본 연구에서는 GnRH가 과배란 처치된 래트의 초기 난포기와 후기 난포기에서 난소기능에 어떠한 영향을 미치는지를 이해하기 위해서, 30IU PMSG와 10IU hCG로 전처치된 미성숙 래트에 있어서 배란반응, 배란 난자의 형태학적 이상 유무 및 핵 성숙도, 난소 중량, 난소의 조직학적인 변화 및 혈중 스테로이드 호르몬 (17-estradiol, progesterone 및 testosterone) 농도에 대하여 GnRH agonist의 효과를 검사하였다.

미성숙 래트의 외경정맥에 카테타를 장착하고, 다음날 (28일령) 대조군에는 4IU, 다배란 처치 군에는 20IU의 PMSG를 피하주사하였다. 각 실험동물은 혈중의 LH농도 변화를 측정하기 위하여 PMSG 투여 직전 (0시간), 투여후 12시간, 그 이후 6시간 간격으로 혈액을 채취하고 72시간에 희생시켰다. 그 결과 다배란 용량의 PMSG 투여는 먼저 배란반응 및 난소중량을 대조군에 비하여 각각 4,7배 및 2.1배나 현저하게 (P<0.05) 증가시켰다

The effects of an antiprogesterone (RU 486) and an antiestrogen (tamoxifen) on ovulatory response and oocyte morphology were examined in pregnant mare serum gonadotropin (PMSG)-primed immatare female rats (28 days of age): a comparison has been made on two different regirnens primed with a "control" dose (4 IU) and a "superovulatory" dose (40 IU) of PMSG. Females for control control regimen received three consecutive injections of lmg RU486, lmg tamoxifen, or vehicle at 24, 36 and 48hr, and were killed at 72l'r after PMSG. Animals for superovalatory regimen received lmg RU486, 2.5mg tamoxifen, or vehicle fouowlag the injection schedule comparable to control regimen, and were killed at 60 and 72hr after PMSG. Compared to vehicle group, there was a significant reduction in ovulatory response as judged by the proportion of rats ovulating andi or by the mean number of oocytes per rat for each treatment of RU486 and tamoxifen in both regimens. The activity of tamoxifen in inhibiting the ovulatory response was greater in control, but less in superovulatory regimen than that of RU486 based on the dose employed for each antisteroid. In both regimens, RU 486 did not have any effect 6n the changes in the proportion of degenerate oocytes as well as ovarian weight, well tamoxifen treatment resulted in a marked promotion of oocyte degeneration as well as a great reduction in ovarian weight, compared to each parameter of vehicle group. RU486 treatment in each regimen did not alter the serum levels of any steroid hormones observed. Howerver, tamoxifen treatment was associated with significant increases in serum 17-estradiol and decreases in progesterone in both regimens; also significant increases in androgens in superovulatory regimen. The results illustrate the relative inhibitory activity of RU486 and tamoxifen indicating major steroid hormone involved in PMSG-induced ovulation: 17-estradiol for control and progesterone for superovulatory regimen. It also appears that tamoxifen-associated elevation of circulating 17-estradiol andi or androgens could be in part, a contributing factor to the promotion of oocyte degeneration presumably by producing a hostile oviductal environment after ovulation.ent after ovulation.