The effects of normal aging on cerebral metabolic processes have been studied with methods developed in this Laboratory: the [C-14] leucine method for local rates of protein synthesis and the [ C-14] deoxyglucose method for local rates of glucose utilization. We have found that rates of glucose utilization and protein synthesis both decrease with age in the components of the primary auditory and visual pathways. These changes may be the consequences of a chronic lack of sensory input due to age-related degenerative changes which are known to occur in both retina and inner ear. Our studies also show that glucose utilization is particularly and significantly decreased in the striatum in aged rats. In order to examine the functional consequences of the senescent changes in the striatum we are studying the effects of age on the metabolic responsiveness to apomorphine, a dopaminergic agonist. Aluminum toxicity has been proposed as an etiological factor in Alzheimer's Disease. Aluminum has been shown to affect numerous biochemical processes including several enzymes in the metabolic pathway for glucose. Experiments have been carried out on the effects of prolonged (2 years) intake of low levels of aluminum in drinking water on local cerebral glucose utilization in aged rats. The results of these studies show decreased glucose utilization in the treated rats in 2 out of 26 regions, ventral pallidum and temporal cortex.
