[3H]acetylcholine nicotinic recognition sites in human brain: characterization of agonist binding.
In the presence of a cholinesterase inhibitor to prevent hydrolysis and atropine to block muscarinic cholinergic receptors, [3H]acetylcholine ([3H]ACh) binding to human brain membranes showed highest levels of nicotinic binding sites in the thalamus. [3H]ACh, in the presence of atropine, binds to heterogeneous high-affinity binding sites in human thalamus. Scatchard analysis of the binding gave a Kd of 0.58 nM and a Bmax of 3.3 pmol/g protein for the 'super high-affinity' site and a Kd of 27 nM and a Bmax of 70 pmol/g protein for the 'high-affinity' site. Moreover, in competition studies nicotinic agonists such (-)-nicotine and carbachol displaceable [3H]ACh-specific binding sites consist of both a high- and a low-affinity population of sites. These results indicate that highest levels of [3H]ACh binding in human brain were found in the thalamus. Moreover, the human thalamus was found to have multiple high-affinity nicotinic agonist sites.
Adem
A
A
Department of Pharmacology, University of Uppsala, Sweden.
Synnergren
B
B
Botros
M
M
Ohman
B
B
Winblad
B
B
Nordberg
A
A
D000109:Acetylcholine / Q000378:metabolism; D000368:Aged; D000470:Alkaloids / Q000378:metabolism; D000818:Animals; D001392:Azocines; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002217:Carbachol / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000378:metabolism; D011807:Quinolizines; D051381:Rats; D011919:Rats, Inbred Strains; D011978:Receptors, Nicotinic / Q000378:metabolism*; D013788:Thalamus / Q000378:metabolism; D000093843:Quinolizidine Alkaloids
D000109:Acetylcholine; D000470:Alkaloids; D001392:Azocines; D002217:Carbachol; D009538:Nicotine; D011807:Quinolizines; D011978:Receptors, Nicotinic; C004712:cytisine; D000093843:Quinolizidine Alkaloids