[Mechanism of Guben Jiannao Liquid on Alzheimer's disease by regulating autophagy based on LKB1/AMPK/mTOR pathway].

Abstract

This study explores the mechanism of Guben Jiannao Liquid on Alzheimer's disease(AD) by regulating autophagy based on the liver kinase B1(LKB1)/adenosine monophosphate-activated protein kinase(AMPK)/mammalian target of rapamycin(mTOR) pathway. Male SD rats were randomly divided into the blank group, model group, low-dose and high-dose groups of Guben Jiannao Liquid, and rapamycin group, with 10 rats in each group. Except for the blank group, all other groups of rats were injected bilaterally in the hippocampus with β-amyloid(Aβ)_(1-42) to establish the AD model. The low-dose(6.21 g·kg~(-1)) and high-dose(12.42 g·kg~(-1)) groups of Guben Jiannao Liquid and rapamycin group(1 mg·kg~(-1)) were given the corresponding drugs by gavage, and the blank and model groups were given an equal volume of saline by gavage for four weeks. Morris water maze was used to test the learning and memory ability of rats in each group; hematoxylin-eosin(HE) and Nissl staining were used to observe the morphological and quantitative changes of neurons and Nissl bodies in the CA1 region of rat hippocampus; immunohistochemistry was utilized to detect Aβ-positive cell expression in the CA1 region of rat hippocampus; transmission electron microscopy was employed to observe ultrastructural changes in rat hippocampal tissue, and Western blot was used to examine the protein expression levels of LKB1, p-AMPK/AMPK, p-mTOR/mTOR, Beclin1, p62, and LC3-Ⅱ in the hippocampal tissue of the rats. The results showed that compared with those in the blank group, rats in the model group had elevated evasion latency and decreased number of platform transversal and residence time in the platform quadrant. The number of neurons in the hippocampal area was reduced, and the morphology was impaired. The average integral optical density value of Aβ-positive cells was elevated; the expression levels of LKB1, p-AMPK/AMPK, Beclin1, and LC3-Ⅱ were decreased, and the expression levels of p-mTOR/mTOR and p62 were increased. Compared with those in the model group, rats in the low-dose and high-dose groups of Guben Jiannao Liquid had shorter evasion latency, higher number of platform transversal, longer residence time in the platform quadrant, increased number of neurons, decreased expression of Aβ-positive cells and average integral optical density values, and increased number of autophagic lysosomes in hippocampal tissue. The expression levels of LKB1, Beclin1, and LC3-Ⅱ were elevated in the hippocampus of rats in the low-dose group of Guben Jiannao Liquid. The expression levels of LKB1, p-AMPK/AMPK, Beclin1, and LC3-Ⅱ were elevated in the hippocampal tissue of rats in the high-dose group of Guben Jiannao Liquid, and the expression levels of p-mTOR/mTOR and p62 were decreased. The findings suggest that Guben Jiannao Liquid can improve cognitive impairment in AD rats, and its mechanism of action may be related to the activation of the LKB1/AMPK/mTOR signaling pathway and the up-regulation of autophagy level.