Effects of acute and chronic cocaine on milk intake, body weight, and activity in bottle- and cannula-fed rats

The effects of cocaine on the milk intake, body weight and activity of bottle- and cannula-fed rats was compared under both acute and chronic dosing conditions. Bottle-fed rats were initially more hypophagic than cannula-fed rats when given acute injections of cocaine (4-40 mg/kg). Following chronic injections of the drug (16 mg/kg), bottle-fed rats developed tolerance, as shown by a rightward shift in the dose-response function for milk intake. Such tolerance was accompanied by a decrease in drug-induced motor activity. In contrast, cannula-fed rats showed marked sensitization of stereotyped movements. Bottle-fed rats showed marked sensitization of stereotyped movements.