PT  - JOURNAL ARTICLE
AU  - Pabreza, L A
AU  - Dhawan, S
AU  - Kellar, K J
TI  - [3H]cytisine binding to nicotinic cholinergic receptors in brain.
DP  - 1991 Jan 01
TA  - Molecular Pharmacology
PG  - 9--12
VI  - 39
IP  - 1
4099  - http://molpharm.aspetjournals.org/content/39/1/9.short
4100  - http://molpharm.aspetjournals.org/content/39/1/9.full
SO  - Mol Pharmacol1991 Jan 01; 39
AB  - Cytisine, a ganglionic agonist, competes with high affinity for brain nicotinic cholinergic receptors labeled by any of several nicotinic 3H-agonist ligands. Here we have examined the binding of [3H]cytisine in rat brain homogenates. [3H]Cytisine binds with high affinity (Kd less than 1 nM), and specific binding represented 60-90% of total binding at all concentrations examined up to 15 nM. The nicotinic cholinergic agonists nicotine, acetylcholine, and carbachol compete with high affinity for [3H]cytisine binding sites, whereas among nicotinic receptor antagonists only dihydro-beta-erythroidine competes with high affinity (in the nanomolar range). Comparison of binding in several brain regions showed that [3H]cytisine binding is higher in the thalamus, striatum, and cortex than in the hippocampus, cerebellum, or hypothalamus. The pharmacology and brain regional distribution of [3H]cytisine binding sites are those predicted for neuronal nicotinic receptor agonist recognition sites. The high affinity and low nonspecific binding of [3H]cytisine should make it a very useful ligand for studying neuronal nicotinic receptors.