The deoxyglucose method in the ferret brain. I. Methodological considerations

Area of Science:

• Neuroscience
• Biochemistry
• Radiochemistry

Background:

• Cerebral glucose utilization is crucial for understanding brain function.
• The 2-deoxyglucose (2-DG) method is a standard technique for measuring glucose metabolism.
• Accurate calculation of rate constants is essential for reliable 2-DG method results.

Purpose of the Study:

• To determine the transfer rate constants of 2-deoxyglucose (2-DG) in the anesthetized ferret brain.
• To assess the influence of metabolized tracer loss on cerebral glucose utilization measurements.
• To evaluate the impact of the rate constant (k4*) for tracer loss on 2-DG lumped constant values.

Main Methods:

• Regional gray matter time-radioactivity curves were measured for 180 minutes post-injection in anesthetized ferrets.
• Rate constants for 2-DG transfer were calculated.
• Simulation experiments were performed to assess the influence of k4* on glucose utilization rates and lumped constants.

Main Results:

• Metabolized 2-DG tracer loss from brain occurs at approximately 1% per minute for the first 180 minutes.
• Assuming k4* as 0 or 0.01 min-1 had a negligible effect on glucose utilization rates in 45-minute experiments.
• The 2-DG lumped constant varied from 0.54 (k4*=0) to 0.68 (k4*=0.01 min-1).

Conclusions:

• The rate of metabolized 2-DG loss is relatively slow in the ferret brain.
• Standard 45-minute 2-DG autoradiographic experiments are robust to variations in the metabolized tracer loss rate constant.
• Consistent analytical methods, including lumped constant determination, are key for accurate glucose utilization measurements.