Abstract: Objective To screen altered proteins of hippocampus in the stress-induced depression (STRID) rat model, and explore the potential molecular mechanism. Methods Twenty Sprague-Dawley rats were randomly divided into the control group and STRID group, 10 rats in each group. Chronic unpredictable mild stress (CUMS) methods including fasting for solids and liquids, electric foot-shock, reversing day and night, cold water swimming, cage tilt, scare stimulation and tail pinch were conducted on STRID rats with no repeats for 28 days to make up the depression animal model. The control group was normally fed during this period. After the stress stimulation, the hippocampus protein samples were used for two dimensional electrophoresis to screen the differentially expressed protein, and then mass spectrum identification and function analyze were conducted. Results Compared with the control group, 34 proteins were altered in STRID group. Among which, 18 were up-regulated, and 16 were down-regulated. The differentially expressed proteins mainly located in cytoplasm, mitochondrion, extracellular exosome and myelin sheath. The involved signaling pathways included metabolic pathway, oxidative phosphorylation pathway, and Alzheimer’ s disease, Parkinson’ s disease and Huntington’ s disease pathways. Conclusion The altered proteins and dysfunction of nerve signaling, and the excess of oxidative phosphorylation in hippocampus of STRID rats may be one of the pathogenesises.

Key words: depressive disorder, proteomics, electrophoresis, gel, two-dimensional, mass spectrometry, rats, SpragueDawley, chronic unpredictable mild stress, stress-induced depression