Mapping of brain areas expressing RNA homologous to two different acetylcholine receptor alpha-subunit cDNAs.

We have used an in situ RNA X RNA hybridization technique to determine, in the central nervous systems of the mouse and rat, the distribution of RNA homologous to cDNA clones encoding the alpha subunit of a putative neural nicotinic acetylcholine receptor and the alpha subunit of the muscle nicotinic acetylcholine receptor. Hybridization of the neural alpha-subunit probe was strongest in the medial habenula but was also detected consistently in the compact part of the substantia nigra and ventral tegmental area, in the neocortex, and in certain parts of the thalamus and hypothalamus. The in situ hybridization technique makes it possible to compile a map of brain regions containing cell bodies expressing RNA coding for a specific receptor type and subsequently to apply the techniques of molecular biology to study these brain receptors.