Time-dependent dissociation of cocaine dose-response effects on sucrose craving and locomotion.
In the present study, rats self-administered sucrose 6 h/day for 10 days. Separate groups of rats were then tested on day 1 or day 30 of forced abstinence. After they had responded to near extinction, rats were injected with either saline or cocaine (2.5, 5, 10, or 20 mg/kg intraperitoneal) and then allowed to respond to a sucrose-paired stimulus. Locomotor activity was assessed during testing. Rats pressed more during the extinction responding phase of testing on day 30 than on day 1 of forced abstinence, and this incubation of craving was accompanied by a time-dependent increase in locomotor activity. Compared with saline, cocaine increased responding for the sucrose-paired cue on day 1 of forced abstinence at the 5 mg/kg dose only. In contrast, responding on day 30 was increased at the 10 and 20 mg/kg doses. Locomotor activity increased dose-dependently at both forced-abstinence time points, suggesting a dissociation between cocaine-induced locomotion and cocaine-elevated responding for a sucrose-paired stimulus. These results also indicate that there are time-dependent changes in how cocaine affects sucrose craving.
Department of Psychology, Western Washington University, Bellingham, Washington 98225-9089, USA. jeff.grimm@wwu.edu
Jeffrey W
JW
Grimm
Carl
C
Buse
Meghan
M
Manaois
Dan
D
Osincup
Amber
A
Fyall
Barbara
B
Wells
D000818:Animals; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D003463:Cues; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005108:Extinction, Psychological / Q000187:drug effects; D005518:Food Preferences / Q000187:drug effects*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans; D013375:Substance Withdrawal Syndrome / Q000523:psychology; D013395:Sucrose / Q000494:pharmacology*; D013997:Time Factors
D018765:Dopamine Uptake Inhibitors; D013395:Sucrose; D003042:Cocaine