Developmental Endocrinology and Treatment of Ovarian Cysts in Cattle

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Developmental endocrinology and treatment of ovarian cysts in cattle were examined, and the following results were obtained.1. Cows with ovarian cysts did not have remarkable abnormality in numbers and affinities of gonadotropin-releasing hormone (GnRH) receptors of the anterior pituitary.2. Numbers of gonadotropin receptors and concentrations of estradiol-17 beta in fluid of ovarian cysts were significantly lower than those of large follicles. The number of luteinizing hormone (LH) receptors in non-luteinized cysts (plasma concentration of progesterone <1 ng/ml) was significantly fewer than that of luteinized cysts (plasma concentration of progesterone *1 ng/ml). More estradiol-17 beta in fluid of non-luteinized cysts was observed when they possessed relatively many LH receptors.3. The addition of cortisol to granulosa cells in vitro caused a significant decrease in the unmber of LH receptors and the estradiol-17 beta production.4. The addition of progesterone to the median eminence o … More f the hypothalamus in in vitro perfusion experiments caused a significant decrease in the GnRH release.5. Ovarian cysts were experimentally induced by the treatment with adrenocorticotropic hormone (ACTH). During development of ACTH-induced cysts, LH and follicle stimulating hormone (FSH) surges from the pituitary which normally found prior to ovulation were disappeared. After ACTH treatment, the increase in plasma progesterone and cortisol levels accompanied by low estradiol- 17 beta level were observed, suggesting that these changes could be the reason for the disappearance of LH and FSH surges.6. Studies on the treatment of ovarian cysts with human chorionic gonadotrpin (hCG) revealed that the efficacy of the drug could be estimated to some extent by determining the concentrations of progesterone in peripheral plasma and estradiolー17 beta in fluid of ovarian cysts.These results suggest that, as a possible mechanism of development of ovarian cysts, cortisol and progesterone production from adrenal are increased by ACTH stimulation under continuous stress, and the former interferes with follicular maturation by decreasing the number of LH receptors and the estradiol-17 beta production in granulosa cell, while the latter inhibits directly GnRH release from the median eminence, thereby resulting in the disappearance of gonadotropin surge and ovulation failure. They also indicate that there is a constant relation between the efficacy of treatment and endocrinological status in cows with ovarian cysts. Less