β-Asarone regulates microglia polarization to alleviate TBI-induced nerve damage via Fas/FasL signaling axis

Acute injury and secondary injury caused by traumatic brain injury (TBI) seriously threaten the health of patients. The purpose of this study was to investigate the role of β-Asarone in TBI-induced neuroinflammation and injury. In this work, the effects of β-Asarone on nerve injury and neuronal apoptosis were investigated in mice with TBI by controlled cortical impingement. The results of this research implied that β-Asarone dose-dependently decreased the mNSS score, brain water content and neuronal apoptosis, but increased the levels of the axonal markers Nrp-1 and Tau in TBI mice. In addition, β-Asarone caused a decrease in the levels of Fas, FasL, and inflammatory factors in cerebrospinal fluid and serum of TBI mice. Therefore, β-Asarone inhibited neuroinflammation and promoted axon regeneration in TBI mice. Besides, β-Asarone treatment inhibited M1 phenotype polarization but promoted M2 phenotype polarization in microglia of TBI mice. Overexpression of Fas and FasL reversed the above effects of β-Asarone. Thus, β-Asarone regulated microglial M1/M2 polarization balance in TBI mice by suppressing Fas/FasL signaling axis. In conclusion, β-Asarone inhibited Fas/FasL signaling pathway to promote the M1/M2 polarization balance of microglia toward M2 polarization, thus alleviating TBI-induced nerve injury.