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)

The demise of the corpus luteum is brought about by an interaction between ovarian oxytocin and uterine prostaglandin F2 alpha (PGF2 alpha) release in sheep. Indirect evidence suggests that a similar, but intra-ovarian, mechanism may also be involved in luteal regression in primates. During early pregnancy, a specific class of interferon (omega interferon) is released from the developing embryo in sheep and this interferon inhibits pulsatile release of uterine PGF2 alpha. Studies in ovariectomized, steroid-treated ewes indicate that conceptus secretory proteins inhibit pulsatile secretion of PGF2 alpha directly via an effect on prostaglandin synthesis and indirectly by maintaining plasma progesterone concentrations that inhibit the development of endometrial oxytocin receptors which normally occurs at the time of luteolysis. As pregnancy progresses, there is an increase in basal secretion of PGF2 alpha and PGE2 from the uterus into the fetal and maternal circulation. The release of maternal PGF2 alpha, but not PGE2, in response to oxytocin is also increased in late pregnancy. Endometrial oxytocin receptor concentrations follow a similar pattern, except at parturition where there appears to be downregulation of receptors. However, the release of PGF2 alpha in response to oxytocin remains high at this time and is further increased if the progesterone receptors are blocked with the anti-progestin RU486. The dissociation between oxytocin receptor numbers and release of prostaglandins in response to oxytocin is also observed under other physiological situations, such as during seasonal anoestrus and after long-term ovariectomy, and requires further investigation. The role of oxytocin in the initiation of labour remains controversial. Although oxytocin concentrations in maternal and fetal plasma are not increased until parturition, uterine oxytocin receptor concentrations, uterine activity and maternal PGF2 alpha release in response to oxytocin are high in late pregnancy. Uterine activity and PG release is not altered by oxytocin in the fetal circulation at any stage of late gestation. We have used the oxytocin analogue CAP to investigate further the possible role of oxytocin in the initiation of labour. CAP can inhibit oxytocin-induced PGF2 alpha release in cyclic sheep, at luteolysis, and in late pregnant sheep by binding to, and blocking, uterine oxytocin receptors. CAP does not inhibit basal fetal or maternal PGF2 alpha or PGE2 concentrations in late pregnancy or at parturition. CAP inhibits oxytocin-induced uterine activity and delays, but does not prevent, the increase in uterine activity associated with labour in this species.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Oxytocin and prostaglandin interactions in pregnancy and at parturition. 130 35

Association of protein kinase C (PKC) activity to the membrane fraction was observed in oxytocin treated human amnion cells (UAC). In addition, oxytocin was shown to induce an antiviral state and to inhibit multiplication of vesicular stomatitis virus (VSV) in UAC. These observations together with earlier findings indicate that activation of inositol phospholipid breakdown with a consecutive activation of PKC is a common signal transduction pathway in interferon action and hormonal stimulation.
 ...
PMID:Oxytocin stimulates translocation of protein kinase C and induces antiviral state in human amnion cells. 132 45

The endometrial oxytocin receptor occupies a central point in the choice between luteolysis and pregnancy in ruminants. Receptor expression determines the time at which luteolysis occurs in nonpregnant animals, and thereby determines the duration of the oestrous cycle. Inhibition of receptor expression by trophoblast interferon (IFN) blocks the process of luteal regression and leads to continued progesterone secretion and the successful growth of the conceptus. Trophoblast IFN is probably required from the time of normal luteolysis during the cycle until luteal oxytocin concentrations of pregnancy decline, thus removing the stimulatory mechanism for the release of the episodes of prostaglandin F2 alpha required for luteolysis.
 ...
PMID:Role of the oxytocin receptor in the choice between cyclicity and gestation in ruminants. 133 56

A type I interferon (IFN) secreted by the trophoblast of early sheep and cow embryos is thought to be responsible for the maternal recognition of pregnancy. The expression of trophoblast IFN is tissue specific and temporally controlled. However, the isolated bovine trophoblast IFN promoter did not confer tissue specificity on the expression of a bacterial chloramphenicol acetyl transferase (CAT) reporter gene, and could not be induced by virus, unlike other type I IFNs. Trophoblast IFN acts locally within the uterus to prevent luteolysis and prolong progesterone secretion. Endometrial IFN receptors are present, and trophoblast IFN decreases expression of endometrial oxytocin receptor and increases expression of endometrial beta 2-microglobulin, MHC class I antigens and Mx (a mediator of IFN antiviral activity) only in the pregnant horn of pregnant ewes with a transected uterus. The primary effect of trophoblast IFN during early pregnancy appears to be an inhibition of oxytocin receptor expression, although studies in ovariectomized ewes suggest that luteal oxytocin may be required to facilitate the inhibition of prostaglandin F secretion by trophoblast IFN. An investigation of the isolated oxytocin receptor promoter should confirm its critical role in the maternal recognition of pregnancy.
 ...
PMID:Trophoblast interferons in early pregnancy of domestic ruminants. 133 57

