Quantitative Proteomics Reveal the Protective Effects of the Combined Chinese Herbal Extracts Against Alzheimer's Disease via Modulating the Expression of Synapse-associated Proteins in Mouse Model

Abstract

BackgroundAlzheimer's Disease (AD) as an age-related, irreversible neurodegenerative disease, characterized by cognitive dysfunction, has become progressively serious as a result of a global increase in life expectancy. As more mechanism of AD were discovered, therapeutic strategies using traditional Chinese medicine are under investigation for AD treatment, with efforts to improve efficacy and clarify the mechanism. Gastrodia, elata Blume, Polygala tenuifolia Willd., Cistanche deserticola Ma, Rehmannia lutinosa (Gaertn.)DC.,Acorus gramineus Aiton, and Curcuma longa L. are well-known chinese herbs with neuroprotective effects and widely used as a combination in traditional Chinese decoction for AD treatment. The purpose of this study was to investigate the synergistic protective efficacy of the combination (composed of extracts from these six Chinese medicines, CuraUltra), and the protein targets on scopolamine-induced cognitive impairment, using the proteomics analysis.MethodsScopolamine-induced cognitive impairment mouse model was established. Behavioral tests, Nissl Staining, cerebral cholinergic system alterations and neuronal apoptosis characteristics were examined to evaluate the ameliorating effects of CuraUltra on cognitive impairment induced by scopolamine. To identify the potential molecular mechanism responsible for the effect on CuraUltra treatment, label-free quantitative proteomics by tandem mass spectrometry (LC-MS/MS) were performed. Critical altered proteins were validated by qPCR and Western blotting. Molecular docking was finally performed to evaluate the binding potential of chemical components with the target proteins.Results Administration of CuraUltra significantly recovered scopolamine-induced cognitive impairment, as evidenced by the improved learning and memory ability, reduced pathological damage of hippocampus, increased content of Ach, decreased activity of AchE, and ameliorated expression levels of the neuronal apoptosis-related protein in the hippocampus of mice. Using quantitative proteomics technology, we observed 252 differentially expressed proteins. Compared with the model group, after CuraUltra treatments, a remarkedly alteration in PPP3CC, PKA, P38MAPK, RASA4, DNAJB1, SNAPIN was also observed. Notably, several significant proteins are in the glutamatergic synapse signaling pathway. Moreover, we confirmed that the PPP3CC appears to decreased as the AD pathological development, and may be positively correlated with the phosphorylation level of PKA, thereby inhibiting the activation of P38MAPK phosphorylation.ConclusionsAdministration of CuraUltra was effective on alleviating scopolamine-induced cognitive impairment, which might be through modulation of glutamatergic synapse. Consequently, our quantitative proteome data obtained from scopolamine-treated model mice successfully characterized AD-related biological alterations and proposed novel protein biomarkers for AD.