抄録
Photic information is transmitted via the retinohypothalamic tract to the suprachiasmatica nucleus (SCN) in the hypothalamus, where circadian rhythms are generated, but the retinal photopigment which mediates circadian entrainment has remained elusive. Recently, melanopsin, an opsin-based photopigment, was localized to the retinal ganglion cell (RGC) layer of rodents and primates. Furthermore melanopsin containing RGCs provide photic information to the SCN revealed by the retrograde labeling. It is well known that phospholipase C (PLC) is distributed in the retina. In order to examine the phototransduction mechanisms of light information absorbed by melanopsin containing RGC immunohistological study was carried out for mouse. Double staining with one of the antibody of PLC subtype, β-1, -3, -4 and that of melanopsin (cordial gift from Dr. Provencio) revealed that some of the positive RGC to antibody of β-4 was also positive to that of melanopsin and that co-immunoreactivity of PLC β-3 and melanopsin was observed at some biplar cell and horizontal cell. This suggested that neurons in innerneuclear layer also have possibilty to sense light by itself in addition to RGC. [Jpn J Physiol 54 Suppl:S165 (2004)]
