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.

Diuron metabolites act as endocrine disruptors and alter aggressive behavior in Nile tilapia (Oreochromis niloticus).

Diuron and its biodegradation metabolites were recently reported to cause alterations in plasma steroid hormone concentrations with subsequent impacts on reproductive development in fish. Since steroid hormone biosynthesis is regulated through neurotransmission of the central nervous system (CNS), studies were conducted to determine whether neurotransmitters that control hormone biosynthesis could be affected after diuron and diuron metabolites treatment. As the same neurotransmitters and steroid hormones regulate behavioral outcomes, aggression was also evaluated in male Nile tilapia (Oreochromis niloticus).