title: Mechanisms Underlying Endothelin-1 Level Elevations Caused by Excessive Fluoride Exposure.
abstract: OBJECTIVE
  To explore the mechanisms underlying endothelin-1 (ET-1) elevations induced by excessive fluoride exposure.
  
  
  METHODS
  We measured serum and bone fluoride ion content and plasma ET-1 levels and compared these parameters among different groups in an animal model. We also observed morphological changes in the aorta and endothelium of rabbits. In cell experiments, human umbilical vein endothelial cells (HUVECs) were treated with varying concentrations of NaF for 24h, with or without 10 µM U0126 pretreatment for 1 h. ET-1 levels in culture fluid and intracellular reactive oxygen species (ROS) levels, as well as ET1 gene, endothelin-converting enzyme-1 (ECE-1), extracellular signal-regulating kinase 1/2 (ERK1/2), pERK1/2 expression levels and RAS activation were measured and compared among the groups.
  
  
  RESULTS
  Plasma ET-1 levels of rabbits increased significantly in fluorinated groups compared with those in the control group. The rabbit thoracic aortas became slightly hardened in fluorinated groups compared with those in the control group, and some vacuoles were present in the endothelial cell cytoplasm of the rabbits in fluorinated groups. In our cell experiments, ET1 gene and ECE-1 expression levels in HUVECs and ET-1 expression levels in the cell culture supernatants increased significantly in some experimental groups compared with those in the control group. These trends paralleled the changes in intracellular ROS levels, RAS activation, and the pERK1/2-to-ERK1/2 ratio. After U0126 was added, ECE-1 expression and ET-1 levels decreased significantly.
  
  
  CONCLUSIONS
  Excessive fluoride exposure leads to characteristic endothelial damage (vacuoles), thoracic aorta hardening, and plasma ET-1 level elevations in rabbits. In addition, the ROS-RAS-MEK1/2-pERK1/2/ERK1/2 pathway plays a crucial-and at least partial-role in ET-1 over-expression, which is promoted by excessive fluoride exposure.
authors.affiliation: Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University; Key Lab of Etiology and Epidemiology, Education Bureau of Heilongjiang Province &amp; Ministry of Health (23618504), Harbin, China.
authors.forename: Liyan
authors.initials: L
authors.lastname: Sun
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Gao
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Xiaona
authors.initials: X
authors.lastname: Liu
authors.forename: Bingyun
authors.initials: B
authors.lastname: Li
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Cui
authors.forename: Dianjun
authors.initials: D
authors.lastname: Sun
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D001835:Body Weight / Q000187:drug effects; D002070:Butadienes / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D004032:Diet; D060766:Drinking Water; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism*; D000072396:Endothelin-Converting Enzymes / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005459:Fluorides / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism; D007477:Ions; D008297:Male; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
chemical_list: D002070:Butadienes; D060766:Drinking Water; D019332:Endothelin-1; D007477:Ions; D009570:Nitriles; D017382:Reactive Oxygen Species; C113580:U 0126; D048049:Extracellular Signal-Regulated MAP Kinases; D000072396:Endothelin-Converting Enzymes; D018631:ras Proteins; D005459:Fluorides