Differential response to kappa-opioidergic agents in dietary fat selection between Osborne-Mendel and S5B/P1 rats.
We have investigated the central effect of a kappa-opioid agonist and an antagonist on the macronutrient preference in two strains of rat, the Osborne Mendel (OM) and S5B/P1 rats, that have different susceptibility to obesity and differential preference for dietary fat intake. OM rats prefer diets high in fat and are sensitive to diet-induced obesity, whereas S5B/P1 prefer a low fat diet and are resistant to high-fat diet-induced obesity. Rats adapted to a two-choice high fat (HF)/low fat (LF) diet were food deprived (20 h) and then infused into the third cerebroventricle with 10 micrograms nor-binaltorphimine (nor-BNI), a selective kappa-antagonist. Nor-BNI preferentially suppressed HF intake, but not LF intake in OM rats, whereas it affected neither diet in S5B rats. Infusion of U50488, a selective kappa-agonist (33 nmol), into the third cerebroventricle in sated rats, potently stimulated the intake of HF only in the OM rats, whereas it induced a significant but moderate stimulation of intake of both HF and LF diets in the S5B/P1 rats. Total energy intake following U50488 was not significantly different between the two strains. These findings suggest that the enhanced sensitivity of the OM rats to kappa-opioid stimulation for dietary fat may contribute to their preference for dietary fat and possibly their increased susceptibility for obesity.
Ookuma
K
K
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge 70808-4124, USA.
Barton
C
C
York
D A
DA
Bray
G A
GA
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000187:drug effects; D004032:Diet; D004041:Dietary Fats; D004435:Eating / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects; D005518:Food Preferences; D008297:Male; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D009765:Obesity / Q000209:etiology; D051381:Rats; D011919:Rats, Inbred Strains; D017473:Receptors, Opioid, kappa / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*
D018712:Analgesics, Non-Narcotic; D004041:Dietary Fats; D009292:Narcotic Antagonists; D009294:Narcotics; D017473:Receptors, Opioid, kappa; C051844:norbinaltorphimine; D009271:Naltrexone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer