Abstract: Objective To detect the effects of the pretreatment of Mdivi-1on mitochondrial membrane potential, the release of AIF, and apoptosis after acute spinal cord injury (ASCI) in rats. Methods Rats were randomly divided into sham operation group (Sham group), single spinal cord injury group (SCI group) , DMSO pretreatment group（DMSO group），Mdivi-1 pretreatment group (Mdivi-1 group). Allen's weight drop method was used to establish ASCI rat model at T10 section. The content of AIF protein in the mitochondria and nucleus in spinal cord of rats was detected by western blot. Mitochondrial membrane potential was deteced by JC-1 labeling. The number of apoptotic cells were assessed by TUNEL staining. Results Compared with Sham group , AIF in mitochondria of SCI group reduced first, then increased ,and the lowest point is 8h(P<0.01); while AIF in the nucleus showed the opposite trend(P<0.01); The mitochondrial membrane potential decreased significantly, while the number of apoptotic cells increased significantly at 8h after ASCI(P<0.01). Compared with SCI group,In Mdivi-1 group, The mitochondrial membrane potential, AIF in mitochondria increased significantly (P<0.01), however, AIF in nucleus (P<0.01) and the number of apoptotic cells reduced significantly at 8h after ASCI (P<0.01). Conclusion Mdivi-1 can protect mitochondrial membrane potential, inhibit the release of AIF in mitochondria and the apoptosis after acute spinal cord injury.

Key words: acute spinal cord injury, mitochondrial membrane potential, apoptosis-inducing factor, apoptosis, Mdivi-1