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Title: Diet-derived nutrients mediate the inhibition of hypothalamic NPY neurons in the arcuate nucleus of mice during refeeding. Author: Becskei C, Lutz TA, Riediger T. Journal: Am J Physiol Regul Integr Comp Physiol; 2009 Jul; 297(1):R100-10. PubMed ID: 19403857. Abstract: Fasting activates orexigenic neuropeptide Y neurons in the hypothalamic arcuate nucleus (ARC) of mice, which is reversed by 2 h refeeding with standard chow. Here, we investigated the contribution of diet-derived macronutrients and anorectic hormones to the reversal of the fasting-induced ARC activation during 2 h refeeding. Refeeding of 12-h-fasted mice with a cellulose-based, noncaloric mash induced only a small reduction in c-Fos expression. Refeeding with diets, containing carbohydrates, protein, or fat alone reversed it similar to chow; however, this effect depended on the amount of intake. The fasting-induced ARC activation was unchanged by subcutaneously injected amylin, CCK (both 20 microg/kg), insulin (0.2 U/kg and 0.05 U/kg) or leptin (2.6 mg/kg). Insulin and leptin had no effect on c-Fos expression in neuropeptide Y or proopiomelanocortin-containing ARC neurons. Interestingly, CCK but not amylin reduced the ghrelin-induced c-Fos expression in the ARC in ad libitum-fed mice, suggesting that CCK may inhibit orexigenic ARC neurons when acting together with other feeding-related signals. We conclude that all three macronutrients and also non-nutritive, ingestion-dependent signals contribute to an inhibition of orexigenic ARC neurons after refeeding. Similar to the previously demonstrated inhibitory in vivo action of peptide YY, CCK may be a postprandial mediator of ARC inhibition.[Abstract] [Full Text] [Related] [New Search]