Increased motivation for self-administered cocaine after escalated cocaine intake.
Escalation in cocaine self-administration is hypothesized to involve increased motivation to consume cocaine. The present study determined the effects of escalated cocaine self-administration in rats on the cocaine dose-response function under a progressive ratio schedule. Two groups of rats were allowed to self-administer cocaine under a fixed ratio schedule, for 1 h (ShA; n = 7) or 6 h (LgA; n = 6) per day. The subjects were then allowed to self-administer five doses of cocaine (0, 0.031, 0.063, 0.125 and 0.25 mg/infusion) under a progressive ratio schedule. The dose-response function was shifted upwards in the LgA compared to the ShA group. In conclusion, the present data suggest that escalation in cocaine self-administration is associated with a significant increase in the incentive motivational value of self-administered cocaine.
Paterson
Neil E
NE
Department of Neuropharmacology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Markou
Athina
A
D000818:Animals; D016739:Behavior, Addictive / Q000523:psychology*; D003042:Cocaine / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D008297:Male; D009042:Motivation; D051381:Rats; D017208:Rats, Wistar; D012646:Self Administration / Q000379:methods / Q000523:psychology
D003042:Cocaine