Influence of mild hypothermia on apoptotic protease activating factor-1 protein expression in the hippocampal CA1 area and learning and memory functions of rats after diffuse brain injury

Abstract

Objective To investigate the influence of mild hypothermia on the apoptotic protease activating factor-1 (Apaf-1) protein expression in the hippocampal CA1 area and learning and memory functions of rats after diffuse brain injury (DBI). Methods Forty-eight male Wistar rats were equally randomized into normal group, sham-operated group, brain injury group and mild hypothermia treatment group (n=12). Rats in the normal group did not receive any treatment; rats in the sham-operated group only received anesthesia, and incision and suture of scalp; rats in the brain injury group and mild hypothermia treatment group were induced the DBI models according to Marmarou method; and rats in the mild hypothermia treatment group were performed hypothermia with ice blanket and ice bag to control the rectal temperature within 30.0-31.0 ℃ for 2 h. After DBI for 2 weeks, the times of searching refuge platform and the protein expression of Apaf-1 were compared among the 4 groups. Results The times of searching refuge platform in the normal group, sham operated group, brain injury group and mild hypothermia treatment group were (10.1 ±1.9), (10.3±1.8), (3.8±2.3) and (6.9±1.1), respectively,with significant differences between each 2 groups (P<0.05). The protein expression of Apaf-1 in the brain injury group and mild hypothermia treatment group was obviously higher than that in the other groups (P<0.05), and significantly lower protein expression of Apaf-1 in the mild hypothermia rats was noted as compared with that in the brain injury rats (P<0.05). Conclusion Mild hypothermia might play a protective role by inhibiting neuronal apoptosis for rats with DBI through the Apaf-1 pathway,which can improve learning and memory abilities. Key words: Craniocerebral trauma; Hippocampus; Apoptotic protease activating factor-1; Mild hypothermia