Glucose utilization in the central nervous system in the acute gliopathy due to 6-aminonicotinamide

Sprague-Dawley rats were injected intraperitoneally with 5 mg. per kg. of 6-aminonicotinamide. The local glucose utilization rate (LGU) was measured throughout the central nervous system using the (14C) 2-deoxyglucose, quantitative autoradiographic technique at 3, 6, 12, and 24 hours after injection. The histologic appearance of selected areas of central nervous system was studied at 6, 12, and 24 hours and 3 and 10 days after injection, following perfusion by buffered aldehydes and plastic embedding. Decreases in LGU o 25 to 36 per cent were found in the lumbar ventral horn, caudal brain stem, and cerebellum at 3 and 6 hours. By 12 hours, virtually all of the structures examined showed decreases in LGU greater than 20 per cent with the reduction in the cord being 40 to 50 per cent. At 24 hours, the majority of areas exhibited definite recovery of LGU. Mild glial swelling, particularly of oligodendroglia, was noted at 12 hours and was obvious by 24 hours. Neuronal changes were not seen. These abnormalities were most marked in the intermediate and ventral gray matter of the cord and certain brain stem nuclei. 6-Aminonicotinamide has a known inhibitory effect on the pentose phosphate shunt and a secondary effect on the direct glycolytic pathway. The reduction in LGU is probably due to the inhibition of these pathways in both glia and neurons, but, the recovery LGU at 24 hours when the glial pathology was increasing suggests that the glia may metabolically protect the neuron at times of stress.