Behavioral analysis of anxiolytic action of phenazepam in conditions of an acute psychogenic stress (predator presentation) in Danio rerio

Abstract

We studied the effect of benzodiazepine anxiolytic phenazepam after the predator presentation to Danio rerio. The test of novelty was used: the fish was placed first in a beaker with a dissolved pharmacological substance (or H2O) and then into a novel tank for 6 min, where the trajectory, the path length, the number of movements to the upper part of the novel tank, the number and time of the pattern of freezing were measured. It is shown that, in response to the novelty of tank, the fish are reacted by submerging to the bottom, increasing the frizing, and reducing the number of movements to the upper half of the novel tank. After phenazepam administration, the fish were not only in the lower, but also in the upper part of the novel tank. The average path length did not change significantly in the range of doses used. The number and time of the frizing, as well as the time spent in the lower part of the novel tank, decreased more than 2 times compared to the control group of animals and showed a dose-dependent effect. The number of movements to the upper part of the novel tank for the experiment increased significantly from 1 in the control to 57 after phenazepam in a dose of 1 mg/l. At the same time, the number of movements of fish to the upper part of the novel tank significantly increased more than 2 times from 3th min of the experiment with the use of phenazepam in a dose of 1 mg/l. Predator presentation (Hypsophrys nicaraguensis) caused an increase in the number of freezing (temporary immobilization) and a decrease in the length of the trajectory of movement in the novel tank as compared with the Danio rerio control group. Phenazapam at a dose of 1 mg/l removed the effects of a predator, while exhibiting a typical effect: the number of movements to the upper part of the tank during the experiment significantly increased to 30; the time at the bottom of the tank was halved. It was concluded that the novelty stress test and the test with a predator are highly sensitive for studying anxiety-phobic reactions in Danio rerio.