title: A long-acting β2-adrenergic agonist increases the expression of muscarine cholinergic subtype‑3 receptors by activating the β2-adrenoceptor cyclic adenosine monophosphate signaling pathway in airway smooth muscle cells.
abstract: The persistent administration of β2‑adrenergic (β2AR) agonists has been demonstrated to increase the risk of severe asthma, partly due to the induction of tolerance to bronchoprotection via undefined mechanisms. The present study investigated the potential effect of the long‑acting β2‑adrenergic agonist, formoterol, on the expression of muscarinic M3 receptor (M3R) in rat airway smooth muscle cells (ASMCs). Primary rat ASMCs were isolated and characterized following immunostaining with anti‑α‑smooth muscle actin antibodies. The protein expression levels of M3R and phospholipase C‑β1 (PLCβ1) were characterized by western blot analysis and the production of inositol 1,4,5‑trisphosphate (IP3) was determined using an enzyme‑linked immunosorbent assay. Formoterol increased the protein expression of M3R in rat ASMCs in a time‑ and dose‑dependent manner, which was significantly inhibited by the β2AR antagonist, ICI118,551 and the cyclic adenosine monophosphate (cAMP) inhibitor, SQ22,536. The increased protein expression of M3R was positively correlated with increased production of PLCβ1 and IP3. Furthermore, treatment with the glucocorticoid, budesonide, and the PLC inhibitor, U73,122, significantly suppressed the formoterol‑induced upregulated protein expression levels of M3R and PLCβ1 and production of IP3. The present study demonstrated that formoterol mediated the upregulation of M3R in the rat ASMCs by activating the β2AR‑cAMP signaling pathway, resulting in increased expression levels of PLCβ1 and IP3, which are key to inducing bronchoprotection tolerance. Administration of glucocorticoids or a PLC antagonist prevented formoterol‑induced bronchoprotection tolerance by suppressing the protein expression of M3R.
authors: Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors: Yuan-Hua
authors: YH
authors: Liu
authors: Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors: Song-Ze
authors: SZ
authors: Wu
authors: Pneumology Group, Department of Integrated Traditional Chinese and Western Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors: Gang
authors: G
authors: Wang
authors: Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors: Ni-Wen
authors: NW
authors: Huang
authors: Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China.
authors: Chun-Tao
authors: CT
authors: Liu
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D000068759:Formoterol Fumarate / Q000494:pharmacology*; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D017208:Rats, Wistar; D043587:Receptor, Muscarinic M3 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D043587:Receptor, Muscarinic M3; D000242:Cyclic AMP; D000068759:Formoterol Fumarate