Glucose utilization rates in single neurons and neuropil determined by injecting nontracer amounts of 2-deoxyglucose.

A nontracer amount of 2-deoxyglucose (DG) was intravenously injected into rats, which were frozen 2 and 4 min later in liquid nitrogen. The freeze-dried samples of cell bodies of anterior horn cells, dorsal root ganglion cells, and cerebellar Purkinje cells, as well as the neuropil adjacent to anterior horn cell bodies, were prepared. Their contents of glucose, glucose 6-phosphate, DG, and 2-deoxyglucose 6-phosphate were microassayed using an enzymatic amplification reaction. NADP cycling. Based on the resulting data and theoretical equations previously described, glucose utilization rate (GUR) and apparent distribution volumes (DVs) of glucose and DG were determined. Anterior horn cell bodies had the highest GUR and their neuropil the lowest, although apparent DVs of glucose and DG were similar in both. This indicates that the glucose supply was equally balanced in all, but that the cell bodies had higher functional activity supported by hexokinase (and other enzymes) related to their energy demands. Dorsal root ganglion cells showed the lowest 2-deoxyglucose 6-phosphate formation rate, but their GUR was slightly higher than that of neuropil because of their markedly large DV of glucose, thus demonstrating that the abundant glucose supply supports the neuronal function. Purkinje cells indicated GUR and apparent DVs similar to molecular and granular layers.