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)

The milk yield and mammary blood flow responses to close-arterial, intra-mammary infusion of IGF-I were investigated in five Saanen goats milked frequently or normally the day before. Animals were infused for 6 h with recombinant human IGF-I (1.3 nmol/min) and milked hourly following i.v. injection of oxytocin beginning 2 h before infusion and then every 2 h. On one occasion animals were milked five times (after i.v. injection of oxytocin) on the day before infusion and on the other they were milked twice, without oxytocin. The ratio of milk yield from the infused to that from non-infused gland increased by 17 +/- 4% (mean +/- S.E.M.) in goats milked twice the day before infusion and by 6 +/- 2% when the infusion was preceded by frequent milking. Maximal responses were obtained 4 h after the start of the infusion and differed significantly (P < 0.05), according to pretreatment milking. Blood flow through the infused gland rose in parallel to the milk yield response. At 5 h, when maximal levels were achieved, blood flow was 182 +/- 23% of the pre-infusion flow rate following twice-daily milking and 139 +/- 3% of the pre-infusion flow rate following more frequent milk removal. Thus, more frequent milk removal on the day before close-arterial infusion of IGF-I attenuated both the milk yield and mammary blood-flow response to the infusion of IGF-I.
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PMID:Milking frequency alters the milk yield and mammary blood flow response to intra-mammary infusion of insulin-like growth factor-I in the goat. 147 38

Granulosa cells derived from preovulatory bovine follicles were cultured in the presence of insulin-like growth factor-I (IGF-I, 10-100 ng/ml), forskolin (10 microM), or a combination of the two agents. Forskolin alone was the most potent stimulator of both oxytocin (OT) and progesterone (P4) secretion. The two hormones had different patterns of secretion during the course of incubation. OT production peaked on Day 5 of culture and declined thereafter, whereas P4 rose gradually to a peak between Days 7 and 9. The addition of IGF-I to forskolin did not augment OT release beyond that achieved with forskolin alone, but it did maintain higher levels of OT secretion beyond the Day-5 peak. Two antisera, (antiserum I and antiserum II) directed against OT and its C-terminally extended forms, respectively, were used to identify the OT forms in culture media and granulosa cell and corpus luteum extracts. Fully processed OT was detected only in small amounts (0.43 ng/mg protein) in granulosa cell extracts, whereas the corpus luteum extracts contained 6 ng/mg protein. However, granulosa cells that had been incubated with forskolin contained stores of the OT precursor oxytocin-neurophysin, which is found in young corpora lutea. These data indicate that forskolin (whose action probably mimics gonadotropin action) is an effective stimulator of OT biosynthesis and release in cultured bovine granulosa cells.
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PMID:Biosynthesis and release of oxytocin by granulosa cells derived from preovulatory bovine follicles: effects of forskolin and insulin-like growth factor-I. 157 71

The expression of IGF-I in bovine luteal tissue was demonstrated by parallel measurement of IGF-I tissue concentration and its mRNA; highest synthesis was observed during Days 12-17 of the cycle and the first months of pregnancy. Tissue levels of IGF-I increased from Days 1-5 to Days 12-17 of the cycle followed by a rapid decrease at luteolysis; there was a continuous decline from early pregnancy until Months 6-9. Microdialysis perfusion experiments with corpora lutea in vitro at Days 8-11 of the cycle revealed a major effect: release of progesterone and oxytocin were highly stimulated in a dose-dependent manner. We suggest that IGF-I could be important in regulating the function of the bovine corpus luteum and may act in an autocrine/paracrine way.
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PMID:Tissue concentration, mRNA expression and stimulation of IGF-I in luteal tissue during the oestrous cycle and pregnancy of cows. 225 Feb 43

