title: Effects of aging on the interaction of quinuclidinyl benzilate, N-methylscopolamine, pirenzepine, and gallamine with brain muscarinic receptors.
abstract: The objective of the present study was to investigate the effects of senescence on the binding characteristics of muscarinic receptors by using [3H]quinuclidinyl benzilate ([3H]QNB) and [3H]N-methylscopolamine ([3H]NMS) as ligands in young (3 months), middle-age (10 months) and old (24 months) male Fischer 344 rats. Muscarinic receptor density was found to decrease significantly with aging in certain brain regions, depending on the ligand employed. Moreover, the relative proportions of M1 and M2 muscarinic receptor subtypes was not significantly altered by aging, except in the aged striatum. Furthermore, the dissociation kinetics of [3H]NMS in the cerebral cortex and their allosteric modulation by gallamine were only slightly influenced by age.
authors.affiliation: Department of Pharmacology and Toxicology, School of Pharmacy, University of Maryland, Baltimore 21201.
authors.forename: W
authors.initials: W
authors.lastname: Surichamorn
authors.forename: O N
authors.initials: ON
authors.lastname: Kim
authors.forename: N H
authors.initials: NH
authors.lastname: Lee
authors.forename: W S
authors.initials: WS
authors.lastname: Lai
authors.forename: E E
authors.initials: EE
authors.lastname: el-Fakahany
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002531:Cerebellum / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism; D005703:Gallamine Triethiodide / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D019832:N-Methylscopolamine; D010890:Pirenzepine / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000378:metabolism; D012602:Scopolamine Derivatives / Q000494:pharmacology
chemical_list: D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D010890:Pirenzepine; D011813:Quinuclidinyl Benzilate; D005703:Gallamine Triethiodide; D019832:N-Methylscopolamine