Measuring anxiety in zebrafish: a critical review.

The scototaxis (dark/light preference) protocol is a behavioral model for fish that is being validated to assess the antianxiety effects of pharmacological agents and the behavioral effects of toxic substances, and to investigate the (epi)genetic bases of anxiety-related behavior. Briefly, a fish is placed in a central compartment of a half-black, half-white tank; following habituation, the fish is allowed to explore the tank for 15 min; the number and duration of entries in each compartment (white or black) are recorded by the observer for the whole session. Zebrafish, goldfish, guppies and tilapias (all species that are important in behavioral neurosciences and neuroethology) have been shown to demonstrate a marked preference for the dark compartment. An increase in white compartment activity (duration and/or entries) should reflect antianxiety behavior, whereas an increase in dark compartment activity should reflect anxiety-promoting behavior. When individual animals are exposed to the apparatus on only one occasion, results can be obtained in 20 min per fish.

Scototaxis as anxiety-like behavior in fish

The average surface pH of the ocean is dropping at a rapid rate due to the dissolution of anthropogenic CO2, raising concerns for marine life. Additionally, some coastal areas periodically experience upwelling of CO2-enriched water with reduced pH. Previous research has demonstrated ocean acidification (OA)-induced changes in behavioural and sensory systems including olfaction, which is due to altered function of neural gamma-aminobutyric acid type A (GABAA) receptors. Here, we used a camera-based tracking software system to examinewhether OA-dependent changes in GABAA receptors affect anxiety in juvenile Californian rockfish (Sebastes diploproa). Anxiety was estimated using behavioural tests that measure light/dark preference (scototaxis) and proximity to an object. After one week in OA conditions projected forthenextcenturyintheCaliforniashore(1125+100 matm,pH7.75),anxiety was significantly increased relative to controls (483+40 matm CO2, pH 8.1). The GABAA-receptor agonist muscimol, but not the antagonist gabazine, caused a significant increase in anxiety consistent with altered Cl 2 flux in OA-exposed fish. OA-exposed fish remained more anxious even after 7 days back in control seawater; however, they resumed their normal behaviour by day 12. These results show that OA could severely alter rockfish behaviour; however, this effect is reversible.

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CO2-induced ocean acidification increases anxiety in rockfish via alteration of GABAA receptor functioning.

Selective serotonin reuptake inhibitors (SSRIs) represent a class of pharmaceuticals previously reported in aquatic ecosystems. SSRIs are designed to treat depression and other disorders in humans, but are recognized to elicit a variety of effects on aquatic organisms, ranging from neuroendocrine disruption to behavioral perturbations. However, an understanding of the relationships among mechanistic responses associated with SSRI targets and ecologically important behavioral responses of fish remains elusive. Herein, linking Adverse Outcomes Pathways (AOP) models with internal dosimetry represent potential approaches for developing an understanding of pharmaceutical risks to aquatic life. We selected sertraline as a model SSRI for a 28-d study with adult male fathead minnows. Binding activity of the serotonin reuptake transporter (SERT), previously demonstrated in mammals and fish models to respond to sertraline exposure, was selected as an endpoint associated with therapeutic activity. Shelter-seeking be...

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Human Therapeutic Plasma Levels of the Selective Serotonin Reuptake Inhibitor (SSRI) Sertraline Decrease Serotonin Reuptake Transporter Binding and Shelter-Seeking Behavior in Adult Male Fathead Minnows

Parametric analyses of anxiety in zebrafish scototaxis.

The present article tried to establish dark/light p reference in five different species of teleosts We proposed, using the data obtained with this method in zebrafishes ( Danio rerio ), Cardinal-tetras (Paracheirodon axelrodi), lambaris ( Astyanax altiparanae ), Nile tilapias ( Oreochromis niloticus ), guppies ( Poecilia reticulata) and banded-knife fishes ( Gymnotus carapo ), that preference for dark environments is a reliable and low-cost index of an xiety/fear in those species A scototactic pattern of exploration was found in all species, and the patte rn of locomotion in the white environment suggests its aversiveness for those species, with the except ion of G carapo and O niloticus  A comparative analysis uncovered species differences in approach- avoidance dimensions of the task The data are discussed in terms of the behavioral ecology of the animals and prey-predator relationships, suggesting a link with predator defense strategies in teleost The dark/light preference model is already establis hed as an “ethoexperimental” anxiety model in rodents (cf Bo urin & Hascoet, 2003) It is based on the natural aversive quality of brightly-l it environments for mice, shaping

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Renata Inah

Papers

A Comparative Analysis of the Preference for Dark Environments in Five Teleosts