Epidural injection of cyclooxygenase-2 inhibitor attenuates pain-related behavior following application of nucleus pulposus to the nerve root in the rat.
Cyclooxygenase-2 (COX-2), the inducible isoform of COX, has been identified as the key enzyme to regulate prostaglandin E2 synthesis in inflammatory conditions. Although it has been reported that COX-2 is present in herniated disc samples obtained from patients, little is known concerning the relationships between COX-2 and painful radiculopathy. The purpose of this study was to evaluate whether epidural injection of COX-2 inhibitor abolishes hyperalgesia induced by nucleus pulposus, which is a pain-related behavior in the rat. Rats, in which nucleus pulposus was relocated on the nerve root, exhibited evidence of mechanical hyperalgesia. Epidural injection of COX-2 inhibitor resulted in decrease in mechanical hyperalgesia 1 h, 3 and 7 days after the epidural injection of COX-2 inhibitor (0.1 mg/kg SC-'236 dissolved in the vehicle). There were no significant differences in sensitivity to thermal noxious stimuli after either application of the nucleus pulposus or epidural injections. These results suggest that prostaglandins and thromboxane, which are produced by COX-2 in inflammatory cells, appear to be related to the inflammatory process produced by application of nucleus pulposus to the nerve root. It is possible that COX-2 plays a significant role in painful radiculopathy following herniated nucleus pulposus.
Kawakami
Mamoru
M
Department of Orthopedic Surgery, Wakayama Medical University, Wakayama City, Japan. kawakami@wakayama-med.ac.jp
Matsumoto
Takuji
T
Hashizume
Hiroshi
H
Kuribayashi
Koichi
K
Tamaki
Tetsuya
T
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D004195:Disease Models, Animal; D006614:Hindlimb; D006358:Hot Temperature; D006930:Hyperalgesia / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D007268:Injections, Epidural; D007403:Intervertebral Disc / Q000637:transplantation; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000503:physiopathology; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D009043:Motor Activity; D010147:Pain Measurement; D011451:Prostaglandin-Endoperoxide Synthases; D011720:Pyrazoles / Q000008:administration & dosage / Q000627:therapeutic use*; D011843:Radiculopathy / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D013126:Spinal Nerve Roots / Q000503:physiopathology; D013449:Sulfonamides / Q000008:administration & dosage / Q000627:therapeutic use*; D014184:Transplantation, Homologous; D000096926:Benzenesulfonamides
D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D011451:Prostaglandin-Endoperoxide Synthases; D011720:Pyrazoles; D013449:Sulfonamides; C119130:4-(5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamide; D000096926:Benzenesulfonamides