Expression of p75(NTR), a marker for basal forebrain cholinergic neurons, in young and aged dogs with or without cognitive dysfunction syndrome.

The canine cognitive dysfunction syndrome (CDS) has been identified as a natural model for Alzheimer's disease (AD). We have used unbiased stereology to estimate the total number of basal forebrain cholinergic neurons expressing the nerve growth factor p75(NTR) receptor in young, aged cognitively-unimpaired (CU) and aged cognitively-impaired (CI) dogs. Aged-CI dogs showed a ∼20% decrement (p = 0.009) in p75(NTR) neurons compared to both the young and the aged-CU animals. These results suggest that the basal forebrain cholinergic system is affected in dogs with CDS and provide additional support for the use this canine syndrome as a model for AD research.