Effects of aging and cholinergic deafferentation on putative muscarinic cholinergic receptor subtypes in rat cerebral cortex.
Despite a 34% decrease in the activity of choline acetyltransferase (ChAT) in the rat cerebral cortex following lesions of the nucleus basalis, there were no changes in the Bmax of the antagonist ligands [3H]quinuclidinyl benzilate ((-)-[3H]QNB) or (-)-[3H]N-methylscopolamine ((-)-[3H]NMS). Furthermore, this treatment produced no significant change in the proportions or affinities of muscarinic receptors having high and low affinity for pirenzepine or (-)-NMS. These data indicate that putative M2 muscarinic receptors are not restricted to ChAT-containing neurons in rat cerebral cortex. In senescent compared to mature rats there was no significant loss of ChAT activity although a significant reduction in the Bmax of both (-)-[3H]QNB and (-)-[3H]NMS binding was observed. However, no changes in the competition of pirenzepine or (-)-NMS for the remaining (-)-[3H]QNB binding sites were observed. Therefore, there is no evidence for any differential regulation of either putative muscarinic receptor subtype in response to cholinergic deafferentation or as a function of the natural aging process.
D000109:Acetylcholine / Q000502:physiology*; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D002540:Cerebral Cortex / Q000378:metabolism*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D003714:Denervation; D008297:Male; D019832:N-Methylscopolamine; D009847:Olivary Nucleus; D010890:Pirenzepine / Q000378:metabolism; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011950:Receptors, Cholinergic / Q000378:metabolism*; D012602:Scopolamine Derivatives / Q000378:metabolism
D011950:Receptors, Cholinergic; D012602:Scopolamine Derivatives; D010890:Pirenzepine; D011813:Quinuclidinyl Benzilate; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine; D019832:N-Methylscopolamine