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

Abstract

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.

Keywords: Chronic unpredictable mild stress; Depression; Dried bear bile; Farnesoid X receptor; Glucocorticoid.

Fig. 1

The effect of DBB on depressive-like behavior in CUMS mice (A) Establishment and drug administration procedure of the CUMS model; (B) Sucrose preference in SPT (N = 8/group); (C) Immobility time in TST (N = 8/group); (D) Immobility time in FST (Brown-Forsythe and Welch ANOVA test with Dunnett T3 multiple comparisons test, N = 8/group). One-way ANOVA with Dunnett multiple comparisons test, **p < 0.01, ***p < 0.001 vs. CUMS group, ^###p < 0.001 vs. Control group. Results are presented as means ± SD. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 2

The effect of DBB on CORT production and its synthesis process in CUMS mice (A) Serum CORT levels (Brown-Forsythe and Welch ANOVA test with Dunnett T3 multiple comparisons test, N = 8/group); (B) Western blotting analysis and quantification of FXR in CUMS mice; (C–E) Q-PCR analysis of adrenal FXR, STAR and HSD3B2 (N = 3/group). One-way ANOVA with Dunnett multiple comparisons test, *p < 0.05, **p < 0.01, ***p < 0.001 vs. CUMS group, ^#p < 0.05, ^##p < 0.01, ^###p < 0.001 vs. Control group. Results are presented as means ± SD. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 3

The effect of DBB on behavior and serum CORT levels induced by GW4064 in mice (A) The administration process of GW4064 and BBP; (B) Sucrose preference in SPT (N = 6/group); (C) Immobility time in TST (N = 6/group); (D) Immobility time in FST (N = 6/group); (E) Serum CORT levels (N = 6/group). One-way ANOVA with Dunnett multiple comparisons test, *p < 0.05, **p < 0.01 vs. GW4064 group, ^##p < 0.01, ^###p < 0.001 vs. Control group. Results are presented as means ± SD.

Fig. 4

The inhibitory effect of DBB on Forskolin-induced cortisol secretion in H295R cells (A) Cell viability under co-treatment with forskolin and different concentrations of BBP (N = 5/group); (B) The cortisol content in H295R cells (N = 4/group); (C–E) Q-PCR analysis of adrenal STAR, HSD3B2 and CYP21A2 (N = 3/group). One-way ANOVA with Dunnett multiple comparisons test, *p < 0.05, **p < 0.01, ***p < 0.001 vs. Forskolin group, ^###p < 0.001 vs. Control group. Results are presented as means ± SD.

Fig. 5

The effect of DBB on H295R cells transfected with FXR overexpression plasmids and treated with GW4064 (A) Western blotting analysis and quantification of FXR in H295R cells; (B) Q-PCR analysis of FXR in H295R cells; (C) Cell viability of H295R cells transfected with FXR overexpression plasmids (N = 5/group); (D) Cortisol content in H295R cells transfected with FXR overexpression plasmids (N = 3/group); (E) Q-PCR analysis of adrenal HSD3B2 (N = 3/group); (F) Cell viability of H295R cells after treatment with GW4064 (N = 5/group); (G) Cortisol content in H295R cells after treatment with GW4064 (N = 3/group); (H) Q-PCR analysis of adrenal HSD3B2 (N = 3/group). One-way ANOVA with Dunnett multiple comparisons test, *p < 0.05, ***p < 0.001 vs. FXR group, ^$$p < 0.01, ^$$$p < 0.001 vs. GW4064 group, ^###p < 0.001 vs. Control group. Results are presented as means ± SD.