Role of anorexia and behavioral activation in amphetamine-induced suppression of feeding: implications for understanding tolerance.
In order to gain further insight into the mechanism of contingent tolerance to amphetamine anorexia (Carlton & Wolgin, 1971), an attempt was made to determine the role of anorexia and behavioral activation (increased locomotion and/or stereotypy) in the initial suppression of feeding produced by the drug. Rats administered chronic injections of either saline or amphetamine (2 or 4 mg/kg) were given milk either directly into the mouth through an intraoral cannula or in a standard drinking tube. It was reasoned that although drug-induced anorexia would affect intake with both methods of feeding to the same degree, the disruptive effect of behavioral activation would be greater in bottle-fed rats. The results revealed that bottle-fed rats given amphetamine showed substantially greater suppression of intake than cannula-fed rats. Saline-treated rats showed almost identical milk intake with the two methods. Recovery of intake occurred in all drugged rats except those given 4 mg/kg and fed by bottle. In the tolerant groups, rats fed by bottle and given 2 mg/kg recovered at a faster rate than cannula-fed rats at either dose. These results demonstrate that in the normal drinking condition, the initial suppression of intake is caused by a combination of anorexia and behavioral interference and that tolerance occurs to both of these effects.
D000818:Animals; D001066:Appetite / Q000187:drug effects*; D001070:Appetitive Behavior / Q000187:drug effects; D001143:Arousal / Q000187:drug effects*; D003913:Dextroamphetamine / Q000494:pharmacology*; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects*; D008297:Male; D009042:Motivation / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains
D003913:Dextroamphetamine