Figure 4. The molecular mechanisms of the neuroprotective effect of icariin. Icariin improves neuronal autophagy through the AMPK/mTOR/ULK1 pathway; It attenuates neuroinflammation by inhibiting TAK1/IKK/NF-κB and HMGB1/RAGE pathways; It reduces neuronal apoptosis by suppression of PERK/eIF2α, JNK/p38 MAPK, and PI3K/AKT pathways.