DOPAMINERGIC AMACRINE NEURONS OF RAT RETINAS WITH PHOTORECEPTOR DEGENERATION CONTINUE TO RESPOND TO LIGHT
DOPAMINERGIC AMACRINE NEURONS OF RAT RETINAS WITH PHOTORECEPTOR DEGENERATION CONTINUE TO RESPOND TO LIGHT
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DOI：
10.1016/0024-3205(80)90365-3
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发表时间：
1980-01-01
期刊：
影响因子：
6.1
通讯作者：
KAMP, CW
中科院分区：
文献类型：
--
作者：
MORGAN, WW;KAMP, CW
白化大鼠暴露于低强度(350-700lx)连续光照4mo。导致视网膜外核层的光感受器节段和细胞体大量退化。只剩下几个异染色质的受体细胞核。没有光感受器片段存在。这些视网膜的内层在形态上保持完好。正常大鼠视网膜内核层含有一组无长突细胞，其神经递质为多巴胺(DA)。短期光照(30分钟或60分钟)显著刺激正常、先前黑暗适应的大鼠这些细胞中DA的更新率。大脑中神经递质更新率的提高与神经冲动活动的增加相关。对长期连续光照损伤大鼠视网膜内核层的多巴胺能无长突细胞进行了研究，以确定它们是否仍对光有反应。处死前1周，连续光照4个月。均恢复到正常14h光照：10h暗光照条件。在这一时间结束时，他们和一组对照组的大鼠被安置在循环照明条件下整整4个月。暗适应约15小时。然后根据α-甲基对酪氨酸抑制DA合成后DA的耗竭来估计视网膜DA转换率。对照组大鼠和感光细胞变性大鼠暗适应视网膜的DA周转率在短期(长达1小时)光照下显著增加2~4倍。由于大鼠是夜间活动和避光的，另一组大鼠在光照4个月后对光的厌恶。并返回到循环照明条件下1wk进行测试。这些大鼠和对照组动物在周期性光照条件下维持4mo。超过80%的人选择了明暗相间的盒子的黑暗面。视网膜退化大鼠的这种行为表明它们继续具有探测光线的能力。随着光感受器的退化，光诱导的视网膜中DA活性的增加可能在这些大鼠继续感知光的能力中发挥作用。
Exposure of albino rats to continuous light of low intensity (350-700 lx) for 4 mo. produces massive degeneration of the photoreceptor segments and cell bodies of the outer nuclear layer of the retina. Only a few heterochromatic, receptor cell nuclei remain. No photoreceptor segments are present. The inner layers of these retinas remain morphologically intact. The inner nuclear layer of the normal rat retina contains a group of amacrine cells with the putative neurotransmitter, dopamine (DA). Short-term exposure to light (30 or 60 min) markedly stimulates the rate of DA turnover in these cells in normal, previously dark-adapted rats. Enhancement of the rate of neurotransmitter turnover in the brain was correlated with an increase in nerve impulse activity. The dopaminergic amacrine cells of the inner nuclear layer were studied to determine if they were still responsive to light in the retinas of rats with destroyed photoreceptors from long-term exposure to continuous illumination. One wk before sacrifice the animals housed in continuous light for 4 mo. were returned to normal 14 h light:10 h dark lighting conditions. At the end of this time they and a group of control rats housed in cyclic lighting conditions for the entire 4 mo. were dark adapted for approximately 15 h. Then the rate of retinal DA turnover was estimated from the depletion of DA following inhibition of DA synthesis by .alpha.-methyl p-tyrosine. The turnover of DA in the dark-adapted retinas of the control rats and of rats with photoreceptor degeneration was dramatically enhanced 2- to 4-fold by short-term exposure (up to 1 h) to light. Since rats are nocturnal and avoid light, the light aversion of another group of rats which were exposed to light for 4 mo. and returned to cyclic lighting conditions for 1 wk was tested. These rats and control animals maintained in cyclic lighting conditions for 4 mo. chose the dark side of a light-dark box over 80% of the time. This behavior of the rats with retinal degeneration implied their continued ability to detect light. The light-induced increase in DA activity in retinas with photoreceptor degeneration may play a role in the continued ability of these rats to perceive light.