title: [Role of DNA methyltransferases in the pathogenesis of neuropathic pain in rats].
abstract: OBJECTIVE
  To explore the role of DNA methyltransferases (DNMTs) in the pathogenesis of neuropathic pain (NPP) in rats following sciatic nerve chronic constriction injury (CCI).
  
  
  METHODS
  A total of 27 adult male Sprague-Dawley rats with successful implantation of lumbar intrathecal catheter were randomly divided into 3 groups: a sham + normal saline group (sham+NS group), a CCI+NS group, and a CCI+5-azacytidine group (CCI+5-AZA group) (n=9 in each group). The rats in the Sham+NS group and the CCI+NS group received NS, while the rats in the CCI+5-AZA group received 10 μmol/L of 5-AZA (a DNMTs inhibition) once a day through spinal injection from the 3th day to 14th day after CCI surgery. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) of ipsilateral hinds in the 3 groups were measured before or at the 3th, 5th, 7th, 10th or 14th day after CCI surgery. At the end of experiments, all rats were killed under deep anesthesia and their lumbar spinal cords were dissected to examine the DNMT1, DNMT3a and DNMT3b expression by RT-PCR, Western blot and immunohistochemistry, respectively.
  
  
  RESULTS
  Compared with the sham+NS group, the MWT and TWL in the CCI+NS group were obviously reduced from the 3th day to the 14th day after surgery (both P<0.05). Compared with the CCI+NS group, the MWT and TWL in the CCI+5-AZA group were obviously increased from the 5th day to the 14th day after surgery (both P<0.05), but they were still reduced compared with the sham+NS group (both P<0.05). The DNMT1, DNMT3a and DNMT3b were highly expressed in the lumbar spinal dorsal horn in all rats, and the positive signals were mainly located in the nucleus. The DNMT1, DNMT3a and DNMT3b levels in the CCI+NS group were increased significantly compared with that in the sham+NS group on the 14th day after surgery (all P<0.05). The DNMT1, DNMT3a and DNMT3b expressions in the CCI+ 5-AZA group were decreased significantly compared with that in the CCI+NS group (all P<0.05), but they still increased compared with that in the sham+NS group (all P<0.05).
  
  
  CONCLUSIONS
  Up-regulation of DNMTs in the lumbar spinal may play an important role in the pathogenesis of NPP in CCI rats. DNMTs inhibitors (5-AZA) could reduce expression of DNMTs and attenuate CCI-induced NPP, which might be a potential therapeutic drug for NPP.
authors.affiliation: Department of Anesthesiology, Teaching Hospital of Fujian Medical University/Fujian Cancer Hospital, Fuzhou 350014, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha 410008, China.
authors.forename: Qulian
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha 410008, China.
authors.forename: Jianqin
authors.initials: J
authors.lastname: Yan
authors.affiliation: Department of Anesthesiology, Teaching Hospital of Fujian Medical University/Fujian Cancer Hospital, Fuzhou 350014, China.
authors.forename: Minghua
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of ICU, Teaching Hospital of Fujian Medical University/Fujian Cancer Hospital, Fuzhou 350014, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Department of Anesthesiology, Teaching Hospital of Fujian Medical University/Fujian Cancer Hospital, Fuzhou 350014, China.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Lin
mesh_terms: D000818:Animals; D001374:Azacitidine; D003250:Constriction; D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases; D019175:DNA Methylation; D007278:Injections, Spinal; D008297:Male; D009437:Neuralgia; D051381:Rats; D017207:Rats, Sprague-Dawley; D066148:Spinal Cord Dorsal Horn; D015854:Up-Regulation
chemical_list: D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases; D001374:Azacitidine