Login I S, Kuan S I, Judd A M, MacLeod R M
Department of Neurology, University of Virginia Health Sciences Center, Charlottesville 22908.
Endocrinology. 1990 Oct;127(4):1948-55. doi: 10.1210/endo-127-4-1948.
We studied the role of calcium in dopaminergic control of the neuroendocrine effects of neurotensin. In primary cultures of dispersed normal female rat anterior pituitary cells the interactions of dopamine and neurotensin were examined with reference to the rate of PRL release, the magnitude of 45Ca2+ uptake, the rate of fractional 45Ca2+ efflux, and the dynamic response of the intracellular calcium concentration (Cai) monitored with the fluorescent dye, Indo-1. Neurotensin stimulated calcium uptake and also mobilized a pool of intracellular calcium to increase Cai in a sustained plateau-like pattern. The response of PRL release and fractional efflux to neurotensin, however, each displayed typical spike and plateau profiles. In the presence of dopamine the stimulation of PRL release and calcium uptake due to neurotensin were abolished, and the rise in Cai was barely detectable, but neurotensin-stimulated fractional efflux persisted almost unchanged. These data suggest that dopamine may modulate Cai by inhibiting calcium uptake and possibly also by enhancing cellular calcium extrusion under stimulated conditions. Further, the increased inositol trisphosphate production reportedly stimulated by neurotensin apparently does not generate a spike-like response of intracellular calcium, and stimulated hormone release may display a spike and plateau pattern solely with a plateau Cai profile.
我们研究了钙在神经降压素神经内分泌效应的多巴胺能控制中的作用。在分散的正常雌性大鼠垂体前叶细胞的原代培养中，参照催乳素释放速率、45Ca2+摄取量、45Ca2+分数流出速率以及用荧光染料Indo-1监测的细胞内钙浓度（Cai）的动态反应，研究了多巴胺与神经降压素的相互作用。神经降压素刺激钙摄取，并动员细胞内钙池，以持续的平台样模式增加Cai。然而，催乳素释放和分数流出对神经降压素的反应各自呈现典型的尖峰和平台特征。在多巴胺存在的情况下，神经降压素对催乳素释放和钙摄取的刺激被消除，Cai的升高几乎检测不到，但神经降压素刺激的分数流出几乎保持不变。这些数据表明，多巴胺可能通过抑制钙摄取以及在刺激条件下可能还通过增强细胞钙外排来调节Cai。此外，据报道由神经降压素刺激的肌醇三磷酸生成增加显然不会产生细胞内钙的尖峰样反应，并且刺激的激素释放可能仅在平台Cai特征下呈现尖峰和平台模式。
