Delta-9-tetrahydrocannabinol enhances food reinforcement in a mouse operant conflict test.
BACKGROUND
Cannabinoid compounds are known to regulate feeding behavior by modulating the hedonic and/or the incentive properties of food.


OBJECTIVE
The aim of this work was to determine the involvement of the cannabinoid system in food reinforcement associated with a conflict situation generated by stress.


METHODS
Mice were trained on a fixed ratio 1 schedule of reinforcement to obtain standard, chocolate-flavored or fat-enriched pellets. Once the acquisition criteria were achieved, the reinforced lever press was paired with foot-shock exposure, and the effects of Delta(9)-tetrahydrocannabinol (THC; 1 mg/kg) were evaluated in this conflict paradigm.


RESULTS
THC did not modify the operant response in mice trained with standard pellets. In contrast, THC improved the instrumental performance of mice trained with chocolate-flavored and fat-enriched pellets. However, the cannabinoid agonist did not fully restore the baseline responses obtained previous to foot-shock delivery. THC ameliorated the performance to obtain high palatable food in this conflict test in both food-restricted and sated mice. The effects of THC on food reinforcement seem to be long-lasting since mice previously treated with this compound showed a better recovery of the instrumental behavior after foot-shock exposure.


CONCLUSIONS
These findings reveal that the cannabinoid system is involved in the regulation of goal-directed responses towards high palatable and high caloric food under stressful situations.
Barbano
Maria Flavia
MF
Departament de Ciencies Experimentals i de la Salut, Universitat Pompeu Fabra, PRBB, C/ Dr. Aiguader 88, 08003 Barcelona, Spain.
Castañé
Anna
A
Martín-García
Elena
E
Maldonado
Rafael
R
D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D003220:Conflict, Psychological; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D004597:Electroshock; D005247:Feeding Behavior / Q000187:drug effects; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009042:Motivation; D012055:Reinforcement Schedule; D013315:Stress, Psychological
D013759:Dronabinol