Distribution and pharmacological characterization of muscarinic-cholinergic receptors in the cockroach brain

• Published in: Archives of insect biochemistry and physiology Vol. 16; no. 2; p. 107
• Main Authors: Orr, G.L. (Michigan State University, East Lansing, MI), Orr, N, Hollingworth, R.M
• Format: Journal Article
• Language: English
• Published: United States 1991
• Subjects: ACETILCOLINA; ACETYLCHOLINE; Animals; Autoradiography; Binding, Competitive; Brain - metabolism; Bungarotoxins - metabolism; CEREBRO; Cockroaches - metabolism; Cyclic AMP - metabolism; ENCEPHALE; Kinetics; LIGAND; LIGANDOS; MACHO; MALE; MEDICAMENT NEUROTROPE; MEDICAMENTOS NEUROTROPICOS; PERIPLANETA AMERICANA; Quinuclidinyl Benzilate - metabolism; RADIOGRAFIA; RADIOGRAPHIE; Receptors, Muscarinic - metabolism; Receptors, Nicotinic - metabolism; TECHNIQUE DES TRACEURS; TECNICAS DE TRAZADORES; Tritium
• DOI: 10.1002/arch.940160204
• ISSN: 0739-4462

The binding of [3H]quinuclidinyl benzilate to a cockroach brain preparation was investigated. Specific binding was saturable with a Kd of 0.25 nM and Scatchard analysis indicated a Bmax of 604 pmol/mg protein. Kinetic analysis indicated that the ligand is binding in a complex fashion while dissociation followed a simple kinetic process. The pharmacology of the site was typical of muscarinic receptors but the site cannot be characterized in terms of vertebrate muscarinic-receptor subtypes. Affinity of the receptor for agonists was modulated by Mg2+ and guanylylimidodiphosphate but not by pertussis toxin indicating the involvement of a pertussis-toxin insensitive G-protein. Carbamylcholine did not inhibit basal or forskolin-stimulated adenylate cyclase activity. The binding site was localized autoradiographically and was restricted to the median and lateral calyces of the brain