[Effects of mitochondrial division inhibitor on neurological function and neuronal apoptosis in rats after cardiopulmonary resuscitation].

OBJECTIVE: To investigate the effects of mitochondrial division inhibitor 1 (mdivi-1) in rats after cardiopulmonary resuscitation (CPR) and its mechanism.

METHODS: Fifty Sprague-Dawley (SD) rats were randomly (random number table) divided into sham group (n = 8), cardiac arrest (CA) model group (n = 14), dimethyl sulfoxide post-treatment control group (DMSO group, n = 14), and mdivi-1 post-treatment group (mdivi-1 group, n = 14). Asphyxial CA was reproduced in animals, and they were resuscitated by CPR. In the mdivi-1 group or DMSO group, the animals were given mdivi-1 (1.2 mg/kg) or DMSO (0.1%) intravenously after restoration of spontaneous circulation ( ROSC ). The neurological functions were assessed using neurological deficit score (NDS) determined at 24, 48 and 72 hours after CPR. The brain tissues were harvested at 72 hours after CPR. The histopathologic changes were assessed by hematoxylin and eosin (HE) staining, and the normal neuron was counted. The neuronal apoptosis was assessed with terminal dexynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, and the expressions of cytochrome C (Cyt-C) protein in mitochondria and cytoplasm from hippocampus were determined by Western Blot.

RESULTS: NDS in all experiment groups was gradually increased after CPR, and they were significantly lower than those of the sham group at 24, 48, and 72 hours (51.5 ± 3.7 vs. 80.0 ± 0.0, 59.3 ± 3.6 vs. 80.0 ± 0.0, 66.7 ± 2.6 vs. 80.0 ± 0.0, all P < 0.05). The number of normal pyramidal neurons in the hippocampal CA1 region was markedly reduced (cells/HP: 4.4 ± 1.1 vs. 23.1 ± 4.0, P < 0.05), the apoptotic index was significantly increased [(86.9 ± 6.9)% vs. (3.4 ± 0.8)%, P < 0.05], the expressions of Cyt-C in mitochondria were significantly decreased (A value: 0.46 ± 0.18 vs. 1.00 ± 0.00, P < 0.05), and the expressions of Cyt-C in cytoplasm were significantly up-regulated (A value: 6.65 ± 0.21 vs. 1.00 ± 0.00, P < 0.05). Compared with the CA group, NDS at 24 hours and 48 hours in mdivi-1 group was slightly increased (55.2 ± 3.3 vs. 51.5 ± 3.7, 64.7 ± 2.4 vs. 59.3 ± 3.6, both P > 0.05), and it was significantly increased at 72 hours (74.5 ± 2.3 vs. 66.7 ± 2.6, P < 0.05), the number of normal pyramidal neurons in the hippocampal CA region was markedly increased (cells/HP: 16.2 ± 2.4 vs. 4.4 ± 1.1, P < 0.05), the apoptotic index was dramatically reduced [(42.3 ± 3.9 )% vs. (86.9 ± 6.9 )%, P < 0.05], the expressions of Cyt-C in mitochondria were significantly increased (A value: 0.83 ± 0.22 vs. 0.46 ± 0.18, P < 0.05), and the expressions of Cyt-C in cytoplasm were significantly decreased (A value: 3.84 ± 0.47 vs. 6.65 ± 0.21, P < 0.05). There was no statistically significant difference in above indexes between CA group and DMSO group.

CONCLUSION: By inhibiting mitochondrial Cyt-C apoptotic pathway to reduce neuronal apoptosis in rats after CA-CPR, mdivi-1 can improve brain function after CPR.