Long-term effects of cholinergic basal forebrain lesions on neuropeptide Y and somatostatin immunoreactivity in rat neocortex.

The effect of cholinergic basal forebrain lesions on immunoreactivity to somatostatin (SOM-i) and neuropeptide-Y (NPY-i) was investigated in the rat parietal cortex, 16-18 months after multiple bilateral ibotenic acid injections in the nucleus basalis complex. As a result of the lesion, the cholinergic fiber density in the cortex decreased by 66% with a concurrent increase in SOM-i fibers by more than 50% and a 124% increase in NPY-i fiber innervation. The neuropeptidergic sprouting response on cholinergic denervation does not match the concurrent cholinergic and peptidergic decline in Alzheimer's disease and as such does not support the cholinergic lesion alone as an animal model for this neurodegenerative disorder.