Anxiety-Related Behaviours Associated with microRNA-206-3p and BDNF Expression in Pregnant Female Mice Following Psychological Social Stress

Stress during pregnancy can induce various psychological disorders in women. However, the association linking psychological stress during pregnancy with abnormal behaviours in females remains largely unknown. We employed a novel psychological stress model by introducing pregnant mice to witness the defeat process of their mated partner (WDPMP) and examined the effects of WDPMP on depression-/anxiety-like behaviours and on the expression of brain-derived neurotrophic factor (BDNF) and miR-206-3p in the hippocampus, medial prefrontal cortex (mPFC) and amygdala. Compared to pregnant control (PC) mice, pregnant stressed (PS) mice showed decreased sucrose preference during the late period of gestation, and after lactation, they spent less time in the open arms of the elevated plus maze and in the light chamber of the light/dark box. After lactation, decreased BDNF expression in both the hippocampus and mPFC of PS mice was found to be associated with enhanced miR-206-3p levels; meanwhile, elevated BDNF associated with decreased miR-206-3p expression was evident in the amygdala of the same PS mice. DNA methylation level in the Bdnf promoter did not show difference between PC and PS mice in the hippocampus. Transfection of miR-206-3p resulted in decreased BDNF levels in vitro. These results suggest that WDPMP stress during gestation can induce long-term mood alterations in pregnant mice, which may correlate with changes in miR-206-3p and BDNF expression in the hippocampus, mPFC and amygdala.