In vivo, BG45 might upregulate the level of synaptic-related genes through specifically inhibiting class I HDACs (HDAC1 and 2), further increase the expression of spinophilin, upregulate pre- and post-synaptic protein expression, thereby possibly improving synaptic plasticity in the early stage of the AD animal model. The gene discussed is PPP1R9B; the disease is Alzheimer disease.