黄体中期における卵巣性ステロイドのパルス状分泌に関する研究

抄録

The possibility of the pulsatile secretion of pituitary gonadotropines (LH and FSH) and ovarian steroids (estradiol and progesterone) was studied. In addition, an evaluation was made of the regulatory factors for steroid secretion of corpus luteum in view of the response behavior of the secretion of LH, FSH, estradiol and progesterone when loaded with hCG and gonadotropin releasing hormone (Gn-RH).
The study was performed on 9 cases of infertile women in the mid-luteal phase of a normal menstrual cycle. In 5 cases, blood was collected every 30 minutes over 24 hours. Thereafter, 2,500 iu of hCG was given twice to another subject at 8 hour intervals, and blood was collected every 30 minutes from immediately after the 1st administration over 16 hours. In the other 3 cases, 15μg of Gn-RH was given at an interval of 90 minutes, and blood was collected every 20 minutes for 16-24 hours. Then, the frequency and amplitude of each pulse for LH, FSH, estradiol and progesterone were calculated under the modified Santen' s rule in situ and when loaded with Gn-RH, and the relationship between pulses of gonadotropins and those of estradiol and progesterone was analysed by determining the number of concomitant pulses. The hormone dynamics when loaded with hCG were also assessed.
The pulse frequency and amplitude in situ of each hormone were 10.6±0.8times/24h and 4.9±0.6miu/ml for LH, 9.9±9.9times/24h and 1.3±0.1miu/ml for FSH, 9.2±0.9times/24h and 34.3±2.7pg/ml for estradiol, 7.4±0.5times/24 and 3.7±0.4ng/ml for progesterone. The coincidence of estradiol pulses and LH pulses was 37 times, and the concomitant ratio of LH pulse to estradiol pulse was 81%. The coincidence of progesterone pulses and LH pulses was 31 times, and the concomitant ratio of LH pulse to progesterone pulse was 84%. Furthermore, the concomitant ratio of FSH pulse to estradiol pulse or progesterone pulse was 61% or 70%, respectively.
The mean plasma concentration of LH, estradiol and progesterone during 8 hours after the 1st administration and 2nd administration of hCG changed from 29.9±2.3 to 41.8±1.6miu/ml, from 140.3±3.0 to 160.6±3.6pg/ml and from 19.2±1.0 to 25.7±0.6ng/ml, respectively. These values increased significantly after the second injection (P<0.001). However, it was from 6.8±0.2 to 7.2±0.2miu/ml for FSH, and no significant difference was obtained during hCG administration.
LH and FSH pulses were observed 43 times each with the administration of Gn-RH, and the amplitude was 39.8±9.8 and 4.7±0.7miu/ml, respectively. In the estradiol pulses, the frequency was 41 times, and the amplitude was 29.0±2.0pg/ml. For the progesterone pulses, the frequency was 39 times, and the amplitude was 3.7±0.2ng/ml. The coincidence of estradiol pulse with LH or FSH pulses was seen 31 times, and the concomitant ratio of LH pulses or FSH pulses to estradiol pulses was in both cases 76%. The concomitancy of LH or FSH pulses with progesterone pulses was seen 33 times, and the concomitant ratio of LH or FSH pulses to the progesterone pulses was both cases 85%. In this way, both estradiol and progesterone showed secretive dynamics corresponding to the luteotrophic effect.
From the results of the present study, it is considered that the dynamic secretion of LH, estradiol and progesterone is pulsatile. However, no affirmative results were obtained on the pulsatile secretion of FSH with longer half-life, and FSH is only slightly related to ovarian steroid secretion in the luteal phase. The spike-like secretion of Gn-RH at the proper interval and the pulsatile secretion of LH and FSH accompanying it may enhance the pulsatile secretion of estradiol and progesterone and may contribute to the maintenance of luteal function. Very little concerning the regulatory mechanism of Gn-RH secretion is known at present.