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(56-03) Endocrine disruption of monoamines and their metabolism in freshwater mussels exposed to a municipal effluent. Gagné, François*,1, Blaise, Christian1, 1 St.-Lawrence Center, Montreal, Quebec ABSTRACT- We examined the potential effects of municipal wastewaters on the metabolism of biogenic amines. Surface water samples were first obtained from sites upstream and downstream along the dispersion plume of a municipal effluent, and extracts prepared using a solid phase C8 mini-column. The potential effects of these extracts were then examined by determining 1) serotonin uptake by HT7 human receptors in transfected Chinese hamster ovary cells, and 2) mono-amine oxidase (MAO) activity and vitellogenin expression in trout hepatocytes. Furthermore, levels of catecholamines, serotonin with its major metabolite 5-hydroxyindolacetate (5-HIA), and MAO activity were determined in nerve tissues of mussels exposed for 98 days at 1.5 km upstream and 8 km downstream of a major urban effluent outfall. Results showed that extracts prepared from surface water samples influenced by the effluent plume contained compounds capable of activating human serotonin receptors and inducing both MAO and vitellogenin in hepatocytes. Activation of the serotonin receptor was significantly correlated with levels of excreted vitellogenin in the extracellular medium (R = 0.95, p < 0.01) and with MAO activity (R = 0.99, p < 0.01) in rainbow trout hepatocytes. Moreover, mussels at the downstream site had depressed levels of serotonin and catecholamines and increased levels of MAO activity in nerve ganglia. Hence, municipal effluents appear to release compounds that are capable of disrupting the normal metabolism of biogenic amines in freshwater mussels and in fish hepatocytes. We also observed that these extracts were capable of activating human serotonin receptors in transfected Chinese hamster ovary cells and MAO activity in hepatocytes. Serotonin and catecholamines are involved in the sexual differentiation process in fish and in the spawning process and maturation of oocytes in bivalves. This initial study suggests that reduced levels of serotonin and increased activity of MAO in nerve ganglia could have disruptive effects on the reproductive cycle and sex ratio of oviparous organisms in rivers contaminated by municipal wastewaters. Key words: Monoamines, Serotonin, monoamine oxidase, mussels |
