title: Ketosis proportionately spares glucose utilization in brain.
abstract: The brain is dependent on glucose as a primary energy substrate, but is capable of utilizing ketones such as β-hydroxybutyrate and acetoacetate, as occurs with fasting, starvation, or chronic feeding of a ketogenic diet. The relationship between changes in cerebral metabolic rates of glucose (CMRglc) and degree or duration of ketosis remains uncertain. To investigate if CMRglc decreases with chronic ketosis, 2-[(18)F]fluoro-2-deoxy-D-glucose in combination with positron emission tomography, was applied in anesthetized young adult rats fed 3 weeks of either standard or ketogenic diets. Cerebral metabolic rates of glucose (μmol/min per 100 g) was determined in the cerebral cortex and cerebellum using Gjedde-Patlak analysis. The average CMRglc significantly decreased in the cerebral cortex (23.0±4.9 versus 32.9±4.7) and cerebellum (29.3±8.6 versus 41.2±6.4) with increased plasma ketone bodies in the ketotic rats compared with standard diet group. The reduction of CMRglc in both brain regions correlates linearly by ∼9% for each 1 mmol/L increase of total plasma ketone bodies (0.3 to 6.3 mmol/L). Together with our meta-analysis, these data revealed that the degree and duration of ketosis has a major role in determining the corresponding change in CMRglc with ketosis.
authors.affiliation: Department of Biomedical Engineering, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4954, USA.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Youzhi
authors.initials: Y
authors.lastname: Kuang
authors.forename: Kui
authors.initials: K
authors.lastname: Xu
authors.forename: Donald
authors.initials: D
authors.lastname: Harris
authors.forename: Zhenghong
authors.initials: Z
authors.lastname: Lee
authors.forename: Joseph
authors.initials: J
authors.lastname: LaManna
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Puchowicz
mesh_terms: D000465:Algorithms; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D004032:Diet; D055423:Diet, Ketogenic; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D007657:Ketone Bodies / Q000378:metabolism; D007662:Ketosis / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D007657:Ketone Bodies; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D019344:Lactic Acid; D005947:Glucose