Thesis (M.A.)--Trinity International University, 2000. / Abstract. Includes bibliographical references (leaves 67-72).

These studies were undertaken to characterize the adenylate cyclase system of the primate (rhesus monkey) corpus luteum, and to correlate gonadotropin-sensitive adenylate cyclase activity with the functional activity of the corpus luteum at specific stages of the luteal phase of the menstrual cycle, particularly near the time of luteolysis. The conversion of [α-³²P] ATP to [³²P] cAMP was assayed in preparations of luteal tissue obtained from rhesus monkeys at midluteal phase of the menstrual cycle. Cyclic AMP production was influenced by the pH, osmolality, and ionic strength of the assay buffer, and was acutely sensitive to Mg⁺². Michaelis-Menten kinetics were seen when the ATP:Mg ratio was constant. The gonadotropins, hLH and hCG but not hFSH, stimulated cAMP production in a similar dose-dependent manner. Deglycosylated hCG blocked the stimulation of adenylate cyclase by hLH and hCG. The addition of GTP increased maximal activation of adenylate cyclase by hLH or hCG but did not alter sensitivity to the hormones. The adenylate cyclase of macaque luteal tissue did not respond to the addition of isoproterenol or epinephrine; furthermore, these catecholamines did not affect hCG-stimulation of adenylate cyclase. Forskolin and fluoride stimulated cAMP production in a dose-dependent manner. The activity of adenylate cyclase was examined in corpora lutea obtained from rhesus monkeys at specific stages in the luteal phase of the menstrual cycle (days 3-5, 6-8, 9-12, 13-15, 16-menses after the midcycle LH surge). Basal adenylate cyclase activity, activity stimulated by GMP-P(NH)P, GTP, GTP + hLH, and GTP + hCG, sensitivity of the enzyme to hLH (measured by K(act)), and peripheral progesterone levels were low in the early luteal phase (days 3-5), increased by midluteal phase (days 6-8 and 9-12), and then decreased by the late luteal phase days 13-15 and 16-menses). In contrast, there were no significant differences among the age groups tested for forskolin-stimulated activity. Thus the adenylate cyclase system of the rhesus monkey undergoes significant changes during the luteal phase which are associated with the development and regression of the corpus luteum of the menstrual cycle. Mechanisms which modulate gonadotropin and nucleotide activation of adenylate cyclase without interfering directly with the catalytic unit are implicated in the changes which accompany luteolysis.

Prostaglandin G/H synthase-2 (PGHS-2) is a key rate limiting enzyme in the prostaglandin (PG) biosynthetic pathway, and PG synthesis is required for ovulation in pigs. The objective of this study was to characterize the expression and regulation of PGHS-2 in porcine follicles prior to ovulation. The combination of equine chorionic gonadotropin (eCG; 750 IU) followed by human chorionic gonadotropin (hCG; 500 IU) 72 h later was used to induce ovulation in prepubertal gilts. Previous studies have shown that ovulation is generally induced between 40 and 44 h post-hCG in this model. Ovariectomies were performed at 0, 24, 30, 34 and 38 h post-hCG (n = 4 or 5 animals per time-point), and all follicles larger than 4 mm in diameter were isolated. The regulation of PGHS-1 and PGHS-2 proteins was studied by immunohistochemistry and Western blot analyses, whereas the regulation of PGHS-2 mRNA was studied by Northern blot. PG production was assessed by radioimmunoassay (RIA). (Abstract shortened by UMI.)

The gonad of the snail Helix aspersa is innervated by a branch of the intestinal nerve. Here it is demonstrated that nerve stimulation causes peristaltic contractions and the acceleration of cilia beating in the proximal part of the hermaphroditic duct. Acetylcholine and serotonin induced peristaltic contractions when applied without nerve stimulation. As well, serotonin induced the acceleration of cilia beating. The neuropeptide FMRFamide caused dilation of the hermaphroditic duct. Pharmacological blocking of acetylcholine and serotonin receptors with concurrent nerve stimulation induced a dilation similar to that caused by FMRFamide application. It is suggested that all three transmitters are released from intestinal nerve terminals to facilitate oocyte transport during ovulation. Nerve stimulation induced an increase in gamete transport rates. Because several candidate chemical messengers failed to induce ovulation when injected into the circulatory system, Helix aspersa appears to initiate ovulation differently from related species. Whereas Aplysia and Lymnaea use hormones, Helix apparently signals ovulation via the intestinal nerve.

No description available.

Metabolites of arachidonic acid, known as eicosanoids, result from two enzymatic pathways: cyclooxygenase (COX) and lipoxygenase (LOX). Indomethacin (INDO), at a dose level of approximately 10 mg/kg, has been commonly used in studies on the role of prostagiandins (PG) in the porcine ovulatory process since it was believed to be specific in its inhibition of the COX pathway. Other evidence suggests that INDO also has inhibitory effects on the formation of LOX metabolites including 12- and 15-hydroxyeicosatetraenoic acid (HETE). There is also evidence that LOX metabolites may have a role in the ovulatory process of the rat and the pig. In the previous studies on PGs in porcine ovulation, the effect of INDO on LOX metabolites was not examined. It has been shown that progesterone has a role in the formation of eicosanoids in the ovary in the rat and the ewe. The results of this study indicate that an intramuscular injection of INDO, at dose levels as high as 5 mg/kg, reduces ovulation rat and preovulatory follicular fluid concentrations of PGF2alpha without affecting concentrations of 12- and 15-HETE in the gonadotropin-primed pig. Indomethacin, at dose levels as low as 1 mg/kg, reduced ovulation rate and intrafollicular PGF2alpha concentrations but 0.1 mg/kg had no effect on ovulation rate or PGF2alpha. In cultured granulosa and theca interna cells, 10 ng or greater of INDO per 3 x 105 cells reduces PGF2alpha accumulation in the media. Accumulation of 12- and 15-BETE in the media was reduced by 100 ng or greater of INDO per 3 x 10 5 cells. To examine the role of progesterone in the formation of eicosanoids, danazol, an inhibitor of steroidogenesis, was added to cultures of porcine follicular cells. This treatment had no effect on progesterone production by either cell type and, similarly, had no effect on eicosanoid production. (Abstract shortened by UMI.)

No description available.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2006. / Härtill 4 uppsatser.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 6, 2009) Thesis advisor: Dr. David J. Patterson, Includes bibliographical references.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1997. / Bibliography: leaves 55-69.