title: Muscarinic cholinergic receptor subtypes in the pigeon bursa of Fabricius: a radioligand binding and autoradiographic study.
abstract: The pharmacological profile and the anatomical localisation of muscarinic cholinergic receptor subtypes were studied in the pigeon bursa of Fabricius, using radioligand binding and autoradiographic techniques with [3H]quinuclidinyl benzilate (QNB) as a ligand. [3H]QNB was specifically bound to sections of bursa of Fabricius. The binding was time-, temperature- and concentration-dependent. The dissociation constant was 0.31 +/- 0.02 nM, and the maximum density of binding sites averaged 38 +/- 2.5 fmol/mg protein. The pharmacological profile of [3H]QNB binding to sections of pigeon bursa of Fabricius was consistent with the labelling of M2, M3 and M4 muscarinic receptor subtypes. Light microscope autoradiography showed the localisation of [3H]QNB binding sites in the medulla, in follicular septa, in the cortico-medullary border and in lesser amounts in the cortical layer. The functional significance of these receptors should be clarified in future studies.
authors.affiliation: Dipartimento of Science Cardiovascolari e Respiratorie, Università "La Sapienza", Roma, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Ricci
authors.forename: E
authors.initials: E
authors.lastname: Bronzetti
authors.forename: L
authors.initials: L
authors.lastname: Felici
authors.forename: E
authors.initials: E
authors.lastname: Ciriaco
authors.forename: J A
authors.initials: JA
authors.lastname: Vega
authors.forename: G
authors.initials: G
authors.lastname: Germanà
mesh_terms: D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D002060:Bursa of Fabricius / Q000378:metabolism*; D008297:Male; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011869:Radioligand Assay; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate