The expiession and function of molecular chaperone in the central nervous system.

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Recently, it has been realized that molecular chaperone is implicated in the protein folding. Chaperonin being composed of two subunits, HSP60 and HSP10 that is one the member of molecular chaperones act in the late stage of the normal protein systhesis. However, the role of chaperonin under the stress condition including ischemic insults has not been fully understood yet. In this study, we investigated the anatomical and chronological patterns for the induction of hsp 60 and hsp 10 genes after cerebral ischemia.1) Focal cerebral ischemia. Using middle cerebral artery occlusion model in Sprague-Dawley rats, the distribution of hsp60 and hsp10 mRNA was examined by in situ hybridization technique and RTPCR. After 30 min of temporary MCA occlusion, both mRNAs were induced in the only ischemic cortex until 24 h of recirculation. In 90 min occlusion, both mRNAs were induced in the periphery of the MCA territory and were also induced in the ipsilateral hippocampus that is distant from the ischemic regions. The induction was maximal at 8 h of recirculation.2) Forebrain ischemia. The ischemic model was produced by the combination of hypotension and bilateral carotid artery occlusion. Both mRNAs were induced in the dentate gyrus first and then in the CA1-4 of hippocampus, putamen, and cerebral cortex. 24 h after 10 min of ischemia, the induction of both mRNAs returned to the control level except in the CA1 sector. However, the expression of both mRNAs in the CA1 disappeared after 4 days of recirculation consistent with the occurrence of the delayed neuronal death.This study clearly demonstrated the anatomical and chronological pattern of both hsp60 and hsp10 mRNAs following either focal or forebrain ischemia in rat for the first time. Since the induction pattern of hsp60 and hsp10 are completely consistent, chaperonin seems to be implicated in the repair of the protein systhesis under the ischemic conditions.