THE ATTENUATION OF ?-AMYLOID PEPTIDE 25-35-INDUCED Tau HYPERPHOSPORYLATION IN CORTICAL NEURONS BY THE REGULA-TION OF GINSENOSIDE Rg1 ON THE ACTIVITY OF GSK-3? and PP2A / 解剖学报

ABSTRACT

Objective To explore whether ginsenoside Rg1 can attenuate ?-amyloid peptide 25-35-induced Tau hyperphosporylation in rat embryo cortical neurons by regulating the activity of GSK-3? and PP2A. Methods Primary cultures of cortical neurons were prepared from the embryonic day 18?2 in Sprague-Dawley rats. The experimental groups were designed as follows1.Neurons culture (control group); 2. Neurons exposed to 20?mol/L A?_ 25-35 for 12 hours (A?-model group); 3.Neurons exposed to 20?mol/L A?_ 25-35 and 10 mmol/L lithium chloride (LiCl), a specific inhibitor of glycogen synthase kinase-3?(GSK-3?), for 12 hours (LiCl group); 4.Neurons exposed to 20?mol/L A?_ 25-35 for 12 hours in the presence of 24-hour pretreatment with ginsenoside Rg1 (Rg1 pretreatment group) . Western blotting and immunocytochemical staining were used to detect the levels of Tau phosphorylation,total Tau and GSK-3? in cortical neurons. Non-radioimmunoassay was introduced to detect the activity of protein phosphatase 2A (PP2A). Results In A?-model group, the levels of Tau protein phosphorylation in the sites of Ser 396 ,Ser 199/202 ,Thr 231 and total Tau were enhanced. Meanwhile, the expression of GSK-3? was also increased, but the activity of PP2A was unchanged. In LiCl group and Rg1 pretreatment group , the hyperposphorylations of Tau protein and total Tau and the expression of GSK-3? were markedly reduced compared to those of the A?-model group (P