Vanillic acid attenuates Aβ_1-42-induced oxidative stress and cognitive impairment in mice

Increasing evidence demonstrates that β-amyloid (Aβ) elicits oxidative stress, which contributes to the pathogenesis and disease progression of Alzheimer's disease (AD). The aims of the present study were to determine and explore the antioxidant nature and potential mechanism of vanillic acid (VA) in Aβ_1-42-induced oxidative stress and neuroinflammation mediated cognitive impairment in mice. An intracerebroventricular (i.c.v.) injection of Aβ_1-42 into the mouse brain triggered increased reactive oxygen species (ROS) levels, neuroinflammation, synaptic deficits, memory impairment, and neurodegeneration. In contrast, the i.p. (intraperitoneal) administration of VA (30 mg/kg, for 3 weeks) after Aβ_1-42-injection enhanced glutathione levels (GSH) and abrogated ROS generation accompanied by an induction of the endogenous nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) via the activation of Akt and glycogen synthase kinase 3β (GSK-3β) in the brain mice. Additionally, VA treatment decreased Aβ_1-42-induced neuronal apoptosis and neuroinflammation and improved synaptic and cognitive deficits. Moreover, VA was nontoxic to HT22 cells and increased cell viability after Aβ_1-42 exposure. To our knowledge, this study is the first to reveal the neuroprotective effect of VA against Aβ_1-42-induced neurotoxicity. Our findings demonstrate that VA could potentially serve as a novel, promising, and accessible neuroprotective agent against progressive neurodegenerative diseases such as AD.