Cannabinoid receptors and reward in the rat: a conditioned place preference study.
BACKGROUND
We wished to investigate further the hypothesis of an endogenous cannabinoid 'aversive counter-rewarding system, as the rewarding properties of cannabinoids using standard procedures remain ambiguous.


OBJECTIVE
The purpose of this study was to confirm the behavioural effects of a highly potent synthetic cannabinoid agonist (HU210) and the selective cannabinoid antagonist SR 141716A using conditioned place preference (CPP).


METHODS
HU210 (20, 60 and 100 microg kg(-1), SR141716A (0.25, 0.5, 2 and 3 mg kg(-1)), cocaine (15 mg kg(-1) and delta9-THC (1.5 mg kg(-1)) were given to male Lister hooded rats using an unbiased CPP design.


RESULTS
SR141716A and cocaine produced place preference at all doses tested, whereas HU210 and delta9-THC produced aversion as expressed by time spent in the drug-paired compartment of the CPP apparatus.


CONCLUSIONS
The aversive effects of cannabinoid agonists and the rewarding effect of the cannabinoid antagonist are suggestive of a cannabinergic tone in the rat brain. Further research is needed to determine the precise relationship of that tone with the reward pathways of the brain.
Cheer
J F
JF
School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, UK. mqxjfc@nottingham.ac.uk
Kendall
D A
DA
Marsden
C A
CA
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D002186:Cannabinoids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003213:Conditioning, Psychological / Q000187:drug effects*; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008297:Male; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000187:drug effects / Q000378:metabolism*; D012201:Reward; D000077285:Rimonabant; D013375:Substance Withdrawal Syndrome
D002186:Cannabinoids; D010880:Piperidines; D011720:Pyrazoles; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D013759:Dronabinol; C062018:HU 211; D000077285:Rimonabant