TLR4 and Cognitive impairment: H2S may reduce cognitive impairment through the inhibition of endoplasmic reticulum stress, caspase-12, CHOP, and TLR4 /NF-κB; a decrease in the level of TNF-α, IL-1β and IL-6, Sirt1, ROS, LP, CPR78, CHOP, caspase-12, Bax; and an increase in synapsin-1 and PSD-95, Bcl-2, HO-2, M2-RK, LDHA, and PDK in the hippocampus.