Esculetin attenuates cerebral ischemia-reperfusion injury and protects neurons through Nrf2 activation in rats.

Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) is a key transcription factor in the antioxidant response and is associated with various chronic diseases. The aim of this study was to explore the action of esculetin, a natural dihydroxy coumarin, on attenuating middle cerebral artery occlusion (MCAO) and reperfusion, and whether its effect is dependent on Nrf2 activation, as well as nuclear factor-kappa B (NF-κB) inhibition. Two doses of esculetin (20 and 40 mg/kg) were tested on rats with MCAO reperfusion. Neurological deficiency, oxidative stress, and pathological analyses were performed to evaluate its effect. An in vitro analysis was also used to confirm whether its action was dependent on the Nrf2/HO-1/NQO-1 pathway. Compared with MCAO reperfusion rats, esculetin improved infarct volume and increased normal-shaped neuron cells by decreasing tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-1β levels. The oxidative stress parameter malondialdehyde (MDA) decreased and the activity of superoxide dismutase (SOD) and glutathione/glutathione disulfide (GSH/GSSG) ratio increased after esculetin treatment. Moreover, esculetin inhibited NF-κB activation induced by MCAO. In vitro, hypoxia/reoxygenation (H/R) impaired the viability of rat neuron cells and esculetin showed a neuron protection effect on cells. Nrf2 inhibitor Brusatol inhibited the activation of Nrf2, heme oxygenase-1 (HO-1), and NAD(P)H quinone oxidoreductase 1 (NQO-1) caused by esculetin and abolished its protection effect. Esculetin protected cerebral neurons from ischemia-reperfusion injury by inhibiting NF-κB and Nrf2/HO-1/NQO-1 activation.