Regulation of prostaglandin production in carrageenan-induced pleurisy by melatonin.
The aim of the present study was to investigate the effect of melatonin on the production of the inflammatory mediator prostaglandins in a model of acute inflammation, carrageenan-induced pleurisy, where prostaglandins are known to play a crucial role. The results show that melatonin (12.5, 25, and 50 mg/kg, intraperitoneally, 15 min before the carrageenan) inhibits the inflammatory response (pleural exudate formation, polymorphonuclear cell infiltration, and prostaglandin production) in a dose-dependent manner. Immunohistochemical examination demonstrated a marked increase in the immunoreactivity to cyclooxygenase-2 (COX-2) in the lungs of carrageenan-treated rats. Pretreatment of carrageenan-treated rats with melatonin (50 mg/kg, intraperitoneally, 15 min before the carrageenan) prevented COX-2 expression. The present results demonstrate that melatonin exerts potent anti-inflammatory effects. Part of these anti-inflammatory effects may be related to a reduction of prostaglandin production during the inflammatory process.
Cuzzocrea
S
S
Institute of Pharmacology, School of Medicine, University of Messina, Italy. salvator@imeuniv.unime.it
Costantino
G
G
Mazzon
E
E
Caputi
A P
AP
D000818:Animals; D002351:Carrageenan; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007150:Immunohistochemistry; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D007527:Isoenzymes / Q000378:metabolism; D016676:Macrophages, Alveolar / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D010996:Pleural Effusion / Q000378:metabolism / Q000473:pathology; D010998:Pleurisy / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011453:Prostaglandins / Q000096:biosynthesis*; D051381:Rats
D007527:Isoenzymes; D011453:Prostaglandins; D002351:Carrageenan; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D008550:Melatonin; D015232:Dinoprostone