Effects of Reserpine and Amphetamine on the Development of Hyperactivity in Maternally Deprived Rat Pups

Abstract

Maternal deprivation for 24 h produced hyperactivity in 2 wk old infant rats kept at nest temperature. Pretreatment with reserpine (0.5 mg/kg), at the time of separation, prevented the development of hyperactivity over the ensuing 24 h; the same dose in mothered littermates had no residual effects on behavior the next day. d-Amphetamine (0.25 and 2.0 mg/kg) produced dose-dependent increases in locomotion and rearing and decreases in self-grooming behavior, which were of comparable magnitude whether the pups were separated and kept warm, normally mothered or separated at room temperature (a condition known to produce decreased activity levels). Cardiac rates were not affected by either drug; reserpine lowered respiratory rates slightly, amphetamine increased body temperature following behavior testing. Altered accumulation of catecholamines at presynaptic terminals is discussed as a possible neurochemical mechanism for behavior changes following maternal separation in this model system.