Muscarinic agonist receptor subtypes in aging rat brain.
Whole brain homogenates from rats aged 6 months (young) and 24 months (old) showed a decline with age of the pre-synaptic cholinergic marker, choline acetyltransferase, and also of total specific binding sites for the muscarinic antagonist L(-)quinuclidinyl benzilate (L-QNB). However, neither the proportion nor the inhibition constants of high and low affinity muscarinic agonist binding sites (defined by displacement of L-QNB binding with carbachol) changed with age. These findings may be relevant to the central cholinergic deficit reported to be associated with cognitive impairment in aging man.
D000375:Aging; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D007700:Kinetics; D008297:Male; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*
D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate; D002795:Choline O-Acetyltransferase