The Anxiolytic Effect of Chlorpheniramine on Zebrafish in the Novel Tank Diving Test

Abstract

Recent research in rodents has demonstrated that the histaminergic system plays a role in anxiety related behaviours and that histamine antagonists produce anxiolytic responses, possibly by interacting with other monoamine neurotransmitters, such as dopamine and serotonin. Because zebrafish (Danio rerio) are an excellent model organism for studying the biological basis of anxiety disorders, it is of interest to characterize the histaminergic system in this species. We investigated whether chlorpheniramine, a histamine antagonist commonly used in rodents would produce an anxiolytic response in zebrafish. Since this drug has never been tested in zebrafish, we performed pilot tests to determine two doses (20mg/L and 25mg/L). Fish were dosed through immersion for 10 minutes and tested in the novel tank diving test, which measures the duration that fish spend in the bottom of the tank compared to the top since more anxious fish prefer to dwell at the bottom of a body of water. We found that at the 20mg/L dose, but not the 25mg/L dose, fish were more likely to engage in exploratory behaviour (i.e. spent less time in the bottom zone). This suggests that 20mg/L is sufficient for producing an anxiolytic response in zebrafish. Other doses should be tested to assess the range at which chlorpheniramine is most effective in zebrafish.

Discipline: Psychology (Honours)

Faculty Mentor: Dr. Melike Schalomon