Spinal NF-kB activation induces COX-2 upregulation and contributes to inflammatory pain hypersensitivity.
Cyclooxygenase-2 (COX-2) is a major contributor to the elevation of spinal prostaglandin E2, which augments the processing of nociceptive stimuli following peripheral inflammation, and dynorphin has been shown to have an important role in acute and chronic pain states. Moreover, the transcription factor, nuclear factor-kappa B (NF-kB), regulates the expressions of both COX-2 and dynorphin. To elucidate the role of spinal NF-kB in the induction of inflammatory pain hypersensitivity, we examined whether activated NF-kB affects pain behavior and the expressions of the mRNAs of COX-2 and prodynorphin following peripheral inflammation. Intrathecal pretreatment with different NF-kB inhibitors, namely, NF-kB decoy or pyrrolidine dithiocarbamate, significantly reduced mechanical allodynia and thermal hyperalgesia following unilateral hindpaw inflammation evoked by complete Freund's adjuvant (CFA). These NF-kB inhibitors also suppressed the activation of spinal NF-kB and the subsequent remarkable elevation of spinal COX-2 mRNA, but not that of prodynorphin mRNA. In addition, the activation of spinal NF-kB following CFA injection was inhibited by intrathecal pretreatments with interleukin-1 beta receptor antagonist or caspase-1 inhibitor. In view of the fact that interleukin-1 beta (IL-1 beta) is the major inducer of spinal COX-2 upregulation following CFA injection, our results suggest that IL-1 beta-induced spinal COX-2 upregulation and pain hypersensitivity following peripheral inflammation are mediated through the activation of the NF-kB-associated pathways.
Lee
Kyung-Min
KM
Department of Anatomy, Pain and Neural Injury Research Center, MRC, School of Medicine, Kyungpook National University, 2-101, Dongin-Dong, Daegu, 700-422, South Korea.
Kang
Bong-Seok
BS
Lee
Hye-Lim
HL
Son
Sun-Joo
SJ
Hwang
Sung-Hun
SH
Kim
Dong-Sun
DS
Park
Jae-Sik
JS
Cho
Hee-Jung
HJ
D000818:Animals; D051546:Cyclooxygenase 2; D004745:Enkephalins / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D005620:Freund's Adjuvant / Q000633:toxicity; D015870:Gene Expression; D006614:Hindlimb / Q000187:drug effects / Q000473:pathology; D006930:Hyperalgesia / Q000503:physiopathology*; D007249:Inflammation / Q000139:chemically induced; D007278:Injections, Spinal; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis* / Q000187:drug effects; D008297:Male; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D010146:Pain / Q000503:physiopathology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000187:drug effects; D011498:Protein Precursors / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000008:administration & dosage; D013116:Spinal Cord / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology; D015854:Up-Regulation
D004745:Enkephalins; D004791:Enzyme Inhibitors; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D007527:Isoenzymes; D016328:NF-kappa B; D011498:Protein Precursors; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D005620:Freund's Adjuvant; C033660:preproenkephalin; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases