外因性ACTHによる豚の卵胞嚢腫の形成について

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It has been suggested that stress acting via the adrenal gland may play a role in the etiology of ovarian cysts in the sow. The purpose of the present experiment was to determine the effects of exogenous ACTH on the estrus and ovulation in the normal sow. Four sows which had displayed several estrous cycles of 18-21 days were used. Three sows received intramuscular (im) injections of 0.5IU/kg ACTH suspended in saline solution twice daily at approximately 09:00h and 17:00h, for 7 or 9 days beginning on Day 16 or 19 after ovulation. The response of the ovary and uterine cervix to the treatment was monitored by rectal palpation. Plasma estrogens, progesterone, cortisol and corticosterone were measured by radioimmunoassay. The remaining sow received a single im injection of 1IU/kg ACTH during the luteal phase. The first 3 sows developed ovarian follicles beginning around the anticipated date of the next estrus. Two sows displayed feeble estrus on Day 23 and 27, respectively, after a previous ovulation. The remaining sow failed to display post-treatment estrus, and mature follicles were found present. Ovulation in all sows was blocked and follicular cysts developed. Plasma estrogen concentrations were generally maintained on a low level, in spite of the involution of the corpora lutea, follicular development and formation of cystic follicules. In 2 of 3 sows, plasma progesterone values were also as low as in the normal follicular phase, except for one sow in which the level rose considerably with the luteinization of the cystic follicles. When a sow was injected with 1IU/kg of ACTH, plasma corticoid values peaked in half an hour after treatment and returned to the basal level at 9 hours. The plasma corticoid pattern was almost the same in the 3 sows which were given ACTH consecutively.These results indicate that the sow exposed to various stressful stimuli may induce hypersecretion of ACTH, and that the preovulatory surge of LH may be suppressed through a feedback mechanism due to depressed estrogen secretion in developing follicles. Therefore ovulation may be blocked and follicles may become cystic.
社団法人日本畜産学会の論文

外因性ACTHによる豚の卵胞嚢腫の形成について

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