Pharmacological modulation of PAF-acether-induced pleuresy in rats and its relevance for inflammation by zymosan

Abstract

H. C. Castro-Faria-Neto, M. A. Martins, P. T. Bozza, S. A. C. Perez, A. C. V. Correa-Da-Silva, M. C. R. Lima, H. N. Cruz, R. S. B. Cordeiro, M. V. Sousa and L. Morhy. Pro-inflammatory activity of enterolobin: a haemolytic protein purified from seeds of the Brazilian tree Enterolobium contortisiliquum. Toxicon, 29, 1143–1150, 1991.—The pro-inflammatory activity of enterolobin, a haemolytic protein from Enterolobium contortisiliquum seeds, was investigated. In doses ranging from 1 to 20 μg/site, enterolobin induced a dose-dependent paw oedema and pleurisy in rats. The effect was apparent after 15 min, peaked at 6 hr and decreased 24 hr after enterolobin was administered. One hour after the intrathoracic injection of enterolobin, the total leukocyte content of the pleural cavity increased significantly, mainly due to mononuclear and neutrophil accumulation. At 24 hr, although the number of mononuclear and neutrophil cells tended to decrease, a great rise in eosinophil counts was noted. Intraperitoneal treatment with the dual lipoxygenase and cyclooxygenase blockers, BW 755c (25 mg/kg) and NDGA (50 mg/kg) or the corticosteroid dexamethasone (0.1 mg/kg) inhibited enterolobin-induced paw oedema by 35, 38 and 47% respectively, whereas indomethacin (2 mg/kg) was inactive. The H1 antagonist, meclizine (25 mg/kg), was also effective against enterolobin oedema while the PAF-antagonists WEB 2086 and PCA 4248 (20 mg/kg) did not modify the reaction. It was concluded that enterolobin is a potent inducer of pleural exudation, cellular infiltration and paw oedema. Furthermore, enterolobin-induced oedema is partially dependent on lipoxygenase metabolites and histamine, while PAF and prostaglandins did not seem to be important in this reaction.