Prostaglandin F2αの黄体直接作用

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It is well known that prostaglandin F2α (PG F2α) regresses the corpora lutea in many animal species. However, the exact mechanism for the luteolysis of PG F2α hasn't been well established yet. No reports so far have clarified the mechanism at all. Recently, we reported that the mechanism may be exhibited by the direct effect on the corpora lutea, based on in vivo experiments. The purpose of the present paper is to investigate the mechanism in mode detail in vitro on the above hypothesis. Wistar strain immature rats, at 25 days of age, received 20 IU of pregnant mare serum. gonadotropin (PMS) subcutaneously, and 56 hours later, 40 IU human chorionic gonadotropin (hCG) intraperitoneously to induce superovulated ovaries. Six days after the hCG treatment, ovariectomy was carried out. In a perifusion (continuous flow incubation) study, the TC-199 medium (1% glucose, pH 7.4) was continually saturated with a mixture of 95% oxygen and 5% carbon dioxide and pumped through polyethylene tubing to the incubation apparatus using a multichannel infusion pump. The incubation chamber, medium volume 0.5 ml, was set in a 37°C water bath. Hemiovaries were placed in an incubation chamber. After 20 minutes of preincubation, the experiment was performed. The perifusion was carried out with the medium for a control period of 60 minutes prior to the stimulation experiment, and then the media containing the stimulus were perifused for 4 hours or 1 hour. The flow rate of the medium was 10 ml/hour. The samples were collected every 20 minutes into a test tube, and the concentration of progesterone was measured. All values, therefore, represented progesterone secreted pg/ml/mg tissue/20 min. and indicated the mean of the duplicate study. In the first long-term stimulation experiment, the perifusion was done with media containing a concentration of PG F2α 20 μg/ml and hCG 1, 10,100 IU/ml for 4 hours. In the control group, the value of progesterone indicated a low level and showed no significant change. In the PG F2α 20 μg/ml group, the value increased gradually according to stimulation, and then after 2.5 hours of stimulation it reached at a plateau, 3.8 times higher than that in the control period. In the hCG 1 IU/ml group, there were no apparent changes during stimulation. On the other hand, in the hCG 10 IU/ml group, the value increased continuously and significantly during stimulation. In the hCG 100 IU/ml group, in contrast with the hCG 10 IU/ml group, the value increased precipitously and arrived at a plateau after 1.5 hours of stimulation. Its value was 8.8 times higher than the value in the control period. In every group except for the control group, it was revealed that PG F2α and hCG stimulated the corpora lutea to secrete progesterone. In the next short-term stimulation experiment, perifusion was carried out with media containing the stimulus for one hour which was followed by media containing no stimulus for 3 hours. In the control group, the value showed a low level and indicated no remarkable change. In the hCG 10 IU/ml group, the value increased gradually according to stimulation. Furthermore, it increased continuously after the termination of stimulation and reached at a high level plateau, 5.1 times higher than that in the control period. In the PG F2α 20 μg/ml group, 60 minutes after stimulation the value reached a peak 2.2 times higher than the control period value, and then in spite of the termination of stimulation, it remained at 1.7 times higher than the control period value for about 2 hours. In the PG F2α 200 μg/ml group, the value reached a peak at 40 minutes after stimulation. Thereafter, it decreased suddenly after the termination of stimulation and remained at 1.6 times higher than the control period value.
日本内分泌学会の論文

Prostaglandin F<SUB>2α</SUB>の黄体直接作用

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