Inhibition of Flavonoids from Scutellaria baicalensis Stems and Leaves against Abnormal Formation of PHF and Regulation of PP in OA Induced Brain Injury in Rats

[Objectives] To explore the inhibitory effects of flavonoids from Scutellaria baicalensis Georgi stems and leaves against abnormal formation of PHF and regulation mechanism of protein phosphatase(PP) in okadaic acid(OA) induced brain injury in rats.[Methods]Male Sprague-Dawley rats were treated with OA(200 ng/kg) in the lateral ventricle to establish a memory impairment model,and Morris water maze was used to screen the memory impairment model.Rats were intragastrically administered with 25,50 and 100 mg/kg SSF daily for 36 d.The protein expressions of PHF,PP1,PP2A-Cα,PP2A-Cβ,PP2 CA and PP2 CB in rat cortex and hippocampus were determined by Western blot.Ginkgo biloba leaf flavonoids were used as positive control drugs.[Results]Compared with the sham-operated rats,the expression of PHF protein in the cortex and hippocampus of the model group was significantly increased(P < 0.01);protein expression of PP2A-Cα and PP2A-Cβin the cortex and hippocampus,and PP2 CB in the hippocampus were significantly decreased(P < 0.05);protein expression of PP2 CA and PP2 CB in the cortex was significantly increased(P < 0.01);protein expression of PP1 in the cortex was significantly decreased(P < 0.01).Compared with the model rats,25,50 and 100 mg/kg SSF 36 d reversed the protein expression of PHF,PP2A-Cα and PP2ACβ in rat cortex and hippocampus and expression of PP1 in rat cortex induced by OA,but had no significant effect on the protein expression of PP2 CA and PP2 CB,G.biloba flavonoids also showed similar results to SSF.[Conclusions] SSF can significantly inhibit the abnormal formation of PHF in rat brain induced by OA.The inhibitory effect may be related to the regulation of PP1,PP2A-Cα and PP2A-Cβ protein expression in cerebral cortex and hippocampus by SSF,but less related to the regulation of PP2 CA and PP2 CB.