The ruminant conceptus secretes proteins during early pregnancy which maintain the corpus luteum. These trophoblast proteins are related to the alpha II-interferons and prevent luteolysis indirectly by disrupting the secretion of endometrial prostaglandin. Although trophoblast interferons appear to be largely confined to the uterine lumen, it remains possible that they also act peripherally. This report describes in vitro studies which suggest that interferon may influence hormone secretion by the ovary directly. The study employed i) a well defined serum-free culture model in which bovine granulosa cells secrete the luteal hormones progesterone and oxytocin, and ii) serum-free and serum-supplemented cultures of cells from early CL. Dose-response experiments were performed using bovine recombinant alpha-interferon (brIFN). Progesterone and oxytocin secretions were measured over 4-5 days of culture and DNA content was also determined. Low concentrations of brIFN (10(-15) mol/l to 10(-11) mol/l) stimulated progesterone secretion by granulosa cells by up to three fold, without significantly affecting oxytocin concentrations or culture DNA content. Concentrations of 10(-10) mol/l to 10(-1) mol/l suppressed progesterone secretion in a log dose-related manner (r = 0.97) with evidence of toxicity (lower oxytocin concentrations and significantly reduced DNA compared with controls). Progesterone secretion by luteal cells in serum-free culture was stimulated in the presence of 10(-15) mol/l brIFN, whilst high concentrations again caused inhibition. The data show that ovarian cells can respond directly to low concentrations of interferon-like proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Direct stimulation of bovine ovarian progesterone secretion by low concentrations of alpha-interferon. 147 25

The neurohypophyseal hormones arginine vasopressin (AVP) and oxytocin are capable of replacing the interleukin 2 (IL 2) requirement for T cell mitogen induction of gamma-interferon (IFN-gamma) in mouse spleen cell cultures. The structural basis for the helper signal by these hormones resides in the six N-terminal amino acids of AVP based on the relative ability of AVP, oxytocin, vasotocin, and pressinoic acid (AVP six N-terminal amino acid peptide) to help in IFN-gamma induction. AVP and pressinoic acid provide maximal help at 10(-10) M, while oxytocin and vasotocin with isoleucine at position three in place of phenylalanine are 10-fold less effective. An AVP competitive antagonist of vasopressor activity blocks the AVP helper signal for production of IFN-gamma, while having no effect on IL 2 help. This suggests that the AVP helper signal operates via binding to an AVP vasopressor-type receptor on lymphocytes.
 ...
PMID:Regulation of lymphokine production by arginine vasopressin and oxytocin: modulation of lymphocyte function by neurohypophyseal hormones. 392 16

The neuroendocrine antidiuretic hormone arginine vasopressin (AVP) was capable of replacing the interleukin 2 (IL 2) requirement for gamma-interferon (IFN gamma) production by Lyt-2+ cells from C57BL/6 mouse spleen cells. The AVP replacement did not stimulate DNA synthesis in the target lymphocytes. This suggested that AVP was capable of replacing an IL 2 function that did not involve stimulation of cellular proliferation or DNA synthesis. This was confirmed by the demonstration that mitomycin C inhibition of IFN gamma production was reversed by IL 2 or AVP without concomitant reversal of blockage of DNA synthesis. Oxytocin, which is structurally related to AVP, was also capable of replacing IL 2 requirement for IFN gamma production, whereas insulin was ineffective. The data show that the neuroendocrine hormones AVP and oxytocin are capable of lymphokine-like activity. This activity may involve the induction of a second messenger such as cyclic GMP.
 ...
PMID:Vasopressin replacement of interleukin 2 requirement in gamma interferon production: lymphokine activity of a neuroendocrine hormone. 618 8

Sixteen peptides were injected intracerebroventricularly to test their effects on rectal temperature of rabbits in a thermoneutral environment. In initial tests 5 micrograms alpha-MSH, ACTH(1--24), oxytocin, vasopressin and glucagon altered body temperature while ACTH(1--10), cholecystokinin, contraceptive tetrapeptide, gastrin, insulin, interferon, leupeptin, LHRH, panhibin (somatostatin), and proctolin did not. Bombesin also altered body temperature but in no consistent direction. In further tests on the effective peptides 1.25--5.0 micrograms alpha-MSH and ACTH(1--24) produced dose-related decreases in rectal temperature as great as 1.0 degrees C. The same doses of oxytocin and glucagon produced small, prolonged hyperthermias which did not exceed 0.4 degrees C. Vasopressin caused rapid development of small increases in rectal temperature; temperature returned to normal in 2--3 hr. The results suggest that five of the peptides tested may have roles in central mediation of normal body temperature, hypothermia, hyperthermia and fever.
 ...
PMID:Central administration of peptides alters thermoregulation in the rabbit. 724 7

