Fecal microbiota transplantation promotes Wnt3a-mediated hippocampal neurogenesis in a rat model of chronic cerebral hypoperfusion.

BACKGROUND

Limited data support the beneficial effects of fecal microbiota transplantation (FMT) against intracranial ischemic injury under chronic cerebral hypoperfusion (CCH). However, a comprehensive understanding is lacking, hindering its clinical translation. In the present study, we evaluated microbial, metabolic, cellular, and behavioral alterations to explore the roles and mechanisms of FMT in hippocampal neurogenesis under CCH.

METHODS

Rats underwent bilateral common carotid artery occlusion to induce CCH. Intestinal microbiota (IM) and fecal/hippocampal metabolites were assessed by 16S ribosomal RNA sequencing and untargeted liquid chromatography-mass spectrometry, respectively. Potential molecular pathways and differentially expressed genes in the hippocampus were identified by RNA sequencing and verified by western blot, immunofluorescence, and dual-luciferase reporter assays. Neurogenesis was quantified by BrdU/DCX, BrdU/nestin, BrdU/GFAP, and BrdU/NeuN labeling. Cognitive function was evaluated with the Morris water maze.

RESULTS

FMT altered IM composition by enriching Verrucomicrobiae, Ruminococcaceae, Akkermansiaceae, Turicibacter, Akkermansia, Verrucomicrobiales, Oscillospirales, Verrucomicrobiota, and Akkermansia_muciniphila. These shifts were associated with significantly elevated metabolites in tryptophan- and arginine-related pathways, including fecal L-tryptophan and hippocampal L-arginine, L-glutamine, indolepyruvate, indoleacetaldehyde, and kynurenic acid. Furthermore, FMT potentiated the Wnt3a/β-catenin/Neurog2/BDNF pathway, promoting hippocampal neurogenesis. FMT-induced activation of Wnt3a/β-catenin/Neurog2 signaling also up-regulated hippocampal C3 expression, contributing to neurogenesis and cognitive recovery under CCH.

CONCLUSION

These findings provide evidence that FMT exerts protective effects against CCH insult through Wnt3a-mediated neurogenesis.