Protective effects of quercetin on traumatic brain injury induced inflammation and oxidative stress in cortex through activating Nrf2/HO-1 pathway.

Abstract

Traumatic brain injury (TBI) has been a serious public health issue. Clinically, there is an urgent need for agents to ameliorate the neuroinflammation and oxidative stress induced by TBI. Our previous research has demonstrated that quercetin could protect the neurological function. However, the detailed mechanism underlying this process remains poorly understood. This research was designed to investigate the mechanisms of quercetin to protect the cortical neurons. A modified weight-drop device was used for the TBI model. 5, 20 or 50 mg/kg quercetin was injected intraperitoneally to rats at 0.5, 12 and 24 h post TBI. Rats were sacrificed three days post injury and their cerebral cortex was obtained from the injured side. The rats were randomly assigned into three groups of equal number: TBI and quercetin group, TBI group, and Sham group. The brain water content was calculated to estimate the brain damage induced by TBI. Immunohistochemical and Western blot assays were utilized to investigate the neurobehavioral status. Enzyme-linked immunosorbent assay and reverse transcription polymerase chain reaction were performed to evaluate the inflammatory responses. The cortical oxidative stress was measured by estimating the activities of malondialdehyde, superoxide dismutase, catalase and glutathione-Px. Western blot was utilized to evaluate the expression of nuclear factor erythroid 2-related factor 2 (Nrf-2) and heme oxygenase 1 (HO-1). Quercetin attenuated the brain edema and microgliosis in TBI rats. Quercetin treatment attenuated cortical inflammatory responses and oxidative stress induced by TBI insults. Quercetin treatment activated the cortical Nrf2/HO-1 pathway in TBI rats. Quercetin ameliorated the TBI-induced neuroinflammation and oxidative stress in the cortex through activating the Nrf2/HO-1 pathway.