The effect of diclofenac on the expression of spinal cord c-fos-like immunoreactivity after ischemia-reperfusion-induced acute hyperalgesia in the rat tail.
Ischemia-reperfusion of the rat tail for 20 min induces local acute hyperalgesia of approximately 1-h duration. We studied how this stimulus affected the expression of c-fos-like immunoreactivity (c-fos-LI) labeling of neurons of the sacral spinal cord, and how diclofenac pretreatment influenced the outcome. After ischemia, the number of c-fos-LI-labeled neurons was significantly increased when assessed at 60, 90, and 120 min after reperfusion (to 183%, 283%, and 164% of control, respectively; all P < 0.01). At 90 min, the number of regional c-fos-LI-labeled neurons was increased to 585% in laminae I-II, 183% in laminae III-IV, 270% in laminae V-X, and 286% in total, compared with respective control values (all P < 0.01). After diclofenac pretreatment (subcutaneous 40 mg/Kg, 30 min before insult) the number of c-fos-LI-labeled neurons at 90 min was increased to 424% in laminae I-II, 150% in laminae III-IV, 142% in laminae V-X, and 183% in total (all P < 0.01). Thus diclofenac pretreatment partially prevented the insult-induced increase in total and regional neuronal c-fos-LI. This acute nociceptive model involves only natural algogens. However, the results were similar to acute chemically induced or chronic adjuvant induced arthritic inflammatory pain models in which increases in c-Fos were partially inhibited by nonsteroidal antiinflammatory drugs.
Lin
Y
Y
Department of Anaesthesia and Pain Management, The University of Sydney at the Royal North Shore Hospital, St. Leonards, Australia.
Mather
L E
LE
Power
I
I
Cousins
M J
MJ
D000208:Acute Disease; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002452:Cell Count; D004008:Diclofenac / Q000494:pharmacology*; D006930:Hyperalgesia / Q000209:etiology / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015424:Reperfusion; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*; D013623:Tail / Q000098:blood supply*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016760:Proto-Oncogene Proteins c-fos; D004008:Diclofenac