Production of [14C]acetylcholine and [14C]carbon dioxide from [U-14C]glucose in tissue prisms from aging rat brain.

Production of [14C]acetylcholine and 14CO2 was examined by using tissue prisms from neocortex, hippocampus, and striatum from rats aged approximately 5 months, 13 months, and 27 months. [14C]Acetylcholine synthesis in the striatum showed highly significant decreases with age for measurements in the presence of both 5 mM- and 31 mM-K+, contrasting with the lack of significant change in 14CO2 production in this region. The neocortex and hippocampus showed only small changes, especially when comparison was made between 13-month and senescent animals. Measurements of the release of [14C]acetylcholine and influence of atropine on this release confirmed the relative stability with age of the cholinergic system in the neocortex.