Oxytocin is synthesized in the granulosa-derived large cells of the ruminant corpus luteum from a gene which is dramatically up-regulated in the first few days after ovulation. In this work, the regulation of granulosa and luteal cells by prostaglandins and insulin (or insulin-like growth factor-I; IGF-I) has been explored by comparing their effects on oxytocin and progesterone production in cell culture. In granulosa cells, chronic exposure to insulin (17 nmol/l) stimulated luteinization as indicated by increased release of oxytocin and progesterone. Prostaglandin F2 alpha (PGF2 alpha) alone had little effect, but synergized with insulin (or IGF-I) to increase the release of both these hormones. In direct contrast, insulin-stimulated oxytocin production by luteal cells was inhibited by PGF2 alpha. The half-maximal dose (EC50) for PGF2 alpha action in both cell preparations was similar (10-100 nmol/l). Dose-response studies revealed that PGF2 alpha increased the potency of insulin in granulosa cells (EC50 for insulin-stimulation of oxytocin release reduced from 141 to 13 nmol/l by 1 mumol PGF2 alpha/l), but not in luteal cells. Insulin-stimulated oxytocin release from granulosa cells was also synergistically increased by PGE1, PGE2 and forskolin, suggesting this effect to be mediated by adenylate cyclase-coupled PGE receptors. The results reveal that the effects of prostaglandins on oxytocin release are dependent on both the developmental stage of the target tissue and on the presence of other regulators of cellular differentiation. Moreover, they suggest that the increase in responsiveness to insulin and IGF-I, which appears to accompany luteinization in the cow, may be an effect of prostaglandins produced locally during the peri-ovulatory period.
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PMID:Chronic regulation of ovarian oxytocin and progesterone release by prostaglandins: opposite effects in bovine granulosa and early luteal cells. 240 66

The effects of streptozotocin-induced diabetes on weight gain, bone growth and GH secretion have been studied in conscious chronically cannulated male rats. In addition to the classic diabetic symptoms (hyperphagia, polydipsia, polyuria, glycosuria and hyperglycaemia), the slow body weight gain (0.95 +/- 0.5 compared with 2.63 +/- 0.5 g/day in non-diabetic controls) was associated with a reduction in bone growth (from 162 +/- 9 to 48 +/- 4 microns/day) and a reduced pituitary GH content (from 1.5 +/- 0.2 to 0.6 +/- 0.06 mg/gland). Serial blood sampling during the day or overnight showed that the normal male episodic GH secretory pattern was obliterated in the diabetic animals. The constant osmotic stimulation of hyperglycaemia and high fluid turnover was reflected in a significant reduction in pituitary oxytocin and arginine vasopressin (AVP) stores. Intravenous insulin infusions (67-1340 pmol/h for 4 or 7 days) caused a large initial weight gain (greater than 20 g in 2 days) followed by a slower increase, and stimulated tibial bone growth (to 100 +/- 16 and 126 +/- 8 microns/day after 4 or 7 days respectively). Insulin infusion for 7 days also increased pituitary GH content (to 1 +/- 0.15 mg/gland), and the normal episodic GH secretory pattern returned. Intravenous infusions of insulin which reduced, but did not completely normalize, blood glucose levels, allowed the resumption of growth and pulsatile GH secretion. Continuous infusion of recombinant human insulin-like growth factor-I (hIGF-I) at 1110 pmol/h for 54 h also caused a large initial rise in body weight in diabetic rats (17.1 +/- 1.6 compared with 7.5 +/- 2.8 g in saline-infused controls) due primarily to increased fluid retention. This effect of hIGF-I occurred without any significant changes in pituitary GH, AVP, oxytocin, blood glucose or bone growth over this short-term infusion, nor was there any obvious effect on spontaneous GH secretion, monitored over the entire infusion period. We conclude that the diabetic rat is not a good model to study growth stimulation by short-term insulin or IGF-I treatments because the insulin-like effects of these peptides obscure their specific growth-promoting activities in this model.
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PMID:Growth hormone and growth in diabetic rats: effects of insulin and insulin-like growth factor-I infusions. 268

