Glucose Transporter 1 Expression Is Regulated by Aged Garlic Extract during Cerebral Ischemia

Abstract

Aged garlic extract is obtained after prolonged hydroethanolic extraction of garlic cloves and is recognized for its high antioxidant content. Although evidence indicates that aged garlic extract delays brain ischemia-induced damage, the molecular mechanisms of this effect are unclear. Moderate concentration of reactive oxygen species induces glucose transporter 1 (GLUT1) expression that in astrocytessupports brainenergy metabolism. This has suggested that reduction of excessive reactive oxygen species formation during severe ischemia maycontribute to neuroprotection. Thus, in view of the high antioxidant properties of aged garlic extract, we investigated the effect of ischemia on GLUT1 expression and its regulation after aged garlic extract treatment. Rats were subjected to middle cerebral artery occlusion during 2 hto produce ischemia and then were sacrificed after different times of reperfusion. In fronto-parietal cortex GLUT1 mRNA expression peaked after 1and 24h of reperfusion. Nevertheless, no significant change on total protein level was observed by Western blotting, buta severe reduction on GLUT1 positive astrocytes was detected by immunofluorescence after 2 h of reperfusion. Remarkably, aged garlic extract (360 mg/kg;i.p.) administered after is chemia increased GLUT1 mRNA expressionin cortex after 2 h of reperfusion and partially prevented the middle cerebral artery occlusion-induced reduction of GLUT1 in astrocytes. These results suggest that GLUT1 over expression in astrocytes may underlie some of the beneficial effects on neuronal survival observed with aged garlic extract treatment.