Neurotoxic effects of carbamazepine on the mosquitofish Gambusia affinis.

In recent years, the presence of pharmaceuticals in the aquatic environment has gained a significant attention. Carbamazepine, a commonly prescribed antiepileptic drug, has been consistently found in aquatic environments at concentrations ranging from nanograms to micrograms, raising concerns about its potential negative impacts on aquatic organisms. The study examined the acute and chronic neurotoxic effects of environmentally relevant and sublethal concentrations of carbamazepine in the mosquitofish Gambusia affinis. After a 96-hour exposure period, the median lethal concentration (LC₅₀) of carbamazepine for G. affinis was determined as 24 mg L ^{- 1}. For the current study, sublethal concentrations i.e., one-tenth (2.4 mg L ^{- 1}) and one-fifth (4.8 mg L ^{- 1}) of the LC₅₀ value were chosen for assessing the neurotoxic effects along with the environmentally relevant concentration (13 ng L ^{- 1}). The research findings indicated that carbamazepine had a disruptive impact on the typical growth and behavior of the fish. During the acute exposure phase, physical deformities were observed in the fish, resulting in neonatal and postneonatal fatalities. Furthermore, the neurotoxic effects of carbamazepine were clearly demonstrated through alterations in various neurological parameters, including acetylcholinesterase, dopamine, gamma-aminobutyric acid, serotonin, monoamine oxidase, 5-hydroxyindole acetic acid, adrenaline, and nor-adrenaline. These findings raise concerns about the survival of fish populations in their natural environment.