title: Inner and outer portions of colonic circular muscle: ultrastructural and immunohistochemical changes in rat chronically treated with otilonium bromide.
abstract: Rat colonic circular muscle, main target of otilonium bromide (OB) spasmolytic activity, is subdivided in an inner and outer portion. Since the inner one is particularly rich in organelles involved in calcium availability (caveolae, smooth endoplasmic reticulum, mitochondria), the expression of specific markers (Caveolin-1, eNOS, calreticulin, calsequestrin) in comparison with the outer portion was investigated. The possible changes of these organelles and related markers, and of muscarinic receptors (Mr2) were then studied after OB chronic exposition. Rats were treated with 2-20 mg/kg/OB for 10 or 30 days. Proximal colon was processed by electron microscopy, immunohistochemistry, and western blot. In colon strips the stimulated contractility response to muscarinic agonist was investigated. The inner portion showed a higher expression of Caveolin-1 and Mr2, but not of eNOS, calreticulin and calsequestrin, compared to the outer portion. Chronic OB treatment caused similar ultrastructural and immunohistochemical changes in both portions. Organelles and some related markers were increased at 10 days; Mr2 expression and muscle contractility induced by methacholine was increased at 30 days. The present findings: 1) provide new information on the immunohistochemical properties of the inner portion of the circular layer that are in favour of a role it might play in colonic motility distinct from that of the outer portion; 2) demonstrate that chronically administered OB interferes with cell structures and molecules responsible for calcium handling and storage, and modifies cholinergic transmission. In conclusion, chronic OB administration in the colonic circular muscle layer directly interacts with the organelles and molecules calcium-related and with the Mr2.
authors.affiliation: Dept of Experimental and Clinical Medicine, Histology and Embryology Research Unit, Florence, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Traini
authors.affiliation: Dept of Experimental and Clinical Medicine, Histology and Embryology Research Unit, Florence, Italy.
authors.forename: Maria Simonetta
authors.initials: MS
authors.lastname: Faussone-Pellegrini
authors.affiliation: Menarini Ricerche SpA, Preclinical Development, Florence, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Evangelista
authors.affiliation: Dept of Experimental and Clinical Medicine, Histology and Embryology Research Unit, Florence, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Mazzaferro
authors.affiliation: Enteric Neuroscience Program, Division of Gastroenterology, Dept of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States of America.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Cipriani
authors.affiliation: Dept of Experimental and Clinical Medicine, Histology and Embryology Research Unit, Florence, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Santicioli
authors.affiliation: Dept of Experimental and Clinical Medicine, Histology and Embryology Research Unit, Florence, Italy.
authors.forename: Maria Giuliana
authors.initials: MG
authors.lastname: Vannucchi
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D037282:Calreticulin / Q000378:metabolism; D002155:Calsequestrin / Q000378:metabolism; D051242:Caveolin 1 / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism
chemical_list: D037282:Calreticulin; D002155:Calsequestrin; D051242:Caveolin 1; D000644:Quaternary Ammonium Compounds; D011976:Receptors, Muscarinic; C013934:octylonium; D052250:Nitric Oxide Synthase Type III; D002118:Calcium