Distribution of antidepressants and their metabolites in brook trout exposed to municipal wastewaters before and after ozone treatment--evidence of biological effects.

This study examined the tissues distribution of selected serotonin reuptake inhibitors (SSRIs) in brook trout exposed for 3 months to continuous flow-through primary-treated effluent before and after ozone treatment. A reliable analytical method was developed for the quantification of trace amounts of antidepressants in small tissue homogenate extracts. Levels of six antidepressants and four of their N-desmethyl metabolites were determined using liquid chromatography-tandem mass spectrometry. Significant amounts of the SSRIs were found in fish tissue-in decreasing order: liver>brain>muscle. Sertraline and its metabolite desmethylsertraline were the predominant substances observed in most tissues (0.04-10.3 ng g(-1)). However, less SSRIs (0.08-1.17 ng g(-1)) were bioaccumulated in the ozonated effluent. The early molecular effects of these SSRIs on the Na/K-dependent ATPase pump activity in brain synaptosomes where also investigated in vitro and in fish exposed to the municipal effluents. With respect to their potential biological effects, in vitro exposure to selected SSRIs induced a reduction of the brain Na/K-ATPase activity in synaptosomes in a dose-dependent manner. Results showed that Na/K-ATPase activity was readily inhibited by exposure to municipal effluent before and, to a lesser extent, after ozone treatment. Moreover, the Na/K-ATPase activity was significantly and negatively correlated with brain tissue concentrations of fluoxetine (r=-0.57; p<0.03), desmethylsertraline (r=-0.84; p<0.001), and sertraline (r=-0.82; p<0.001). The present study reveals that SSRIs are readily available in fish, biologically active and corroborates previous findings on the serotonergic properties of municipal effluents to aquatic organisms.

Effects of Montreal municipal sewage effluents on immune responses of juvenile female rainbow trout (Oncorhynchus mykiss).

The objective of this study was to examine the immunotoxicity of treated Montreal sewage effluents on juvenile female rainbow trout (Oncorhynchus mykiss). A comprehensive panel of immunological assays was used to evaluate the effects of exposure for 1 and 4 weeks to 1, 3, 10 and 20% sewage effluent. Phagocytic ingestion of fluorescent latex beads by head kidney macrophages and granulocytes was suppressed following 1-week of exposure, with the highest exposure concentration being the most suppressive. Phagocytic activity returned to control levels after 4 weeks of exposure. The cytotoxic activity of head kidney derived non-specific cytotoxic cells was enhanced after a 1-week exposure, especially at the lowest exposure concentration, and returned to control levels after 4 weeks of exposure. In vitro lymphocyte proliferation in response to LPS and ConA activation was not affected following sewage effluent exposure, but nonactivated, spontaneous proliferation of lymphocytes was suppressed in a dose-dependent manner after 4 weeks of exposure. Plasma lysozyme activity was elevated at lowest exposure concentration after 4 weeks. No changes were noted in either the blood leukocyte/erythrocyte ratio or in the proportion of circulating lymphocytes and thrombocytes. The proportion of circulating granulocytes increased following exposure for 4 weeks to the low effluent concentration. Plasma cortisol levels were not affected by effluent exposure suggesting that mechanisms other than stress influenced the observed immunomodulation. In summary, this study demonstrates that sewage effluent can alter the immune functions of rainbow trout.