DLG4 and Cognitive impairment: Although anesthesia and surgery can destroy the hippocampal synaptic plasticity of POCD rats, downregulate synapsin-I, PSD95, SYP, and GAP43, decrease synaptic length, number, branches, and density, and increase synaptic gap width, these effects can be reversed by young plasma, which suggests that young plasma improves cognitive impairment caused by surgery and anesthesia in aged rats by improving synaptic plasticity.