Effects of an Antagonist of the Gastrin-Releasing Peptide Receptor in an Animal Model of Uveitis

Abstract

Some studies have shown the role of gastrin-releasing peptide (GRP) on the production and release of cytokines both in animal models and in humans with inflammatory diseases, but there are no reports on the effects of GRP in ocular inflammatory disease, mainly uveitis. The authors report on the effects of the GRP receptor (GRPR) antagonist RC-3095 in a well-established model for uveitis induced by the administration of lipopolysaccharide (LPS), comparing its effects with those of glucocorticoids. Adult male Wistar rats (weight range, 250-300 g; n = 6 per group) were randomly divided into four groups: saline, LPS + saline, LPS + dexamethasone, LPS + RC-3095. Two hours after LPS administration, RC-3095 (0.3 mg/kg, single dose, subcutaneously) or dexamethasone (1 mg/kg, each 6 hours, subcutaneously) was administered. After 24 and 48 hours, rats were anesthetized, aqueous humor was sampled, and the irides were removed. Aqueous humor tumor necrosis factor-alpha, monocyte chemoattractant protein-1 concentration, myeloperoxidase activity were determined. In addition, oxidative damage to the irides was determined by the measure of thiobarbituric acid reactive substances and protein carbonyl content. The acute administration of RC-3095 exhibited anti-inflammatory actions, characterized by a reduction of myeloperoxidase activity and a decrease in tumor necrosis factor-alpha and monocyte chemoattractant protein-1 levels, to a greater extent than dexamethasone. In addition, RC-3095 elicits important action against irides oxidative damage. These findings suggest that GRP participates in the inflammatory response in an animal model of uveitis, making GRPR a target for new therapeutic options in the treatment of uveitis.