Our previous studies showed that cysteinyl leukotriene receptor-1 (CysLT1) antagonist pranlukast has a neuroprotective effect on cerebral ischemia in rats and mice. However, whether the neuroprotective effect of pranlukast is its special action or a common action of CysLT1 receptor antagonists remains to be clarified. This study was performed to determine whether montelukast, another CysLT1 receptor antagonist, has the neuroprotective effect on focal cerebral ischemia in mice, and to observe its dose- and time-dependent properties. Permanent focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO). Montelukast was injected intraperitoneally either as multiple doses (once a day for 3 days and 30 min before MCAO) or as a single dose (at 30 min before, 30 min after, or 1 h after MCAO), respectively, and pranlukast and edaravone were used as controls. The neurological deficits, infarct volumes, brain edema, neuron density, and Evans blue extravasation in the brain were determined 24 h after MCAO. Pretreatments with multiple doses or a single dose of montelukast (0.1 and 1.0 mg/kg) before MCAO significantly attenuated all the ischemic insults. Post-treatment with a single dose of montelukast (0.1 and 1.0 mg/kg) at 30 min after MCAO also significantly decreased brain edema and infarct volume, but not neurological deficits. However, post-treatment with a single dose of montelukast at 1 h after MCAO had no significant effect. Pranlukast showed the same effects as montelukast, but edaravone attenuated the ischemic insults only with multiple doses before MCAO. Thus, montelukast has a dose- and time-dependent neuroprotective effect on permanent focal cerebral ischemia in mice, with an effective dose range of 0.1–1.0 mg/kg and a therapeutic window of 30 min. These findings further support the therapeutic potential of CysLT1 receptor antagonists in the treatment of cerebral ischemia at earlier phases.
