Abstract
The impact of Abeta deposition upon cholinergic intrinsic cortical and striatal, as well as basal forebrain long projection neuronal systems was qualitatively and quantitatively evaluated in young (2-6 months) and middle-aged (10-16 months) APPswe/PS1DeltaE9 transgenic (tg) mice. Cholinergic neuritic swellings occurred as early as 2-3 months of age in the cortex and hippocampus and 5-6 months in the striatum of tg mice. However, cholinergic neuron number or choline acetyltransferase (ChAT) optical density measurements remained unchanged in the forebrain structures with age in APPswe/PS1DeltaE9 tg mice. ChAT enzyme activity decreased significantly in the cortex and hippocampus of middle-aged tg mice. These results suggest that Abeta deposition has age-dependent effects on cortical and hippocampal ChAT fiber networks and enzyme activity, but does not impact the survival of cholinergic intrinsic or long projection forebrain neurons in APPswe/PS1DeltaE9 tg mice.