Groups of 9 or 10 cows were assigned to one of three treatments 1) machine-milking three times daily, 2) machine-milking six times daily, and 3) suckling three times daily in addition to machine- milking three times daily. Treatments were conducted during the first 6 wk postpartum; thereafter, all cows were milked three times daily. During treatment, milk production was highest for suckled cows and lowest for cows milked three times daily. The DMI were similar for suckled cows and cows milked three times daily but higher for those milked six times daily. Body weight loss was greatest for suckled cows and least for cows milked three times daily. During wk 7 to 18 postpartum, cows milked six times daily exhibited a carry-over effect on milk production that was greater than that of other groups, During treatment, plasma growth hormone and IGF-I concentrations were elevated for suckled cows and, to a lesser extent, for cows milked six times daily. Prolactin and oxytocin similarly increased, but insulin decreased in suckled cows and, to a lesser extent, in cows milked six times daily. Posttreatment differences persisted for insulin and IGF-I, but not for the other hormones. Increased frequency of udder emptying increased milk production, and suckling was superior to machine-milking. High milk production was associated with elevated growth hormone, IGF-I, prolactin, and oxytocin, although cause and effect could not be established. The failure of suckled cows to increase feed intake to match output requires further investigation.
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PMID:Relationship between frequent milking or suckling in early lactation and milk production of high producing dairy cows. 867 55

The bovine oxytocin gene is massively up-regulated during the early development of the corpus luteum. Oxytocin transcription is induced in a highly synchronous fashion in the granulosa cells of the dominant follicle at the time of ovulation. The possibility to isolate large numbers of differentiating granulosa-luteal cells from exactly defined stages of development allows the investigation of the factors controlling oxytocin expression in vivo by molecular and cell biology methods. Using primary cultures of bovine granulosa cells the synergistic activation of oxytocin transcription by the cAMP pathway and stimulation of IGF-I or insulin receptors could be established. Analysis of transcription factors isolated from the nuclei of bovine granulosa cells and corpus luteum led to the identification of the tissue-specific orphan receptor SF-1 binding to the promoter of the actively transcribed oxytocin gene. The luteinizing bovine granulosa cells provide the only easily accessible experimental system established so far in which the endogenous oxytocin gene is expressed. Although the link between increased cAMP level and receptor tyrosine kinase activation on the one hand and the induction of oxytocin transcription on the other has not been established yet, these experiments constitute one of the few direct approaches to investigate the complexity of events that regulate oxytocin expression in vivo.
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PMID:Regulation of oxytocin expression in the bovine corpus luteum. Orphan receptors and the oxytocin promoter. 871 54

Peritubular myoid cells, surrounding the seminiferous tubules in the testis, have been found in all mammalian species, but their organization in the peritubular interstitial tissue varies by species. In laboratory rodents, including rats, hamsters and mice, only one layer of myoid cells is seen in the testis. The cells in these animals are joined by junctional complexes as are epithelial cells. On the other hand, several cellular layers exist in the lamina propria of the seminiferous tubule in the human and some other animals. Myoid cells contain abundant actin filaments which are distributed in the cells in a species-specific manner. In the rat, the filaments within one myoid cell run both longitudinally and circularly to the long axis of the seminiferous tubule, exhibiting a lattice-work pattern. The arrangement of the actin filaments in the cells changes during postnatal development, and the disruption of spermatogenesis, such as cryptorchidism, seems to affect further the arrangement of the filaments. Other cytoskeletal proteins, including myosin, desmin/vimentin and alpha-actinin, are also found in the cells. Myoid cells have been shown to be contractile, involved in the transport of spermatozoa and testicular fluid in the tubule. Several substances (prostaglandins, oxytocin, TGF beta, NO/cGMP) have been suggested to affect the contraction of the cell, though the mechanisms of the contraction are still unknown. Recent in vitro studies have demonstrated that the cells secrete a number of substances including extracellular matrix components (fibronectin, type I and IV collagens, proteoglycans) and growth factors (PModS, TGF beta, IGF-I, activin-A). Some of these substances are known to affect the Sertoli cell function. Furthermore, it has been reported that myoid cells contain androgen receptors and are involved in retinol processing. Considering all this, it is evident that peritubular myoid cells not only provide structural integrity to the tubule but also take part in the regulation of spermatogenesis and the testicular function. Their precise roles, however, remain to be solved.
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PMID:Peritubular myoid cells in the testis: their structure and function. 872 59

