HCG가 자궁운동성에 미치는 영향 -2. 흰쥐 발정 주기간의 혈장 성호르몬농도에 미치는 영향

Abstract

In the previous experiment. one of authors reported that diminished effect af exogenous hCG on the uterine motility is probably due to the alteration of ovarian function. In this study. the experiment was designed ta determine whether diminished uterine motility induced by hCG is mediated through the altered secretian of ovarian steroids. The cyclic changes in the concentration of plasma estradiol, progesterone and testosterone during estrous cycle were measured in the rats having a regular 5 day-cycle. and the effects of previous hCG administrations on the concentrations were observed. The rats were divided into three groups, namely, the control, the rats stimulated with hCG on the day of proestrus and the rats stimulated with hCG continuously during the entire estrous cycle. Peripheral blood collections were performed arbitrarily at 10: 00 a.rn. on the day of proestrus because of a wide diurnal variation and to fix sampling time throughout the remainder of the estrous cycle. Values obtained on each day of the cycle were compared with the values observed during another day of the cycle on the one hand, and with the values of another groups on the other hand. Following were the results: 1. Plasma progesterone levels of normal rats varied somewhat from day to day: the concentration tended to increase on the day of estrus and it was further elevated on the morning of mctaestrus and then declined on diestrus. 2. Single stimulation of hCG on the day of proestrus showed a slight increase in plasma progesterone concentration of estrus and metaestrus but the differences were not significant as compared to the control rats. 3. Continuous stimulation of hCG resulted in a marked increase in plasma progesterone concentration especially on the day of metaestrus. Stimulation could still be effective on the day of diestrus although the changes wer~ not so wide. 4. During the latter half of the estrous cycle, there were no significant differences in plasma estradiol levels between the rats with both single or continuous hCG stimulation and control rats, although the levels tended to be higher in the rats with stimulation than in the control animals. 5. There were no significant variations in the mean concentration of testosterone in peripheral blood during the entire estrous cycle of the control rats. 6. Single injection of hCG on the day of proestrus induced an insignificant rise in plasma testosterone level, however, marked elevation was observed by continual stimulation. 7. From above results, the followings are suggested: a) hCG acts on the ovulated ovary promoting progesterone and testosterone release and to a lesser ex- tent estrogen. b) A significant effect of hCG on progesterone secretion rather than estrogen may contribute to the diminished uterine motility. c) A significant effect of hCG on plasma testosterone concentration could probably modify the estrogen activity.