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ARS Home » Pacific West Area » Davis, California » Western Human Nutrition Research Center » Obesity and Metabolism Research » Research » Publications at this Location » Publication #256753
Title: Brain functional magnetic resonance imaging response to glucose and fructose infusions in humans

Author
item PURNELL, JONATHAN - Oregon Health & Science University
item KLOPFENSTEIN, BETHANY - Oregon Health & Science University
item STEVENS, ALEXANDER - Oregon Health & Science University
item HAVEL, PETER - University Of California
item Adams, Sean
item DUNN, TAMARA - University Of California
item KRISKY, CHRISTINE - Oregon Health & Science University
item ROONEY, WILLIAM - Oregon Health & Science University

Submitted to: Diabetes Obesity and Metabolism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2010
Publication Date: 3/20/2011
Citation: Purnell, J.Q., Klopfenstein, B.A., Stevens, A.A., Havel, P.J., Adams, S.H., Dunn, T.N., Krisky, C., Rooney, W.D. 2011. Brain fMRI response to glucose and fructose infusions in humans. Diabetes Obesity and Metabolism. 13(3):229-34.

Interpretive Summary: The metabolic fate of dietary sugars such as glucose and fructose is important in modulating lipid metabolism in peripheral tissues such as liver, and fructose appears to differ from glucose in that it tends to promote new fat synthesis to a greater extent in the liver. In addition to actions and metabolism in peripheral tissues, sugars may also be sensed by the brain, leading to physiological effects body-wide. Glucose-sensing neurons in the central nervous system (CNS) have been described, but little is known about fructose-sensing nerves. Magnetic resonance imaging (MRI) scanning was used to identify regions of the brain that respond to glucose vs. fructose intravenous injection, through the use of blood oxygen level dependent (BOLD) changes. BOLD signal in the cortical control areas increased during glucose infusion corresponding with increased plasma glucose and insulin levels. In contrast, BOLD signal decreased in the cortical control areas during fructose infusion, corresponding with increases of plasma fructose and lactate. Conclusion: In normal weight humans, cortical responses as assessed by BOLD fMRI to infused glucose are opposite to those of fructose. Differential brain responses to these sugars and their metabolites may provide insight into the neurologic basis for dysregulation of food intake and metabolism during high dietary fructose intake.

Technical Abstract: Objective: In animals, intracerebroventricular glucose and fructose have opposing effects on appetite and weight regulation. In humans, functional brain magnetic resonance imaging (fMRI) studies during carbohydrate ingestion suggest that glucose may regulate HT signaling but are potentially confounded by upper alimentary track neural inputs and changes in gut hormone secretion during ingestion. We therefore sought to determine the brain response to intravenously(IV)infused carbohydrates, and if this response differed between glucose and fructose,in humans. Methods: Nine healthy, normal weight subjects underwent blood oxygenation level dependent(BOLD) fMRI measurements during either IV glucose (0.3 mg/kg), fructose (0.3 mg/kg), or saline, administered over 2-minutes in a randomized, double-blind, crossover study. Blood was sampled every 5-minutes during a baseline period and following infusion for 60-minutes total for glucose, fructose, lactate, and insulin levels. Results: No significant brain BOLD signal changes were detected in response to IV saline. BOLD signal in the cortical control areas increased during glucose infusion (p = 0.002), corresponding with increased plasma glucose and insulin levels. In contrast, BOLD signal decreased in the cortical control areas during fructose infusion (p = 0.006), corresponding with increases of plasma fructose and lactate. Neither glucose nor fructose infusions significantly altered BOLD signal in the HT. Conclusion: In normal weight humans, cortical responses as assessed by BOLD fMRI to infused glucose are opposite to those of fructose. Differential brain responses to these sugars and their metabolites may provide insight into the neurologic basis for dysregulation of food intake during high dietary fructose intake.