title: Protective effect of metformin on gentamicin-induced vestibulotoxicity in rat primary cell culture.
abstract: OBJECTIVE
  One of the antidiabetic drugs, metformin, have shown that it prevented oxidative stress-induced death in several cell types through a mechanism involving the opening of the permeability transition pore and cytochrome c release. Thus, it is possible that the antioxidative effect of metformin can also serve as protection against gentamicin-induced cytotoxicity related to reactive oxygen species (ROS). The aim of this study was to examine the protective effect of metformin on gentamicin-induced vestibulotoxicity in primary cell culture derived from rat utricle.
  
  
  METHODS
  For vestibular primary cell culture, rat utricles were dissected and incubated. Gentamicin-induced cytotoxicity was measured in both the auditory and vestibular cells. To examine the effects of metformin on gentamicin-induced cytotoxicity in the primary cell culture, the cells were pretreated with metformin at a concentration of 1 mM for 24 hours, and then exposed to 2.5 mM gentamicin for 48 hours. The intracellular ROS level was measured using a fluorescent dye, and also measured using a FACScan flow cytometer. Intracellular calcium levels in the vestibular cells were measured with calcium imaging using Fura-2 AM.
  
  
  RESULTS
  Vestibular cells were more sensitive to gentamicin-induced cytotoxicity than auditory hair cells. Metformin protects against gentamicin-induced cytotoxicity in vestibular cells. Metformin significantly reduced a gentamicin-induced increase in ROS, and also reduced an increase in intracellular calcium concentrations in gentamicin-induced cytotoxicity.
  
  
  CONCLUSIONS
  Metformin significantly reduced a gentamicin-induced increase in ROS, stabilized the intracellular calcium concentration, and inhibited gentamicin-induced apoptosis. Thus, Metformin showed protective effect on gentamicin-induced cytotoxicity in vestibular primary cell culture.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Se Hee
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Ji Won
authors.initials: JW
authors.lastname: Chang
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jae-June
authors.initials: JJ
authors.lastname: Song
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hak Hyun
authors.initials: HH
authors.lastname: Jung
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Gi Jung
authors.initials: GJ
authors.lastname: Im
keywords: Calcium; Gentamicins; Labyrinth vestibule; Metformin; Reactive oxygen species