Effect of postnatal light deprivation on the ontogenesis of dopamine neurons in rat retina.
In rats raised from birth under a regular dark-light cycle, retinal dopamine (DA) levels were low at 12 days, increased progressively and steeply at 16, 20, 30 and 60 days and peaked at about 75 days postnatally. Dark-rearing from birth suppressed the magnitude of the normal developmental pattern of DA concentrations in retina and at 20, 30 and 60 days of age they were markedly smaller compared with those in age-matched controls grown under regular cyclic illumination. In adult rats reared up to the age of 60 days in regular cyclic lighting and then transferred to complete darkness for additional periods of 7-60 days, there were marked reductions in retinal DA levels. In rats reared in total darkness for 16, 20 or 30 days after birth and then transferred to regular dark-light conditions for additional periods of up to 30 or 60 days, retinal DA levels were always higher than those in animals with continuous light deprivation. They were similar to or even higher than those in rats grown under regular dark-light cycle. Findings suggest that light stimulation is essential for the postnatal ontogenetic increases of synthesis and storage of DA within retinal DAergic neurons. Suppressed DA accumulation in retina induced by dark-rearing from birth is not irreversible and can be completely corrected by re-exposure to regular lighting conditions regardless of the durations of postnatal light deprivation.
D000818:Animals; D004298:Dopamine / Q000032:analysis*; D008027:Light; D051381:Rats; D012160:Retina / Q000254:growth & development* / Q000528:radiation effects; D009435:Synaptic Transmission; D013997:Time Factors
D004298:Dopamine