The immunosuppressants cyclosporin A and FK506 equally ameliorate brain damage due to 30-min middle cerebral artery occlusion in hyperglycemic rats.

In the present experiments, we compared the anti-ischemic effects of the immunosuppressants cyclosporin A (CsA) and FK506 in hyperglycemic animals subjected to 30 min of middle cerebral artery (MCA) occlusion. Both immunosuppressants were given as pre-treatment, the effect of treatment being evaluated by 2,3, 5-triphenyltetrazolium (TTC) staining after 3 days of recovery. Both FK506 and CsA reduced the infarct volume to less than 1/3 of control. In spite of CsA's known effect as a blocker of the mitochondrial transition (MPT) pore, it failed to give a more robust effect than FK506. If anything, FK506, which lacks an effect on the MPT pore, had a more pronounced anti-ischemic effect. We conclude that, in this model of infarction, an MPT may not play a major pathogenetic role.