NOS1 and major depressive disorder: Previous studies have found that the NOS1AP SNP rs386231 was associated with an increase in the severity of depression (36), and in mouse model experiments, it has been found that the decline in viral-mediated CAPON (carboxy-terminal PDZ ligand of NOS1) in the inner prefrontal cortex significantly reversed the chronic and unpredictable depression-like behavior of mildly stressed mice (37).