Immunohistochemical expression of Bcl-2, Bax and cytochrome c following focal cerebral ischemia and effect of hypothermia in rat

Recent studies suggest that mild hypothermia significantly alleviate damage following cerebral ischemia though the precise mechanism is poorly defined . In the present study, middle cerebral artery occlusion (MCAo) was induced in Sprague-Dawley (SD) rats for 1 h followed by varying periods of reperfu sion. Cerebral infarcts identified by hematoxylin & eosin (H&E) staining re vealed extensive lesion in normothermic (NT) 37 degrees C and small lesion in hypothermic (HT) 33 degrees C group of rats. Immunohistochemical analysi s revealed Bcl-2 was induced in many neurons of HT group, while Bar and cyt ochrome c was induced in few neurons. In situ detection of DNA fragmentatio n using 3'-OH end labeling method (terminal dUTP nick-end labelling (TUNEL) ) indicated, higher number of TUNEL-positive cells in NT group, but signifi cantly decreased in HT group. The expression pattern revealed many neurons at the penumbra region could survive in HT group whereas, many neurons are committed to die in NT group. Our results suggest that hypothermia is selec tively interfering at more than one place and providing protection. (C) 200 0 Elsevier Science Ireland Ltd. All rights reserved.