Neuroactive Pollution Disrupts Cognition in Fish by Causing Sex-Specific Effects on Spatial Learning

Area of Science:

• Environmental toxicology
• Neuroscience
• Ecotoxicology

Background:

• Cognitive functions are vital for animal survival and are threatened by environmental pollutants.
• Neuroactive pharmaceuticals are common aquatic contaminants, posing risks to wildlife cognition.
• Amitriptyline, an antidepressant, is a prevalent pharmaceutical pollutant.

Purpose of the Study:

• To investigate the impact of amitriptyline exposure on spatial learning in guppies (Poecilia reticulata).
• To determine if amitriptyline affects cognitive performance in a sex-specific manner.

Main Methods:

• Wild-caught guppies were exposed to control, low (52 ng/L), or high (496 ng/L) concentrations of amitriptyline for 11 days.
• Spatial learning was assessed using a repeated-trial maze assay over 12 trials.
• Maze solve times and navigational errors were quantified to measure learning performance.

Main Results:

• All groups showed spatial learning, indicated by improved performance over trials.
• Male guppies exposed to amitriptyline made significantly more navigational errors compared to controls.
• Female guppies' learning performance was not affected by amitriptyline exposure.
• Amitriptyline exposure reversed sex differences in spatial learning accuracy, with males performing worse than females at higher concentrations.

Conclusions:

• Amitriptyline exposure impairs spatial learning in male guppies, demonstrating sex-specific cognitive effects.
• Environmental risk assessments must consider sex differences in wildlife responses to pharmaceutical pollutants.
• Widespread pharmaceutical pollutants like amitriptyline pose a significant ecological threat to aquatic wildlife cognition.