Neonatal Sevoflurane Exposure Impairs Learning and Memory by the Hypermethylation of Hippocampal Synaptic Genes

• Published in: Molecular neurobiology Vol. 58; no. 3; pp. 895 - 904
• Main Authors: Fan, Xin-Yu, Shi, Guang, Zhao, Ping
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2021; Springer Nature B.V
• Subjects: 5-Methylcytosine - analogs & derivatives; 5-Methylcytosine - metabolism; Anesthesia; Animals; Animals, Newborn; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cognition - drug effects; Cognitive ability; CpG Islands - genetics; Deoxyribonucleic acid; DNA; DNA (Cytosine-5-)-Methyltransferases - metabolism; DNA methylation; DNA Methylation - drug effects; DNA Methylation - genetics; DNMT1 protein; Genes; Hippocampus; Hippocampus - drug effects; Hippocampus - metabolism; Learning; Memory; Memory - drug effects; Models, Biological; Neonates; Neurobiology; Neurology; Neurosciences; Pattern recognition; Postsynaptic density proteins; Rats; Rats, Sprague-Dawley; Rodents; Sevoflurane; Sevoflurane - pharmacology; Spatial memory; Spatial Memory - drug effects; Synapses - drug effects; Synapses - genetics; Synapses - ultrastructure; Synaptic density; Synaptic plasticity; Syp protein; Transcription; Translocation; Sevoflurane; 5-AZA; DNA methylation; Synaptic proteins; Spatial memory
• DOI: 10.1007/s12035-020-02161-4
• ISSN: 0893-7648

Sevoflurane anesthesia is widely used in pediatric patients. Clinical studies report memory impairment in those exposed to general anesthesia early in life. DNA methylation is essential for the modulation of synaptic plasticity through regulating the transcription of synaptic genes. Therefore, we tested whether neonatal sevoflurane exposure affects learning and memory underlying the hippocampal DNA methylation of synaptic genes. Male Sprague-Dawley rats were exposed to 3% sevoflurane or air for 2 h daily from postnatal day 7 (P7) to P9. 5-aza-2-deoxycytidine (5-AZA), an inhibitor of DNA methyltransferases (DNMTs), was intraperitoneally injected 30 min before sevoflurane or air exposure on P7–9. The rats were euthanized 6, 12, 24 h, and 28 days after the last sevoflurane exposure, followed by the determination of global and gene-specific DNA methylation. The expression of synaptic proteins and synaptic density and the transcription of Dnmts and ten eleven translocations (Tets) in the hippocampus were measured. The ability of learning and memory was assessed using Morris water maze, novel object recognition, and intruder tests. Repeated neonatal sevoflurane exposure impaired cognitive, social, and spatial memory. The memory impairment was associated with the increased Dnmt1, Dnmt3a, and 5-methylcytosine level and the decreased Tet1 and 5-hydromethylcytosine level. Sevoflurane subsequently induced hypermethylation of Shank2 , Psd95 , Syn1 , and Syp gene and down-regulated the expression of synaptic proteins, which finally led to the decrease of synaptic density in a time-dependent manner. Notably, 5-AZA pretreatment ameliorated learning and memory in sevoflurane-treated rats. In conclusion, neonatal exposure to sevoflurane can impair learning and memory through DNA methylation of synaptic genes.