Masri H, Goureau O, Hecquet C, Simon A, Nguyen-Legros J
Laboratoire de neurocytologie oculaire, INSERM U. 86, Paris, France.
C R Acad Sci III. 1996 Aug;319(8):687-91.
Photoreceptor disc shedding and their phagocytosis by the retinal pigment epithelium undergo a daily rhythm entrained by an intrinsic oscillator involving melatonin and dopamine in non-mammals. Such a mechanism is not demonstrated in mammals, but the rhythm of photoreceptor renewal can be modulated by exogenous melatonin and dopamine. The present experiments were designed to show whether a direct action of DA occurs on pigment epithelial cells, and to identify the receptor mediating this action. Primary cultures of bovine retinal pigment epithelium were incubated with bovine rod outer segments in the presence of dopamine, D1 and D2 agonists, D1 antagonist and forskolin. Dopamine, D1 agonist and forskolin decreased phagocytosis, while D2 agonist was inactive. Thus dopamine slows pigment epithelium phagocytosis in vitro through a D1 receptor. Increased phagocytosis following blockade of the receptor by an antagonist suggests a more complex modulation of phagocytosis by dopamine.
在非哺乳动物中，光感受器盘的脱落及其被视网膜色素上皮细胞的吞噬作用呈现出每日节律，该节律由涉及褪黑素和多巴胺的内在振荡器所调节。在哺乳动物中尚未证实存在这样的机制，但光感受器更新的节律可被外源性褪黑素和多巴胺所调节。本实验旨在表明多巴胺是否对色素上皮细胞有直接作用，并确定介导该作用的受体。在存在多巴胺、D1和D2激动剂、D1拮抗剂和福司可林的情况下，将牛视网膜色素上皮细胞的原代培养物与牛视杆细胞外段一起孵育。多巴胺、D1激动剂和福司可林降低了吞噬作用，而D2激动剂则无活性。因此，多巴胺通过D1受体在体外减缓色素上皮细胞的吞噬作用。拮抗剂阻断该受体后吞噬作用增强，这表明多巴胺对吞噬作用的调节更为复杂。
