Purpose:Huannao Yicong Decoction (HYD) is a herbal formula that has long been used for the treatment of Alzheimers disease (AD).Although the therapeutic effect of HYD has been previously characterized in animal studies,but do not involve at cellular levels.In present study,we sought to explore the influence of HYD extract on the level of β-amyloid peptide (Aβ),presenilin (PS1)-associated protein and ultrastructure of human APP/PS1 double Transgenic cell.Approach:The viability of cells was evaluated using CCK-8 assay.The ultrastructures of cells were investigated with transmission electron microscope (TEM),the concentrations of Aβ1-40,Aβ1-42 and APP in the supernatant were determined by EUSA,the levels of PS1-associated proteins were determined by Western-blot analyses.Results:Treated Sprague Dawley (SD) rats with HYD extract at 5 times clinical equivalent dose and demonstrated a significant increase in cell activity with 15% drug serum as compared to control (P=0.001).TEM analysis demonstrated that AD cell models ultrastructure was destroyed,however,following 48h of treatment with HYD extract,the ultrastructure was relieved to a varying degree.Moreover,HYD extract could inhibit the production of APP,Aβ1-40 and Aβ1-42 protein.Similarly,48h of HYD extracttreatment inhibited PS1 protein expression while activated CDC42 protein expression.Conclusions:HYD extract can be used to treat AD.Mechanistically,HYD extract appears to decrease activity of PS1 protein by promoting the expression of CDC42.At the same time,HYD extract can inhibit lipid peroxidation,enhance vitality of neurons,reduce the production of Aβ1-40,Aβ1-42,APP.