Ramos J A, Pais J R, Cebeira M, Fernandez-Ruiz J
Department of Biochemistry, School of Medicine, Complutensis University, Madrid, Spain.
J Steroid Biochem. 1987;27(4-6):683-9. doi: 10.1016/0022-4731(87)90137-3.
Studies were undertaken to evaluate the effects of estradiol and prolactin on striatal dopamine receptor activity. Dopamine receptors were quantified in partially purified striatal membranes by equilibrium binding using [3H]spiroperidol. When we investigated whether the D-2 dopamine receptor activity changes during the estrous cycle, the results suggest an increase in dopamine receptor density in diestrous, without modifications in the affinity. The finding that in ovariectomized rats the dopamine receptor binding parameters remained unchanged, suggests that gonadal steroids are not essential in the mechanism of action of this receptor. Results of activity of D-2 dopamine receptors showing that hyperprolactinemia fails to increase the number of these receptors do not support the hypothesis that circulating prolactin regulates the activity of these striatal dopamine receptors. Administration of estradiol benzoate (250 micrograms/kg per day) to hyperprolactinemic rats, by s.c. injection, significantly decreased both the density and the affinity of the striatal dopamine receptors. The present data indicate that, although prolactin does not seem to modify the activity of striatal dopamine receptors, it could modulate the estrogen-induced hypersensitivity of these receptors.
开展了多项研究以评估雌二醇和催乳素对纹状体多巴胺受体活性的影响。使用[3H]螺哌啶通过平衡结合法对部分纯化的纹状体膜中的多巴胺受体进行定量。当我们研究发情周期中D-2多巴胺受体活性是否发生变化时，结果表明动情后期多巴胺受体密度增加，而亲和力无改变。卵巢切除大鼠中多巴胺受体结合参数保持不变这一发现表明，性腺类固醇在该受体的作用机制中并非必不可少。D-2多巴胺受体活性结果显示高催乳素血症未能增加这些受体的数量，不支持循环催乳素调节这些纹状体多巴胺受体活性的假说。通过皮下注射向高催乳素血症大鼠给予苯甲酸雌二醇（每天250微克/千克），可显著降低纹状体多巴胺受体的密度和亲和力。目前的数据表明，虽然催乳素似乎不会改变纹状体多巴胺受体的活性，但它可能会调节雌激素诱导的这些受体的超敏反应。
