Objectives To investigate the effects of activation of Autophagy on cerebral injury after cardiopulmonary resuscitation (CPR) in Wistar rat.
Methods First 36 healthy adult male Wistar rats were induced ventricular fibrillation (VF) by alternating current for 7 minutes and then received CPR. Before VF (0) and at 1, 2, 4, 8 and 12 hours after return of spontaneous circulation (ROSC), cerebral cortex were harvested to determine the expressions of beclin-1 and LC3II by Weston blot. Further 60 healthy adult male Wistar rats were used to observe the effects of Autophagy activator Rapamycine (Rapamycine group, 20), Autophagy inhibitor 3-Methyladenine (3-MA group, 20) and Normal saline (Control group, 20) on the expressions of beclin-1, LC3II and the formation of autophagic vacuole in the cerebral cortex after ROSC. The neurologic deficit score (NDS) was used to evaluate the neurologic function at 24, 48 and 72h respectively after ROSC. The numbers of viable neurons and apoptotic neurons in the parietal cortex were counted by H&E staining and TUNEL staining after 72h. One-way ANOVA was used for the expressions of beclin-1 and LC3II and neurons counting. Rank sum test was used for NDS.
Results The expressions of beclin-1 and LC3 II were significantly lower at 2 and 4h after ROSC than the levels before VF (P < 0.05). The expressions of beclin-1 and the conversion of LC3 II in cerebral cortex at 2 and 4h after ROSC in the Rapamycine group were significantly higher than that in Control group and 3-MA group (P < 0.05). The numbers of autophagic vacuole in the Rapamycine group at 2 and 4h after ROSC were significantly higher than the Control and 3-MA group. The number of viable neurons at 72h after ROSC in the Rapamycine group was 19 ± 516 ± 4/400pixs, higher than 16 ± 4/400pixs in Control group and 15 ± 3/400pixs in 3-MA group (P < 0.05). The number of the TUNEL positive cells in the Rapamycine group was 12 ± 4/400pixs and was lower than 15 ± 6/400pixs in the Control group and 17 ± 5/400pixs in 3-MA group (P < 0.05). The NDS scores of animals in Control group and 3-MA group at 24, 48 and 72h after ROSC were inferior to Rapamycine group.
Conclusions The Autophagy of neurons in the cerebral cortex was attenuated in Wistar rats after ROSC. The activation of Autophagy can decrease the number of apoptotic neurons, preserve viable neurons and improve neurologic function.