on the basal levels of prolactin, LH or GH were inverse to the effects seen with narcotics and endorphins, therefore endorphins may play a role in regulating the basal levels of these hormones. Narcotics analgesics depress the increased blood levels of prolactin, gonadotropins or TSH elicited by specific measures. While chronic administration of morphine results in tolerance to the stimulant effect of ACTH, and possibly of prolactin secretion, tolerance does not develop to the stimulant effect on GH secretion. The analgesic potency of narcotic analgesics correlates with their suppressive effect on the pituitary-gonadal system and the potency with which endorphins bind to the opiate receptors correlates with their prolactin releasing activity. It is assumed that narcotic analgesics and endorphins exert their hormonal effects by altering the release of neurotransmitters in the CNS. Thus, a release of hypothalamic releasing hormones is involved rather than a direct action on the pituitary. The central neurotransmitter systems involved in the hormonal effects of narcotics are now being intensively investigated by various groups of workers.
 ...
PMID:[Narcotic analgesics and endorphins and the release of pituitary hormones (author's transl)]. 611 Jun 21

Plasma oxytocin (OT) concentrations were measured by radioimmunoassay (RIA) method without extracting plasma in 11 normal menstruating women. Mean plasma OT level began to increase steadily from the 7th day of the menstrual cycle and this level rose up to 20 +/- 5 microU/ml (Mean +/- S.E.) on the 10th day of the cycle. OT level declined to 13 +/- 6 microU/ml on the day of LH peak and continuously declined for another 2 days - then rose. The OT level was higher during the follicular phase than during the luteal phase. In 1 individual OT measured in 2 cycles a year apart showed the highest level of OT coincided with LH and FSH peak and abruptly declined. When there was the highest level of progesterone, the OT level was measurable 1 out of 11 cycles. From this study, we conclude that OT may have a role in human ovulation either synergistically or alone with other ovulatory mechanisms and ovarian estradiol and progesterone control the secretion of OT and also suggests that OT may play some role in the regulation of the luteolysis and the menstrual cycle in women.
 ...
PMID:Human ovulation and plasma oxytocin. 614 Nov

Recent work in our laboratory on the role of peptides to influence release of pituitary hormones by direct action on the gland and also some of the interactions of these peptides at the hypothalamic level to alter release of pituitary hormones will be reviewed. Considerable evidence from hypothalamic stimulation and lesion studies suggests the existence of a separate FSH-releasing factor (FSHRF). We have been able to purify a bioactive FSHRF which appears to be distinct from LHRH. Consequently, we believe that a distinct FSHRF will ultimately be isolated. With regard to prolactin, it is now clear that it is under dual control by both prolactin-inhibiting (PI) and prolactin-releasing factors (PRF). Although dopamine acts as a PIF, our recent fractionation studies indicate the existence of a peptidic PIF in hypothalamic extracts which can be separated from dopamine and GABA. The peptidic PIF is eluted from Sephadex in the same position originally described by us a number of years ago. Thus, inhibitory control is probably mediated by a combination of factors which would include dopamine, possibly GABA and a peptidic PIF. A number of peptides have been shown to have PRF activity which include TRF and also VIP. In recent studies, we have shown a prolactin-releasing action of oxytocin on male hemipituitaries or dispersed pituitary cells. Furthermore, high doses of oxytocin given intravenously released prolactin in male rats. There is a correlation between estrogen-induced prolactin release and an increase in plasma oxytocin and a correlation between suckling-induced oxytocin and prolactin release. These results suggest that oxytocin may be an important PRF.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Recent studies on the role of brain peptides in control of anterior pituitary hormone secretion. 614 38

We have used a derivative of PGE2, sulprostone, to induce abortion in the second trimester of pregnancy in 26 women. 500 micrograms of sulprostone were administered i.m. every four or six hours and clinical rating of the efficiency of the treatment was done using a scale ranging from 20 to 100. FSH, prolactin, 17-beta-estradiol, progesterone, hPL and beta-hCG plasma levels were monitored during treatment. The drug was effective in 20 cases (79.9%) while in three cases additional administration of oxytocin was necessary and in three cases no effect was seen. Treatment was interrupted, due to the appearance of unpleasant side effects, in only one case. No specific variation in hormone levels was seen. In three cases in which only two doses of the drug were sufficient to induce abortion, hormone levels dropped more rapidly and to a greater extent than in the remaining cases. A correlation exist between the rate of decrease in progesterone and 17-beta-estradiol plasma levels and the time required for the treatment to induce abortion.
 ...
PMID:The use of sulprostone to induce abortion in the second trimester. 618 29

The interaction of the ovarian steroid hormones (estrogen and progesterone) and the polypeptide hormone of posterior pituitary origin (oxytocin) appear to regulate the ovine estrous cycle by controlling production of the uterine luteolytic hormone PGF2 alpha. From our results, it appears that these steroid hormones may control PGF2 alpha release by regulating the availability of receptors for oxytocin in the endometrium, the primary site of PGF2 alpha production. Secondarily the ovarian steroid hormones may also regulate basal endogenous levels of oxytocin in the blood stream which may reinforce the luteolytic release of PGF2 alpha. Similar mechanisms may also be operative during the initiation of parturition in which steroid hormones, OT, and PGF2 alpha appear to play major roles (26). In addition to the known interdependence of steroid hormones and the gonadotropins (FSH, LH, and prolactin) required to initiate follicular growth, ovulation, and CL function, there appears to be a second interdependence required to terminate the ovarian cycle via the uterine luteolytic hormone PGF2 alpha, namely by the interaction between ovarian steroids and the posterior pituitary hormone, OT. Thus for both the initiation and termination of the ovarian cycle, there is evidence of a close interaction between the ovary and brain.
 ...
PMID:Hormone receptor control of prostaglandin F2 alpha secretion by the ovine uterus. 624 81


<< Previous 1 2 3 4 5 6 7 8 9 Next >>