Inflammatory properties of municipal effluents to Elliptio complanata mussels - lack of effects from anti-inflammatory drugs

The purpose of this study was to identify the pharmacological effects of anti-inflammatory drugs in freshwater mussels (Elliptio complanata) exposed to a primary-treated municipal effluent. Mussel specimens were injected with either increasing concentrations of ibuprofen or with a municipal effluent extract, and then left to stand for 24 h at 15 °C. They were also exposed to dilutions of a primary-treated effluent for 30 days at 15 °C under semi-static conditions. Gill and gonad cylcooxygenase (COX) were then determined after the incubation period. The influence of various drugs found in municipal effluents on serotonin and dopamine synaptosome transport was determined in visceral ganglia. The results show that injections of ibuprofen reduced COX activity nearly 4-fold in gills and 1.4-fold in gonads. However, COX activity was induced in both tissues after 24 h in mussels injected with a municipal effluent extract and after 30 days in those exposed to dilutions of the effluent. Moreover, synaptosomal dopamine transport activity was increased by ibuprofen, aspirin, caffeine and estradiol-17β (E2), and decreased by loperamide and carbamazepine, suggesting increased and decreased turnover rates of this catecholamine, respectively. Serotonin transport activity was much less affected, decreasing with high doses of loperamide and increasing with ibuprofen, but with less intensity than with dopamine. The results suggest that although ibuprofen can effectively reduce COX activity in gill and gonadal tissues, exposure to both the municipal effluent and its organic extract increased COX activities, indicating the absence of NSAID (non-steroidal anti-inflammatory drugs)-related effects. Besides their known estrogenic and serotonergic properties, municipal effluents appear to elicit a state similar to inflammation in freshwater mussels.