成人男子におけるgonadotropins及びtestosterone分泌のpulsatile pattern及び日内変動に及ぼすbromocriptineの影響

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To investigate the effects of bromocriptine on the secretion mechanism of pituitary gonadotropins and testosterone, 5 mg of bromocriptine was administered to five young adult men who were normal in their endocrinological states. Blood samplings were taken from two hours before until six hours after the administration every 15 min., and after that, blood samplings were continued until 21 hours every one hour by an intravenous indwelling catheter. Serum FSH, LH, prolactin and testosterone levels were determined by RIA, and the changes of the pulsatile patterns of FSH and LH, and the circadian profile of these hormones by the administration of bromocriptine were analysed.<BR>Serum prolactin levels decreased significantly (p<0.005) from two hours after the administration of bromocriptine and remained in a very low range until the end of the experiment. The basal levels of FSH showed a significant decrease from two to six hours after the administration (p<0.005). Also the basal levels of LH showed a significant decrease from two to six hours after the administration (p<0.005). However, the basal levels of serum FSH and LH did not show significant decreases after that until the end of the experiment. No significant change was observed in the amplitude or the frequency of the pulsatile patterns of FSH and LH until six hours after the administration of bromocriptine. The serum levels of testosterone were also significantly decreased from two to six hours after the administration (p<0.005), but they did not show a significant decrease after that until the end of the experiment. The circadian profile of serum prolactin levels showed a significant rise during 20 to 23 o'clock (p<0.005) and 4 to 8 o'clock (p<0.005) in the control group. With the administration of bromocriptine, however, these nocturnal surges of prolactin diminished. There was no conspicuous circadian profile in serum FSH and LH levels in either the control or the bromocriptine administered group. But in serum testosterone levels, there was an obvious circadian profile. The basal levels of serum testosterone during 18 to 21 o'clock were significantly lower than those of 6 to 9 o'clock both in the control group and in the bromocriptine administered group (p<0.005, p<0.005). From these facts it is suggested that bromocriptine acts mainly on the pituitary rather than the hypothalamus to decrease the serum levels of gonadotropins, and it may also play some role in the steroidogenesis of the testis. However, the action of bromocriptine which decreases serum gonadotropins or testosterone seems to be moderate.
一般社団法人日本内分泌学会の論文

成人男子におけるgonadotropins及びtestosterone分泌のpulsatile pattern及び日内変動に及ぼすbromocriptineの影響

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