High-fat diet alters weight, caloric intake, and haloperidol sensitivity in the context of effort-based responding.
High-fat (HF) diets result in weight gain, hyperphagia, and reduced dopamine D2 signaling; however, these findings have been obtained only under free-feeding conditions. This study tested the extent to which HF diet affects effort-dependent food procurement and the extent to which dopamine signaling is involved. Male Sprague-Dawley rats consumed either a HF (n=20) or a standard-chow (n=20) diet. We assessed the sensitivity to effort-based reinforcement in 10 rats from each group by measuring consumption across a series of fixed-ratio schedules (FR 5-FR 300) under a closed economy and quantified performance using the exponential-demand equation. For each FR, acute injections of 0 or 0.1 mg/kg of haloperidol, a D2 antagonist, were administered to assess dopamine-related changes in consumption. Rats fed a HF diet consumed more calories and weighed significantly more than rats fed standard-chow. Food consumption decreased in both groups in an effort-dependent manner, but there were no group differences. Haloperidol reduced responding in an FR-dependent manner for both groups. Animals exposed to a HF diet showed an altered sensitivity to haloperidol relative to rats fed a standard diet, suggesting that HF diet alters sensitivity to DA signaling underlying effort-based food procurement.
Department of Psychology, Idaho State University, Pocatello, Idaho, USA.
Stephen H
SH
Robertson
Steven R
SR
Boomhower
Erin B
EB
Rasmussen
D000818:Animals; D001835:Body Weight / Q000502:physiology; D059305:Diet, High-Fat / Q000009:adverse effects*; D004041:Dietary Fats; D004298:Dopamine / Q000378:metabolism; D002149:Energy Intake / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D006220:Haloperidol; D006963:Hyperphagia / Q000378:metabolism / Q000523:psychology*; D020738:Leptin; D008297:Male; D009765:Obesity; D051381:Rats; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D015430:Weight Gain
D004041:Dietary Fats; D020738:Leptin; D017448:Receptors, Dopamine D2; D006220:Haloperidol; D004298:Dopamine