CD38 is a multifunctional enzyme, mediating the synthesis and hydrolysis of cyclic ADP-ribose (cADPR) from NAD to ADP-ribose.CD38 has been studied in a wide range of cellular processes such as cell cycle regulation, gene expression, insulin secretion, and transmitter release via Ca2+ signaling pathway.Moreover,.a recent paper has revealed the role of CD38 as a molecule critical for social behavior by regulating oxytocin secretion.However,the roles of CD38 in hippocampus-dependent synaptic plasticity and behavior are largely unknown.In this study, we found that adult CD38 KO mice showed partial defects in L-LTP maintenance at SC-CA1 synapses.In addition, this physiological deficit was accompanied by the impairment in novel object recognition task.These results suggest that CD38 is a key molecule for L-LTP maintenance at hippocampus SC-CA1 synapses, thereby regulating some types of hippocampus-dependent memory formation.