TLR4 and Cerebral ischemia: Otherwise, DEX can increase the expression of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) or active PI3K/AKT pathway or inactive TLR-4 signaling pathway in cerebral ischemia/reperfusion injury, which suggests that many other pathways may be related to DEX-induced neuroprotection (Ma et al. 2004; Dahmani et al. 2008; Kim et al. 2017).