Effects of trophic exposure to diclofenac and dexamethasone on hematological parameters and immune response in freshwater fish

The aim of the present study was to evaluate the effects of diclofenac and dexamethasone on hematological parameters and immune response in the fish species Hoplias malabaricus after trophic exposure. Fish were fed twice every week with Astyanax sp., which were given an intraperitoneal inoculation with diclofenac (0μg/kg, 0.2μg/kg, 2.0μg/kg, or 20.0μg/kg) or dexamethasone (0.03μg/kg, 0.3μg/kg, or 3.0μg/kg). After 12 doses, the hematological parameters and lipopolysaccharide-induced nitric oxide production by head kidney monocytic lineage were evaluated. Exposed fish also received 1mg/kg of carrageenan intraperitoneal, and cell migration to the peritoneal cavity was evaluated after 4h. Diclofenac and dexamethasone altered the red blood cell count, as well as hematocrit and hemoglobin levels. The total blood leukocyte count decreased in all groups. A significantly reduced carrageenan-induced leukocyte migration to the peritoneal cavity, particularly of polymorphonuclear cells, was observed at all tested doses, suggesting a possible immunosuppressive effect. The basal nitric oxide synthesis of head kidney cell cultures was reduced at the highest dose of diclofenac and was increased at the highest dose of dexamethasone. The lipopolysaccharide-stimulated nitric oxide production was reduced in all treatments, thus corroborating the immunosuppressive effect. Although some fish responses were variable for different drugs, the results suggested that trophic exposure to diclofenac and dexamethasone can lead to hematological changes and immunotoxic effects, causing negative impacts in aquatic organisms.