Background: Learning and memory impairments are important indexes in assessing Alzheimer's disease (AD). Lonicera japonica (L. japonica), a traditional Chinese herbal medicine, inhibits inflammation, but its role in neuroprotection is unclear. Polysaccharide is the main active ingredient in L. japonica. Here, we aimed to validate the effects of L. japonica polysaccharide (LJP) on lipopolysaccharide (LPS)-induced cognitive impairment and the underlying mechanism.
Methods: The Chinese medicine system pharmacology database and analysis platform was used to predict the target of L. japonica; the GeneCards system was used to predict the AD target. We also performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Experiments were performed after bioinformatic analysis for verification. A chronic learning and memory impairment model was established by a single administration of LPS. Learning and memory abilities of Kunming mice were examined after 7 days of induction. The protective effects of LJP on LPS-induced impairment were investigated. Neuronal damage was observed by Nissl staining. Key proteins involved in the autophagy pathway were examined.
Results: Bioinformatic analysis showed that there were 151 genes in the intersection of the target and ADrelated genes, and KEGG analysis suggested that these genes may act via multiple pathways. LPS-induced changes in learning and memory in mice were significantly attenuated by LJP. Nissl staining revealed that the neurons in the control group were lost and cellular arrangement was disrupted. LJP alleviated the pathological changes in the neurons of mice. The autophagy pathway was selected to verify the mechanism. ATG5, Beclin 1, Vps34, and LC3 II expression in the LPS group was significantly increased, and it was further increased in the LJP group.
Conclusions: LJP improved behavioral changes and neuronal loss associated with LPS-induced learning and memory impairments. The underlying mechanism may be related to the regulation of the autophagy pathways.
Keywords: L. japonica polysaccharide (LJP); Network pharmacology; autophagy; cognitive impairment; lipopolysaccharide (LPS).