Dose dependent effects of serotonergic agents on anxiety.

Unlabelled: The role of serotonin in depression and anxiety is still highly controversial. In this experiment the effect of two substances upon anxiety was studied in rats.

Methods: Forty adult (45-55 weeks old) male Wistar rats were used to study the following behavioral parameters on elevated plus maze test: open arm and closed arm entries; open arm, closed arm and central square activity duration, open arm preference and total distance traveled.

Results: A single injected dose of the antidepressant fluoxetine had no significant effect on animals' activity in the open-arm test, neither in a small dosage (5 mg/kgbw) nor in a higher one (10 mg/kgbw), whereas a single high dose of buspirone significantly impeded the open-arm activity of the rats. None of the substances influenced the general locomotor activity significantly, but the higher doses of buspirone mainly blocked the closed-arm entries and they even decreased the total distance traveled.

Conclusion: Acute fluoxetine and buspirone administration influenced the rats' behavior in the elevated plus-maze test in a dose dependent manner. Anxiolytic effects occur after small doses but anxiogenic-like effects were noticed in rodents when higher doses were used.