Effect of diazepam and A beta-carboline on open-field and T-maze behaviors in 2-day-old chicks.

The effects of diazepam and the beta-carboline FG 7142 in chicks were examined on several behavioral measures in open-field and T-maze tasks. In the open field, only the higher doses of diazepam affected behavior, suggesting a sedative-like effect, while FG 7142 influenced behavior as would a fear-inducing manipulation. After a low dose of either drug was injected, testing in a T-maze showed that diazepam improved and FG 7142 impaired the escape performance from the isolation chamber, without affecting the time spent in the T-corridor. In three groups of chicks selected on the basis of their first escape performance, only lower performance chicks were affected by an anxiolytic dose of diazepam. T-maze results suggest that: (a) T-maze is more sensitive than open-field test to behavior changes induced by anxiolytic doses of diazepam; (b) isolation chamber behavior could be an index of general emotionality in young chicks; (c) diazepam and FG 7142 do not modify the social motivation to escape the maze; (d) higher performance chicks present an escape behavior of a less anxious type than lower performance chicks. The results suggest that the GABAergic system is involved in the behavioral expression of fear and anxiety in young chicks.