Differential behavioral responses of male and female adult rats treated with five psychotropic drugs in the neonatal stage.

Male and female rats received during infancy either handling or injections of saline, phenobarbital, haloperidol, diazepam, chlorpromazine, and amphetamine. On reaching adulthood, the behavior of these animals was measured in an open-field arena and in a Lashley III maze. Saline injections per se affected the behavior of males but were unable to change that of females. The drugs provoked increased ambulation and/or decreased defecation of males in the open field, whereas with the females the opposite was observed, that is, a decreased ambulation and/or an increased defecation. Consequently, the early drug treatments abolished the sexual differences normally observed in ambulation and defecation of rats. Four of the 5 drugs tested deteriorated the maze performance of both male and female rats.