Biology Research Division, Graduate School of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan.
Neurosci Lett. 2010 Mar 31;473(1):62-6. doi: 10.1016/j.neulet.2010.02.023. Epub 2010 Feb 18.
In the light-adapted vertebrate retina, nitric oxide (NO) modulates synaptic transmission between photoreceptors and second-order neurons. Although NO is believed to be a mediator of adaptation, its effect on photoreceptors in situ is not known yet. Therefore, we studied rod and cone activities in rat eyes in situ, using the electroretinogram (ERG). Rod and cone ERGs were functionally isolated by intravitreal 20mM glutamate, which suppressed the activity of all retinal cells except rods and cones for about 90min. The addition of NO-donor, SNAP, to the glutamate solution decreased the amplitude of the rod single-flash ERG by approximately 40%, compared to the amplitude of the rod ERG isolated by glutamate alone, but it increased the amplitude of the isolated, intense paired-flash cone ERG by approximately 40%. An excess of the NO-scavenger, CPTIO, had no significant effect on either rod or cone ERGs. A broad-spectrum NO-synthase inhibitor, L-NAME, increased the amplitude of the rod ERG by approximately 50%, but had no significant effect on the cone ERG. We suggest that NO directly modulates the light-evoked activity of rod and cone photoreceptors in situ, but in opposite ways.
在光适应的脊椎动物视网膜中，一氧化氮（NO）调节光感受器和二级神经元之间的突触传递。尽管 NO 被认为是适应的介质，但它对原位光感受器的影响尚不清楚。因此，我们使用视网膜电图（ERG）在原位研究大鼠眼睛中的杆状和锥状细胞活动。通过玻璃体内注射 20mM 谷氨酸可将杆状和锥状细胞 ERG 功能分离，该方法可抑制除杆状和锥状细胞以外的所有视网膜细胞的活性约 90 分钟。与单独使用谷氨酸分离的杆状单闪光 ERG 相比，将 NO 供体 SNAP 添加到谷氨酸溶液中会使杆状单闪光 ERG 的幅度降低约 40%，但会使分离的强对闪光锥状 ERG 的幅度增加约 40%。过量的 NO 清除剂 CPTIO 对杆状和锥状 ERG 均无明显影响。一种广谱的 NO 合酶抑制剂 L-NAME 会使杆状 ERG 的幅度增加约 50%，但对锥状 ERG 无明显影响。我们认为，NO 直接调节原位杆状和锥状光感受器的光诱发活性，但方式相反。
