Effect of U—74389G on apoptosis and bcl—2 expression following traumatic brain injury in rats

Objective To investigate the relationship of oxidative stress with apoptosis and bcl-2 expression following traumatic brain injury (TBI). Methods Male SD rats were subjected to lateral fluid percussion brain injury (FPI) of moderate severity. U-74389G (20 mg/kg) was administered intravenously before FPI. The neurological functions were estimated by beam-walk test and beam-balance test. In addition to morphological evidence of apoptosis, TUNEL histochemistry was used to identify DNA fragmentation in situ at both light and electron microscopic levels. Whereas characteristic of internucleosomal DNA fragmentation of apoptosis was demonstrated by DNA gel electrophoresis. Bcl-2 protein expression was detected by immunohistochemistry. Results The scores of beam-walk test and the beam-balance test were significantly improved (P<0.01) in the treated animals. The treatment significantly reduced the number of apoptotic cells that we counted in the areas from ipsilateral to the injured hemisphere at various time points following TBI. No DNA ladder was detected in the treated rats. Bcl-2 expression was observed in the cerebral cortex, subcortical white matter, dentate gyrus, and hippocampal CA1 and CA3 region ipsilateral to injured hemisphere. Bcl-2 positive cells displayed normal nuclear morphology. Little Bcl-2 positive cells revealed morphological feature of apoptosis or necrosis. The immunoreactivity of Bcl-2 protein decreased significantly in the hippocampus ipsilateral impact site as early as 6 hours after injury. In the U-74389G treated groups, the down-regulation of bcl-2 expression was halted. Conclusions U-74389G may block oxidative stress and halt the down-regulation of bcl-2 expression. These may be one of the molecular mechanisms of the neuroprotective effects by U-74389G.