Abnormal DNA methylation in the lumbar spinal cord following chronic constriction injury in rats

• Published in: Neuroscience letters 2016-01, Vol.610, p.1-5
• Main Authors: Wang, Ying, Lin, Zhi-Ping, Zheng, Hui-Zhe, Zhang, Shuang, Zhang, Zong-Luan, Chen, Yan, You, Yi-Sheng, Yang, Ming-Hua
• Format: Article
• Language: English
• Subjects: Animals; Chronic constriction injury; Constriction; DNA (Cytosine-5-)-Methyltransferase 1; DNA (Cytosine-5-)-Methyltransferases - genetics; DNA (Cytosine-5-)-Methyltransferases - metabolism; DNA Methylation; DNA methyltransferases; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Glutamate Decarboxylase - genetics; Glutamate Decarboxylase - metabolism; Glutamate decarboxylase 1 promoter; Glutamate decarboxylase 67; Lumbosacral Region; Male; Methyl-DNA binding domain proteins; Neuralgia - metabolism; Neuralgia - physiopathology; Neuropathic pain; Promoter Regions, Genetic; Rats, Sprague-Dawley; RNA, Messenger - metabolism; Spinal Cord - metabolism; Spinal Cord Injuries - metabolism; Spinal Cord Injuries - physiopathology
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2015.10.048

•The role of abnormal DNA methylation in the lumbar spinal cord in neuropathic pain was explored in this study.•DNMT3a, DNMT3b and MeCP2 expression increased, MBD2 expression decreased, and DNMT1, MBD1 and MBD3 expression hardly changed in the lumbar spinal cord in CCI rats on day 14 after surgery.•GAD 67 expression decreased, and GAD 1 promoter methylation increased in the lumbar spinal cord in CCI rats on day 14 after surgery. Pathogenesis of neuropathic pain is complex and not clearly understood. Glutamate decarboxylase 67 (GAD 67) is a key synthetic enzyme for the main inhibitory transmitter gamma-aminobutyric acid (GABA), and diminishes in the spinal dorsal horn in rats following chronic constriction injury (CCI). GAD 67 is coded by gene GAD 1. DNA methylation can regulate the expression of GAD 67 by regulating the methylation of GAD 1 promoter in the psychotic brain. DNA methylation is primarily mediated by DNA methyltransferases (DNMTs) and methyl-DNA binding domain proteins (MBDs). In this study, in order to discover whether DNA methylation regulates GAD 67 expression in the spinal cord in CCI rats and is involved in neuropathic pain, we examined mRNA levels of DNMTs, MBDs and GAD 67 with real-time reverse transcriptase-polymerase chain reaction (qRT-PCR), and methylation of GAD 1 promoter with Pyromark CpG Assays in the lumbar spinal cord in CCI rats on day 14 after surgery. Our results showed that DNMT3a, DNMT3b and methyl-CpG binding protein 2 (MeCP2) expression increased, MBD2 expression decreased, and DNMT1, MBD1 and MBD3 expression hardly changed in the lumbar spinal cord in CCI rats on day 14 after surgery. GAD 67 expression decreased, and methylation of GAD 1 promoter increased in the lumbar spinal cord in CCI rats on day 14 after surgery. These results indicate that decreased GAD 67 may be associated with increased GAD 1 promoter methylation, which may be mediated by DNMT3a, DNMT3b, MeCP2 and MBD2 in CCI rats. These indicate that abnormal DNA methylation may be highly involved in CCI-induced neuropathic pain.