Local increases of subcutaneous beta-endorphin immunoactivity at the site of thermal injury.
To examine interactions between exogenous opioid analgesia and endogenous opioid generation at a site of burn-induced tissue injury, we measured beta-endorphin (BE) and corticosterone (C) in aliquots of plasma and wound fluid withdrawn from subcutaneous wire mesh chambers beneath the site of a 3-5% surface area burn. After brief inhalational anesthesia at the time of thermal injury, rats received morphine (4 mg/kg, single dose), fentanyl (0.02 mg/kg hourly for 4 h), or no opioid. Systemic hormone responses and behavioral changes were minimal as expected for the minimal percentage burn. In all three groups intrachamber BE and C rose above baseline at 1, 2 and 4 h postburn, then returned to baseline at 24 h. Systemic opioid treatment produced analgesia (by tail flick latency testing) but did not reduce intrachamber hormone responses. Thus local BE and C responses at the site of thermal injury are regulated differently from systemic pituitary-adrenal responses.
Cepeda
M S
MS
Analgesic Peptide Research Unit, Department of Anesthesia, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Lipkowski
A W
AW
Langlade
A
A
Osgood
P F
PF
Ehrlich
H P
HP
Hargreaves
K
K
Szyfelbein
S K
SK
Carr
D B
DB
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001826:Body Fluids / Q000378:metabolism; D002056:Burns / Q000150:complications / Q000276:immunology*; D003345:Corticosterone / Q000097:blood / Q000378:metabolism*; D008297:Male; D010146:Pain / Q000188:drug therapy / Q000209:etiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D001615:beta-Endorphin / Q000097:blood / Q000187:drug effects / Q000378:metabolism*
D000701:Analgesics, Opioid; D001615:beta-Endorphin; D003345:Corticosterone