光损伤大鼠光感受器丧失后视杆和视锥通路的功能变化

Functional changes in rod and cone pathways after photoreceptor loss in light-damaged rats.

作者信息

Takahashi Tomomi, Machida Shigeki, Masuda Tomoyuki, Mukaida Yasuko, Tazawa Yutaka

机构信息

Department of Ophthalmology, Iwate Medical University, School of Medicine, Morioka, Iwate, Japan.

出版信息

Curr Eye Res. 2005 Aug;30(8):703-13. doi: 10.1080/02713680590968592.

DOI:10.1080/02713680590968592

PMID:16109651

Abstract

PURPOSE

To determine the functional changes in the rod and cone pathways after photoreceptor loss by continuous light exposure.

METHODS

Fifty-four male Sprague-Dawley rats were exposed to diffuse fluorescent light of 2000 lux for 24 or 48 hr. Two weeks after the light exposure, full-field scotopic and photopic electroretinograms (ERGs) were elicited by different stimulus intensities with a maximum luminance of 0.84 log cd-s/m2. The amplitudes of the a- and b-waves of the scotopic ERGs and the b-wave of the photopic ERGs were measured. The animals were sacrificed after the ERG recordings, and the number of surviving rod and cone nuclei in the outer nuclear layer was counted.

RESULTS

The logarithm (log) of the amplitudes of the maximum rod a-wave (rod Va(max)) and b-wave (rod Vb(max)) was reduced monotonically with a decrease in the rod nucleus counts (p < 0.0001). The regression line for the rod Va(max) decrease was significantly steeper than that for the rod Vb(max) (p < 0.005). The maximum b-wave amplitudes of the photopic ERGs (cone Vb(max)) were significantly correlated with the number of cone nuclei in a log-linear fashion. The slopes of the regression lines for the rod Vb(max) and cone Vb(max) were 0.0067 and 0.0140, respectively, which indicates that the amplitude of the cone b-wave was more severely affected than that of the rod b-waves by light-induced photoreceptor degeneration (p < 0.005).

CONCLUSIONS

The amplitudes of the rod and cone ERGs were correlated with rod and cone nuclei counts in a log-linear fashion in light-damaged rats. The functional loss from the photoreceptor death had a greater effect on the cone pathway than on the rod pathway when the retinal function was assessed by the b-wave.

摘要

目的

通过持续光照确定光感受器丧失后视杆和视锥通路的功能变化。

方法

将54只雄性Sprague-Dawley大鼠暴露于2000勒克斯的漫射荧光下24或48小时。光照两周后，用最大亮度为0.84 log cd-s/m2的不同刺激强度诱发全视野暗视和明视视网膜电图（ERG）。测量暗视ERG的a波和b波以及明视ERG的b波的振幅。在ERG记录后处死动物，计数外核层中存活的视杆和视锥细胞核的数量。

结果

最大视杆a波（视杆Va(max)）和b波（视杆Vb(max)）振幅的对数（log）随着视杆细胞核数量的减少而单调降低（p < 0.0001）。视杆Va(max)降低的回归线比视杆Vb(max)的回归线明显更陡（p < 0.005）。明视ERG的最大b波振幅（视锥Vb(max)）与视锥细胞核数量呈对数线性显著相关。视杆Vb(max)和视锥Vb(max)回归线的斜率分别为0.0067和0.0140，这表明光诱导的光感受器变性对视锥b波振幅的影响比对视杆b波的影响更严重（p < 0.005）。