Title:Flavonoids from Stems and Leaves of Scutellaria baicalensis Georgi Regulate
the Brain Tau Hyperphosphorylation at Multiple Sites Induced by
Composited Aβ in Rats
Volume: 21
Issue: 4
Author(s): Ding Shengkai and Shang Yazhen*
Affiliation:
- Institute of Traditional Chinese Medicine, Chengde Medical College, An Yuan Road, Chengde Medical College,
Chengde, China
Keywords:
Scutellaria baicalensis georgi, flavonoids, Alzheimer's disease, tau protein, hyperphosphorylation, neurofibrillary tangles (NFTs).
Abstract: Background: Neurofibrillary Tangles (NFTs), formed by hyperphosphorylation of Tau
protein in Alzheimer's Disease (AD), arethe main pathomechanisms of neuronal degeneration,
which indicate a sign of brain disorder. NFTs are positively correlated with the degree of cognitive
impairment in AD.
Objective: The objective of this study isto investigate the effect of flavonoids from the stems and
leaves of Scutellaria baicalensis Georgi (SSF) on the hyperphosphorylated expression levels at
multiple sites of Tau protein induced by β-amyloid protein 25-35 (Aβ25-35) in combination with aluminum
trichloride (AlCl3) and recombinant human transforming growth factor-β1(RHTGF-β1)
(composited Aβ) in rats.
Methods: The AD rat models were established by intracerebroventricular injection of Aβ25-35 and
AlCl3 combined with RHTGF-β1. On day 45, after the operation, the Morris water maze test was
conducted to screen the memory impairment of AD models. The successful model rats were randomly
divided into the model group and the three-dose drug group. The drug group rats were orally
administered SSF daily for 38 days. Western blotting was performed to detect the protein expression
of P-Tau (Thr 181), P-Tau (Thr 217), P-Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P--
Tau (Ser 396), and P-Tau (Ser 404) in the hippocampus and cerebral cortex of rats.
Results: Compared with the sham group, the expression of P-Tau (Thr 181), P-Tau (Thr 217), P--
Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-Tau (Ser 396), and P-Tau (Ser 404)was significantly
increased in the hippocampus and cerebral cortex of the model group (P < 0.01). However,
the three doses of SSF, i.e., 35, 70, and 140 mg/kg, regulated the expression of phosphorylated Tau
proteinto varying degrees in the hippocampus and cerebral cortex of AD model rats (P < 0.01).
Conclusion: SSF could significantly reduce the protein expression levels of P-Tau (Thr 181), PTau
(Thr 217), P-Tau (Thr 231), P-Tau (Ser 199), P-Tau (Ser 235), P-Tau (Ser 396), and P-Tau (Ser
404), induced by the intracerebroventricular injection of composited Aβ, in rats’ brain. These results
indicated that the neuro-protection and the improvement in the impaired memory of rats by
SSF were due to the inhibition of hyperphosphorylation of Tau protein at multiple sites in rats'
brain.