title: Activation of transient receptor potential vanilloid subtype 1 increases secretion of the hypofunctional, transplanted submandibular gland.
abstract: Hyposecretion occurs in most patients early after submandibular gland autotransplantation for severe keratoconjunctivitis sicca. Endogenous transient receptor potential vanilloid subtype 1 (TRPV1) has been recently demonstrated in rabbit submandibular glands, and activation of TRPV1 by capsaicin increases secretion in isolated glands, but the TRPV1-mediated secretory mechanism remains to be elucidated. The purpose of this study was to verify whether activation of TRPV1 by capsaicin could improve the secretion of transplanted gland and its underlying mechanism. The salivary flow of the transplanted glands was significantly decreased, and the mRNA and protein levels of TRPV1 and aquaporin 5 (AQP5) were downregulated in the transplanted glands. Topical capsaicin cream increased secretion and upregulated levels of TRPV1 and AQP5 in transplanted glands. Moreover, in cultured submandibular gland cells, capsaicin increased the mRNA expression of AQP5 and led to redistribution of AQP5 from the cytoplasm to the plasma membrane via TRPV1 activation. Capsaicin enhanced the phosphorylation of extracellular signal-regulated kinase (ERK). Preincubation of cells with PD98059, an inhibitor of ERK kinase, suppressed the capsaicin-induced mRNA expression of AQP5. In summary, the capsaicin-induced secretory mechanism involved activation of TRPV1 and upregulation of AQP5 in an ERK-dependent manner and promoted the redistribution of AQP5 in submandibular gland cells. Activation of TRPV1 may provide a new therapeutic strategy to improve submandibular gland hypofunction.
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, 100191, P.R. China. pathophy@bjmu.edu.cn
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Cong
authors.forename: L
authors.initials: L
authors.lastname: Shi
authors.forename: B
authors.initials: B
authors.lastname: Xiang
authors.forename: Y M
authors.initials: YM
authors.lastname: Li
authors.forename: Q W
authors.initials: QW
authors.lastname: Ding
authors.forename: C
authors.initials: C
authors.lastname: Ding
authors.forename: L L
authors.initials: LL
authors.lastname: Wu
authors.forename: G Y
authors.initials: GY
authors.lastname: Yu
mesh_terms: D000818:Animals; D051402:Aquaporin 5 / Q000235:genetics / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D012039:Regional Blood Flow; D012463:Saliva / Q000378:metabolism*; D012472:Salivation / Q000187:drug effects*; D018689:Sensory System Agents / Q000494:pharmacology*; D013363:Submandibular Gland / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism / Q000637:transplantation*; D050916:TRPV Cation Channels / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014182:Transplantation, Autologous; D015854:Up-Regulation
chemical_list: D051402:Aquaporin 5; D005419:Flavonoids; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D018689:Sensory System Agents; D050916:TRPV Cation Channels; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D002211:Capsaicin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one