Voluntary consumption of amphetamine, cocaine, ethanol and morphine by rats as influenced by a preceding period of forced drug intake and clozapine.
Forced nicotine intake was previously found to decrease a subsequent free choice selection, whereas clozapine (CL) caused a marked increase in its consumption. Here these findings are extended to ethanol, cocaine, morphine and amphetamine. Forced intake of ethanol, cocaine, morphine and amphetamine had no major effect on a subsequent voluntary intake. CL, a dopamine D4 antagonist, increased the voluntary consumption of amphetamine and morphine with no effects on ethanol or cocaine intake. Only for cocaine was it found that low-consuming rats increased but high-consuming rats decreased their voluntary cocaine intake by CL. Thus, forced drug exposure per se does not lead to subsequent enhancement of voluntary intake; CL exerts differential effects on intake of these drugs, and a specific dopaminergic set point may govern the voluntary intake of cocaine by individual rats.
D000284:Administration, Oral; D000661:Amphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002492:Central Nervous System Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D003024:Clozapine / Q000494:pharmacology*; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D015259:Dopamine Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009294:Narcotics / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012646:Self Administration; D019966:Substance-Related Disorders / Q000209:etiology