Cellular localization of melatonin receptor Mel1b in pigeon retina.

Melatonin, an important neuromodulator involved in circadian rhythms, modulates a series of physiological processes via activating its specific receptors, namely Mel1a (MT 1), Mel1b (MT 2) and Mel1c receptors. In this work, the localization of Mel1b receptor was studied in pigeon retina using double immunohistochemistry staining and confocal scanning microscopy. Our results showed that Mel1b receptor widely existed in the outer segment of photoreceptors and in the somata of dopaminergic amacrine cells, cholinergic amacrine cells, glycinergic AII amacrine cells, conventional ganglion cells and intrinsically photosensitive retinal ganglion cells, while horizontal cells, bipolar cells and Müller glial cells seemed to lack immunoreactivity of Mel1b receptor. That multiple types of retinal cells expressing Mel1b receptor suggests melatonin may directly modulate the activities of retina via activating Mel1b receptor. • Mel1b exists in photoreceptors, dopaminergic ACs, cholinergic ACs, glycinergic AII ACs, RGCs and ipRGCs. • HCs, BCs and Müller glial cells seems to lack immunoreactivity of Mel1b receptor in pigeon retina. • Researches on circadian rhythm-related Mel1b in the retina of pigeon contributes to studies of the biological rhythm. [ABSTRACT FROM AUTHOR]