Modulating bile acid isomerization and brain distribution by multiflorin A mitigates neuroendocrine stress and ameliorates anxiety-like behavioral alterations.

ETHNOPHARMACOLOGICAL RELEVANCE: Bile acids (BAs) have long been recognized in traditional ethnic medicines as a regulator of emotion and mental states; however, the underlying biological mechanisms by which BAs influence neuropsychological functions remain largely unclear. Multiflorin A (MA), an acetylated flavonoid glycoside and the signature bioactive constituent of Pruni Semen, is believed to ameliorate psychological stress via targeting the bile system. AIM OF THE STUDY: This study aimed to investigate alterations in bile acid metabolism and distribution in SPS-induced PTSD-associated anxiety-like behavioral alterations and the therapeutic effects of MA and ursodeoxycholic acid (UDCA). MATERIALS AND METHODS: SPS-stressed mice exhibiting anxiety-like behaviors were treated with MA. Behavioral tests, histopathology, targeted BAs metabolomics, metagenomics, neurotransmitter profiling, proteomics, and immunofluorescence were performed. UDCA was used as a reference compound to explore the involvement of BAs in MA-mediated neuroprotective effects. RESULTS: SPS exposure induced anxiety-like behavioral deficits, accompanied by dysregulation of systemic BAs homeostasis, characterized by peripheral BAs depletion, central accumulation of hydrophobic BAs, partial blood-brain barrier disruption, and synaptic impairment. MA and UDCA treatment significantly improved behavioral performance, alleviated histopathological damage, and partially restored gut microbiota composition and BAs profiles, including increased levels of isomerized bile acids such as UDCA and alloLCA. These changes were accompanied by restoration of tight junction, PSD-95 expression, and neurotransmitter balance. Proteomics showed partial reversal of SPS-induced synaptic and neurotransmitter dysregulation, consistent with reduced neural hyperexcitability. CONCLUSION: MA may ameliorate PTSD-associated anxiety-like behavioral alterations through modulation of the gut microbiota-bile acid-brain interactions, supporting a role for BAs metabolism in neuropsychiatric regulation.