CYCLOSPORINE-A PREVENTS ISCHEMIA-INDUCED REDUCTION OF MUSCARINIC ACETYLCHOLINE-RECEPTORS WITH SUPPRESSION OF MICROGLIAL ACTIVATION IN GERBIL HIPPOCAMPUS

We previously reported the late onset reduction of muscarinic acetylch oline receptors (LORMAR) which begins 7 days after a 5-min period of e xperimentally induced forebrain ischemia in the gerbil hippocampus. Th is study demonstrated that post-ischemic administration of cyclosporin A (CsA) reduced LORMAR 10 days after 5 min of forebrain ischemia in t he gerbil hippocampus, suggesting that immunosuppression by CsA may re duce damage to the cholinergic system after ischemia. Microglia positi ve for HLA-DR class II antigen which presented in the hippocampal CA1 area, the region most vulnerable to ischemia, were also reduced by CsA . CsA may suppress microglial activation especially with regard to the antigen-presenting function, and LORMAR may be attenuated by this mod ulation of microglial function.