Impact of denervation of capsaicin sensitive sensory afferent nerves on apoptosis of retinal cells

Abstract

Objective To investigate the impact of acute stress induced by myocardial ischemia on the apoptosis of retina cells in normal rats and the rats with sensory nerve denervated, and to explore the potential protective role of sensory nerve in the pathology. Methods Twenty-four healthy adult male Sprague-Dawley rats (24 eyes), weighing 250-300g, were randomly divided into two groups: coronary artery occlusion (CAO) groups of 3 hour group and 6 hour group. Twelve denervated adult male Spraque-Dawley rats (24 eyes), weighing 250-300g, were randomly divided into denervated coronary artery occlusion (CAO) groups of 3 hour group and 6 hour group. The acute myocardial ischemia model was established by occluding the left anterior descending branch of coronary artery of the rats. The samples were processed for caspase-3 activity detection and TUNEL staining after CAO, as scheduled. Results Retinal edema was seen under the light microscope in CAO group. The apoptotic retinal cells were mainly located in inner nuclear layer, retinal ganglion cell layer, outer nuclear layer, and pigment epithelium. The apoptotic levels of the retinal cells in the animals of D-CAO group were significantly greater, comparing with normal rats in CAO groups (P ＜ 0.01). Conclusions (1) The stress induced by coronary artery occlusion could provoke a significant increase in apoptosis of rat retinal cells, which is mainly located in inner nuclear layer, retinal ganglion cell layer, outer nuclear layer and pigment epithelium. It may indicate that the stress evoked by acute myocardial ischemia, as a nociceptive stimulus,may initiate the pathology of retinal injury. (2) The stress produces a greater apoptosis of rat retinal cells in D-CAO than in CAO animals, which may imply that sensory nerves are involved in the modulation of apoptotic injury of retina. Key words: Stress; Myocardial ischemia; Retina; Apoptosis; Sensory nerve