Genistein-3'-sodium sulfonate improves neuroinflammation, blood-brain barrier function, and microglial activation after chronic cerebral hypoperfusion by regulating TGR5.

This study investigated the effects of genistein-3'-sodium sulfonate (GSS) on chronic cerebral hypoperfusion (CCH) and the involvement of Takeda G-protein-coupled receptor 5 (TGR5) (also known as GPBAR1 (G protein-coupled bile acid receptor 1)) in its mechanism of action. In a mouse model of CCH, induced by bilateral common carotid artery stenosis (BCCAS), GSS treatment was combined with stereotaxic injection of TGR5 siRNA or expression vectors. Anxiety and depressive behaviors were evaluated using the elevated plus maze, light-dark box, tail suspension, and forced swim tests. Histological changes and blood-brain barrier (BBB) integrity were assessed by hematoxylin and eosin and Evans blue staining. Furthermore, an in vitro low-glucose hypoxia (LGH) microglia activation model was used. Protein and mRNA levels of TGR5, tight junction proteins, microglial markers, inflammatory molecules and caspase-3 were measured by western blotting and qRT-PCR. GSS treatment or TGR5 overexpression reversed the LGH-induced decrease in BV2 cell viability, whereas TGR5 knockdown had the opposite effect. In CCH mice, GSS or TGR5 overexpression improved behavior, alleviated histopathology, reduced injury scores and preserved BBB integrity. Along with these changes, TGR5, ZO-1, claudin-5, and CD206 increased, while the expression of IBA-1, iNOS, CD40, CD68, NF-κB p65, IL-1β, and caspase-3 decreased at protein and mRNA levels. In addition, TGR5 silencing promoted the effects of BCCAS and LGH. Overexpressing TGR5 promoted the effects of GSS, while TGR5 silencing partly abrogated these effects. These findings indicate that GSS can inhibit microglial mobilization and neuroinflammation by activating TGR5, offering a potential targeted therapy for cerebral ischemia and mitigating behavioral changes in CCH through TGR5 regulation.