title: Glucagon induces airway smooth muscle relaxation by nitric oxide and prostaglandin E₂.
abstract: Glucagon is a hyperglycemic pancreatic hormone that has been shown to provide a beneficial effect against asthmatic bronchospasm. We investigated the role of this hormone on airway smooth muscle contraction and lung inflammation using both in vitro and in vivo approaches. The action of glucagon on mouse cholinergic tracheal contraction was studied in a conventional organ bath system, and its effect on airway obstruction was also investigated using the whole-body pletysmographic technique in mice. We also tested the effect of glucagon on lipopolysaccharide (LPS)-induced airway hyperreactivity (AHR) and inflammation. The expression of glucagon receptor (GcgR), CREB, phospho-CREB, nitric oxide synthase (NOS)-3, pNOS-3 and cyclooxygenase (COX)-1 was evaluated by western blot, while prostaglandin E₂ (PGE₂) and tumour necrosis factor-α were quantified by enzyme-linked immunoassay and ELISA respectively. Glucagon partially inhibited carbachol-induced tracheal contraction in a mechanism clearly sensitive to des-His1-[Glu9]-glucagon amide, a GcgR antagonist. Remarkably, GcgR was more expressed in the lung and trachea with intact epithelium than in the epithelium-denuded trachea. In addition, the glucagon-mediated impairment of carbachol-induced contraction was prevented by either removing epithelial cells or blocking NOS (L-NAME), COX (indomethacin) or COX-1 (SC-560). In contrast, inhibitors of either heme oxygenase or COX-2 were inactive. Intranasal instillation of glucagon inhibited methacholine-induced airway obstruction by a mechanism sensitive to pretreatment with L-NAME, indomethacin and SC-560. Glucagon induced CREB and NOS-3 phosphorylation and increased PGE₂ levels in the lung tissue without altering COX-1 expression. Glucagon also inhibited LPS-induced AHR and bronchoalveolar inflammation. These findings suggest that glucagon possesses airway-relaxing properties that are mediated by epithelium-NOS-3-NO- and COX-1-PGE₂-dependent mechanisms.
authors.affiliation: Laboratório de Inflamação Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil Instituto de Nutrição Universidade do Estado do Rio de Janeiro, São Francisco Xavier, n° 524, CEP 20559-900 Rio de Janeiro, Brazil Laboratório de Imunofarmacologia Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil.
authors.forename: Daniella B R
authors.initials: DB
authors.lastname: Insuela
authors.affiliation: Laboratório de Inflamação Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil Instituto de Nutrição Universidade do Estado do Rio de Janeiro, São Francisco Xavier, n° 524, CEP 20559-900 Rio de Janeiro, Brazil Laboratório de Imunofarmacologia Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil.
authors.forename: Julio B
authors.initials: JB
authors.lastname: Daleprane
authors.affiliation: Laboratório de Inflamação Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil Instituto de Nutrição Universidade do Estado do Rio de Janeiro, São Francisco Xavier, n° 524, CEP 20559-900 Rio de Janeiro, Brazil Laboratório de Imunofarmacologia Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil.
authors.forename: Luciana P
authors.initials: LP
authors.lastname: Coelho
authors.affiliation: Laboratório de Inflamação Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil Instituto de Nutrição Universidade do Estado do Rio de Janeiro, São Francisco Xavier, n° 524, CEP 20559-900 Rio de Janeiro, Brazil Laboratório de Imunofarmacologia Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil.
authors.forename: Adriana R
authors.initials: AR
authors.lastname: Silva
authors.affiliation: Laboratório de Inflamação Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil Instituto de Nutrição Universidade do Estado do Rio de Janeiro, São Francisco Xavier, n° 524, CEP 20559-900 Rio de Janeiro, Brazil Laboratório de Imunofarmacologia Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil.
authors.forename: Patrícia M R
authors.initials: PM
authors.lastname: e Silva
authors.affiliation: Laboratório de Inflamação Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil Instituto de Nutrição Universidade do Estado do Rio de Janeiro, São Francisco Xavier, n° 524, CEP 20559-900 Rio de Janeiro, Brazil Laboratório de Imunofarmacologia Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Martins
authors.affiliation: Laboratório de Inflamação Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil Instituto de Nutrição Universidade do Estado do Rio de Janeiro, São Francisco Xavier, n° 524, CEP 20559-900 Rio de Janeiro, Brazil Laboratório de Imunofarmacologia Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil, n° 4365, Manguinhos, CEP 21040-360 Rio de Janeiro, Brazil vfrias@ioc.fiocruz.br.
authors.forename: Vinicius F
authors.initials: VF
authors.lastname: Carvalho
mesh_terms: D000281:Administration, Intranasal; D000403:Airway Resistance / Q000187:drug effects; D000818:Animals; D001249:Asthma / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D016535:Bronchial Hyperreactivity / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D059329:Cholinergic Neurons / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism*; D005934:Glucagon / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D066298:In Vitro Techniques; D008297:Male; D008805:Mice, Inbred A; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000276:immunology / Q000294:innervation / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D014132:Trachea / Q000187:drug effects* / Q000276:immunology / Q000294:innervation / Q000378:metabolism
chemical_list: D001993:Bronchodilator Agents; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D009569:Nitric Oxide; D005934:Glucagon; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D015232:Dinoprostone
keywords: glucagon; lung; muscle; nitric oxide; prostaglandins