Dufy B, Vincent J D, Fleury H, Du Pasquier P, Gourdji D, Tixier-Vidal A
Nature. 1979;282(5741):855-7. doi: 10.1038/282855a0.
Secretory activity of the anterior pituitary gland is regulated by the brain through stimulatory and inhibitory substances released from nerve endings in the median eminence of the hypothalamus and carried by the adenohypophysial portal blood system to their respective target cells. These hypothalamic influences are modulated by the feedback action of peripheral hormones. Prolactin (PRL) secreting cells are, at least partially, under the stimulatory influence of thyrotropin releasing hromone (TRH) and of oestrogens. However, they are mainly controlled by inhibitory substances among which dopamine (DA) is one of the most potent in vivo as well as in vitro. The inhibitory effect of DA is reversed by oestrogen in vitro. The mechanism by which these factors interact on their target cells is poorly understood. The recent discovery that anterior pituitary cells are excitable and that they are able to generate Ca2+-dependent action potentials has led to the suggestion that these effects are involved in a stimulus-secretion coupling at the membrane level. In this paper, we report that DA inhibits both the spontaneous and TRH-induced action potentials in clonal PRL pituitary cells. In addition, oestradiol-17 beta is able to reverse the inhibitory effect of DA.
垂体前叶的分泌活动受大脑调节，调节方式是通过下丘脑正中隆起神经末梢释放的刺激和抑制物质，这些物质由腺垂体门脉血液系统输送到各自的靶细胞。外周激素的反馈作用可调节这些下丘脑的影响。分泌催乳素（PRL）的细胞至少部分受促甲状腺激素释放激素（TRH）和雌激素的刺激影响。然而，它们主要受抑制物质控制，其中多巴胺（DA）在体内和体外都是最有效的抑制物质之一。雌激素在体外可逆转DA的抑制作用。这些因素在其靶细胞上相互作用的机制尚不清楚。最近发现垂体前叶细胞具有兴奋性，并且能够产生钙依赖性动作电位，这表明这些效应参与了膜水平的刺激-分泌偶联。在本文中，我们报告DA可抑制克隆PRL垂体细胞中的自发动作电位和TRH诱导的动作电位。此外，17β-雌二醇能够逆转DA的抑制作用。
