Resveratrol modulates the Akt/GSK-3β signaling pathway in a middle cerebral artery occlusion animal model

Abstract

Cerebral ischemia is a major cause of neurodegenerative disease. It induces neuronal vulnerability and susceptibility, and leads to neuronal cell death. Resveratrol is a polyphenolic compound that acts as an anti-oxidant. It exerts a neuroprotective effect against focal cerebral ischemic injury. Akt signaling pathway is accepted as a representative cell survival pathway, including proliferation, growth, and glycogen synthesis. This study investigated whether resveratrol regulates Akt/glycogen synthase kinase-3β (GSK-3β) pathway in a middle cerebral artery occlusion (MCAO)-induced ischemic brain injury. Adult male rats were intraperitoneally injected with vehicle or resveratrol (30 mg/kg) and cerebral cortices were isolated 24 h after MCAO. Neurological behavior test, corner test, brain edema measurment, and 2,3,5-triphenyltetrazolium chloride staining were performed to elucidate the neuroprotective effects of resveratrol. Phospho-Akt and phospho-GSK-3β expression levels were measured using Western blot analysis. MCAO injury led to severe neurobehavioral deficit, infraction, and histopathological changes in cerebral cortex. However, resveratrol treatment alleviated these changes caused by MCAO injury. Moreover, MCAO injury induced decreases in phospho-Akt and phospho-GSK-3β protein levels, whereas resveratrol attenuated these decreases. Phosphorylations of Akt and GSK-3β act as a critical role for the suppression of apoptotic cell death. Thus, our finding suggests that resveratrol attenuates neuronal cell death in MCAO-induced cerebral ischemia and Akt/GSK-3β signaling pathway contributes to the neuroprotective effect of resveratrol.

Keywords: Akt; GSK-3β; MCAO; Resveratrol.

Fig. 1

Neurobehavioral scores (a), corner test (b), and brain edema measurement (c) in vehicle + sham, resveratrol + sham, vehicle + middle cerebral artery occlusion (MCAO), and resveratrol + MCAO animals. Resveratrol attenuated the neurological behavior deficits and brain edema induced by ischemic stroke. Data (n = 8) are represented as the mean ± S.E.M. * p < 0.01, ** p < 0.05 vs. vehicle + sham animals, # p < 0.05 vs. vehicle + MCAO animals

Fig. 2

Representative photograph of TTC staining (a), infarct volume (b), and hematoxylin and eosin staining (c-f) in cerebral cortex of vehicle + sham, resveratrol + sham, vehicle + middle cerebral artery occlusion (MCAO), and resveratrol + MCAO animals. Infarct volume was calculated by ratio of infarction area to total area. Resveratrol attenuated the MCAO-induced infarct region. C-F photos indicate the square areas of A. Arrows indicate shrunken and condensed nuclei and open arrows indicate swelled and vacuolated forms. Scale bar = 100 μm. Data (n = 4) are represented as the mean ± S.E.M. * p < 0.01, ** p < 0.05 vs. vehicle + sham animals, # p < 0.05 vs. vehicle + MCAO animals

Fig. 3

Western blot analysis of phospho-Akt and phospho-GSK-3β in cerebral cortex of vehicle + sham, resveratrol + sham, vehicle + middle cerebral artery occlusion (MCAO), and resveratrol + MCAO animals (a). Densitometric analysis is represented as a ratio of phospho-Akt (b) and phospho-GSK-3β (c) intensity to β-actin intensity. Data (n = 4) are shown as the mean ± S.E.M. * p < 0.01, ** p < 0.05 vs. vehicle + sham animals, # p < 0.05 vs. vehicle + MCAO animals