Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Invest Ophthalmol Vis Sci. 2012 Mar 15;53(3):1467-72. doi: 10.1167/iovs.11-9006.
The a-wave of the photopic electroretinogram (ERG) of macaque monkeys is made up of the electrical activities of cone photoreceptors and post-photoreceptoral neurons. However, it is not known whether the contributions of these two components change in retinas with inherited photoreceptor degeneration. The purpose of this study was to determine the contributions of cones and post-photoreceptoral neurons to the a-wave of the photopic ERGs in rhodopsin Pro347Leu transgenic (Tg) rabbits.
Ten Tg and 10 wild-type (WT) New Zealand White rabbits were studied at 4 and 12 months of age. The a-waves of the photopic ERGs were elicited by xenon flashes of different stimulus strengths before and after the activities of post-photoreceptoral neurons were blocked by intravitreal injections of a combination of 0.2 to 0.4 mM of 6-cyano-7-nitrouinoxaline-2,3(1H,4H)-dione, disodium (CNQX) and 2 to 4 mM of (±)-2-amino-4-phosphonobutyric acid.
The percentage contribution of the cone photoreceptors to the photopic ERG a-waves increased with increasing stimulus strength, and the percentage ranged from 54% to 75% in 4-month-old WT rabbits. In contrast, the percentage contribution of the cone photoreceptors in 4-month-old Tg rabbits ranged from 32% to 51% (P < 0.05). The mean percentage contribution of cone photoreceptors became still smaller at 11% to 48% in 12-month-old Tg rabbits.
These results suggest that the relative contribution of cone photoreceptors to the photopic ERG a-wave is smaller in retinas with inherited photoreceptor degeneration. This indicates that the a-waves of the photopic ERGs in patients with retinitis pigmentosa must consider this lower contribution from the cone photoreceptors.
灵长类动物明视闪光视网膜电图（ERG）的 a 波由视锥光感受器和光感受器后神经元的电活动组成。然而，尚不清楚这两个组成部分在遗传性光感受器变性的视网膜中是否会发生变化。本研究旨在确定视锥细胞和光感受器后神经元对视色素 Pro347Leu 转基因（Tg）兔明视闪光 ERG 的 a 波的贡献。
在 4 个月和 12 个月大时，研究了 10 只 Tg 和 10 只野生型（WT）新西兰白兔。在光感受器后神经元的活性被玻璃体腔注射 0.2 至 0.4mM 的 6-氰基-7-硝基喹喔啉-2,3(1H,4H)-二酮、二钠盐（CNQX）和 2 至 4mM 的（±）-2-氨基-4-膦酸丁酸的混合物阻断后，用不同刺激强度的氙闪光诱发明视闪光 ERG 的 a 波。
视锥光感受器对明视 ERG a 波的贡献百分比随刺激强度的增加而增加，在 4 个月大的 WT 兔中，百分比范围为 54%至 75%。相比之下，4 个月大的 Tg 兔的视锥光感受器的贡献百分比范围为 32%至 51%（P<0.05）。在 12 个月大的 Tg 兔中，平均视锥光感受器的贡献百分比仍然更小，为 11%至 48%。
这些结果表明，遗传性光感受器变性的视网膜中视锥光感受器对视明 ERG a 波的相对贡献较小。这表明，色素性视网膜炎患者的明视 ERG 的 a 波必须考虑到视锥光感受器的这种较低贡献。
