Cellular expression of alpha 7 nicotinic acetylcholine receptor protein inthe temporal cortex in Alzheimer's and Parkinson's disease - A stereological approach

Cognitive deficits in Alzheimer's and Parkinson's disease are closely relat ed to disturbed cholinergic transmission. The decrease of nicotinic acetylc holine receptor protein has been assessed by Western blotting and immunohis tochemistry. Stereology, however, has not been used to assess numbers of re ceptor-expressing human cerebrocortical neurons. Our approach applies a com bination of alpha7 subunit-immunohistochemistry with a stereological techni que using defined stretches of pial surface as reference standard. The numb er of alpha7 subunit protein-expressing neurons in the Alzheimer temporal c ortices amounted to approximately half of that of controls while numbers in Parkinson patients lay in between. No differences in the total number of n eurons were seen. These results corroborate nonstereological studies on Alz heimer cortices and for the first time show a similar decrease in receptor expression in Parkinson's disease. They provide evidence that not only Alzh eimer dementia but also cognitive deficits in Parkinson's disease may be re lated to decreased nicotinic receptor expression. (C) 2000 Academic Press.