SYN2 and sexually transmitted disease: As synaptic plasticity is the neurobiological basis of cognitive function,[26] we then detected the expression of hippocampal synapse‐related proteins, including synaptophysin (Syp), postsynaptic density protein‐95 (Psd‐95), growth associated protein (Gap‐43), and synapsin IIa (Syn‐IIa) in VD and sham group.