Age-related changes in activity of Fischer 344 rat brain acetylcholinesterase molecular forms.

Total acetylcholinesterase (AChE) and the molecular forms of the enzyme from six brain regions were compared in young adult (6 mo) and aged (24 mo) Fischer 344 rats. Total AChE activity was significantly reduced in aged striatum (48.7%), parietal cortex (39%), cerebellum (30.2%), and medulla/pons (23.1%). Forebrain of aged rats showed nonsignificant reduction of AChE (18.4%), but olfactory bulbs exhibited no differences in aged rats. The ratio of G4/G1 molecular forms, as isolated on sucrose density gradients, was unaltered in all aged rat brain tissues examined. These results indicate that aged rats exhibit reduced brain AChE, but there is no evidence for selective effects on individual molecular forms.