The 25(OH)D/VDR signaling may play a role in major depression.

Although the current evidences may suggest that the 25(OH)D associated with depression, still there exists conflicting results. In addition, little known is concerning the relationship between the 25(OH)D and the chronic stress-induced depressive-like behaviors. We detected the 25(OH)D levels in serum and the VDR protein expression in different brain regions aiming to explore the relationship between 25(OH)D/VDR signaling and major depression. The chemiluminescent microparticle immunoassay (CMIA) was used to detect the serum concentration of 25(OH)D in patients, the enzyme-linked immunosorbent assay (ELISA) was applied to measure the serum 25(OH)D levels in both CRS-treated and CSDS-treated mice models of MDD. Meanwhile, the VDR protein expression levels were validated among three MDD related brain regions from CRS-treated mice by western blotting. In this study, we mainly observed that the concentration of the 25(OH)D was decreased in the serum of MDD patients comparing to healthy controls. Consistent with the clinical findings, the CRS-treated mice also displayed down-regulated 25(OH)D level comparing with control mice. While in the CSDS model, the serum 25(OH)D status of depressive mice remained unchanged. Moreover, we found the protein level of VDR was significantly decreased in the hippocampus while increased in the hypothalamus of CRS-treated mice. Nevertheless, the prefrontal cortex exhibited no change regarding VDR protein expression compared with control mice. Taken together, these findings further confirmed that the 25(OH)D together with VDR may involve in the pathophysiological mechanism of depression-like behaviors induced by chronic stress.