title: Fluorocitrate, an inhibitor of glial metabolism, inhibits the up-regulation of NOS expression, activity and NO production in the spinal cord induced by formalin test in rats.
abstract: Previous experiments have suggested that nitric oxide plays an important role in nociceptive transmission in the spinal cord. In order to explore the involvement of glia in the NO-mediated nociceptive transmission, the present study was undertaken to investigate the effect of fluorocitrate (FC), an inhibitor of glial metabolism, on NOS expression and activity and NO production in the spinal cord during the process of peripheral inflammatory pain and hyperalgesia induced by formalin test in rats. Sixty adult male Sprague-Dawley rats were randomly assigned into sham, formalin, formalin + normal saline (NS), and formalin + FC groups. The NOS expression, NOS activity and NO production was detected by NADPH-d histochemistry staining, NOS and NO assay kit, respectively. It was found that formalin test significantly up-regulated NOS expression and activity and NO production in the laminae I-II of the dorsal horn and the grey matter around the central canal in the lumbar spinal cord at 1 h after the formalin test. Selective inhibition of glia metabolism with intrathecal administration of FC (1 nmol) significantly inhibited the up-regulation in NOS expression and activity and NO production normally induced by the formalin test, which was represented with decreases in the number and density of the NADPH-d positive cells in the dorsal horn and grey matter around the central canal, and decrease in density of NADPH-d positive neuropil in the dorsal horn in formalin + FC group compared with formalin group. The results suggested that glia may be involved in the NO-mediated nociceptive transmission in the spinal cord.
authors.affiliation: Department of Pathophysiology, Institute of Basic Medicine, Hebei Medical University, 361 Zhongshan East Road, Shijiazhuang, 050017, People's Republic of China.
authors.forename: Xiao-Cai
authors.initials: XC
authors.lastname: Sun
authors.forename: Wei-Na
authors.initials: WN
authors.lastname: Chen
authors.forename: Shu-Qin
authors.initials: SQ
authors.lastname: Li
authors.forename: Jin-Song
authors.initials: JS
authors.lastname: Cai
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Li
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Xian
authors.forename: Yu-Yan
authors.initials: YY
authors.lastname: Hu
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Qing-Jun
authors.initials: QJ
authors.lastname: Li
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002951:Citrates / Q000494:pharmacology*; D008297:Male; D009457:Neuroglia / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D002951:Citrates; D009569:Nitric Oxide; C007744:fluorocitrate; D019001:Nitric Oxide Synthase