Isorhamnetin Alleviates Inflammation-Induced Crosstalk between Kynurenine Pathway and Gut Microbiota in Depressed Mice

Depression is a widespread psychiatric disorder with complex pathogenesis and unsatisfactory therapeutic effects. As a native flavonoid, Isorhamnetin (ISO) has been deemed to exert neuroprotective effects by antioxidation and regulation of immunity. However, no reports of anti-depressed effect of ISO have yet been found. The present study was conducted to clarify the mechanism basis of anti-depressed effect of ISO utilizing behavioral, biochemical, molecular approaches in vitro and in vivo and bio-informatics analysis. The effects of ISO on depressed mice was investigated through the SPT and FST, and the lesions were examined by H&E staining. Besides, the inflammatory factor and indicator in kynurenine pathway were assessed through detection kits, and the microbiota were checked by 16sRNA. Molecular docking study was performed to investigate the target of ISO. Additionally, Western blot was used to test the activation of PI3K/AKT signaling pathway. The results indicated that ISO could enhance the sugar water preference of mice in SPT and reduce immobility time in FST. Further more, ISO suppressed peripheral and central inflammation, regulated the changes in kynurenine pathway and gut microbiota, inhibited activation of PI3K/AKT pathway, and presented good binding patterns with target proteins on PI3K/AKT signaling pathway. Collectively, these findings demonstrate that ISO alleviated depression-like behaviour by normalizing inflammation-induced dysregulation of the crosstalk between KP and gut microbiota disorder through regulated PI3K/AKT/NF-kappa B pathway.