Rats were injected with DMSO, pioglitazone or rosiglitazone 24 hours before and at the time of MCAO. Infarction volume was assayed 24 hours after MCAO (A). Rosiglitazone, 0.1 mg/kg, significantly reduced infarction volume at 24 hours, although rosiglitazone 0.05 mg/kg did not. Protection was lost with higher doses (B; Mann-Whitney U p=0.002; n=16 (vehicle); n=5 (0.05 mg/kg); n=4 (0.1 mg/kg), n=7 (0.35mg/kg and 1mg/kg). Pioglitazone at doses of 1.0 and 3.5 mg/kg significantly reduced infarction volume at 24 hours, although doses of 0.5 and 7 mg/kg were not significantly different from DMSO treated rats [C; Mann-Whitney U; p=0.001 for 1mg/kg and p<0.05 for 3.5mg/kg; n=16 (DMSO); n=8 (0.5 mg/kg); n=7 (1mg/kg); n=8 (3.5 mg/kg); n=5 (7mg/kg)]. Bars represent S.E.M.