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 ?-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 (?mol/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.

SUBMITTER: Zhang Y 

PROVIDER: S-EPMC3734783 | biostudies-literature | 2013 Aug

REPOSITORIES: biostudies-literature