Electrophysiological And Morphological Properties Of Retinal Ganglion Cells In RCS Rats During Retinal Degeneration

Purpose: To study the electrophysiological and morphological properties of RCS rats retinal ganglion cells during retinal degeneration. To explore the changes of the functional properties and morphological properties of RCS rats retinal ganglion cells and to explore the relations between the changes of RGCs and retinal whole function and morphology during retinal degeneration.Methods: RCS rats, control and normal rats are adopted. Examine the whole retinal fuction by checking F-ERG. Then one retina was stained by HE and contralateral retina was prepared for retinal slices. Whole cell recordings were made from retinal ganglion cells in three kinds of rats. Compare the RMP, IR, and threshold, amplitude, wave-width, frequency of action potential of RGCs in three kinds of rats. Retinal ganglion cells were stained by Lucifer Yellow which was injected into cells during whole cell recordings for the purpose of morphological study of RGCs.Results: 1. Photoreceptors of RCS rats were degenerated progressively. At late stage of retinal degeneration the structures of RPE and PRC layer were disorganized. But the morphology of inner nuclear layer and RGC layer appeared normal.2. The amplitude of a wave and b wave of F-ERG decreased gradually and presented with silent-pattern when and after postnatal 7 weeks.3. Three different discharge patterns of RGCs in response to maintained depolarizing currents were recorded, which were single firing, transient firing and sustained firing. The proportions of each firing type changed significantly during postnatal development. There were no significant differences of the proportion of three AP types between RCS, normal and control rats within 6-week old age. During postnatal 7-8 weeks the proportions of transient firing were 35.7% and 37.5% respectively, and that of sustained firing was 64.3% and 62.5% respectively in normal and control rats. The proportions of transient firing and sustained firing in RCS rats were 46.7% and 26.7% respectively. During this period there were some RGCs without action potential (26.7%) in RCS rats. But there was no same phenomena in normal and control rats. During postnatal 9-12 weeks the proportions of sustained firing were 72.7% and 71.4% respectively, which were significantly higher than that of transient firing, 27.3% and 28.6% respectively in normal and control rats. But the patterns of AP in RCS rats RGCs changed greatly. The proportions of transient firing (21.1%) and sustained firing (10.5%) in RCS rats decreased significantly. The ability of sustained firing in RCS rats decreased. At the same time RGCs with no AP appeared frequently (62.2%). And a single firing RGCs appeared.4. The electrophysiological properties of RCS rats changed significantly during retinal degeneration. At the early stage the RMP were same between RCS rats and normal rats, which were all high. Then decreased gradually. At the late stage RMP and IR fluctuated greatly, and there were significant differences of RMP and IR between RCS rats and normal rats(P<0.05). The active membrane properties of RCS rats also changed greatly. During early stage development the amplitude of AP increased and the threshold of AP decreased. But during late stage they fluctuated greatly(P<0.05). The stable and maximal frequency of RCS rats appeared same with that of normal rats during early stage development, but decreased greatly in late stage(P<0.01). The response of stable and maximal frequency to different depolarizing currents was lower than that of normal and control rats(P<0.05).5. During late stage when the photoreceptors and the whole function of retina decreased severely there were still some RGCs remaining good functions of firing. .6. The transient firing type existed during the whole development period. The proportion of sustained firing type in RCS rats decreased and that of transient firing type was higher than sustained firing type during late stage.7. There were no significant differences of the morphological properties of RGCs dyed by Lucifer Yellow between RCS rat...