Résumé
AIM: To investigate the effects of Scutellaria barbata flavonoids (SBF) on neurofibrillary tangle (NFT) aggregation, tau protein phosphorylation and the regulated mechanism of glycogen synthase kinase (GSK) 3βand protein phosphatase (PP) 2A in the rats induced by amyloid βprotein 25-35 (Aβ25-35) in combination with AlCl3 and re-combinant human transforming growth factor ( RHTGF)-β1( composited Aβ) .METHODS:The male SD rats were used to establish the simulated Alzheimer disease ( AD) model by intracerebroventricular injection of composited Aβ.The Morris water maze was applied for screening the successful model rats with learning and memory deficits .The successful model rats were daily and orally administrated with SBF at doses of 35, 70 and 140 mg/kg or positive control drug Ginkgo biloba leaves flavonoids ( GLF) at 140 mg/kg for 37 d.The silver nitrate staining was used to determine the cortical NFT .The protein levels of total tau, phosphorylated protein of tau at Ser199 and Ser214 sites, GSK3βand PP2A in hippocampus and cortex were determined by Western blot .The mRNA expression of GSK3βand PP2A in the hippocampus and cortex was detected by RT-PCR.RESULTS:Compared with sham group , the cell number of positive NFT with silver nitrate staining in model rat cerebral cortex was significantly increased .The protein levels of phosphorylated tau protein at Ser 199 and Ser214 sites, GSK3βin the hippocampus and cerebral cortex in the model rats dramatically elevated , and PP2A was marked decreased as compared with the sham group rats.Meanwhile, the mRNA expression of GSK-3βsignificantly increased but PP2A was de-creased.However, these above abnormalities were differently attenuated by treating with SBF at different doses or GLF at 140 mg/kg for 37 d.CONCLUSION: SBF suppresses the NFT aggregation by inhibition of the regulatory functions of GSK-3βand PP2A, thus reducing the phosphorylation of tau protein .