title: The effect of caffeine on hearing in a guinea pig model of acoustic trauma.
abstract: OBJECTIVE
  Caffeine is a widely consumed substance affecting the metabolism of adenosine and cellular metabolism of calcium. Noise also affects these metabolic pathways while inducing hearing loss. The aim of this study was to determine the effect of daily intake of caffeine on hearing loss after an episode of acoustic trauma in guinea pigs.
  
  
  METHODS
  In this pilot study, forty guinea pigs were randomly divided into four groups: group I (control, n=10) received intraperitoneal saline, group II (n=10) received intraperitoneal caffeine (120 mg/kg/day) for 14 days, group III (n=10) was exposed to noise (tone of 6 kHz at 120 dB for one hour) and group IV (n=10) was exposed to noise as group III and received caffeine as group II. Auditory brainstem responses were measured at four different frequencies (8, 16, 20, and 25 kHz) prior to and at intervals of 1h, 3 days, 10 days, and 14 days after the initial treatment. On day 14, morphological analysis was performed to assess the effects of caffeine on acoustic trauma.
  
  
  RESULTS
  Aggravated hearing loss was observed in group IV after 10 days of follow-up. After 14 days, one of the four frequencies (8 kHz) tested showed statistically significant greater impairment in hearing (8.2 ± 3.6 dB, p=0.026). Auditory hair cells showed no difference while spiral ganglion cell counts were diminished in group IV (p<0.05).
  
  
  CONCLUSIONS
  These findings indicate that caffeine may have a detrimental effect on hearing recovery after a single event of acoustic trauma.
authors.affiliation: McGill Auditory Sciences Laboratory, Montreal Children's Hospital, Department of Otolaryngology-Head and Neck Surgery, McGill University, Montréal, Québec, Canada.
authors.forename: Mario A
authors.initials: MA
authors.lastname: Mujica-Mota
authors.affiliation: McGill Auditory Sciences Laboratory, Montreal Children's Hospital, Department of Otolaryngology-Head and Neck Surgery, McGill University, Montréal, Québec, Canada.
authors.forename: Karina
authors.initials: K
authors.lastname: Gasbarrino
authors.affiliation: McGill Auditory Sciences Laboratory, Montreal Children's Hospital, Department of Otolaryngology-Head and Neck Surgery, McGill University, Montréal, Québec, Canada; Jewish General Hospital, Department of Otolaryngology-Head and Neck Surgery, Montréal, Québec, Canada.
authors.forename: Jamie M
authors.initials: JM
authors.lastname: Rappaport
authors.affiliation: McGill Auditory Sciences Laboratory, Montreal Children's Hospital, Department of Otolaryngology-Head and Neck Surgery, McGill University, Montréal, Québec, Canada.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Shapiro
authors.affiliation: McGill Auditory Sciences Laboratory, Montreal Children's Hospital, Department of Otolaryngology-Head and Neck Surgery, McGill University, Montréal, Québec, Canada. Electronic address: sam.daniel@mcgill.ca.
authors.forename: Sam J
authors.initials: SJ
authors.lastname: Daniel
mesh_terms: D000818:Animals; D002110:Caffeine / Q000008:administration & dosage*; D003051:Cochlea / Q000648:ultrastructure; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D006309:Hearing / Q000187:drug effects*; D006317:Hearing Loss, Noise-Induced / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D007274:Injections, Intraperitoneal; D008855:Microscopy, Electron, Scanning; D010865:Pilot Projects; D058915:Purinergic P1 Receptor Antagonists / Q000008:administration & dosage
chemical_list: D058915:Purinergic P1 Receptor Antagonists; D002110:Caffeine