Journal
NEUROPSYCHIATRIC DISEASE AND TREATMENT
Volume 17, Issue -, Pages 297-304Publisher
DOVE MEDICAL PRESS LTD
DOI: 10.2147/NDT.S278422
Keywords
electroconvulsive shock; learning impairment; (2R 6R)-hydroxynorketamine; autophagy
Categories
Funding
- National Natural Science Foundation of China [81701341]
- Guangdong Provincial Medical Science and Technology Research Foundation [A2020446]
- Science and Technology Plan Project of Guangdong Province [2019B030316001]
- Guangzhou Municipal Key Discipline in Medicine (2017-2019)
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This study aimed to explore the mechanism of action of ketamine metabolites in protecting against learning impairment, showing that ketamine metabolites can yield cognitive protection by suppressing autophagy.
Purpose: Learning impairment after electroconvulsive therapy (ECT) is common. Ketamine, an anesthetic used for ECT, has been demonstrated to attenuate cognitive impairment after ECT. However, the mechanism by which ketamine occurs in this case is still unknown. We aimed to explore the role of ketamine metabolite (2R,6R)-hydroxynorketamine [(2R,6R)-HNK] in the protection against learning impairment and investigate whether autophagy is involved in the protective effect. Materials and Methods: A rat depression model received electroconvulsive shock (ECS; simulated ECT in animal models) daily for 3 days. The Morris water maze was used to assess the spatial learning function of the rats. Western blotting was used to detect the expression of Beclin-1, light chain (LC)3-II/LC3-I, p62, mammalian target of rapamycin (mTOR), and p-mTOR in the hippocampus. Results: The escape latency for the maze in the ECS group was significantly longer than that in the sham ECS group (P=0.042). Meanwhile, the escape latency in the (2R,6R)-HNK+ECS group was significantly shorter than that in the ECS group (P=0.005). The LC3-II/LC3-I ratio and Beclin-1 expression level significantly increased, and the p62 expression level significantly decreased in the ECS group, compared with those in the sham ECS group (all P<0.001). The (2R,6R)-HNK+ECS group showed lower LC3-II/LC3-I ratio (P<0.001) and Beclin-1 expression level (P<0.001) and higher p62 (P<0.001) and p-mTOR expression levels (P=0.048) than did the ECS group. After small-molecule enhancer of rapamycin 28 (SMER28) administration, the role of (2R,6R)-HNK in protecting against learning impairment and inhibiting autophagy was abrogated, showing no difference in the escape latency; the difference in the LC3-II/LC3-I ratio and p62 expression level between the SMER28 +(2R,6R)-HNK+ECS and ECS groups was not as significant as that between the (2R,6R)HNK+ECS and ECS groups (P<0.05-0.01 vs P<0.001). Conclusion: (2R,6R)-HNK yields cognitive protection by suppressing autophagy through the mTOR in the ECS-treated rat
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