What is the function of oxytocin in males

That were regressing whereas the remaining 3 heifers were not yet undergoing luteolysis. Therefore, data for these 6 heifers were reanalyzed separately with CL status replacing day as a main effect. Data for only those heifers with functional CL on Days 13, 16, and 19 were then reanalyzed. All tests of hypotheses were made using the appropriate error terms according to expectation of the mean squares [32]. Planned comparisons were made using contrast statements of the GLM procedure. Least-squares means were obtained using the Least Squares Means statement of the GLM procedure, and the appropriate standard errors were generated from the ANOVA. RESULTS Decreases in mean CL weight p 0.05 ; and mean concentrations of plasma progesterone p 0.01 ; were detected in heifers slaughtered on Day 19 post-estrus Table 2 ; , indicating that CL regression had been initiated in the group of Day 19 heifers. Mean concentration of plasma estradiol did not differ significantly p 0.5 ; among days of the estrous cycle Table 2 ; . Mean concentration of endometrial oxytocin receptors increased p 0.06 ; during Days 13-19, and the greatest increase p 0.05 ; occurred between Days 16 and 19 Table 2 ; . Mean Kd of oxytocin receptors was not significantly affected by day of the estrous cycle Table 2 ; . Endometrial PI hydrolysis was influenced by interaction of day and oxytocin treatment Fig. 2 ; such that oxytocin-induced incorporation of [3 H]inositol into inositol phosphates increased p 0.01 ; between Days 13 and 19 Fig. 2 ; . The greatest increase p 0.001 ; in oxytocin-stimulated PI hydrolysis was detected between Days 16 and 19. Across both treatments, endometrial PI hydrolysis increased p 0.05 ; during the estrous cycle and, across all days, was increased p 0.001 ; by treatment with oxytocin. Endometrial PGF secretion was influenced by interaction of day and oxytocin treatment Fig. 3 ; such that.

12 excessive use of oxytocin may cause water retention, hyponatremia and seizures water intoxication. JONES, C. W. & PICKERING, B. T. 1969 ; . Changes in the hormone content of the rat neurohypophysis induced by substituting 2 % saline for drinking water. J. Endocr. 43, vi. KASTIN, J. A. 1967 ; . M.S.H. and vasopressin activities in pituitaries of rats treated with hypertonic saline. Fedn Proc. 26, 225. LEDERIS, K. 1962 ; . The distribution of vasopressin and oxytocin in hypothalamic nuclei. Mem. Soc. Endocr. 12, 227-236. MOSES, A. M. 1963 ; . Adrenal neurohypophysial relationships in the dehydrated rat. Oxytocin is for injection into a muscle or infusion into a vein. Spectrum DDD receptor agonist 2- N-phenylethyl-Npropyl ; amino-5-hydroxytetralin PPHT ; was effective, but the DD receptor agonist SKF38393 was not. The response to PPHT was blocked by the broad-spectrum dopamine receptor antagonist eticlopride. Moreover, the finding that RBI257, a recently developed D receptor-specific antagonist, blocked responses to PPHT appeared to support the hypothesis that inhibition of IK resulted from the activation of a D receptor Wilke et al. 1998 ; . However, another compound U101958, also developed as a D receptor antagonist TenBrink et al. 1996 ; , was found to show agonist activity. Furthermore, the dopamine receptor agonist quinpirole at 100 ; had no effect Wilke et al. 1998 ; . The pharmacological profile of the receptor mediating these responses is not consistent with results from cell lines transfected with the human D receptor cDNA Chabert et al. 1994; Liu et al. 1996; Watt & Neve, 1998 ; . These observations raised questions about the identity of the receptor, and led to the consideration of factors that could complicate the interpretation of experiments with dopamine receptor ligands. One important problem is that many of the pharmacological probes used to investigate dopamine receptor function also bind to sigma receptors. Although the sigma receptor was initially classified as a novel opioid receptor Martin et al. 1976 ; , subsequent studies demonstrated that the sigma binding site represents a distinct pharmacological entity Su, 1982 ; . Sigma receptor ligands comprise a diverse group of chemically unrelated compounds Su, 1993 ; , including ditolylguanidine DTG ; , pentazocine, and N-allylnormetazocine SKF10047; the drug for which this receptor was initially named ; . One of the most widely used sigma receptor ligands, haloperidol, is also well known as a dopamine receptor antagonist. Other drugs known to bind to both sigma and dopamine receptors include apomorphine, chlorpromazine, and PPHT. The rat pituitary expresses sigma receptor binding sites Wolfe et al. 1989 ; , thus making plausible the hypothesis that the inhibition of neurohypophysial K current is mediated by sigma receptors. We pursued these issues first by conducting experiments to rule out the involvement of dopamine receptors. Drug actions were tested in genetically altered mice which lack D, D, or D receptors. The results of these experiments are presented here, and show that wild-type mice and mice lacking dopamine receptors responded similarly to putative dopamine receptor agonists. With dopamine receptors thus ruled out, a series of experiments were conducted to test the role of sigma receptors. The actions of a large number of ligands were tested and found to inhibit neurohypophysial IK. The pharmacological signature of this response was consistent with known sigma receptor selectivity. These experiments support the conclusion that rat and mouse neurohypophyses contain sigma receptors coupled to K channels, implying that sigma receptor activation can modulate the release of oxytocin and vasopressin.

