title: Diet-derived nutrients modulate the effects of amylin on c-Fos expression in the area postrema and on food intake.
abstract: The pancreatic hormone amylin decreases food intake via activation of area postrema (AP) neurons. We investigated whether amylin's potency to reduce food intake and to induce c-Fos expression in the AP/nucleus of the solitary tract region is affected by the feeding conditions and specifically by the macronutrient composition of the diet. Whereas a low dose of amylin (5 microg/kg s.c.) induced very little c-Fos expression in ad libitum chow fed rats, it caused a strong c-Fos expression in 24-hour food-deprived rats and in rats that received a nutrient-deficient non-caloric mash (NCM; vanilla-flavoured cellulose) 24 h before injection. To reveal the contribution of single nutrients to the low c-Fos expression after chow feeding, amylin-induced c-Fos was analyzed after feeding NCM that was selectively supplemented with glucose, fat (lard), or protein (casein), matching the intake of these nutrients of chow-fed rats. While the rats fed NCM supplemented with glucose or fat displayed an equally strong amylin-induced activation as fasted rats or rats fed plain NCM, a significantly lower c-Fos expression was observed in rats fed a protein-supplemented NCM or a NCM containing all three nutrients. In line with this lower activation, the same dose of amylin failed to reduce food intake in NCM/protein-fed rats, while amylin caused a reduction in feeding when animals received NCM, NCM/glucose, or NCM/fat. Interestingly, amylin effectively reduced food intake in ad libitum chow fed rats despite the low level of amylin-induced c-Fos expression in the AP under these conditions. We conclude that the anorectic potential of amylin may be attenuated by diet-derived proteins, whereas this effect appears to be overridden when the amount of carbohydrates/fat is high relative to the protein content, such as, e.g., in standard chow.
authors: Institute of Veterinary Physiology, University of Zürich, Zürich, Switzerland.
authors: Signe
authors: S
authors: Michel
authors: Csilla
authors: C
authors: Becskei
authors: Elif
authors: E
authors: Erguven
authors: Thomas A
authors: TA
authors: Lutz
authors: Thomas
authors: T
authors: Riediger
mesh_terms: D000682:Amyloid / Q000378:metabolism* / Q000494:pharmacology; D000821:Animal Feed; D000818:Animals; D000897:Anti-Ulcer Agents / Q000378:metabolism* / Q000494:pharmacology; D001066:Appetite / Q000187:drug effects / Q000502:physiology; D031608:Area Postrema / Q000187:drug effects / Q000502:physiology*; D001786:Blood Glucose; D004040:Dietary Carbohydrates / Q000494:pharmacology; D004041:Dietary Fats / Q000494:pharmacology; D004044:Dietary Proteins / Q000494:pharmacology; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D005508:Food Deprivation / Q000502:physiology; D058228:Islet Amyloid Polypeptide; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000682:Amyloid; D000897:Anti-Ulcer Agents; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D058228:Islet Amyloid Polypeptide; D016760:Proto-Oncogene Proteins c-fos