LOCALIZATION OF M(3) MUSCARINIC RECEPTOR SUBTYPE AND MESSENGER-RNA IN THE HUMAN EYE

Cholinergic agents used to lower intraocular pressure in the medical management of glaucoma act on muscarinic receptors in the eye. Recently, subtypes of muscarinic receptors have been recognized in many tissues including the eye. To localize the M(3) muscarinic receptor subtype and m(3) messenger RNA (mRNA) in the human eye, we used in vitro ligand binding and in situ hybridization techniques on post-mortem sections. We used an M(3) antagonist, [H-3]-4-DAMP ([H-3]-4-diphenylacetoxy-N-methylpiperidine methiodide) to identify M(3)-binding sites and a [S-35]-labelled oligonucleotide probe to detect and localize m(3) mRNA. M(3) and m(3) mRNA were both localized in the ciliary muscle, ciliary epithelium, iris, corneal epithelium and anterior lens epithelium. The m(3) transcript was also detected in the trabecular meshwork and corneal endothelium.