Intra-VTA baclofen attenuates cocaine self-administration on a progressive ratio schedule of reinforcement.
The effect of microinjections of baclofen into the ventral tegmental area (VTA), nucleus accumbens, or striatum on cocaine self-administration reinforced on a progressive ratio schedule was investigated. Intra-VTA baclofen produced the most potent modulation of cocaine intake, causing a significant reduction in cocaine-reinforced break points at a dose (56 ng/side) that was substantially lower than doses necessary to produce comparable reductions in the nucleus accumbens or striatum. During the time that cocaine-reinforced responding was suppressed, rats demonstrated the capacity to complete several hundred responses on a concurrently available food-reinforced lever, indicating that the effect of baclofen on cocaine intake was not due to a generalized disruption in operant responding. The results indicate that GABA(B) receptors in the VTA may have the potential to modulate reward processes associated with cocaine use.
Brebner
K
K
Institute of Neuroscience, Carleton University, Ottawa, ON, K1S 5B6, Canada.
Phelan
R
R
Roberts
D C
DC
D000818:Animals; D001418:Baclofen / Q000008:administration & dosage / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D005502:Food; D018755:GABA Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D017072:Neostriatum / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D018080:Receptors, GABA-B / Q000187:drug effects; D012055:Reinforcement Schedule; D012646:Self Administration; D017557:Ventral Tegmental Area / Q000502:physiology
D018755:GABA Agonists; D018080:Receptors, GABA-B; D001418:Baclofen; D003042:Cocaine