Gut-Brain Axis-Based Polygala Tenuifolia and Magnolia Officinalis Improve D-gal-Induced Cognitive Impairment in Mice Through cAMP and NF-κB Signaling Pathways

Dan Yang,1 Wen Li,1 Qiuping Chen,1 Si Liu,1 Chengjie Peng,1 Fengcheng Deng,1 Yingqi Meng,1 Yang Yang,1 Ping Yan,1 Hui Ao,1,2 Lihua Huang1,2 1School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, People’s Republic of China; 2State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, 611137, People’s Republic of ChinaCorrespondence: Hui Ao; Lihua Huang, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, People’s Republic of China, Email [email protected]; [email protected]: Polygala tenuifolia Willd. (PT) is commonly used to address cognitive impairment (CI), while Magnolia officinalis Rehd. et Wils (MO) is often prescribed for gastrointestinal issues as well as CI. This study seeks to explore the impacts and mechanisms behind the combined therapy of PT and MO (PM) in treating CI, based on the concept of the gut-brain axis.Methods: The characteristic components of PT, MO, and PM were identified using ultra-high performance liquid chromatography-tandem triple quadrupole mass Spectrometry (UPLC-MS/MS). A mouse model was established by D-gal induction, and the effects of PT, MO, and PM on CI were evaluated through behavioral tests, pathological staining, and Enzyme-Linked Immunosorbent Assay (ELISA). Subsequently, network pharmacology was used to analyze the potential mechanisms by which PM improves CI, followed by validation through Western blotting (WB), traditional Chinese medicine (TEM), Immunofluorescence (IF), and 16S rRNA.Results: PT, MO, and PM can each alleviate cognitive decline and neuropathological damage in D-gal mice to varying degrees, reduce the expression of pro-inflammatory factors (TNF-α, IL-1β, IL-6, IFN-γ, LPS) in serum or hippocampal tissue, and increase SOD and GSH levels. Network pharmacology analysis and molecular experiments confirmed that PM upregulates the expression of tight junction s (TJs), enhances the expression of proteins in the cAMP pathway, and inhibits p-NF-κB-p65 expression. PM reverses D-gal-induced gut microbiota dysbiosis, increases the abundance of SCFA-producing bacteria, and decreases the abundance of LPS-producing bacteria.Conclusion: PM alleviates CI by reducing inflammation and oxidative stress, protecting the blood-brain barrier (BBB) and intestinal barrier, inhibiting the NF-κB pathway, activating the cAMP pathway, and regulating gut microbiota. Keywords: polygala tenuifolia, magnolia officinalis, cognitive impairment, cAMP Signaling Pathway, NF-κB Signaling Pathway, gut microbiota