DESCENDING MODULATION FROM THE REGION OF THE LOCUS-COERULEUS ON NOCICEPTIVE SENSITIVITY IN A RAT MODEL OF INFLAMMATORY HYPERALGESIA

Citation
M. Tsuruoka et Wd. Willis, DESCENDING MODULATION FROM THE REGION OF THE LOCUS-COERULEUS ON NOCICEPTIVE SENSITIVITY IN A RAT MODEL OF INFLAMMATORY HYPERALGESIA, Brain research, 743(1-2), 1996, pp. 86-92
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
0006-8993
Volume
743
Issue
1-2
Year of publication
1996
Pages
86 - 92
Database
ISI
SICI code
0006-8993(1996)743:1-2<86:DMFTRO>2.0.ZU;2-H
Abstract
The aim of the present study was to evaluate the action of the descend ing modulation system from the locus coeruleus (LC) in a rat model of unilateral hyperalgesic inflammation. Unilateral hindlimb inflammation was produced by a subcutaneous injection of carrageenan (6 mg in 0.15 ml saline). One week before testing, rats received bilateral lesions of the LC using anodal current. Nociception was assessed by measuring withdrawal of the paw from a noxious thermal stimulus. Four hours afte r carrageenan injection, paw withdrawal latencies (pWLs) in the inflam ed paw of the LC-lesioned rats were significantly shorter than those o f the sham-operated rats. This difference in PWL between the two group s was not observed at 7 days, whereas edema and hyperalgesia still rem ained in the inflamed paw. At 4 h, systemic naloxone produced a furthe r decrease of the PWL in the LC-lesioned rats but not in the sham-oper ated rats. These results suggest that inflammation-induced activation of the descending modulation system from the LC occurs in only the acu te phase of inflammation and that a decrease in the extent of the deve lopment of hyperalgesia in the acute phase of inflammation might depen d on the interaction between the descending modulation system from the LC and the opioid inhibitory system.