Dried bear bile exerts its antidepressant effect by modulating adrenal FXR to reduce peripheral glucocorticoid levels

Depression is a psychological disorder associated with prolonged stress, which involves abnormal activation of the hypothalamic-pituitary-adrenal (HPA) axis, leading to elevated levels of glucocorticoids (GC). Excessive GC can cause damage to the structure and function of the hippocampus, thereby triggering depressive symptoms. Studies suggest that the bile acid receptor farnesoid X receptor (FXR) may play a role in adrenal GC synthesis. This study aimed to explore the potential therapeutic effects of dried bear bile (DBB) on depression and its mechanism. We used the chronic unpredictable mild stress (CUMS) mouse model and FXR agonist GW4064 stimulated mice, as well as H295R human adrenal cortical carcinoma cells, employing behavioral tests, biochemical analysis, and gene expression analysis to assess the effects of DBB treatment on depressive behavior, serum corticosterone (CORT) levels, and adrenal FXR and steroid biosynthesis-related gene expression. The results showed that in both CUMS and GW4064-stimulated mice, DBB treatment significantly improved depressive-like behaviors and reversed serum CORT levels. Additionally, DBB suppressed the expression of steroidogenic regulatory genes in the adrenal glands of CUMS mice. In H295R cells, DBB treatment effectively reduced cortisol secretion induced by Forskolin, inhibited the expression of steroid biosynthesis-related genes, and suppressed cortisol production and HSD3B2 expression under conditions of FXR overexpression and FXR activation. Our findings suggest that DBB regulates adrenal FXR to modulate glucocorticoid synthesis and exerts antidepressant effects. DBB may serve as a potential therapeutic agent for depression by regulating GC levels and steroidogenesis pathway. Further research is underway to test the antidepressant effects of each DBB component to understand their specific contribution.