The immediate and the delayed effects of buspirone on zebrafish (Danio rerio) in an open field test: A 3-D approach

Behavioral changes in zebrafish induced by acute administration of buspirone have been interpreted to be the result of reduced anxiety. The purpose of the current study was to determine whether the effects of short-term and mid-term habituation to an open field corroborated the anxiolytic hypothesis. We exposed single zebrafish for 60 min to 5 mg L buspirone and tested them twice, immediately after exposure and again 3.5 h later. Each session lasted 20 min. Distance from bottom of tank, velocity, duration freezing, distance from center and horizontal distribution, and preferred spatial location were analyzed with a 3-D tracking system. In the early session (starting at 10:30), 20 min habituation of control zebrafish only marginally increased distance from bottom, which was still 90% higher in zebrafish treated with buspirone. When extending the habituation to 3.5 h, the picture became more complex. Distance from bottom did not further increase in control zebrafish. More importantly, some signs of increased anxiety were present in the buspirone group, such as increased freezing, reduced velocity, and increased bottom-dwelling. However, analyzing data of individual fish excluded rebound anxiety as unlikely. The delayed effects might be drug side effects, such as motor impairment and/or dizziness. The immediate and the delayed effects of buspirone have the appearance to be unrelated.

► Buspirone has immediate and delayed effects on zebrafish behavior.
► The immediate effects seem at least partly to be anxiolytic.
► The delayed effects seem to be adverse side effects of the drug.