Mechanisms of cell in following brain ischemia and reconstruction of disturbed function by neural graft

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Using model rats with ischemia/reperfusion in the middle cerebral artery, we investigated the mechanism of ischemic cell death and tried to reconstruct disturbed brain function by neural graft.1.Distribution of mu-calpain, its activation and neroral deathWe raised an antibody against acetylated N-terminal peptides of mu-calpain 80 KD.This antibody recognized mu-calpain proenzyme before deletion of the N-terminal. Using this antibody we found that mu-calpain proenzyme distributed very heavily in the nucleus and in lesser amount in the cytoplasm of neurons in both CNS and PNS.It does'nt distribute in any other cells except red blood cells. In the very early stage (0-30min) of the ischmia/reperfusion, the N-terminal peptides were deleted, proenzyme was transformed to an active form (calpain activation), MAP2 immunoreaction was disappeared, cytoskeleton damage was detected, and argyrophilic dark neurons were detected. COS7 cells that were transduced MAP2C cDNA by pSV.SPORT1 vecter bore MAP2-and tubulin positive processes, became resistant to glucose/oxygen-free situation, and were never argyrophilic.2.Dysfunction of the BBBTwo to three hours after reperfusion, damages in astrocytes and BBB were detected. The extravasation of IgG,complement factor (such as C3b) etc.was detected, suggesting the elevation of brain immune activity and cytotoxicity. Treatment with dexamethasone suppressed the extravasation of IgG and made the latter infarction smaller.3.Reconstruction of disturbed brain function by neural graftFetal striatal cell grafts in infarct striatum reduced the number of amphetamine-induced rotations. The grafts were detected by preloaded rhodamine fluorescene. The graft cells increased fura-2 fluorescene that indicated [Ca^<++>]_i after application of electrical stimuli (train stimuli) in the host striatum or cortex, suggesting the functional inputs to the graft from the host brain. This may in part underlie the functional amelioration following neural graft.