Development and expression of amyloid-β peptide 42 in retinal ganglion cells in rats

The previous studies have shown that amyloid-β peptide (Aβ) was mainly found in neurons of neurodegenerative diseases, such as Alzheimer's disease (AD) and glaucoma and little is known about its expression in normal nerve cells. The aim of the present study was to investigate the expression of amyloid-β peptide 42 (Aβ-42) in retinal ganglion cells of the postnatal rats. Rats were divided into seven experimental groups: 3, 6, 13, 15, 25, 60, and 90 days postnatal groups. Rats from 15 and 25 days postnatal groups were further divided into light-exposure and non light-exposure group. Cryosections or flat-mounted retinas of rat eyes were used for testing Aβ-42 by immunocytochemistry staining. Aβ-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 Aβ-42 in retina was increasing as the rats got older, reached to highest level in 60 days after birth. Furthermore, the expression of Aβ-42 was not detected in rats kept under dark indicating that light is required for the expression of Aβ-42 in retina. This is the first report showing that normal retinal ganglion cells express Aβ-42, and that the expression of Aβ-42 in retinal ganglion cells requires the exposure to light. These data suggest that Aβ-42 may play a important role in vision development.