Cholinergic Muscarinic Binding By Lymphocytes: Changes With Age Antagonist Treatment And Senile Dementia

Abstract

Lymphocytes respond to cholinergic agonists with increased cyclic- GMP levels, enhanced RNA and protein synthesis, and altered immune function (1–3). These induced alterations are diminished or blocked by the specific muscarinic antagonist, atropine, implying the presence of muscarinic cholinergic receptor sites on lymphocytes. Indeed, recently muscarinic receptors were demonstrated and characterized in murine lymphocytes (4–6) and in peripheral circulating human blood lymphocytes (7). These findings imply that lymphocytes may prove useful as peripheral markers for the muscarinic cholinergic system. However, it remains to be established if changes in lymphocyte muscarinic receptors can be evoked by treatment with muscarinic agonists and antagonists, similar to changes in muscarinic receptors of the brain (8–10). Further, as hypofunction of central cholinergic systems has been implicated in the deterioration of faculties during aging (11–13) and in the etiology of senile dementia (14–21), a peripheral marker for central muscarinic cholinergic function would be very useful (20–21). It is, therefore, of interest to know whether any changes occur in muscarinic binding by peripheral lymphocytes during normal aging and in senile dementia. We report here that the number of muscarinic cholinergic receptor sites on lymphocytes is increased after treatment with antimuscarinic drugs. Furthermore, there is a tendency for a continuous increase in the number of receptors with age. And, in contrast, lymphocytes derived from people with senile dementia exhibit a marked reduction in the number of muscarinic receptor binding sites.KeywordsMuscarinic ReceptorCholinergic SystemSenile DementiaMuscarinic AgonistCholinergic AgonistThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.