Turner B B
Department of Physiology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614.
Life Sci. 1990;46(19):1399-406. doi: 10.1016/0024-3205(90)90340-w.
Sex-dependent differences in corticosteroid binding were assessed in individual pituitaries from adult male and female rats that had been adrenalectomized 12 h before sacrifice. Soluble binding was assayed in duplicate on LH-20 columns. Gonadally intact females showed significantly less 3H-dexamethasone binding than did intact males (p less than 0.01). This difference was confirmed in a second study (p less than .001). However, when ovariectomized females were compared with gondadectomized males, there was no difference in receptor concentration. Estrogen was able to reverse the effect of ovariectomy: ovariectomized females receiving estrogen (10 micrograms/rat/day) had significantly fewer receptors than intact males; p less than 0.01). Progesterone (500 micrograms/rat/day) did not antagonize the effect of estrogen in the pituitary. A sex difference was also found in the Type I (mineralocorticoid) receptor subpopulation which comprised approximately 10% of the total receptors, with females having fewer receptors than males. These results demonstrate that in the pituitary, the level of functional corticosteroid receptors is subject to a 20% down-regulation by circulating levels of estrogen. This raises the possibility that the lower number of receptors in females may act to reduce their sensitivity to the negative feedback effects of glucocorticoids at the level of the pituitary.
在处死前12小时进行肾上腺切除的成年雄性和雌性大鼠的个体垂体中评估皮质类固醇结合的性别差异。在LH - 20柱上一式两份测定可溶性结合。性腺完整的雌性大鼠显示出的3H - 地塞米松结合明显少于完整的雄性大鼠（p小于0.01）。在第二项研究中证实了这种差异（p小于0.001）。然而，当将去卵巢的雌性大鼠与去势的雄性大鼠进行比较时，受体浓度没有差异。雌激素能够逆转卵巢切除术的影响：接受雌激素（10微克/大鼠/天）的去卵巢雌性大鼠的受体明显少于完整的雄性大鼠；p小于0.01）。孕酮（500微克/大鼠/天）不会拮抗雌激素对垂体的作用。在占总受体约10%的I型（盐皮质激素）受体亚群中也发现了性别差异，雌性的受体少于雄性。这些结果表明，在垂体中，功能性皮质类固醇受体的水平受循环雌激素水平下调20%的影响。这增加了一种可能性，即雌性中较低的受体数量可能会降低它们在垂体水平对糖皮质激素负反馈作用的敏感性。
