Upregulation of spinal cyclooxygenase-2 in rats after surgical incision.
BACKGROUND
Although upregulation of cyclooxygenase (COX)-2 in spinal cord after peripheral inflammation has been well documented, the effect of surgery on spinal COX-2 has not been examined in detail. The present study uses a bilateral foot incision in rats to examine the magnitude and duration of surgically induced changes in spinal COX-2 protein.


METHODS
A longitudinal incision was made in both plantar hind paws of isoflurane-anesthetized rats. Spinal cords were removed at various postoperative times (1-48 h), and spinal COX-2 protein levels were compared with the results of Western blot analysis. Ropivacaine-induced blockade of sciatic nerve function was used to determine the importance of afferent nerve activity on spinal COX-2 after incision. Dexamethasone and the COX-2-selective inhibitor L-745,337 were administered intrathecally to modulate spinal COX-2 after incision.


RESULTS
COX-2 protein levels increased in the lumbar spinal cord at 3 (1.32-fold) and 6 (1.26-fold) h after bilateral foot incision. At later times, lumbar COX-2 levels were no different than in control animals not undergoing surgery. Cervical COX-2 protein levels remained unchanged. Sciatic nerve blockade with ropivacaine did not prevent the increase in lumbar spinal COX-2 protein levels after incision. Intrathecal dexamethasone decreased lumbar spinal COX-2 levels after incision, and an intrathecal COX-2-selective inhibitor did not reduce the COX-2 upregulation.


CONCLUSIONS
After bilateral foot incision in rats, lumbar spinal COX-2 protein levels increase, although the magnitude and duration are less than reported in models of peripheral inflammation. This COX-2 upregulation does not seem to be mediated by afferent nerve activity.
Kroin
Jeffrey S
JS
Department of Anesthesiology, Rush Medical College, 1653 West Congress Parkway, Chicago, IL 60612, USA. jkroin@rush.edu
Ling
Zao D
ZD
Buvanendran
Asokumar
A
Tuman
Kenneth J
KJ
D000577:Amides / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology; D007189:Indans / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D009407:Nerve Block; D011184:Postoperative Period; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077212:Ropivacaine; D012584:Sciatic Nerve / Q000187:drug effects; D013116:Spinal Cord / Q000201:enzymology* / Q000601:surgery; D015854:Up-Regulation
D000577:Amides; D000779:Anesthetics, Local; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D005938:Glucocorticoids; D007189:Indans; D007527:Isoenzymes; C093700:L 745337; D000077212:Ropivacaine; D003907:Dexamethasone; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases