Chronic social defeat stress caused region-specific oligodendrogenesis impairment in adolescent mice

INTRODUCTION: Social stress in adolescents precipitates stress-related emotional disorders. In this study we aimed to investigate oligodendrogenesis in three stress-associated brain regions, medial prefrontal cortex (mPFC), habenula, and amygdala in adolescent mice exposed to social defeat stress. METHODS: Four-week-old adolescent mice were subjected to social defeat for 10 days, followed by behavioral tests and evaluations of oligodendroglial proliferation and differentiation. RESULTS: Stressed mice showed reduced social interaction, more stretched approach posture, lower sucrose preference, but no changes in the forced swimming test. EdU labeled proliferative cells, newly formed NG2(+)EdU + oligodendrocyte precursor cells (OPCs), and Olig2(+)EdU(+) oligodendrocyte lineage cells (OLLs) were significantly decreased in the mPFC and the lateral habenula, but not in the amygdala and the medial habenula in socially defeated mice. APC(+)Edu(+) newly-generated mature oligodendrocytes (OLs) were decreased in the mPFC in stressed mice. However, the total number of NG2(+) OPCs, APC(+) mature OLs, and Olig2(+) OLLs were comparable in all the brain regions examined between stressed and control mice except for a decrease of APC(+) mature OLs in the prelimbic cortex of stressed mice. CONCLUSION: Our findings indicate that adolescent social stress causes emotion-related behavioral changes and region-specific impairment of oligodendrogenesis.