title: Localization of melanopsin-immunoreactive cells in the Mongolian gerbil retina.
abstract: Melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in circadian rhythm and pupil responses. The purpose of this study was to reveal the organization of melanopsin-immunoreactive (IR) neurons in the Mongolian gerbil retina using immunocytochemistry. Melanopsin-IR cells were primarily located in the ganglion cell layer (GCL; M1c; 75.15%). Many melanopsin-IR cells were also observed in the inner nuclear layer (INL; M1d; 22.28%). The M1c and M1d cell types extended their dendritic processes into the OFF sublayer of the inner plexiform layer (IPL). We rarely observed bistratified cells (M3; 2.56%) with dendrites in both the ON and OFF sublayers of the IPL. Surprisingly, we did not observe M2 cells which are well observed in other rodents. Melanopsin-IR cell somas were small to medium in size and had large dendritic fields. They had 2-5 primary dendrites that branched sparingly and had varicosities. Melanopsin-IR cell density was very low: they comprised 0.50% of the total ganglion cell population. Moreover, none of the melanopsin-IR cells expressed calbindin-D28K, calretinin, or parvalbumin. These results suggest that in the Mongolian gerbil, melanopsin-IR cells are expressed in a very small RGC subpopulation, and are independent of calcium-binding proteins-containing RGCs.
authors.affiliation: Department of Biology, School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, and Brain Science and Engineering Institute, Kyungpook National University, Daegu 702-701, South Korea.
authors.forename: Mi-Jin
authors.initials: MJ
authors.lastname: Jeong
authors.affiliation: Department of Biology, School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, and Brain Science and Engineering Institute, Kyungpook National University, Daegu 702-701, South Korea. Electronic address: cjjeon@knu.ac.kr.
authors.forename: Chang-Jin
authors.initials: CJ
authors.lastname: Jeon
mesh_terms: D000818:Animals; D002452:Cell Count; D003712:Dendrites; D005849:Gerbillinae; D007150:Immunohistochemistry; D012160:Retina / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000378:metabolism*; D017299:Rod Opsins / Q000378:metabolism*; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin
keywords: Calcium-binding proteins (CBPs); Cell density; Cell type; Immunocytochemistry; Melanopsin-immunoreactive (IR); Mongolian gerbil