OBJECTIVETo explore the effect of mild to moderate hypothermia on the expressions of apoptosis-related genes in the brain tissue of rats after cardiopulmonary resuscitation (CPR).

METHODSCPR models were established by asphyxia in 15 male SD rats, which were randomized equally into normal temperature group, 34 degrees celsius hypothermia group and 32 degrees celsius hypothermia group. The brain tissues of the rats were obtained after treatment for 12 h to observe the pathological changes. The expression of caspase-3 in cerebral cortex neurons was determined with immunohistochemistry, and the expressions of Bcl-2 and Bax were detected by Western blotting.

RESULTSCompared with normal temperature group, the two hypothermia groups (especially 32 degrees celsius group) showed significantly decreased expression of caspase-3 in the cortical neurons (P<0.05). Bcl-2 protein expression was significantly increased in the hypothermia groups, especially in 32 degrees celsius hypothermia group (P<0.05). There was no significant difference in Bax protein expression among the 3 groups.

CONCLUSIONMild hypothermia can relieve brain injury by down-regulating caspase-3 expression and up-regulating Bcl-2 protein expression to inhibit apoptosis of the brain neurons. Hypothermia at 32 degrees celsius offers better protection of the brain tissue than hypothermia at 34 degrees celsius.