Functional changes in rod and cone pathways after photoreceptor loss in light-damaged rats
Functional changes in rod and cone pathways after photoreceptor loss in light-damaged rats
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DOI：
10.1080/02713680590968592
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发表时间：
2005-08-01
影响因子：
2
通讯作者：
Tazawa, Y
中科院分区：
文献类型：
--
作者：
Takahashi, T;Machida, S;Tazawa, Y
目的：研究连续光照下光感受器丧失后视杆和视锥通路的功能变化。方法：雄性Sprague-Dawley大鼠54只，于2000勒克斯漫射荧光灯照射24、48小时。光照2周后，以最大亮度为0.84 log cd-s/m的不同刺激强度激发全视野暗位和光位视网膜电图（ERGs）(2)。测量了暗位ERGs的a波和b波振幅以及光位ERGs的b波振幅。ERG记录后处死大鼠，计数外核层存活的棒状核和锥状核数量。结果：随着棒核数的减少，最大棒a波（棒Va(max)）和b波（棒Vb(max)）振幅的对数（log）单调减小（p < 0.0001）。叶片Vamax下降的回归线明显陡峭于叶片Vbmax的回归线（p < 0.005）。光敏ERGs的最大b波振幅（锥核Vbmax）与锥核数呈对数线性显著相关。杆状体Vb（max）和锥状体Vb（max）的回归线斜率分别为0.0067和0.0140，表明锥状体b波振幅受光感受器退化的影响比杆状体b波振幅更严重（p < 0.005）。结论：光损伤大鼠视杆和视锥的eeg振幅与视杆和视锥核数呈对数线性相关。当用b波评价视网膜功能时，光感受器死亡导致的功能丧失对视锥通路的影响大于对视杆通路的影响。
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/m(2). 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 Vamax decrease was significantly steeper than that for the rod Vbmax (p < 0.005). The maximum b- wave amplitudes of the photopic ERGs (cone Vbmax) 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.