Objective: We investigated the effect of icariin (ICA) combined with Panax notoginseng  saponins (PNS) on intestinal microbiota and hippocampal protein expression in amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice, a model of Alzheimer’s disease (AD).
Methods: Transgenic mice were treated with icariin and PNS. The Morris water maze (MWM) was used to assess spatial memory, and the gut microbiota and differential protein expression in the hippocampus were investigated using high-throughput screening techniques. Differential protein expression was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting.
Results: The MWM results showed that the mice treated with the medium dose of ICA+PNS spent significantly more time in the target quadrant compared with the AD group. Bacterial diversity was the lowest in the AD group, with significantly greater diversity in the ICA + PNS treatment group. Three proteins were selected for proteomic analysis, and qRT-PCR and Western blot were used to detect the expression of 2ʹ-5ʹ-oligoadenylate synthetase ubiquitin like 1 (Oasl1), trichoplein keratin filament-binding protein (TCHP), and tumor necrosis factor receptor associated 3-interacting protein 1 (MIPT3). Compared with control mice, MIPT3 expression was increased and Oasl1 and TCHP were reduced in the AD group. These abnormal protein expressions tended to normalization after treatment with medium dose of ICA and PNS.
Conclusion: Treatment with ICA and PNS ameliorated memory impairment in an AD mouse model. The mechanisms may be related to modulation of the intestinal microbiota and expression of Oasl1, TCHP, and MIPT3.
Keywords: Alzheimer’s disease, icariin, Panax notoginsenoside, gut microflora, proteomics, Morris water maze