Changes in expression of autophagy-related proteins, Beclin-1 and LC3, and effects of rapamycin on their expression in hypoxic-ischemic hippocampus

Abstract:

Objective To observe changes in the expression of autophagy-related proteins, Beclin-1 and LC3, in the hippocampal tissue of neonatal rats with hypoxic-ischemic brain damage (HIBD) at different time points, and to investigate the effect of rapamycin (Ra) on the expression of the above two proteins. Methods A total of 108 7-dayold Sprague-Dawley rats were randomly divided into sham, HIBD, and Ra groups (n=36 each). The HIBD model was established using the modified Rice method. For sham rats, only the left common carotid artery was separated without ligation or hypoxic treatment. For Ra-treated rats, 0.5 mg/kg Ra was administered by an intraperitoneal injection 1 hour before model establishment. The rats were anesthetized and sacrificed to collect brain tissues at 0, 6, 12, 24, 48, and 72 hours after model establishment. Changes in the expression of Beclin-1 and LC3 proteins in rat hippocampus were examined by Western blot. Results The expression level of Beclin-1 in HIBD rats began to increase at 0 hour, peaked at 24 hours, and then declined thereafter, similar as those of Beclin-1 and LC3-II in Ra-treated rats. The expression level of LC3-II in HIBD rats began to increase at 0 hour, peaked at 12 hours, and then declined thereafter. At all time points, both Beclin-1 and LC3-II expression levels were significantly higher in HIBD and Ra-treated rats than in sham rats (P<0.05); except LC3-II at 12 hours, Beclin-1 and LC3-II expression levels were significantly higher in Ra-treated rats than in HIBD rats (P<0.05). Conclusions Hypoxia-ischemia activates autophagy in rat hippocampal cells, while Ra enhances the expression process of autophagy.