Effects of sucrose, glucose and fructose on peripheral and central appetite signals
ABSTRACT In the Western world, consumption of soft drinks has increased the last three decades and is partly responsible for the epidemic-like increase in obesity. Soft drinks, originally sweetened by sucrose, are now sweetened by other caloric sweeteners, such as fructose. In this study, we investigated the short-term effect of sucrose, glucose or fructose solutions on food intake and body weight in rats, and on peripheral and central appetite signals. Rats received water containing either of the sugars and standard rat chow for two weeks. Rats receiving water alone and standard chow were controls. All rats offered the sugar solutions increased their total caloric intake. The increased caloric intake occurred despite the fact that the rats offered either of the sugar solutions consumed less chow. As a consequence of the increased caloric intake, the sugar-drinking rats had elevated serum levels of free fatty acids, triglycerides and cholesterol. In addition, consuming sugar solutions resulted in increased serum leptin, decreased serum PYY and down-regulated hypothalamic NPY mRNA. Serum ghrelin was increased in rats receiving fructose solution. Moreover, consumption of sucrose or fructose solution resulted in up-regulated hypothalamic CB1 mRNA. Hypothalamic POMC mRNA was down-regulated in rats receiving glucose or fructose. In conclusion, consumption of glucose, sucrose or fructose solution results in caloric overconsumption and body weight gain through activation of hunger signals and depression of satiety signals as well as activation of reward components. The weight-promoting effect of these sugar solutions may possibly be ameliorated by the down-regulation of NPY mRNA and increased serum leptin.
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ABSTRACT: Consummatory behavior is driven by both caloric and emotional need, and a wide variety of animal models have been useful in research on the systems that drive consumption of food and drugs. Models have included selective breeding for a specific trait, manipulation of gene expression, forced or voluntary exposure to a substance, and identification of biomarkers that predict which animals are prone to overconsuming specific substances. This research has elucidated numerous brain areas and neurochemicals that drive consummatory behavior. Although energy homeostasis is primarily mediated by the hypothalamus, reinforcement is more strongly mediated by nuclei outside the hypothalamus, in mesocorticolimbic regions. Orexigenic neurochemicals that control food intake can provide a general signal for promoting caloric intake or a more specific signal for stimulating consumption of a particular macronutrient, fat, carbohydrate, or protein. The neurochemicals involved in controlling fat ingestion--galanin, enkephalin, orexin, melanin-concentrating hormone, and the endocannabinoids--show positive feedback with this macronutrient, as these peptides both increase fat intake and are further stimulated by its intake. This positive association offers some explanation for why foods high in fat are so often overconsumed. Consumption of ethanol, a drug of abuse that also contains calories, is similarly driven by the neurochemical systems involved in fat intake, according to evidence that closely relates fat and ethanol consumption. Further understanding of the systems involved in consummatory behavior will enable the development of effective therapies for the treatment of both overeating and drug abuse.ILAR journal / National Research Council, Institute of Laboratory Animal Resources 03/2012; 53(1):35-58. DOI:10.1093/ilar.53.1.35 · 1.05 Impact Factor
Conference Paper: The High Cholesterol ParadoxWAPF European Conference; 01/2014
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ABSTRACT: The consumption of fructose has increased tremendously over the last five decades, which is to a large extent due to the development of high fructose corn syrup (HFCS), a commercial sugar additive that contains high amounts of free fructose. HFCS is often added to processed food and beverages partly because it is a powerful sweetener but even more so because the production is cheap. Although fructose in combination with fiber, vitamins and minerals, as present in fruits, is a healthy source of energy, isolated fructose, in processed food products has been associated with several health disorders such as insulin resistance and hypertension. Apart from its metabolic consequences, a growing body of literature suggests that free fructose can also affect neuronal systems. High fructose intake may on the one hand affect central appetite regulation by altering specific components of the endocannabinoid system. On the other hand it appears to impact on cognitive function by affecting phosphorylation levels of insulin receptor, synapsin 1 and synaptophysin. The present report reviews the recent evidence showing a negative effect of free fructose consumption on central appetite control, as well as cognitive function.03/2015; 2. DOI:10.3389/fnut.2015.00005