Hernández M L, de Miguel R, Ramos J A, Fernández-Ruiz J J
Department of Biochemistry, Faculty of Medicine, Complutense University, Madrid, Spain.
Brain Res. 1990 Sep 24;528(1):175-8. doi: 10.1016/0006-8993(90)90215-w.
Prolactin can modulate the adrenal medulla function, but it has not yet been established whether its action is directly exerted on the adrenal medulla cells. In this work, we have studied the effect of several concentrations of prolactin on the synthesis, storage and release of norepinephrine and epinephrine using cultured bovine adrenal chromaffin cells. In these cells, prolactin inhibited the activity of tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine synthesis, in a dose-dependent manner, from a concentration above 50 ng/ml of prolactin in the incubation medium. Surprisingly, this dose-dependent decrease was not accompanied by changes in the catecholamine release, since the secretion of both norepinephrine and epinephrine as well as the total catecholamine secretion were not significantly altered by the different prolactin concentrations. Moreover, the cellular content of both catecholamines was not altered by prolactin. In summary, these observations allow us to conclude that prolactin exerts a direct inhibitory effect on the tyrosine hydroxylase activity in cultured adrenal chromaffin cells without altering catecholamine release.
催乳素可调节肾上腺髓质功能，但它对肾上腺髓质细胞的作用是否直接发挥尚未明确。在本研究中，我们利用培养的牛肾上腺嗜铬细胞，研究了几种浓度的催乳素对去甲肾上腺素和肾上腺素合成、储存及释放的影响。在这些细胞中，从孵育培养基中催乳素浓度高于50 ng/ml起，催乳素以剂量依赖的方式抑制酪氨酸羟化酶（儿茶酚胺合成中的限速酶）的活性。令人惊讶的是，这种剂量依赖性降低并未伴随儿茶酚胺释放的变化，因为不同浓度的催乳素对去甲肾上腺素和肾上腺素的分泌以及总儿茶酚胺分泌均无显著影响。此外，催乳素并未改变两种儿茶酚胺的细胞内含量。总之，这些观察结果使我们得出结论，催乳素对培养的肾上腺嗜铬细胞中的酪氨酸羟化酶活性具有直接抑制作用，而不改变儿茶酚胺的释放。
