Peroxisome proliferator-activated receptors (PPARs) are members of the
nuclear hormone receptor superfamily of
ligand-activated
transcription factors that are related to
retinoid,
steroid and
thyroid hormone receptors. The
PPAR-gamma receptor subtype appears to play a pivotal role in the regulation of cellular proliferation and
inflammation. The
thiazolidinedione rosiglitazone (
Avandia) is a
peroxisome proliferator-activated receptor-gamma (
PPAR-gamma) agonist, that was recently approved by the Food and Drug Administration for treatment of type II
diabetes mellitus. In the present study, we have investigated the effects of
rosiglitazone in animal models of acute
inflammation (
carrageenan-induced paw oedema and
carrageenan-induced
pleurisy). We report here for the first time that
rosiglitazone (given at 1, 3 or 10 mg/kg i.p. concomitantly with
carrageenan injection in the paw oedema model, or at 3, 10 or 30 mg/kg i.p. 15 min before
carrageenan administration in the
pleurisy model) exerts potent anti-inflammatory effects (e.g. inhibition of paw oedema, pleural exudate formation, mononuclear cell infiltration and histological injury) in vivo. Furthermore,
rosiglitazone reduced: (1) the increase in the staining (immunohistochemistry) for
nitrotyrosine and
poly (ADP-ribose) polymerase (PARP), (2) the expression of
inducible nitric oxide synthase (iNOS),
cyclooxygenase-2 (COX-2), intercellular adhesion molecules-1 (ICAM-1) and
P-selectin in the lungs of
carrageenan-treated rats. In order to elucidate whether the protective effect of
rosiglitazone is related to activation of the
PPAR-gamma receptor, we also investigated the effect of a
PPAR-gamma antagonist,
bisphenol A diglycidyl ether (BADGE), on the protective effects of
rosiglitazone. BADGE (30 mg/kg i.p.) administered 30 min prior to treatment with
rosiglitazone significantly antagonized the effect of the
PPAR-gamma agonist and thus abolished the anti-inflammatory effects of
rosiglitazone. We propose that
rosiglitazone and other potent
PPAR-gamma agonists may be useful in the
therapy of
inflammation.