Sugar solutions alter liver and hypothalamic appetite regulation

Rats given access to a sugar solution quickly adjust intake so as to compose a diet with 50–60% of total calories from sugar. An analysis of the changes in hypothalamic and hepatic genes known to influence intake, body weight, and body composition under these conditions has not yet been performed. Rats were fed either a 16% solution of fructose, sucrose, or glucose as well as water and standard chow overnight. Controls were permitted access to water and chow only. Forty micron slices were used to extract mRNA from each hypothalamus. Experiment 1 was conducted using four Rat Obesity RT 2 Profiler™ PCR Arrays. Dopamine receptors 1a and 2 and Neuropeptide Y (NPY) were upregulated in the fructose group. Galanin, Brs3, AGRP, INSR, Gh1, Trhr, Atrn, NMB, TNF and Thrb were downregulated in the fructose group. Experiment 2 was performed using the same hypothalamic RNA to confirm these changes by RT‐PCR. Sucrose increased hypothalamic leptin receptor message; fructose and glucose significantly suppressed leptin receptor message. Experiment 3 examined several hepatic cytokine message levels. Fructose upregulated IL2 message, glucose downregulated TNF‐a, IL1‐β, and IL2 message, and sucrose downregulated TNF‐a and CEBP‐β message. These changes are discussed in relation to the changes in food selection patterns that occur when a choice of palatable sugar solution and standard maintenance diet is given.