title: Sensorineural hearing loss from quinolinic acid: a neurotoxin in middle ear effusions.
abstract: Quinolinic acid (QUIN) is an endogenous metabolite that exerts a neurotoxic effect by binding to specific neuronal receptors. Studies involving a broad spectrum of infectious and inflammatory central nervous system diseases have suggested a role for QUIN in causing neuronal injury. Since there is evidence for presence of the QUIN receptor in mammalian cochleas, QUIN was measured in middle ear effusions (MEEs). Gas chromatography/mass spectrometry detected QUIN in each of 65 diluted human MEEs, with a mean of 482 +/- 75 (SEM) nmol/L and a range from 15 to 2667 nmol/L. QUIN was also detected in each of 197 chinchilla MEEs from five different models of otitis media, with a mean of 10.6 +/- 1.3 (SEM) mumol/L and a range from 0.23 to 146.0 mumol/L (corrected for dilution). To determine whether QUIN causes sensorineural hearing loss (SNHL), QUIN solutions were placed on round window membranes (RWM) for 20 to 240 minutes, in 20 chinchillas. SNHL was detected by electrocochleography in QUIN-exposed animals, but not in saline controls. We conclude that QUIN is present in MEEs and that QUIN in the middle ear has the potential to cross the RWM and cause sensorineural hearing loss, possibly by binding to specific neuronal receptors in mammalian cochleas.
authors.affiliation: Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, PA 15213-2583.
authors.forename: R F
authors.initials: RF
authors.lastname: Yellon
authors.forename: E
authors.initials: E
authors.lastname: Rose
authors.forename: M A
authors.initials: MA
authors.lastname: Kenna
authors.forename: W J
authors.initials: WJ
authors.lastname: Doyle
authors.forename: M
authors.initials: M
authors.lastname: Casselbrant
authors.forename: W F
authors.initials: WF
authors.lastname: Diven
authors.forename: T L
authors.initials: TL
authors.lastname: Whiteside
authors.forename: J D
authors.initials: JD
authors.lastname: Swarts
authors.forename: M P
authors.initials: MP
authors.lastname: Heyes
mesh_terms: D000818:Animals; D001300:Audiometry, Evoked Response; D002648:Child; D002682:Chinchilla; D003051:Cochlea / Q000294:innervation*; D008401:Gas Chromatography-Mass Spectrometry; D006319:Hearing Loss, Sensorineural / Q000139:chemically induced* / Q000175:diagnosis; D006801:Humans; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects*; D010034:Otitis Media with Effusion / Q000150:complications / Q000378:metabolism*; D017378:Quinolinic Acid / Q000009:adverse effects* / Q000032:analysis; D012405:Round Window, Ear / Q000187:drug effects
chemical_list: D017378:Quinolinic Acid