AN IMMUNOSUPPRESSANT, FK506, PROTECTS HIPPOCAMPAL-NEURONS FROM FOREBRAIN ISCHEMIA IN THE MONGOLIAN GERBIL

We examined whether an immunosuppressant, FK506, inhibits delayed neur onal death in the gerbil hippocampal CA1 sector after 5-min forebrain ischemia. After reperfusion, gerbils were injected intravenously with FK506. Gerbils in the early injection group were injected with FK506 i mmediately after reperfusion, and gerbils in the delayed injection gro up were injected with FK506 1 or 2 h postischemia. The body temperatur e of the FK506-treated gerbils in the normothermic group was maintaine d at 37.5-38.0 degrees C for 2 h postischemia. In the chronic survival group, neuroprotection was assessed after recovery for 45 days. Seven or 45 days after reperfusion, neuronal density in the CA1 was assesse d following perfusion fixation. FK506 ameliorated cell death in the CA I in a dose-dependent manner in every group, although it showed a hypo thermic effect. FK506 is neuroprotective against forebrain ischemia in gerbils.