A comparison of the effects of the CB(1) receptor antagonist SR141716A, pre-feeding and changed palatability on the microstructure of ingestive behaviour.
BACKGROUND
The cannabinoid CB(1) receptor inverse agonist SR141716A (rimonabant) is known to cause hypophagia and this study uses microstructural data to elucidate the relevant behavioural mechanisms.


OBJECTIVE
The aim of these studies was to determine the behavioural changes induced by SR141716A in animals consuming either a fat or carbohydrate solution. These behavioural changes were directly compared with those induced by behavioural manipulations that modify motivational state and palatability.


METHODS
Male hooded Lister rats drank a highly palatable fat emulsion (10% Intralipid) or a carbohydrate solution (10% sucrose) during 30-min test sessions. Microstructural analyses of licking patterns were made after either administration of SR141716A (0, 0.3, 1 and 3 mg/kg, ip) or one of the after behavioural manipulations: pre-feeding, addition of quinine to the fat solution or changes in sucrose concentration.


RESULTS
Intake of the fat solution was decreased after both the drug treatment and the behavioural manipulations of pre-feeding and addition of quinine. Pre-feeding and SR141716A-induced reductions were mediated via changes in bout number whereas addition of quinine caused a decrease in bout size. Although sucrose drinking was also decreased by pre-feeding, reduced sucrose concentration and SR141716A, the drug did not significantly alter the microstructure of intake.


CONCLUSIONS
The effects of SR141716A on consumption of Intralipid solutions are likely to reflect changes in motivational state rather than modified hedonic impact.
Thornton-Jones
Zoë D
ZD
Department of Psychology, University of Sussex, Brighton, BN1 9QG, UK.
Kennett
Guy A
GA
Vickers
Steven P
SP
Clifton
Peter G
PG
D000821:Animal Feed; D000818:Animals; D004435:Eating; D005247:Feeding Behavior / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D008297:Male; D009042:Motivation; D010880:Piperidines / Q000008:administration & dosage / Q000494:pharmacology*; D011720:Pyrazoles / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors*; D000077285:Rimonabant; D013649:Taste
D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D000077285:Rimonabant