Behavior and brain uptake of fluorodeoxyglucose in mature and aged C57BL/6 mice

This paper describes regional brain energy metabolism, sensorimotor, and memory functions in mature (12 months) and old (24 months) C57BL/6 mice. Male mice were tested across a variety of sensorimotor procedures and in the Morris water maze before evaluating brain uptake of fluorodeoxyglucose (FDG) in the resting state. Mature mice outperformed older mice during the difficult sensorimotor and memory tasks, but not the easier tasks. This suggested that the greater sensorimotor and memory demands of a task compromised the performance of the older mice. This conclusion was consistent with the relative FDG uptake decreases found in regions mediating sensorimotor coordination (vestibular, cerebellar, ventral thalamic regions) and some limbic regions linked to memory (mammillary body, posterior cingulate, and piriform cortices). The inferior colliculus and flocculus had the greatest metabolism in mature mice, as shown by resting FDG uptake, and these regions showed the most marked hypometabolism in the older mice. The data also showed that the neurobehavioral correlative pattern in older mice was modified. In conclusion, brain regions with higher energy metabolism, and the behaviors to which they are related, were affected most greatly by aging in C57BL/6 mice—suggesting that these areas are more metabolically vulnerable to aging effects.