Enduring behavioral effects of weaning-through-puberty cocaine dosing in the rat

Abstract

To determine whether cocaine administration during a developmental period corresponding to middle and late childhood results in enduring changes in behavior, we injected rats with 5 or 20 mg/kg/d of cocaine s.c. from weaning (postnatal day 21; P21) through P60; controls included uninjected and vehicle-injected controls. The 20-mg/kg dose resulted in a transient, male- limited weight reduction for the last 10 days of dosing, which rapidly recovered to normal after dosing ceased. Approximately 5 months later, the subjects were given a brief battery of behavioral tests. Female 20-mg subjects received fewer reinforcements than control subjects in a DRL-20 task. Female subjects also displayed altered patterns of cocaine-stimulated changes in open-field activity. No significant lasting effects were seen in males. These data suggest that the central nervous system retains sufficient plasticity into later development to produce long-lasting functional changes in response to drug administration and that cocaine consumption during the rat equivalent of childhood produces very long lasting plastic changes in behavior.