c-Fos Immunoreactivity in the Neurons of the Lateral Geniculate Nucleus in Albino Rats by Light Exposure after Dark Rearing

PURPOSE To investigate the effect of dark rearing immediately after birth on the maturation of the visual relay neurons in the lateral geniculate nucleus. METHODS Fifty neonatal rats were used. Neonates of the control groups were raised under a normal light/dark cycle. Neonates of the experiment groups were dark reared and isolated from light during the entire experimental period, then exposed to the sun light for 1 hour before sacrifice. RESULTS In the control groups, the neurons in the dorsal lateral geniculate nucleus developed normally at each age tested. In the experiment groups, the cytoplasm of the large neurons in the dorsal lateral geniculate nucleus of 2-week-old rats contained small vesicles, and the cytoplasm of the large neurons of 4-week-old rats was converted into a vacuole-like space. Moreover, c-Fos immunoreactivity of the large neurons in the dorsal lateral geniculate nucleus in the experiment groups was significantly increased compared to that of the control groups. CONCLUSIONS We suppose that the maturation of the neurons in the lateral geniculate nucleus might be influenced by light stimulation during the critical period. Furthermore, c-Fos could be a marker of the functional activity of the visual relay neurons of the lateral geniculate nucleus in albino rats.