雄ラットにおけるGonadotropinの中枢性調節に関する研究:第一報-Testosterone代謝産物脳内投与の, 血中Gonadotropin値に与える影響

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Testosterone (T), 5α-dihydrotestosterone (5α-DHT), 5α-androstane-3α, 17β-diol (3α-diol) and estradiol-17β (E) or cholesterol (control) were implanted into the hypothalamic median eminence-arcuate nucleus (ME-ARC) region of long-term castrated male rats. Serum LH and FSH levels were measured before and after the implantation.<BR>T or E implantation resulted in a 65.5% (P<0.01) or 80.2% (P<0.01) decrease in serum LH levels respectively, within 7 days after the intrahypothalamic application. 5α-DHT or 3α-diol implantation in the ME-ARC region also resulted in a significant lowering of serum LH levels, although their inhibitory action was less effective than that of T or E. There were no significant differences in serum LH levels 20 min after the intraperitoneal injection of 2 μg/kg of LH-RH between the control group and the T, 5α-DHT, 3α-diol or E group. E implantation also resulted in a 34.7% (P<0.01) decrease in serum FSH levels at the 7th day, but other steroids failed to reduce serum FSH levels after the intrahypothalamic application.<BR>These studies suggest that aromatization of T to E is not indispensable to the negative feedback effect of androgen on the hypothalamic LH-RH release. It might also be supposed that E is one of the factors regulating the serum FSH level.
日本内分泌学会の論文