Gut microbiota drives dietary lignans to improve perimenopausal depression via activating hippocampal ERβ/GluN2A/PSD95 pathway

Dietary lignans (Diet-LIG) are a class of estrogenic plant polyphenols whose improve potential for perimenopausal depression (PMD), a condition driven by estrogen deficiency, remains unexplored. This study aims to investigate whether Diet-LIG intake can alleviate perimenopausal depressive symptoms and to explore the underlying mechanisms. The randomized controlled trial conducted in the study revealed that one-month supplementation significantly alleviated depressive and anxiety symptoms and elevated serum estradiol in perimenopausal women. This clinical benefit was associated with increased fecal levels of gut bacterial metabolites (enterolactone and enterodiol) the enzyme β-glucuronidase, and the enrichment of specific bacteria, notably Bacteroides ovatus. Animal studies showed that Diet-LIG upregulated ERβ protein expression in the hippocampal tissue of PMD mice. KEGG analysis of hippocampal proteomics showed that differentially expressed proteins between the Diet-LIG intervention and PMD groups were primarily enriched in the glutamatergic synapse pathway. Golgi staining and Western blot analysis confirmed that Diet-LIG supplementation improved neuronal plasticity, with significantly increased expression of GluN2A and PSD95 proteins. Humanized fecal microbiota transplantation experiments and in vitro cell interventions with Bacteroides ovatus monoculture medium revealed that the antidepressant effects of Diet-LIG are not directly mediated solely by the modulated gut microbiota, but instead rely on the bioactivity of metabolites produced through gut microbiota-driven conversion. In vitro validation experiments, the knockdown of ERβ in HT22 cells significantly suppressed GluN2A and PSD95 expression and blocked their induction by Diet-LIG metabolites. In conclusion, gut microbiota drives Diet-LIG to activate hippocampal ERβ, which regulates the GluN2A/PSD95 pathway and enhances hippocampal neuronal plasticity, thereby ameliorating perimenopausal depressive symptoms. (Chinese Clinical Trial Registry [ChiCTR], ID Number: ChiCTR2400082537.).