Effects of methylphenidate on the aggressive behavior, serotonin and dopamine levels, and dopamine-related gene transcription in brain of male Nile tilapia (Oreochromis niloticus).

The occurrence of pharmaceuticals in the aquatic environment has increased considerably in the last decades, causing negative biochemical, physiological, and behavioral effects in aquatic organisms. In this study, we evaluated the effects of methylphenidate (MPH) on the aggressive behavior, dopamine-related gene transcript levels, monoamine levels, and carboxylesterase transcript levels and activity in the brain of male Nile tilapia (Oreochromis niloticus). Carboxylesterase activity was also measured in the liver and gills.