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Aim: The aim of this study was to investigate the effect and molecular mechanism of Scutellaria baicalensis Georgi stems and leaves flavonoids (SSF) in promoting neurogenesis and improving memory impairment induced by the PI3K-AKT-CREB signaling pathway. Methods: Alzheimer's disease (AD) was induced in the male Wistar rats by intracerebroventricular injection of amyloid beta peptide 25-35 (Aβ25-35) in combination with aluminum trichloride (AlCl3) and recombinant human transforming growth factor-β1(RHTGF-β1) (composited Aβ). The Morris water maze was used to screen the successful establishment of the memory impairment model of rats. The screened successful model rats were randomly divided into a model group and three groups of three different doses of the drug (SSF). Rats in the drug group were treated with 35, 70, and 140 mg/kg of SSF for 43 days. The Eight-arm maze was used to measure the spatial learning and memory abilities of the rat, including working memory errors (WME) and reference memory errors (RME). Immunohistochemistry was used to detect the expression of BrdU, an indicator of neuronal proliferation, in the hippocampal gyrus of rats. The mRNA and protein expressions of TRKB, PI3K, AKT, P-AKT, and IGF2 in the PI3K-AKT-CREB signaling pathway in the hippocampus and cerebral cortex of the rats were determined by quantitative real-time PCR (qPCR) and Western blotting methods. Results: Compared to the sham group, the spatial memory ability of rats with composited Aβ was decreased, the number of WME and RME (P < 0.01) was increased, the expression of BrdU protein (P < 0.01) in the hippocampal gyrus was reduced, the mRNA and protein expression levels of TRKB, AKT, and IGF2 (P < 0.01, P < 0.05) in the hippocampus and cerebral cortex were lowered, and the mRNA expression level of PI3K (P < 0.01) in the cerebral cortex and the protein expression level of PI3K (P < 0.01) in the hippocampus were augmented. However, compared to the model group, the three-doses of SSF improved memory disorder induced by composited Aβ, reduced the number of WME and RME, increased the expression of BrdU protein in the hippocampal gyrus, and differently regulated the mRNA and protein expressions in composited Aβ rats. Conclusions: SSF improved memory impairment and neurogenesis disorder induced by composited Aβ in rats by activating the PI3K-AKT-CREB signaling pathway and up-regulating the mRNA and protein expressions of TRKB, PI3K, AKT, CREB, and IGF2.

Aim: To investigate the effects and mechanism of flavonoids from stems and leaves of Scutellaria baicalensis Georgi (SSF) on the disorders in learning and memory and neuroplasticity induced by beta amyloid 25-35 (Aβ25-35) combined with aluminum trichloride (AlCl3) and human recombinant transfer factor-β1 (RHTGF-β1) (composited Aβ) in rats. Methods: A rat Alzheimer's disease (AD) model was established by intracerebroventricular injection of Aβ25-35 combined with AlCl3 and RHTGF-β1. The successful AD model of rats was screened with Morris water maze. The successful model rats were randomly divided into a model group and three doses of SSF treated group. The Morris water maze was used to detect the rats’ learning and memory abilities. The real-time fluorescence quantitative (qPCR) was applied to assay the mRNA expressions of CaM, CamkIV and Ferritin, as well as the neuroplasticity factors of HuB, HuC and HuD. The Western blotting was used to measure the protein expressions of CaM, CamkIV, HuB/D, HuC+HuD and Ferritin in CaM-CamkIV-CREB signal pathway. Results: Compared with sham group, the abilities of learning and memory in the model group were significantly impaired (P Conclusion: The improvement of SSF on the learning and memory disorder induced by composited Aβ is primarily derived from the positive regulation in CaM-CamkIV-CREB signal pathway and activation in neuroplasticity.

Aim: The present study aims to investigate the effect of flavonoids from stem and leaf of Scutellaria Baicalensis Georgi (SSF) on multi-sites phosphorylation of tau protein in the cerebral cortex and hippocampus of rats induced by okadaic acid (OA) and the regulative mechanism of the protein kinases. Methods: The model of AD-like memory impairment and neuronal injuries was established in male SD rats who were microinjected with OA (200 ng/kg) to establish a memory impairment model and screened for successful model rats by Morris water maze on day 21 after surgery. The successful model rats were continuously administered with intragastric infusion (ig) SSF 25, 50 and 100 mg/kg or Ginkgo biloba leaves flavonoids (GLF) 200 mg/kg for 36 d. The relative protein expressed levels of phosphorylated tau protein at sites of Ser199, Ser202, Ser214, Ser404 and Thr231, protein kinases (CDK5, PKA, pTyr216-GSK3β and pSer9-GSK3β) were detected by Western blotting. Results: The relative protein expressed levels of p-tau(Ser199), p-tau(Ser202), p-tau(Ser214), p-- tau(Ser404), p-tau(Thr231) and pTyr216-GSK3β were significantly increased in both cerebral cortex and hippocampus regions of the model rats subjected to intracerebroventricular injection of OA (P Conclusion: The results demonstrated that SSF could inhibit the hyperphosphorylation of tau in rats’ cerebral cortex and hippocampus induced by microinjection of OA, which may be related to the activities of protein kinase CDK5, PKA and GSK3β.