Protective Effects of Icariin on Traumatic Brain Injury

Background: Neuroinflammation is central to the pathology of traumatic brain injury (TBI). Icariin (ICA) is a flavonoid derived from the genus Epimedium, a traditional Chinese herb and a potential therapeutic drug for TBI. This study aims to explore the protective effect of ICA on TBI and its mechanism. Methods: Sprague-Dawley rats were exposed to controlled cortical impact to produce a neuroinflammatory response. The treatment groups received ICA (15 mg/kg, 30 mg/kg, and 60 mg/kg), while the sham group was gavaged with equal volumes of saline. The beam-balance testing and prehensile traction test were used for neurological scoring. Pathological changes were observed by H & E staining. The protein expression levels of inflammatory factors were measured by Western blot analysis. Results: It was found that ICA significantly improved the neuroethology function and alleviated the pathological injury in TBI rats. The protein expression levels of inflammatory factors COX-2, IL-1β, and TNF-α and its regulatory proteins p-NF-ΚB-p65, p-ERK1/2, p-JNK, and p-p38 were increased in the cerebral cortex injured by TBI. The protein expression levels of inflammatory cytokines were markedly decreased in the cerebral cortex of TBI rats when administrated with ICA. Conclusion: The present study demonstrates that ICA may be a promising therapeutic strategy for reducing inflammation in TBI.