title: TNF-α inhibition using etanercept prevents noise-induced hearing loss by improvement of cochlear blood flow in vivo.
abstract: OBJECTIVE
  Exposure to loud noise can impair cochlear microcirculation and cause noise-induced hearing loss (NIHL). TNF-α signaling has been shown to be activated in NIHL and to control spiral modiolar artery vasoconstriction that regulates cochlear microcirculation. It was the aim of this experimental study to analyse the effects of the TNF-α inhibitor etanercept on cochlear microcirculation and hearing threshold shift in NIHL in vivo.
  
  
  METHODS
  After assessment of normacusis using ABR, loud noise (106 dB SPL, 30 minutes) was applied on both ears in guinea pigs. Etanercept was administered systemically after loud noise exposure while control animals received a saline solution. In vivo fluorescence microscopy of strial capillaries was performed after surgical exposure of the cochlea for microcirculatory analysis. ABR measurements were derived from the contralateral ear.
  
  
  METHODS
  Guinea pigs (n = 6, per group).
  
  
  RESULTS
  Compared to controls, cochlear blood flow in strial capillary segments was significantly increased in etanercept-treated animals. Additionally, hearing threshold was preserved in animals receiving the TNF-α inhibitor in contrast to a significant threshold raising in controls.
  
  
  CONCLUSIONS
  TNF-α inhibition using etanercept improves cochlear microcirculation and protects hearing levels after loud noise exposure and appears as a promising treatment strategy for human NIHL.
authors.affiliation: Walter Brendel Centre of Experimental Medicine (WBex), University of Munich (LMU), Germany.
authors.forename: Warangkana
authors.initials: W
authors.lastname: Arpornchayanon
authors.forename: Martin
authors.initials: M
authors.lastname: Canis
authors.forename: Friedrich
authors.initials: F
authors.lastname: Ihler
authors.forename: Claudia
authors.initials: C
authors.lastname: Settevendemie
authors.forename: Sebastian
authors.initials: S
authors.lastname: Strieth
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001309:Auditory Threshold / Q000187:drug effects; D002196:Capillaries / Q000187:drug effects* / Q000276:immunology / Q000503:physiopathology; D003051:Cochlea / Q000098:blood supply*; D004195:Disease Models, Animal; D000068800:Etanercept; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D006168:Guinea Pigs; D006317:Hearing Loss, Noise-Induced / Q000276:immunology / Q000503:physiopathology / Q000517:prevention & control*; D007074:Immunoglobulin G / Q000494:pharmacology*; D008297:Male; D008833:Microcirculation / Q000187:drug effects*; D018124:Receptors, Tumor Necrosis Factor; D012039:Regional Blood Flow / Q000187:drug effects; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000068800:Etanercept