Neural Regeneration Research ›› 2018, Vol. 13 ›› Issue (6): 989-998.doi: 10.4103/1673-5374.233441

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Puerarin protects rat brain against ischemia/ reperfusion injury by suppressing autophagy via the AMPK-mTOR-ULK1 signaling pathwa

Jin-Feng Wang1, Zhi-Gang Mei1, Yang Fu2, Song-Bai Yang3, Shi-Zhong Zhang1, Wei-Feng Huang1, Li Xiong4, Hua-Jun Zhou5, Wei Tao1, Zhi-Tao Feng1   

  1. 1 Third-Grade Pharmacological Laboratory on Chinese Medicine Approved by State Administration of Traditional Chinese Medicine, Medical College of China Three Gorges University, Yichang, Hubei Province, China;
    2 Xiangyang Hospital of Traditional Chinese Medicine, Xiangyang, Hubei Province, China;
    3 Yichang Hospital of Traditional Chinese Medicine, Clinical Medical College of Traditional Chinese Medicine, China Three Gorges University, Yichang, Hubei Province, China;
    4 Department of Medicine and Therapeutics, the Chinese University of Hong Kong, Hong Kong Special Administrative Region, China;
    5 The Institute of Neurology, the First College of Clinical Medical Sciences, China Three Gorges University, Yichang, Hubei Province, China
  • Received:2018-04-25 Online:2018-06-15 Published:2018-06-15
  • Contact: Zhi-Gang Mei, M.D. or Zhi-Tao Feng, M.D.,meizhigang@ctgu.edu.cn or fengzhitao2008@126.com.
  • Supported by:

    This work was supported by the National Natural Science Foundation of China, No. 81202625; the Open Fund of Key Laboratory of Cardiovascular and Cerebrovascular Diseases Translational Medicine, China Three Gorges University, China, No. 2016xnxg101.

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Abstract:

Puerarin suppresses autophagy to alleviate cerebral ischemia/reperfusion injury, and accumulating evidence indicates that the AMPKmTOR signaling pathway regulates the activation of the autophagy pathway through the coordinated phosphorylation of ULK1. In this study, we investigated the mechanisms underlying the neuroprotective effect of puerarin and its role in modulating autophagy via the AMPK-mTOR-ULK1 signaling pathway in the rat middle cerebral artery occlusion model of cerebral ischemia/reperfusion injury. Rats were intraperitoneally injected with puerarin, 50 or 100 mg/kg, daily for 7 days. Then, 30 minutes after the final administration, rats were subjected to transient middle cerebral artery occlusion for 90 minutes. Then, after 24 hours of reperfusion, the Longa score and infarct volume were evaluated in each group. Autophagosome formation was observed by transmission electron microscopy. LC3, Beclin-1 p62,AMPK, mTOR and ULK1 protein expression levels were examined by immunofluorescence and western blot assay. Puerarin substantially reduced the Longa score and infarct volume, and it lessened autophagosome formation in the hippocampal CA1 area following cerebral ischemia/reperfusion injury in a dose-dependent manner. Pretreatment with puerarin (50 or 100 mg/kg) reduced Beclin-1 expression and the LC3-II/LC3-I ratio, as well as p-AMPK and pS317-ULK1 levels. In comparison, it increased p62 expression. Furthermore, puerarin at 100 mg/kg dramatically increased the levels of p-mTOR and pS757-ULK1 in the hippocampus on the ischemic side. Our findings suggest that puerarin alleviates autophagy by activating the APMK-mTOR-ULK1 signaling pathway. Thus, puerarin might have therapeutic potential for treating cerebral ischemia/reperfusion injury.

Key words: nerve regeneration, puerarin, autophagy, cerebral ischemia/reperfusion, AMPK-mTOR-ULK1 signaling pathway, light chain 3, p62, ischemic stroke, AMPK/mTOR, traditional Chinese medicine, middle cerebral artery occlusion, neural regeneration