title: Melanopsin containing retinal ganglion cells are light responsive from birth.
abstract: Photoentrainment of the biological clock located in the suprachiasmatic nucleus (SCN) begins shortly after birth. Here we show using c-FOS immunoreactivity as a marker for neuronal activity that the melanopsin/PACAP containing retinal ganglion cells (RGCs) which project to the SCN as the retinohypothalamic tract (RHT) are responsive to light from birth. After postnatal day 12 where the classical photoreceptors become functional other RGCs and cells of the inner nuclear cell layer also respond to light. Light also induces c-FOS immunoreactivity in the retinorecipient SCN from the first postnatal day and accordingly PACAP immunoreactive fibres are visible in the SCN. The results indicate that the retina is light responsive before functional rods and cones and that the RHT is functional from birth supporting that photoentrainment of the biological clock begins shortly after birth.
authors.affiliation: Department of Clinical Biochemistry, Bispebjerg Hospital, University of Copenhagen, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark. J.Hannibal@inet.uni2.dk
authors.forename: Jens
authors.initials: J
authors.lastname: Hannibal
authors.forename: Jan
authors.initials: J
authors.lastname: Fahrenkrug
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects*; D007150:Immunohistochemistry / Q000379:methods; D008027:Light; D008297:Male; D009414:Nerve Growth Factors / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism; D036801:Parturition / Q000528:radiation effects*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011247:Pregnancy; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000166:cytology* / Q000254:growth & development; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000528:radiation effects*; D017299:Rod Opsins / Q000378:metabolism*; D014795:Visual Pathways / Q000378:metabolism; D000099210:Melanopsin
chemical_list: D009414:Nerve Growth Factors; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D016760:Proto-Oncogene Proteins c-fos; D017299:Rod Opsins; D000099210:Melanopsin; C495403:Adcyap1 protein, rat