Melamed E, Frucht Y, Vidauri J, Uzzan A, Rosenthal J
Brain Res. 1986 May;391(2):280-4. doi: 10.1016/0165-3806(86)90293-2.
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.
在出生后处于正常明暗周期饲养的大鼠中，视网膜多巴胺（DA）水平在12天时较低，在16、20、30和60天时逐渐且急剧升高，并在出生后约75天时达到峰值。从出生开始黑暗饲养抑制了视网膜中DA浓度正常发育模式的幅度，在20、30和60日龄时，与在正常周期性光照下生长的年龄匹配对照组相比，其DA浓度明显较小。在正常周期性光照下饲养至60日龄，然后转移到完全黑暗环境中再饲养7 - 60天的成年大鼠中，视网膜DA水平显著降低。在出生后在完全黑暗中饲养16、20或30天，然后转移到正常明暗条件下再饲养长达30或60天的大鼠中，视网膜DA水平始终高于持续光照剥夺的动物。它们与在正常明暗周期下生长的大鼠相似，甚至更高。研究结果表明，光刺激对于视网膜多巴胺能神经元内DA合成和储存的出生后个体发育增加至关重要。出生后黑暗饲养诱导的视网膜中DA积累受抑制并非不可逆转，并且无论出生后光照剥夺的持续时间如何，重新暴露于正常光照条件下都可以完全纠正。
