Bioaccumulation of Psychoactive Contaminants and Their Effects on Brain–Gonad–Sperm Neurotransmitter Networks in Fish

Psychoactive compounds (PSYCs) in aquatic environments raise concern due to the evolutionary conservation of neurotransmitter systems across vertebrates. While their potential to affect neural function is increasingly recognized, much less is known about their influence on fish reproduction, which relies on neurotransmitters both via the brain-gonadal axis and directly within sperm, independent of neural control. Here, we investigated the effects of environmentally relevant concentrations of a mixture of seven PSYCs (citalopram, donepezil, gabapentin, methamphetamine, sertraline, tramadol, and venlafaxine) on European perch (<i>Perca fluviatilis</i>) during a 23 day exposure. Neurotransmitter levels were quantified in brain, gonads, and sperm using LC-HRMS/MS, accompanied by bioaccumulation assessment, histopathology, and sperm quality analysis. All tested compounds bioaccumulated in brain and gonads and, notably, in sperm. Exposure to PSYCs modified neurotransmitter levels across tissues, disrupting correlation patterns between neurochemicals in brain, gonads, and sperm. No significant changes were observed in gonadal histopathology or sperm-quality parameters; however, the observed molecular alterations suggest potential consequences under longer or chronic exposures. These findings identify sperm as a previously overlooked target for psychoactive pollutants and reveal neurochemical disruption along the brain-gonad-sperm axis as a previously unrecognized mechanism through which PSYCs may affect fish physiology.