Rat dopaminergic hypersensitivity. II. Effects of sex.

Two groups of 5 male and 5 female Sprague-Dawley rats each were tested for dopaminergic hypersensitivity on d-amphetamine or apomorphine following a drug abuse-kindling model. In constrast to the males, the female animals did not develop hypersensitivity on either drug, had a higher baseline stereotyped behavior on low doses of d-amphetamine, and lower baseline for apomorphine. Furthermore, on apomorphine the females showed tolerance instead of hypersensitivity with a significant decrease of stereotyped behavior a posttest as compared with pretest. Female rats do not develop a readily demonstrable dopaminergic hypersensitivity with this procedure and show an absence of reverse tolerance to apomorphine.