Changes In Expression Of Substance P And Calcitonin Gene-related Peptide In Retina Following Coronary Artery Occlusion And Its Intervention In Rats

Objective: The aim of the study was to investigate the changes in expression of substance P (SP) and Calcitonin gene-related peptide (CGRP) in retina following acute myocardial ischemic stress induced by coronary artery occlusion. The effect of antagonists ofα- adrenergic,β- adrenergic receptors, atropine and morphine on the up-regulation of the expression of SP and CGRP was studied.Methods: 414 adult male Sprague-Dawley rats (828 eyes) , weighing 270-300g, were randomly divided into thirteen groups (immunohistochemistry: 6 eyes/group; ELISA: 48 eyes/group) : control group; sham-operated (Sham) 0.5 hour group, 1 hour group, 3 hour group and 6 hour group; coronary artery occlusion (CAO) groups: 0.5 hour group, 1 hour group, 3 hour group and 6 hour group and medicine intervention groups: Regitine group, Esmolol group, Morphine group and Atropine 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 immunohistochemistry and EIA after CAO as scheduled.Results: (1) Substance P levels of the animals in CAO group were significantly elevated in retina comparing with control group (P<0.05) and sham groups (P< 0.05) and pecked at 3 hours after CAO. Medicine intervention could attenuate the up-regulation of expression of substance P in retina (P<0.05). (2) CGRP levels of the animals in CAO groups were significantly elevated in retina compared to control group (P<0.05) and sham groups (P< 0.05) and peaked at 3 hours after CAO. Rigitine, esmolol, morphine and atropine could attenuate the up-regulation of expression of CGRP in retina (P<0.05).Conclusions: (1) Coronary artery occlusion can provoke a significant increase of SP and CGRP in retina of rats. It demonstrates that acute myocardial ischemia, as a nociceptive stimulus, may activate the neurogenic reactions in body and SP and CGRP might play an important role in the whole process while the neurogenic mechanisms may contribute to the developments of retinal injury. (2) Rigitine, esmolol, Morphine and atropine could attenuate the expressions of SP and CGRP in retina after CAO. It may imply that mechanisms of adrenergic, opioid and acetylcholinergic receptors are involved in the reception , transfering and modulation of nociceptive information, and suppress the activation of the neurogenic mechanism induced by nociceptive stimulus.