Sex differences in stereotyped behavior in the rat

Neurologically intact female rats exhibited more intense and more prolonged stereotyped behavior in response to 5 mg/kg doses of d-amphetamine than males. They also displayed greater stimulation of activity in response to 1.5 mg/kg doses of the drug. Prior treatment with intrastriatal injections of 6-hydroxydopamine (6HDA) eliminated the sex difference in response to 5 but not to 1.5 mg/kg amphetamine. Neither intact nor 6HDA treated rats differed in the amount of stereotyped behavior elicited by the dopamine agonist apomorphine suggesting that the sex difference in amphetamine-elicited stereotypy is not the result of differences in strial receptor mechanisms. The present results could arise from sex differences in amphetamine uptake and metabolism which have been described recently although other explanations are possible.