Nippon Ronen Igakkai Zasshi. Japanese Journal of Geriatrics
Print ISSN : 0300-9173
Changes of Muscarinic Cholinergic Binding by Human Lymphocytes with Normal Aging and Alzheimer's Disease
Yoh-ichi Kaku
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1991 Volume 28 Issue 2 Pages 217-225

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Abstract

A potent, new muscarinic cholinergic antagonist, L-[N-methyl-3H] quinuclidinyl benzilate methyl chloride ([3H-]-NM-QNB) was used to detect functional changes of muscarinic acetylcholine receptors (mAChR) on human lymphocytes in relation to age.
Using techniques developed for the study of mAChR in brain homogenate, direct binding to whole live lymphocytes was shown for [3H]-NM-QNB. We examined Group of healthy adult females (41-66 years old, N=34) and patients with“probable”Alzheimer's disease (55-75 years old, N=11).
It was shown that mAChR on lymphocytes were divided into two subtypes; high affinity (Ms) and low affinity types (Mw) for a ligand, [3H]-NM-QNB. For the healthy controls (age range 41∼66 years old, N=31), a negative correlation (r=-0.172) was found between Kd (Ms) and age. Also the negative correlation between Bmax (Ms) and age was shown to be weak (r=-0.164).
The regression equations are:
Y=-11.9X+1306.4(Kd(Ms); N=31)
Y=-80.6X+8296.1(Bmax(Ms); N=31)
where, X and Y designate the age of individuals and Kd (or Bmax), respectively. Hence, for patients with Alzheimer's disease, no significant changes with age in Kd (Ms) or Bmax (Ms) were obtained. Furthermore, correlations between the stage of clinical dementia of patients and Kd (Ms), and between the staging and Bmax (Ms) were shown to be strong (p<0.05). Significant change (p<0.05) in Bmax (Ms) was recognized in lymphocytes from patients with Alzheimer's disease (N=11), compared with age-matched controls (N=20).
There results suggest that the binding properties of [3H]-NM-QNB to mAChR on lymphocytes may be useful in the study of changes associated with aging, and also in the evaluation of the clinical dementia rating of Alzheimer's disease.

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