Expression of Amyloid-β peptide 42 in retinal ganglion cells of postnatal rats is light-exposure-dependent

Aims: The aim of the present study was to investigate the expression of amyloid-β peptide 42 (A β -42) in retinal ganglion cells in postnatal rats. Sprague-Dawley rats were divided into 7 experimental groups: 3, 6, 13, 15, 25, 60, and 90 day postnatal groups. Rats from 15 and 25 day postnatal groups were further divided into light-exposure and non light-exposure group. Cryosections or flat-mounted retinas of rat eyes were used for immunocytochemistry staining for A β -42. A β -42 expression was not observed in rats within 13 days after birth, but was easily detectable in all groups of rats over 15 days after birth. In addition, the expression of A β -42 in retina was increasing as the rats got older, reached to highest level in 60 days after birth, and remained at that level even in 90 days after birth. Furthermore, the expression of A β -42 was not detected in rats kept under dark indicating that light is required for the expression of A β -42 in retina. This is the first report showing that normal retinal ganglion cells express A β -42, and that the expression of A β -42 in retinal ganglion cells requires the exposure to light. These data suggest that A β -42 may play a important role in vision development. The biological function and reuglation of A β -42 in normal retinal ganglion cells require further investigation.