Feeding response to mercaptoacetate in Osborne-Mendel and S5B/PL rats.
The purpose of this experiment was to determine if Osborne-Mendel (OM) rats, which are susceptible to dietary-induced obesity, and S5B/PL (S5B) rats, which are resistant to dietary-induced obesity, differ in their feeding responses to mercaptoacetate (MA), which blocks fatty acid oxidation, or 2-deoxy-D-glucose (2DG), which blocks glucose utilization. 2DG (100 mg/kg or 200 mg/kg) increased food intake in both strains of rats on a high-fat diet (56% energy from fat). Mercaptoacetate (600 mumol/kg) increased food intake in OM but not S5B rats on a high-fat diet. When maintained on a low-fat diet (10% energy from fat), MA (400 mumol/kg or 600 mumol/kg) stimulated food intake in OM rats, whereas S5B rats increased food intake only after the highest dose of MA (600 mumol/kg). MA stimulated carbohydrate and protein intake in OM rats maintained on a macronutrient selection diet, whereas S5B rats maintained on this diet did not significantly increase intake of any macronutrient after MA. These results demonstrate that OM and S5B rats have a similar food intake response to 2DG but a dissimilar response to MA. The variable response to MA in these strains may be due to a difference in peripheral or central signaling systems related to fatty acid oxidation or a difference in metabolic environments between the strains, which in turn affects the feeding response to MA. These studies suggest that a difference in control of fatty acid oxidation may account for the difference in susceptibility to obesity when eating a high-fat diet.
Singer
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LK
Pennington Biomedical Research Center, Baton Rouge, LA 70808-4124, USA.
York
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DA
Bray
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GA
D000818:Animals; D003847:Deoxyglucose / Q000494:pharmacology; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D004435:Eating / Q000187:drug effects*; D002149:Energy Intake; D005518:Food Preferences / Q000187:drug effects; D008297:Male; D051381:Rats; D011922:Rats, Mutant Strains; D013864:Thioglycolates / Q000008:administration & dosage / Q000494:pharmacology*
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D013864:Thioglycolates; C017487:2-mercaptoacetate; D003847:Deoxyglucose