Targeted Metabolomic Pathway Analysis and Validation Revealed Glutamatergic Disorder in the Prefrontal Cortex among the Chronic Social Defeat Stress Mice Model of Depression

Abstract

Major depressive disorder (MDD) is a severe psychiatric disease that has critically affected life quality for millions of people. Chronic stress is gradually recognized as a primary pathogenesis risk factor of MDD. Despite the remarkable progress in mechanism research, the pathogenesis mechanism of MDD is still not well understood. Therefore, we conducted a liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection of 25 major metabolites of tryptophanic, GABAergic, and catecholaminergic pathways in the prefontal cortex (PFC) of mice in chronic social defeat stress (CSDS). The depressed mice exhibit significant reduction of glutamate in the GABAergic pathway and an increase of L-DOPA and vanillylmandelic acid in catecholaminergic pathways. The data of real-time-quantitative polymerase chain reaction (RT-qPCR) and Western blotting analysis revealed an altered level of glutamatergic circuitry. The metabolomic and molecular data reveal that the glutamatergic disorder in mice shed lights to reveal a mechanism on depression-like and stress resilient phenotype.

Validation of the targeted metabolomic pathway in the hippocampus and comparative analysis with the prefrontal cortex of social defeat model mice

“…The mice used here were the same animals used in our previous study where only the PFC tissue was used for research, and for which the results of behavioral tests are described in detail (Wang et al . ). In brief, after the CSDS process and behavioral tests, of the 30 mice in the social defeat group, two mice were excluded because they had open wounds exceeding 1 cm, 13 mice were stress ‐ resilient, and the rest were stress ‐ susceptible.…”

“…After the sucrose preference test, each mouse was individually placed in an open field arena (50 × 50 × 40 cm) for 5 min (Wang et al . ). Activity was recorded by a video ‐ tracking apparatus, and distance traveled, time spent in the center zone, and numbers of rearings and entries into the center zone were measured.…”

“…The process of LC ‐ MS/MS analysis was performed as previously described (Wang et al . ). In brief, using L ‐ Phe (2Cl) ‐ OH as an internal standard, brain tissue samples were diluted by a 400 μL internal standard methanol ‐ water mixed solution (4/1, v/v) and after centrifugation (14 000 g , 10 min, 4°C) the supernatant was discarded.…”

“…In brief, as previously described (Wang et al . ), the HIPPO tissues were lysed in radioimmunoprecipitation assay buffer with protease inhibitor cocktail (Beyotime Biotechnology, Shanghai, China). The proteins were separated on 8−12% SDS gels, followed by transferring to polyvinylidene difluoride membranes (Millipore, Billerica, USA).…”

“…), and glutamic acid (Glu), L ‐ 3,4 ‐ dihydroxyphenylalanine (L ‐ DOPA), and vanillylmandelic acid (VMA) alterations were found in the PFC of CSDS model mice (Wang et al . ).…”