Oestradiol acting on a progesterone-primed uterus stimulates prostaglandin (PG) F2 alpha synthesis by the endometrium. In some species (notably the sheep, cow and goat) oxytocin released from the ovary also forms part of the physiological stimulus for increased endometrial PGF2 alpha production. The corpus luteum contains high concentrations (> 1 microgram/g tissue) of this peptide in these species. The intracellular mechanisms by which these three hormones control endometrial PGF2 alpha synthesis and release are far from clear. Oxytocin stimulates the synthesis of inositol phosphates and diacylglycerol in the endometrium of some species, but whether this pathway is involved in endometrial PGF2 alpha synthesis is still open to question. There is evidence that increased endometrial PGF2 alpha synthesis is dependent upon increased endometrial protein synthesis but, apart from the recorded effects of steroid hormones on the concentrations of phospholipase A2, prostaglandin H synthase and oxytocin receptors, it is not known what other endometrial proteins are involved. Some disorders of menstruation are associated with abnormal PG production by the endometrium, but the reasons for this abnormality are not clear. During early pregnancy an increase in PGF2 alpha synthesis by the endometrium is prevented, except in the pig where the PGF2 alpha produced is directed from the venous drainage to the uterine lumen. In those species in which endometrial PGF2 alpha synthesis is dependent upon oxytocin secreted by the ovary, the conceptus secretes an interferon-tau (previously named trophoblast protein-1) which prevents oestradiol and oxytocin acting on a progesterone-primed uterus from stimulating endometrial PGF2 alpha synthesis. The identities of the factors produced by the conceptus which prevent endometrial PGF2 alpha synthesis during early pregnancy in other species are not known, although it is clear that they are not interferons.
 ...
PMID:The control of prostaglandin production by the endometrium in relation to luteolysis and menstruation. 748 81

Luteolysis in sheep is associated with uterine secretion of pulses of prostaglandin F2 alpha (PGF2 alpha) due to the action of luteal oxytocin on endometrial oxytocin receptors. For pregnancy to become established inhibition of oxytocin receptors is important as an antiluteolytic mechanism. The maternal recognition of pregnancy in cattle and sheep involves production, by the trophoblast, of a type 1 interferon (IFN-tau) that suppresses uterine development of oxytocin receptors and the generation of luteolytic episodes of PGF2 alpha. The action of IFN-tau in surgically prepared unilaterally pregnant ewes was investigated. Finn-Dorset ewes were anaesthetized on day 6 or 7 of the oestrous cycle and one uterine horn was surgically isolated at the uterine bifurcation from the body of the uterus. Ewes were mated at the subsequent oestrus either by a fertile or by a vasectomized ram and killed on day 13 or 16 after mating. On day 16, in the non-pregnant ewes, there was no measurable uterine IFN-tau but there were high concentrations of oxytocin receptors in both horns. In the pregnant ewes on day 16 after mating, the oxytocin receptor concentration was 45 +/- 11 fmol mg-1 protein in the pregnant horn and 585 +/- 131 fmol mg-1 in the non-pregnant horn. Antiviral activity was 5.8 x 10(7) +/- 5.2 x 10(7) U ml-1 in the pregnant horn and 2.9 x 10(3) +/- 1.2 x 10(3) U ml-1 in the non-pregnant horn. Thus, 16 days after mating, the pregnant horn exhibited high antiviral activity but oxytocin receptors were suppressed, while in the same endocrine environment (characteristic of pregnancy) there were low IFN-tau and high oxytocin receptor concentrations in the isolated horn equivalent to those expected at the onset of luteolysis. In situ hybridization to ovine mRNA encoding the oxytocin receptor and autoradiographic studies using the 125I-labelled oxytocin antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH2(9)]-vasotocin both showed that the large amount of oxytocin receptor message and binding sites in the endometrium of the isolated horn were localized in the luminal epithelium. Immunocytochemical studies showed that there was a suppression of oestradiol receptors in the pregnant horn but high concentrations equivalent to those at oestrus were present in the isolated horn. The content of progesterone receptors was low in the stromal tissue only in both horns, a pattern of localization similar to that seen in the late luteal phase and in early pregnancy.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Local action of trophoblast interferons in suppression of the development of oxytocin and oestradiol receptors in ovine endometrium. 749 Jul 9


1 2 3 4 5 6 7 8 Next >>