Localization of mRNA for the muscarinic M1 receptor in rat stomach.

Cholinergic stimulation of receptors in the oxyntic mucosa results in secretion of mucus, pepsinogen and hydrochloric acid. There has been speculation as to the cellular localization of these receptors in the mucosa and as to which subtype is present in the different cell types. In the present study, utilizing radioactive riboprobes for the M1 muscarinic receptor subtype, we carried out in situ hybridization to determine which cells of the gastric corpus transcribe mRNA for this receptor. The antisense M1 probe hybridized strongly on the zymogen cells and, to a lesser extent, on the surface mucous cells and the muscle layers. Control sections from brain also displayed specific hybridization.