Decrease in Operant Responding Under Obesogenic Diet Exposure is not Related to Deficits in Incentive or Hedonic Processes.
Obesity. 2018-12-30; 27(2): 255-263
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Ducrocq F(1)(2), Hyde A(1)(2), Fanet H(1)(2)(3), Oummadi A(1)(2), Walle R(1)(2), De Smedt-Peyrusse V(1)(2)(3), Layé S(1)(2)(3), Ferreira G(1)(2)(3), Trifilieff P(1)(2)(3), Vancassel S(1)(2)(3).
(1)INRA, Nutrition and Integrative Neurobiology, UMR 1286, Bordeaux, France.
(2)Université de Bordeaux, France.
(3)OptiNutriBrain, International Associated Laboratory (NutriNeuro France-INAF
Canada), Bordeaux, France.
OBJECTIVE: A growing body of evidence suggests that obesity could result from
alterations in reward processing. In rodent models, chronic exposure to an
obesogenic diet leads to blunted dopamine signaling and related incentive
responding. This study aimed to determine which reward-related behavioral
dimensions are actually impacted by obesogenic diet exposure.
METHODS: Mice were chronically exposed to an obesogenic diet. Incentive and
hedonic processes were tested through operant conditioning and licking
microstructures, respectively. In parallel, mesolimbic dopamine transmission was
assessed using microdialysis.
RESULTS: Prolonged high-fat (HF) diet exposure led to blunted mesolimbic dopamine
release, paralleled by a decrease in operant responding in all schedules tested.
HF-fed and control animals similarly decreased their operant responding in an
effort-based choice task, and HF-fed animals displayed an overall lower calorie
intake in this task. Analysis of the licking microstructures during consumption
of a freely accessible reward suggested a decrease in basal hunger and a
potentiation of gastrointestinal inhibition in HF-fed animals, without changes in
CONCLUSIONS: These results suggest that the decrease in operant responding under
prolonged HF diet exposure is mainly driven by decrease in hunger as well as
stronger postingestive negative feedback mechanisms, rather than by a decrease in
incentive or hedonic responses.
© 2018 The Obesity Society.