GABAergic anxiolytic drug in water increases migration behaviour in salmon

Gustav Hellström,Tomas Brodin,Anders Alanärä,Lo Persson,Jerker Fick,Jonatan Klaminder,Fia Finn,Micael Jonsson

doi:10.1038/ncomms13460

Gustav Hellström, Tomas Brodin + Show 6 more

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https://doi.org/10.1038/ncomms13460

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Abstract

Migration is an important life-history event in a wide range of taxa, yet many migrations are influenced by anthropogenic change. Although migration dynamics are extensively studied, the potential effects of environmental contaminants on migratory physiology are poorly understood. In this study we show that an anxiolytic drug in water can promote downward migratory behaviour of Atlantic salmon (Salmo salar) in both laboratory setting and in a natural river tributary. Exposing salmon smolt to a dilute concentration of a GABAA receptor agonist (oxazepam) increased migration intensity compared with untreated smolt. These results implicate that salmon migration may be affected by human-induced changes in water chemical properties, such as acidification and pharmaceutical residues in wastewater effluent, via alterations in the GABAA receptor function.

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We investigated whether exposure to environmental relevant concentrations of oxazepam, a positive allosteric modulator of the GABAA receptor and a common agent in anxiolytic pharmaceuticals, affected the migration behaviour of Atlantic salmon smolt
The migration intensity of exposed fish was steadily decreasing over time, which is in line with the elimination rate of oxazepam from fish muscle tissue (Fig. 4)

Summary

Introduction

Access to the published version may require subscription. N.B. Exposing salmon smolt to a dilute concentration of a GABAA receptor agonist (oxazepam) increased migration intensity compared with untreated smolt These results implicate that salmon migration may be affected by human-induced changes in water chemical properties, such as acidification and pharmaceutical residues in wastewater effluent, via alterations in the GABAA receptor function. Sustained stress grounded in anticipation of fear and danger may permeate an individual’s motivation, choices and behaviour, and has been found to influence a wide range of ecological characteristics, including species distribution and population demographics[13], complementing more established ecological drivers such as resource availability and environmental conditions Such anxiety-related emotion-based stress is thought to be adaptive, as it may minimize unnecessary risk taking and maintain alertness even though no immediate stressor, such as a predator, might be present[12]. Altered behaviour in fish due to modulation of the GABAA receptor function following exposure to anthropogenic water pollution, such as pharmaceutical residues and/or acidification, has been highlighted as a major concern in aquatic ecotoxicology and conservation[17,20]

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