Behavioural studies on the effects of d-amphetamine and estradiol benzoate alone and in combination

The effects of d-amphetamine sulphate on grooming, rearing, and ambulatory behaviour in the T-maze was studied in rats. Low doses (0.25-2.0 mg/kg) produced a dose-dependent change in behaviour; ambulatory behaviour was increased while grooming and rearing behaviour was decreased. The results suggest that the behavioural changes are a direct effect of amphetamine rather than a secondary consequence of a competition between different types of behaviour. The effects of d-amphetamine sulphate and/or estradiol benzoate on grooming, rearing, and ambulatory behaviours in the T-maze and open field were also studied. Rats chronically treated with estradiol or oil were injected with amphetamine or saline just prior to evaluation in the maze or open field. Amphetamine treatment, irrespective of environment or hormone treatment, stimulated ambulatory behaviour while inhibiting grooming behaviour. Estradiol specifically antagonized the amphetamine induced reduction of grooming in the maze only. The results suggest that amphetamine has an independent action on T-maze behaviour whereas estradiol has an effect that depends on the environment for its manifestation.