Vitexin reverses the autophagy dysfunction to attenuate MCAO-induced cerebral ischemic stroke via mTOR/Ulk1 pathway

Stroke, as a kind of acute cerebrovascular diseases, has greatly influenced the patients' quality of life and left a huge public health burden. Vitexin is a flavone C-glycoside (apigenin-8-C-β-D-glucopyranoside) present in several medicinal and other plants. This study aims to explore the role of vitexin in middle cerebral artery occlusion (MCAO)-induced cerebral ischemic stroke. The results showed that the MCAO-induced brain infarction was obviously decreased by vitexin. And the abnormal protein levels of Caspase-3, Bcl-2-associated X protein (Bax), antigen identified by monoclonal antibody (Ki-67) and B cell lymphoma 2 (Bcl-2) in MCAO model rats were reversed by vitexin. Further research indicated that vitexin alleviated MCAO-induced oxidative injury by reducing the levels of lactate dehydrogenase (LDH), malondialdehyde (MDA) and nitric Oxide (NO). In addition, vitexin attenuated the secretion of pro-inflammatory cytokine (interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α)) and increased anti-inflammatory cytokine (IL-10) production to ameliorate MCAO-induced inflammation. What's more, vitexin repressed the MCAO-induced autophagy through mechanistic target of rapamycin (mTOR)/Ulk1 pathway. Specifically, the MCAO-induced decreased expression of mTOR, peroxisome proliferator-activated receptor γ (PPARγ) and p62 were inhibited by vitexin. At the same time, MCAO-induced increased expression of Ulk1, Beclin1 and rate of LC3Ⅱ/LC3Ⅰ also were repressed by vitexin. But the inhibition of vitexin on the MCAO-induced oxidative injury, apoptosis and inflammation were reversed by rapamycin. These results implied that vitexin suppressed the autophagy dysfunction to attenuate MCAO-induced cerebral ischemic stroke via mTOR/Ulk1 pathway.