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R Kehat, E Zemel, H Soreq, A Loewenstein, I Perlman; AChE Gene Expression under Functional Deficits Induced by Light Stress to the Rat Retina . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3487.
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Purpose: The potential for photoreceptors injury is substantial, yet most survive throughout animal's life. This may be due to the constant renewal of their outer segments (OS). Acetylcholinesterase (AChE) has been demonstrated in inner segments of mammalian photoreceptors. Since AChE is involved in neurite growth and stress responses, the purpose of this study was to investigate possible role of AChE in the recovery of photoreceptors from light-induced retinal damage. Methods: Albino rats were exposed to 24 hrs of bright light. Retinal function was assessed from the electroretinograms (ERGs) that were recorded 0,1,2,4,7,14 and 30 d after light exposure. The amplitudes of the ERG a-, b- waves were plotted as a function of log stimulus intensity and the curves were fitted to a hyperbolic relationship. At the same time intervals, rats were sacrificed and their eyes enucleated. AChE-S, -R mRNA levels and distributions were examined by in-situ hybridization and cytochemical staining revealed AChE activity in the presence of BChE but not AChE inhibitors. Results: After light exposure, the Vmax of a-, b- waves deteriorated till 4-7 d, then slightly recovered but remained significantly low (p<0.001). AChE-S, -R mRNA and AChE activity levels were low in normal retina, but, increased after light exposure in the inner segments (IS) of the photoreceptors, especially the AChE-R mRNA and AChE activity. This expression reduced during 30 d follow-up. Conclusion: These results suggest that the stress-induced AChE-R protein is highly expressed in rat photoreceptors in response to an exposure to damaging light. Whether this expression of AChE is beneficial and plays a role in recovery processes or a detrimental one that leads to photoreceptors death needs to be further studied.
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