Regional expression of Bcl-2 mRNA and mitochondrial cytochrome c release after experimental brain injury in the rat

Regional levels of anti-apoptotic Bcl-2 mRNA and the cytosolic cytochrome c protein were measured after lateral fluid percussion (FP) brain injury in rats. Levels of Bcl-2 mRNA were significantly decreased in the injured left cortex (IC) and ipsilateral hippocampus (IH), but not in the contralateral right cortex (CC) and hippocampus (CH) after brain injury. Levels of Bcl-2 rnRNA were significantly decreased as early as 2 h and stayed decreased as long as 48 h in the: IC and IH in after injury. Levels of the cytosolic cy tochrome protein were significantly increased in the IC and IH, but not in the CIC and CH after brain injury. Levels of cytosolic cytochrome c were si gnificantly increased in the IC at 30 min, 48 and 72 h, and in the IH at 2 h and as long as 72 h after injury. The increase of cytosolic cytochrome c suggests that the mitochondrial release of cytochrome is increased in the I C and IH after lateral FP brain injury. These data show that the reduction of anti-apoptotic Bcl-2 and increases of mitochondrial release of cytochrom e c protein occur only in the IC and IH, regions which have been observed t o undergo apoptosis rand neuronal cell loss after lateral FP brain injury. Therefore, it is likely that the reduction of Bcl-2 and the increased cytoc hrome c protein in the cytosol contribute to the observed apoptosis and neu ronal cell death in the IC and In after lateral FP brain injury in rats. (C ) 2001 Published by Elsevier Science B.V.