title: Prostaglandin E receptor subtype EP4 agonist serves better to protect cochlea than prostaglandin E1.
abstract: OBJECTIVE
  The present study aimed to examine whether an E-prostanoid receptor 4 (EP4) agonist has superior protective effects to those of prostaglandin E1 (PGE1) in a guinea pig model of noise trauma.
  
  
  METHODS
  Drugs were locally applied on the round window membrane of guinea pig cochleae, followed by exposure of the test animals to intense noise. Protective effects mediated by an EP4 agonist were compared with those mediated by PGE1. Auditory function was monitored by measurements of the auditory brainstem response (ABR), and histological damage was assessed by immunohistochemical analysis of cochlear specimens.
  
  
  RESULTS
  Animals treated with an EP4 agonist exhibited significantly better hearing recovery than those pretreated with PGE1. Histologically, the numbers of remaining outer hair cells in cochleae treated with the EP4 agonist were significantly higher than in those treated with PGE1.
  
  
  CONCLUSIONS
  The selective activation of EP4 has a stronger protective effect on cochleae against noise trauma than does the broad activation of EPs by PGE1.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Hori
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Norio
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Hamaguchi
authors.forename: Juichi
authors.initials: J
authors.lastname: Ito
mesh_terms: D000527:Alprostadil / Q000494:pharmacology*; D000818:Animals; D001307:Auditory Perception / Q000502:physiology; D003051:Cochlea / Q000187:drug effects* / Q000473:pathology; D016057:Evoked Potentials, Auditory, Brain Stem; D006168:Guinea Pigs; D006317:Hearing Loss, Noise-Induced / Q000473:pathology / Q000517:prevention & control; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000819:agonists*
chemical_list: C545650:PTGER4 protein, human; D058309:Receptors, Prostaglandin E, EP4 Subtype; D000527:Alprostadil
keywords: E-prostanoid receptor; Hearing loss; Local application; Noise trauma