Anxiety is a complex disorder with large clinical relevance, whose study with animal models is important for research about their mechanisms and drugs for their treatment. The zebrafish appears as a potential animal model for pharmacological research in anxiety. A model of anxiety is the light-dark preference, which has been validated behaviorally in zebrafish, however, requires a pharmacological validation. The objective is to describe the sensitivity of the light-dark preference in zebrafish adults for the most common drugs in clinical anxiety, were administered by immersing the animal in the solution: Benzodiazepines (Clonazepam), 5-HT1A partial agonists (Buspirone), Tricyclic Antidepressant (Imipramine), Antidepressant SSRIs (Fluoxetine and Paroxetine), Antipsychotics (Haloperidol and Risperidone); Psychostimulant (Diethylpropion), Beta blockers (Propranolol) and CNS depressants (Ethanol). The parameters analyzed were the time spent by the animal in a dark environment, the time of the first latency and number of midline crossings. Clonazepam administered 300 s increased the time in the dark at lower concentrations and reduced locomotor activity, administration during 600 s of the intermediate concentration decreased over time in the dark and the first latency, and increased locomotor activity, indicating anxiolytic effect. Buspirone raised the time spent in the dark, probably due to reduction of motor activity. Imipramine and fluoxetine increased time in the dark and the first latency and decreased the number of alternations, indicating anxiogenic action. Paroxetine did not alter the time in the dark, however the first time increased latency and decreased locomotor activity. Haloperidol decreased anxiety in the lowest concentration, curiously raised motor activity at the highest concentration, instead of risperidone, which decreased the activity at the highest concentration. Diethylpropion did not change over time in the dark but increased the time of the first latency and decreased motor activity only at lower concentrations. Propranolol reduced only time in the dark. Ethanol was effective in reducing anxiety with the intermediate concentration and decreased locomotor activity in a lower concentration. Data corroborate with the literature in Danio rerio both intraperitoneal administration in this model as in other models for water delivery and in rodents, when it was possible to compare.
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