title: Co-expression of two subtypes of melatonin receptor on rat M1-type intrinsically photosensitive retinal ganglion cells.
abstract: Intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in circadian and other non-image forming visual responses. An open question is whether the activity of these neurons may also be under the regulation mediated by the neurohormone melatonin. In the present work, by double-staining immunohistochemical technique, we studied the expression of MT1 and MT2, two known subtypes of mammalian melatonin receptors, in rat ipRGCs. A single subset of retinal ganglion cells labeled by the specific antibody against melanopsin exhibited the morphology typical of M1-type ipRGCs. Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons. Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth. It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.
authors.affiliation: Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.
authors.forename: Wen-Long
authors.initials: WL
authors.lastname: Sheng
authors.affiliation: Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.
authors.forename: Wei-Yi
authors.initials: WY
authors.lastname: Chen
authors.affiliation: Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.
authors.forename: Xiong-Li
authors.initials: XL
authors.lastname: Yang
authors.affiliation: Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Zhong
authors.affiliation: Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.
authors.forename: Shi-Jun
authors.initials: SJ
authors.lastname: Weng
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003593:Cytoplasm / Q000378:metabolism; D015870:Gene Expression; D007150:Immunohistochemistry; D008297:Male; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D044122:Receptor, Melatonin, MT1 / Q000235:genetics / Q000378:metabolism*; D044123:Receptor, Melatonin, MT2 / Q000235:genetics / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D044122:Receptor, Melatonin, MT1; D044123:Receptor, Melatonin, MT2