An autoradiographic analysis of cholinergic receptors in mouse brain

Autoradiographic techniques were used to localize cholinergic receptors in the central nervous system of female DBA mice. Nicotinic receptors were identified using [3H]-L-nicotine and alpha-[125I]-bungarotoxin (BTX); [3H]-quinuclidinyl benzilate (QNB) was used to examine muscarinic receptor binding. There was little overlap between the regional distribution of binding sites for these ligands. Nicotine binding was highest in thalamic nuclei, the superior colliculus and the interpeduncular nucleus. For BTX binding, high density receptor populations were identified in the hippocampus, caudate putamen, colliculi (superior and inferior) and various nuclei in the hypothalamus and hindbrain. Muscarinic receptors were distributed more uniformly than nicotinic receptors; the colliculi, hippocampus and cerebral cortex had the highest level of QNB binding. Species differences between rats and mice in terms of cholinergic receptor binding are discussed.