Furthermore, we found that HINT1 plays a role in a social isolation (SI) mouse model, characterized by behavioral abnormalities similar to those in schizophrenia, and potential interactions among HINT1, N-methyl-D-aspartate receptor (NMDAR), and DA type 2 receptor (D2R) may underlie the schizophrenia-like behavioral deficits induced by SI [39, 40]. The gene discussed is DRD2; the disease is schizophrenia.