Neuronal hyperexcitability and oxidative stress play critical roles in neuronal cell death in
stroke. Therefore, we studied the effects of (2S,3S,4R)-N?-cyano-N-(6-amino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxymethyl-2H-
benzopyran-4-yl)-N'-
benzylguanidine (KR-31378), possessing both
antioxidant and K(+) channel-modulating activities, on
brain ischemia-
reperfusion injury models. Treatment with
KR-31378 (30 mg/kg, i.v.) significantly reduced
infarct area and
edema by 24% and 36%, respectively, in rats subjected to 2 h of
middle cerebral artery occlusion and 22 h of reperfusion with significant attenuation of elevated lipid peroxidation (99% of normal) and
glutathione loss (60% of normal) in ischemic hemisphere. We further studied its neuroprotective mechanism in fetal rat primary mixed cortical culture. Incubation of cortical neurons with
KR-31378 protected FeSO(4)-induced cell death in a concentration-dependent manner (IC(50)=12 microM). Its
neuroprotective effect was neither mimicked by other K(+) channel openers nor abolished in the presence of
ATP-dependent K(+) channel (K(
ATP)) blockers, indicating that its effect was not related to K(+) channel opening activity. The mechanism of protection is rather attributable to the
antioxidant property of
KR-31378 since it suppressed the intracellular accumulation of
reactive oxygen species and ensured lipid peroxidation by 120% and 80%, respectively, caused by FeSO(4). We further studied its effect on
antioxidant defense, enzymatic and nonenzymatic systems. Treatment of neurons with FeSO(4) resulted in decrease of
catalase (8% of control) and
glutathione peroxidase (14% of control) activities, which were restored by
KR-31378 treatment (70% and 57% of control, respectively). In addition, it attenuated the depletion of
glutathione contents (60% of control) caused by FeSO(4). These results suggest that
KR-31378 exerts a beneficial effect in focal
ischemia, which may be attributed to its
antioxidant property.