CX3CR1 and depressive symptom measurement: However, Glu and D-serine levels in DD group were significantly enhanced than those in depression and diabetes group (P < 0.05, P < 0.01); CX3CR1 blocker treatment of DD group significantly reduced the levels of Glu and D-serine in hippocampus all group (P < 0.05, P < 0.01).