PREFERENCE AND DIET TYPE AFFECT MACRONUTRIENT SELECTION AFTER MORPHINE, NPY, NOREPINEPHRINE, AND DEPRIVATION

Preference and diet type affect macronutrient selection after morphine , NPY, norepinephrine, and deprivation. Am. J. Physiol. 266 (Regulator y Integrative Comp. Physiol. 35): R426-R433, 1994. - The orexigenic ag ents morphine, neuropeptide Y (NPY), and norepinephrine (NE) and depri vation have been reported to induce selection of specific macronutrien ts: fat, carbohydrate (CHO), CHO, and fat, respectively. We utilized a nalysis of covariance to compensate for the influence of baseline pref erence on feeding induced by six experimental procedures: morphine, NP Y, NE, 24 and 48 h food deprivation, and chronic dietary restriction. Rats received one of two dietary regimens: three macronutrient diets c ontaining CHO, protein, or fat (regimen I) and two nutritionally compl ete diets that were high CHO or high fat (regimen II). Baseline prefer ence significantly influenced dietary selection after all six experime ntal procedures studied in regimen I and after NPY, NE, 48 h food depr ivation, and chronic dietary restriction in regimen II (covariate P < 0.05). In both dietary regimens, morphine (5 mg/kg) increased consumpt ion of fat, NPY (5 mu g icv) increased selection of CHO, and consumpti on of all diets was induced equally after NE injections (20 mu g icv). After 24 or 48 h food deprivation, animals consumed more fat in regim en I and more CHO diet in regimen II. Restricting food intake by 20% i ncreased fat and protein consumption in regimen I but had no effect in regimen II. Diet selection is affected by prior preference, feeding s timulus, and type of diet choice presented.