Generalized induction of 72-kDa heat-shock protein after transient focal ischemia in rat brain.

The time course of 72-kDa heat-shock protein (hsp72) induction was evaluated by immunoblotting in cerebral cortex, striatum, hippocampus, cerebellum, liver, and kidney of rats subjected to 60-min focal cerebral ischemia following proximal unilateral occlusion of the right middle cerebral artery (MCA). Neurological examinations indicated that maximum deficits in reflex and sensorimotor functions occurred 24-48 h after reperfusion (40% lower than baseline), while significant recovery occurred at 72 h (33% higher than 48 h). hsp72 was present in all tissues at 6 h. The regions perfused by the occluded MCA showed a higher induction than the corresponding contralateral ones. hsp72 reached its maximum level in ipsilateral cerebral cortex and striatum at 24 h, whereas in the contralateral cortex and cerebellum the protein reached its maximum expression at 48 h, that is 24 h before functional recovery. This delay suggests a role of the protein in plastic events sustaining neurological recovery.