Involvement of beta-endorphin in the modulation of paw inflammatory edema in the rat.
This study investigates the role of the opiod receptors and of the opioid peptide beta-endorphin in the development of yeast-induced inflammation in the rat paw. Pretreatment with the opioid receptor antagonist naltrexone (10 mg/kg i.p.) exacerbates the paw edema, while morphine pretreatment (5 and 10 mg/kg) reduces it. In addition, the intravenous injection of a specific anti-beta-endorphin antibody aggravates the yeast-induced inflammation. On the contrary, both the kappa-opioid receptor antagonist MR 1452 (2.5, 5 and 10 mg/kg i.p.) and the delta-opioid receptor antagonist ICI 174-864 (2.5, 5 and 10 mg/kg i.p.) do not interfere with the inflammatory process. After intraplantar injection, naltrexone, morphine and the anti-beta-endorphin antibody do not interfere with the yeast-induced inflammatory edema. Our data suggest that beta-endorphin exerts an inhibitory regulation on the inflammatory responses through the activation of mu-opioid receptors probably located on immune cells, rather than in the paw.
Sacerdote
P
P
Department of Pharmacology, University of Milan, Italy.
Bianchi
M
M
Panerai
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AE
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D001575:Benzomorphans / Q000494:pharmacology; D004487:Edema / Q000378:metabolism*; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D005528:Foot; D007249:Inflammation / Q000378:metabolism*; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000378:metabolism*; D015003:Yeasts / Q000378:metabolism; D001615:beta-Endorphin / Q000037:antagonists & inhibitors / Q000276:immunology / Q000494:pharmacology*
D000906:Antibodies; D001575:Benzomorphans; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D004743:Enkephalin, Leucine; D009271:Naltrexone; D001615:beta-Endorphin; C029552:Mr 1452; D009020:Morphine; C040643:N,N-diallyl-tyrosyl-alpha-aminoisobutyric acid-phenylalanyl-leucine