The aim of our in vitro experiments with isolated porcine ovarian follicles was to study the effects of gonadotropins, GH, IGF-I and oxytocin (OT) on release of ovarian steroid, OT, IGF-I, insulin-like growth factor-binding protein-3 (IGFBP-3), prostaglandin F (PGF), prostaglandin E (PGE) and cAMP. It was found that quarters of ovarian follicles cultured for 8 days produced significant amounts of progesterone, estradiol-17 beta, OT and IGFBP-3 with peaks of accumulation from the 3rd to the 8th day of culture. Addition of serum promoted progesterone, estradiol and OT release, whilst accumulation of IGFBP-3 was maintained to a greater extent in serum-free medium. GH (10 ng/ml or above) was able to inhibit androstenedione, OT, PGF and IGFBP-3, to stimulate IGF-I and cAMP, and to alter testosterone and PGE release by follicles cultured in serum-supplemented and/or serum-free medium. IGF-I (10 ng/ml or more) inhibited androstenedione and PGF secretion, stimulated testosterone, estradiol, OT and cAMP production, but did not influence progesterone, IGFBP-3 or PGE output in these conditions. OT (100 ng/ml) was able to inhibit androstenedione and to stimulate testosterone, IGF-I, PGF and PGE, but not estradiol or IGFBP-3 release. A stimulatory effect of LH on progesterone and OT and an inhibitory influence of LH on estradiol secretion in the serum-supplemented medium were observed. FSH in these conditions stimulated OT, but not progesterone or estradiol secretion. The use of this experimental model suggests the involvement of gonadotropins, OT, GH and IGF-I in the control of ovarian steroid and nonapeptide hormone, growth factor, growth factor-binding protein, prostaglandin and cyclic nucleotide production. The stimulatory effect of GH on IGF-I, and the stimulatory influence of IGF-I on OT, as well as coincidence of the majority of effects of IGF-I and OT, suggest the existence of a GH-IGF-I-OT axis. On the other hand, the different patterns of action of GH and IGF-I on OT, estrogen and IGFBP-3 suggest that part of the GH effect on ovarian cells is IGF-I independent.
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PMID:Isolated porcine ovarian follicles as a model for the study of hormone and growth factor action on ovarian secretory activity. 979 73

Transcriptional regulation of the oxytocin and oxytocin receptor genes underly to a large degree the highly specific and often transient physiologies associated with this peptide hormone system. Using a variety of homologous transcription assays we have endeavoured to identify and characterize the cis and trans elements responsible for the regulation in vivo of the oxytocin peptide gene and the gene for the oxytocin receptor. The bovine ovarian granulosa cell model is a primary culture system where under stimulation by insulin or IGF-I and LH the endogenous oxytocin gene is massively upregulated. We have identified a proximal response element at -160, which in vivo binds the competing nuclear receptors, SF1 and COUP-TF. Additionally ovarian specific transcription factors bind at two additional sites in the distal promoter region. For the bovine oxytocin receptor gene, we have taken advantage of the high endogenous expression of the receptor in the endometrium of the estrous cycle. Using a combination of primary cell culture techniques and in vitro binding of nuclear protein extracts from tissues expressing the receptor in vivo, we have shown there to be a combination of constitutive and inhibitory elements controlling oxytocin receptor gene expression. Similar results were obtained for the human oxytocin receptor gene. At birth there may additionally be a specific stimulatory effect on transcription in the myometrium.
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PMID:The molecular basis of oxytocin and oxytocin receptor gene expression in reproductive tissues. 1002 17


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