Generalized decrease in brain glucose metabolism during fasting in humans studied by PET
In prolonged fasting, the brain derives a large portion of its oxidative energy from the ketone bodies, beta-hydroxybutyrate and acetoacetate, thereby reducing whole body glucose consumption. Energy substrate utilization differs regionally in the brain of fasting rat, but comparable information has hitherto been unavailable in humans. We used positron emission tomography (PET) to study regional brain glucose and oxygen metabolism, blood flow, and blood volume in four obese subjects before and after a 3-wk total fast. Whole brain glucose utilization fell to 54% of control (postabsorptive) values (P less than 0.002). The whole brain rate constant for glucose tracer phosphorylation fell to 51% of control values (P less than 0.002). Both parameters decreased uniformly throughout the brain. The 2-fluoro-2-deoxy-D-glucose lumped constant decreased from a control value of 0.57 to 0.43 (P less than 0.01). Regional blood-brain barrier transfer coefficients for glucose tracer, regional oxygen utilization, blood flow, and blood volume were unchanged.
- Research Organization:
- Montreal Neurological Institute, Quebec (Canada)
- OSTI ID:
- 5877592
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 256
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BRAIN
POSITRON COMPUTED TOMOGRAPHY
GLUCOSE
METABOLISM
BLOOD FLOW
BLOOD-BRAIN BARRIER
FASTING
FLUORINE ISOTOPES
GLYCOLYSIS
MAN
OXYGEN
SPECIFICITY
ALDEHYDES
ANIMALS
BODY
CARBOHYDRATES
CENTRAL NERVOUS SYSTEM
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
ELEMENTS
EMISSION COMPUTED TOMOGRAPHY
HEXOSES
ISOTOPES
MAMMALS
MONOSACCHARIDES
NERVOUS SYSTEM
NONMETALS
ORGANIC COMPOUNDS
ORGANS
PRIMATES
SACCHARIDES
TOMOGRAPHY
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics