Co-Treatment with the Herbal Medicine SIP3 and Donepezil ImprovesMemory and Depression in the Mouse Model of Alzheimer’s Disease

BACKGROUND: Alzheimer's disease (AD) is a lethal, progressive neurodegenerative disorder that has been linked to a deficiency of the neurotransmitter acetylcholine. Currently, many acetylcholinesterase inhibitors, such as donepezil, are widely used for the treatment of AD. On the other hand, the efficacy of long-term donepezil use is limited. SIP3, a mixture of three herbal extracts from Santalum album, Illicium verum, and Polygala tenuifolia, is a new formula derived from traditional Korean herbal medicine. OBJECTIVE: We assessed the synergistic effect of SIP3 and donepezil co-treatment on symptoms of AD using APP/PS1 transgenic mice. METHODS: In this study, a Drosophila AD model and SH-SY5Y clles were used to assess the toxicity of SIP3, and APPswe/PS1dE9 (APP/PS1) transgenic mice were used to evaluate the cognitive-behavioral and depression-like behavior effect of SIP3 and donepezil co-treatment on symptoms of AD. The cerebral cortex or hippocampus transcriptomes were analyzed by RNA sequencing and miRNA to investigate the molecular and cellular mechanisms underlying the positive effects of SIP3 on AD. RESULTS: In the passive avoidance test (PAT) and Morris water maze (MWM) test, the combination of SIP3 and donepezil improved the learning capabilities and memory of APP/PS1 mice in the mid-stage of AD compared to the group treated with donepezil only. In addition, co-administration of SIP3 and donepezil effectively reduced the depression-like behavior in the forced swimming and tail suspension tests. Furthermore, RNA sequencing of the cerebral cortex transcriptome and miRNA of the hippocampus showed that the gene expression profiles after a low dose SIP3 co-treatment were more similar to those of the normal phenotype mice than those obtained after the donepezil treatment alone. The Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, showed that differentially expressed genes were involved in the locomotor behavior and neuroactive ligand-receptor interactions. These results suggest that a co-treatment of low dose SIP3 and donepezil improves impaired learning, memory, and depression in the mid-stage of AD in mice. CONCLUSION: Co-treatment of low dose SIP3 and donepezil improves impaired learning, memory, and depression in the mid-stage of AD in mice.