CARDIAC RHABDOMYOMA; RARE CAUSE OF FETAL DEATH TaI Geva; Francesco Santini; Warren Pear; Shirley G. Driscoll; Richard Van Praagh, Boston PULMONARY COMPLICATIONS OF COMBINAlION THERAPY WITH CYCLOPHOSPHAMIDE AND PREDNISONE Ronald P. San; Thomas E. Walsh; Westby Fisher.
Does not cause notable changes in hypothalamic LHRH secretion during proestrus 28 ; . Microinfusion of IL-1 bilaterally into the MPOA also reduces hypothalamic LHRH release and prevents the spontaneous expression of Fos within LHRH cell nuclei during the afternoon of proestrus 27 ; . However, the physiological relevance of these results remains largely unknown. In fact, LHRH neurons do not seem to express any of the CRF and IL-1 type 1 and 2 receptors Nappi, R. E., and S. Rivest, unpublished data ; . Moreover, the MPOA displays a very low to barely detectable signal for both CRF receptor transcripts in intact cycling and stressed female rats 61 ; . Similarly, the gene encoding type I IL-1 receptor has been shown to be expressed in few discrete cell groups, and no specific labeling for type 1 IL-1R mRNA was detected over neurons of the MPOA 62 ; . Systemic LPS administration induces a profound downregulation of LHRH-R mRNA expression in the anterior pituitary regardless of the phase of the estrous cycle. This suggests that activation of the acute-phase response is also able to interfere with the HPG axis at the pituitary level independently of the circulating gonadal steroid concentrations. Interestingly, systemic administration of IL-1 does not affect LH secretion 63 ; , whereas peripheral administration of endotoxin strongly decreases circulating LH levels 31, 59 ; . It is, therefore, likely that a complex cascade of cytokines produced during the acute-phase response is required to decrease the activity of the HPG axis. Concomitant actions of several circulating factors probably operate at the level LHRH neuronal activity and or the pituitary gland as paracrine activity ; to mediate the inhibition of reproductive function in response to immune challenge. The effect of food deprivation on LHRH-R gene expression in the anterior pituitary was more variable and occurred at specific periods of the estrous cycle. We cannot exclude the possibility that sex steroids play a role in the ability of metabolic challenges to alter the expression of LHRH-R in the adenohypophysis, although the pattern of inhibition does not follow the marked hormonal changes generally observed during the cycle. It is of interest to note that in cycling female rats that did not have a regular estrous cycle during food deprivation, a significant down-regulation of pituitary LHRH-R mRNA was found in all animals and palonosetron.