雌二醇和睾酮对雄鼠下丘脑-垂体的反馈调节作用

4组(每组n=5)成年雄性 S-D 大鼠,去势后7天,分别肌注7天的丙酸睾丸酮(T 组)、苯甲酸雌二醇(E_2组)、丙酸睾丸酮+胃灌注三苯氧胺(T+FTMX 组)和豆油(对照组)。然后用放射免疫法测定各组大鼠下丘脑促性腺激素释放激素(GnRH)含量和外周血促黄体生成素(LH)水平。结果示:T 和E_2组大鼠平均血浆 LH 水平分别为1.42±0.23和1.87±0.19U/L,均明显低于对照组的4.46±0.31U/L(P 均<0.01)。下丘脑的 GnRH 含量分别为3196±331和2862±791pg/100mg 湿重组织,均显著高于对照组的1057±34pg/100mg 湿重组织(P 均<0.01)。T+TMX 组大鼠的平均血浆 LH 水平和下丘脑 GnRH 含量和 T 组无差别(P 均>0.05)。

Feedback effects of estradiol and testosterone on hypothalamic-pituitary axis in castrated male rats

Four groups(n=5)of adult male SD rats were treated starting from 7th day after cas- tration with testosterone propionate 2.5 mg daily(T group),estradiol benzoate 10μg daily(E_2 group), testosterone propionate 2.5mg plus tamoxifen 200μg daily(T+TMX group)or soy bean oil(control group)respectively,for 7 days.Then the GnRH concentration in hypothalamus and plasma LH were measured by RIA.The mean plasma LH levels were 1.42±0.23 and 1.87±0.19U/L in T and E_2 groups respectively,both of them being significantly lower than 4.46±0.31U/L in the control group(P >0.01).The GnRH concentrations in the hypothalamus were 3196±331 and 2862±791pg/100mg wet tissue,respectively,which were significantly higher than 1057±34pg/100mg wet tissue in the con- trol group(P<0.01).The plasma LH(1.89±0.21U/L)and the hypothalamicGnRHconcentrations (2681±109pg/100mg wet tissue)in T+TMX group were quite similar to those in the T group(P> 0.05).It is concluded that in male rats(1)there is a feedback effect of both E_2 and T on the hypothala- mic-pituitary axis;(2)T exerts its own effect on the hypothalamic-pituitary axis which is independent from aromatization of T into E_2.