EFFECT OF ESTROGEN ON ANDROGEN RECEPTOR DYNAMICS IN FEMALE RAT PITUITARY
EFFECT OF ESTROGEN ON ANDROGEN RECEPTOR DYNAMICS IN FEMALE RAT PITUITARY
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DOI：
10.1210/endo-121-1-84
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发表时间：
1987-07-01
期刊：
影响因子：
4.8
通讯作者：
RESKO, JA
中科院分区：
文献类型：
--
作者：
HANDA, RJ;STADELMAN, HL;RESKO, JA
我们研究了雌激素在调节雌性大鼠脑下垂体雄激素受体(AR)数量中的作用。实验选用雌性SD大鼠，体重240~280g，摘除卵巢3d。用人工合成的配体17α-甲基-~3H-三烯醇酮进行结合和交换实验，测定了脑垂体胞浆和核部分的AR数。去卵巢雌性大鼠单次注射苯甲酸雌二醇[(EB)10ug/100gbw]后，胞浆AR增加60%，12h时显著高于油组(P<0.01)。EB后48h，胞浆AR水平持续升高(对照组的213%)。垂体胞内AR的饱和分析表明，17α-甲基-~3H-三烯醇酮有一个高亲和力的单一结合部位，其表观解离常数(Kd)为0.5倍。在EB和油处理的动物中，在EB给药前给予放线菌酮(1 mg/kg bw)可阻止EB诱导的AR的升高，而在EB后8h测得AR。注射双氢睾酮(1.5 mg)后24 h，核内AR迅速增加，胞质AR迅速下降。EB处理的动物与油处理的对照组相比，核AR的增加明显更大(P<；0.05)。这些观察结果表明，雄激素和雌激素在雌性大鼠脑垂体中存在潜在的协同作用，提示雄激素可能在调节垂体激素的周期性释放中发挥重要作用。
We examined the role of estrogen in regulating the number of androgen receptors (AR) in the pituitary gland of the female rat. Female Sprague-Dawley rats (240-280 g) that were ovariectomized for 3 days were used in this study. AR numbers were determined in pituitary cytosol and nuclear fractions by binding and exchange assays using the synthetic ligand 17.alpha.-methyl-3H-trienolone. The administration of a single dose of estradiol benzoate [(EB) 10 .mu.g/100 g BW] to ovariectomized female rats resulted in a 60% increase in cytosolic AR which was significantly (P < 0.01) elevated above that of oil-treated controls by 12 h post EB. Cytosolic AR levels remained elevated for as long as 48 h post EB (213% of controls). Saturation analysis of pituitary cytosolic AR revealed a single, high affinity binding site for 17.alpha.-methyl-3H-trienolone exhibiting an apparent dissociation constant (Kd) of 0.5 .times. 10-10 M in both EB- and oil-treated animals the adminstration of cycloheximide (1 mg/kg BW) before EB administration prevented the EB-induced rise in AR when measured 8 h post EB. When dihydrotestosterone (1.5 mg) was injected 24 h after EB or oil, there was a rapid increase in nuclear AR accompanied by a rapid decrease in cytosolic AR. The increase in nuclear AR was significantly greater (P < 0.05) in EB-pretreated animals vs. oil-treated controls. These observations show that a potential synergism exists between androgen and estrogen in the female rat pituitary and suggest that androgens may play an important role in regulating cyclic pituitary hormone release.