Expression and interaction of TNF-α and VEGF in chronic stress-induced depressive rats

The incidence of depression increases annually but the pathogenesis is not yet fully understood. The aim of the present study was to explore the expression and interaction of tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) in chronic stress-induced depressive rats. A total of 20 adult healthy Sprague Dawley rats (180-220 g) were randomly divided into the control and experimental depression groups. The depression model was established with a chronic stress method, and the success of model construction was assessed through weigh measurements and the sugar consumption and open-field tests. The expression of TNF-α and VEGF was detected using the reverse transcription quantitative polymerase chain reaction (RT-qPCR), western blotting and immunohistochemistry. Compared with the control group, the weight of the rats in the experimental group was found to be reduced (P<0.05). The open-field test showed significant differences in the horizontal and vertical motion of the rats between the two groups, and the rats in the experimental group exhibited a significantly reduced ability to adapt to a new environment (P<0.05). Furthermore, the sensitivity of the rats in the experimental group to reward stimulation was decreased. The relative mRNA expression levels of TNF-α and VEGF in the hippocampus of the experimental group were lower than those in the control group, and western blot analysis revealed that the protein expression of VEGF and TNF-α was reduced in the experimental group. Neurons of the experimental group exhibited reduced immunohistochemical staining compared with neurons from the normal hippocampus in the control group. In conclusion, the present study investigated the association between the occurrence of depression and TNF-α and VEGF at the mRNA and protein levels using RT-qPCR, western blotting, immunohistochemistry and animal behavior experiments. The results provide a fundamental basis for follow-up clinical research.