Traumatic brain injury (TBI) signifies a major cause of death and disability. TBI causes central nervous system (CNS) damage under a variety of mechanisms, including protein aggregation, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Astrocytes and microglia, cells of the CNS, are considered the key players in initiating an inflammatory response after injury. Several evidence suggests that activation of astrocytes/microglia and ROS/LPO have the potential to cause more harmful effects in the pathological processes following traumatic brain injury (TBI). Previous studies have established that lupeol provides neuroprotection through modulation of inflammation, oxidative stress, and apoptosis in Aβ and LPS model and neurodegenerative disease. However, the effects of lupeol on apoptosis caused by inflammation and oxidative stress in TBI have not yet been investigated. Therefore, we explored the role of Lupeol on antiapoptosis, anti-inflammatory, and antioxidative stress and its potential mechanism following TBI. In these experiments, adult male mice were randomly divided into four groups: control, TBI, TBI+ Lupeol, and Sham group. Western blotting, immunofluorescence staining, and ROS/LPO assays were performed to investigate the role of lupeol against neuroinflammation, oxidative stress, and apoptosis. Lupeol treatment reversed TBI-induced behavioral and memory disturbances. Lupeol attenuated TBI-induced generation of reactive oxygen species/lipid per oxidation (ROS/LPO) and improved the antioxidant protein level, such as nuclear factor erythroid 2-related factor 2 (Nrf2) and heme-oxygenase 1 (HO-1) in the mouse brain. Similarly, our results indicated that lupeol treatment inhibited glial cell activation, p-NF-κB, and downstream signaling molecules, such as TNF-α, COX-2, and IL-1β, in the mouse cortex and hippocampus. Moreover, lupeol treatment also inhibited mitochondrial apoptotic signaling molecules, such as caspase-3, Bax, cytochrome-C, and reversed deregulated Bcl2 in TBI-treated mice. Overall, our study demonstrated that lupeol inhibits the activation of astrocytes/microglia and ROS/LPO that lead to oxidative stress, neuroinflammation, and apoptosis followed by TBI.
Keywords: cognitive impairment; glia activation; lupeol; neurodegenerative diseases; neuroinflammation; oxidative stress; traumatic brain injury.