The Deoxyglucose Method in the Ferret Brain. II. Glucose Utilization Images and Normal Values

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Abstract
To measure cerebral glucose utilization with the autoradiographic deoxyglucose method, the tracer transfer rate constants and lumped constants must be known. 2-Deoxyglucose (2-DG) and fluorodeoxyglucose (FDG) constants were determined in 18 gray and white matter brain structures of the anesthetized ferret. The ferret is a domestic carnivore particularly suitable for deoxyglucose studies because of its small brain size and low body weight. The average gray matter rate constants for tracer transfer across the blood-brain barrier are similar for 2-DG and FDG in the ferret brain ( K*1 = 0.21 ml/g/min and k*2 = 0.39 min−1). The rate constant for the rate-limiting step of tracer phosphorylation, k*3, is 1.6 times higher for FDG than for 2-DG (0.21 vs. 0.13 min−1). Loss of metabolized tracer is about 1–1.5%/min throughout the ferret brain for both tracers as estimated for a 180 min experimental period. Taking into account this loss, the lumped constant is 0.92 for FDG and 0.68 for 2-DG. Glucose utilization values in the brain of the anesthesized ferret range from 33 μmol/100 g/min in the corpus callosum to 104 μmol/100 g/min in the caudate nucleus. Representative glucose utilization images of coronal sections of the ferret brain are shown. Brain structures are identified on the same slices counterstained with thionin.