Current and emerging concepts of follicle growth and ovulation, hypothalamic-pituitaryovarian interactions, corpus luteum function and estrous cycle regulation in cattle, sheep and swine are reviewed. Follicles grow, regress and are replaced by other large follicles continuously throughout the cycle; intra-ovarian factors appear to play important roles in this process. Estradiol concentrations ...

In luteal cells, prostaglandin (PG)F2a mobilizes intracellular calcium concentration ([Ca]i), generates reactive oxygen species (ROS), depletes ascorbic acid (AA) levels, inhibits steroidogenesis, and ultimately induces cell death. We investigated the hypothesis that [Ca]i mobilization stimulates ROS, which results in depletion of cellular AA in rat luteal cells. We used a self-referencing AA-s...

The effect of the somatostatin analogue octreotide on the secretion of progesterone and insulin-like growth factor binding protein-1 (IGFBP-1) from human granulosa-luteal cells was investigated. Octreotide (10(-11), 10(-10) and 10(-9) M) alone induced a significant decrease in progesterone secretion (maximum suppression 69 +/- 5% of control: P < 0.0001). In contrast, treatment with octreotide i...

Low progesterone levels are associated with luteal phase deficiency in women with polycystic ovary syndrome (PCOS). The mechanisms regulating progesterone biosynthesis in the granulosa cells from women with PCOS is largely unknown. Fractalkine is expressed in human ovaries, and is reported to regulate progesterone production in granulosa cells of healthy women. In the current study, we aimed to...

The physiological role of luteinizing hormone-releasing hormone (LH-RH) in mediating the secretion of gonadotrophins is well established. However, administration of large doses of LH-RH produces a paradoxical anti-fertility effect. Thus, in women, agonists of LH-RH have been shown to inhibit ovulation (Nillius, Bergquist & Wide, 1978) and interfere with corpus luteum function (Casper & Yen, 197...

was explored during various stages of pseudopregnancy, including natural and induced luteal regression. Induced luteolysis was achieved during mid-pseudopregnancy by removal of an oestradiol capsule placed at the onset of pseudopregnancy, which suppressed ovarian oestradiol production. Activity of manganese superoxide dismutase (Mn SOD) was significantly and positively correlated with ovarian p...