Autoradiographic localization of nicotinic receptor binding in rat brain using [3H]methylcarbamylcholine, a novel radioligand.
Light microscopic autoradiography was used to visualize the neuroanatomical distribution of nicotinic receptors in rat brain using a novel radioligand, [3H]methylcarbamylcholine (MCC). Specific [3H]MCC binding to slide-mounted tissue sections of rat brain was saturable, reversible and of high affinity. Data analysis revealed a single population of [3H]MCC binding sites with a Kd value of 1.8 nM and Bmax of 20.1 fmol/mg protein. Nicotinic agonists and antagonists competed for [3H]MCC binding sites in slide-mounted brain sections with much greater potency than muscarinic drugs. The rat brain areas containing the highest densities of [3H]MCC binding were in thalamic regions, the medial habenular nucleus and the superior colliculus. Moderate densities of [3H]MCC binding were seen over the anterior cingulate cortex, the nucleus accumbens, the zona compacta of substantia nigra and ventral tegmental area. Low densities of [3H]MCC binding were found in most other brain regions. These data suggest that [3H]MCC selectively labels central nicotinic receptors and that these receptors are concentrated in the thalamus, the medial habenular nucleus and the superior colliculus of the rat brain.
Yamada
S
S
Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
Gehlert
D R
DR
Hawkins
K N
KN
Nakayama
K
K
Roeske
W R
WR
Yamamura
H I
HI
D000818:Animals; D001345:Autoradiography; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002217:Carbachol / Q000031:analogs & derivatives*; D002794:Choline / Q000031:analogs & derivatives* / Q000378:metabolism; D007700:Kinetics; D008024:Ligands; D008297:Male; D010277:Parasympathomimetics / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011978:Receptors, Nicotinic / Q000378:metabolism*
D008024:Ligands; D010277:Parasympathomimetics; D011978:Receptors, Nicotinic; C053765:N-methylcarbamylcholine; D002217:Carbachol; D002794:Choline