Effects of chronic d-amphetamine on social behavior of the rat: implications for an animal model of paranoid schizophrenia.

Hooded rats in a social colony were given increasing daily doses of d-amphetamine up to 8 mg/kg. Time-lapse 16 mm cinematographically recorded behavior was analyzed for the following: grooming, feeding, sex, sleeping, resting, sterotypy, agonistic behavior, muricidal activity, and the location and movement of each rat. Subordiant rats receiving d-amphetamine actively withdrew from social interactions by retreating to strategically defensible locations in the environment. They remained hypervigilant of other rats and overreacted to their approaches by either fleeing or by defensively rearing and "boxing". On the other hand, when the dominant rat received the maximum dose, it seemed totally oblivious to the other rats. The responses to drug treatment in subordinant rats may provide a model for the social behavior of frightened paranoid schizophrenics.