Beyer C, Kolbinger W, Reisert I, Pilgrim C
Abteilung Anatomie und Zellbiologie, Universität Ulm, Germany.
Neurosci Lett. 1994 Oct 24;180(2):231-4. doi: 10.1016/0304-3940(94)90527-4.
Pituitary prolactin (PRL) secretion is inhibited by hypothalamic GABAergic and dopaminergic (DAergic) systems. PRL, in turn, appears to be capable of activating these neurons, thus, providing for a negative feedback regulation. We have recently shown that cultured hypothalamic GABAergic- but not DAergic neurons respond to PRL with a rapid increase in intracellular free calcium. Here, we demonstrate that cultured hypothalamic DAergic neurons can be activated in terms of synthesis of dihydroxyphenylalanine (DOPA) by long-term PRL treatment. Short-term PRL treatment was ineffective. It is concluded that hypothalamic DAergic neurons are indeed capable of responding to PRL. However, their response differs from that of GABAergic neurons with respect to time scale and signal transduction. We suggest that the two types of hypothalamic cells are involved in separate feedback loops that provide for tonic and rapid regulation of pituitary PRL secretion, respectively.
垂体催乳素（PRL）的分泌受到下丘脑γ-氨基丁酸能（GABAergic）和多巴胺能（DAergic）系统的抑制。反过来，PRL似乎能够激活这些神经元，从而实现负反馈调节。我们最近发现，培养的下丘脑GABA能神经元——而非多巴胺能神经元——对PRL的反应是细胞内游离钙迅速增加。在此，我们证明，长期用PRL处理可使培养的下丘脑多巴胺能神经元在二羟基苯丙氨酸（DOPA）合成方面被激活。短期PRL处理无效。结论是，下丘脑多巴胺能神经元确实能够对PRL作出反应。然而，它们的反应在时间尺度和信号转导方面与GABA能神经元不同。我们认为，这两种类型的下丘脑细胞分别参与不同的反馈回路，分别对垂体PRL分泌进行持续性和快速调节。
