Sakamoto Katsuhiko, Liu Cuimei, Kasamatsu Manami, Pozdeyev Nikita V, Iuvone P Michael, Tosini Gianluca
Neuroscience Institute and NSF Center for Behavioural Neuroscience, Morehouse School of Medicine, 720, Westview Dr. SW, Atlanta, GA 30310-1495, USA.
Eur J Neurosci. 2005 Dec;22(12):3129-36. doi: 10.1111/j.1460-9568.2005.04512.x.
In mammals a subpopulation of retinal ganglion cells are intrinsically photosensitive (ipRGCs), express the photopigment melanopsin, and play an important role in the regulation of the nonimage-forming visual system. We have recently reported that melanopsin mRNA and protein levels in the rat retina are under photic and circadian control. The aim of the present work was to investigate the mechanisms that control melanopsin expression in the rat retina. We discovered that dopamine (DA) is involved in the regulation of melanopsin mRNA, possibly via dopamine D2 receptors that are located on these ipRGCs. Interestingly, we also discovered that pituitary adenylate cyclase-activating peptide (PACAP) mRNA levels are affected by DA. Dopamine synthesis and release in the retina are regulated by the rod and the cone photoreceptors via retinal circuitry; our new data indicate that DA controls melanopsin expression, indicating that classical photoreceptors may modulate the transcription of this new photopigment. Our study also suggests that DA may have an important role in mediating the light signals that are used for circadian entrainment and for other responses that are mediated by the nonimage-forming visual system.
在哺乳动物中，视网膜神经节细胞的一个亚群具有内在光敏性（ipRGCs），表达光色素黑素视蛋白，并在非成像视觉系统的调节中发挥重要作用。我们最近报道，大鼠视网膜中黑素视蛋白的mRNA和蛋白质水平受光照和昼夜节律控制。本研究的目的是探究控制大鼠视网膜中黑素视蛋白表达的机制。我们发现多巴胺（DA）可能通过位于这些ipRGCs上的多巴胺D2受体参与黑素视蛋白mRNA的调节。有趣的是，我们还发现垂体腺苷酸环化酶激活肽（PACAP）的mRNA水平受DA影响。视网膜中多巴胺的合成和释放由视杆和视锥光感受器通过视网膜回路调节；我们的新数据表明DA控制黑素视蛋白的表达，这表明经典光感受器可能调节这种新光色素的转录。我们的研究还表明，DA可能在介导用于昼夜节律同步以及由非成像视觉系统介导的其他反应的光信号方面发挥重要作用。
