Neuroprotective effect of pretreatment with Mentha longifolia L. extract on brain ischemia in the rat stroke model

Recent studies have suggested that Mentha longifolia L. extracts (ME) have anti-inflammatory and antioxidant activities. In this paper, we attempted to determine the effect of ME in a rat stroke model. Five groups of experimental animals were used (n=14); the first and second groups (control and sham, respectively) received intraperitoneal injections of daily-distilled water; the other three groups received 50, 100, and 200 mg/kg/day of ME for 21 days. Two hours after the last dose, each group was subdivided into a middle cerebral artery occlusion (MCAO) group operated for neuropathological assessment (neurologic deficit scores, infarct volume, brain edema, and blood-brain barrier (BBB) permeability), and an intact subgroup for the assessment of brain and serum antioxidant capacity and lipid peroxidation, respectively. Pretreatment with ME resulted in a significant reduction in total infarct volume, brain water content and Evans Blue extravasation in the ischemic hemisphere compared with the control. ME in doses of 100 and 200 mg/kg/day increased brain antioxidant capability in comparison with the control. The antioxidant capacity of the serum in the 100 mg/kg/day group was significantly higher than that of the control group. The level of malondialdehyde (MDA) in the brain was significantly elevated in the control group in comparison with other pretreated groups. Moreover, ME in doses of 100 and 200 mg/kg/day reduced the MDA level in the serum. This study showed that intraperitoneal injection of ME reduced infarct volume, brain edema, blood-brain barrier permeability, as well as lipid peroxidation, and improved antioxidant power