APOPTOSIS IN THE AGED DOG BRAIN

Apoptosis similar to that seen in Alzheimer's disease patients was fou nd in the brain of aged dogs by the TUNEL method of detecting in situ DNA fragmentation. Apoptosis was observed in both neurons and glial ce lls, and was morphologically characterized by round and swollen cytopl asm and aggregated nuclear chromatin, although these changes were slig ht. Neurons and astrocytes in the gray matter and oligodendrocytes in the white matter were affected. The number of ApopTag-positive brain c ells increased slightly with age, but was not correlated to the number of senile plaques. A good correlation between the number of ApopTag-p ositive cells and the dementia index was clearly found. The present st udy indicates that brain cell apoptosis could account for dementia in aged dogs and suggested that aged dogs may be useful as a simplified a nimal model for Alzheimer's disease in man.