Major depressive disorder (MDD) has become a potential cause of death and disability among young people worldwide. Numerous studies have indicated that the different cerebrospinal fluid (CSF) proteins may be used as mediums for MDD. Given the emergent interest of CSF proteins in MDD, we validated proteins expression in the choroid plexus (CP), the brain region that produces CSF in the lateral ventricle, the third ventricle, and the fourth ventricle of the central nervous system (CNS). The CSF constantly exchanges molecular substances with the brain tissue, which can dynamically reflect the metabolic microenvironment of the brain. In our previous study, Pepsin A (PGA) and periostin (POSTN) was associated with depressive-like behaviors of depressed macaca fascicularis models in CSF. Moreover, proteins that are expressed in the CP can be secreted into the CSF and may be associated MDD. This study sought to demonstrate the discrepancy of PGA and POSTN in the CP between Lipopolysaccharide (LPS)-induce depressed mice models and wild type (WT) mice. Our findings suggest that PGA and POSTN expression in CP of mice could be a possible candidate pathogenesis involved in MDD, which may contribute to a better understanding and treatment of MDD. (C) 2020 Elsevier Inc. All rights reserved.