title: Toluene-induced hearing loss in the guinea pig.
abstract: Toluene is a high-production industrial solvent, which can disrupt the auditory system in rats. However, toluene-induced hearing loss is species dependent. For instance, despite long-lasting exposures to high concentrations of aromatic solvent, no study has yet succeeded in causing convincing hearing loss in the guinea pig. This latter species can be characterized by two metabolic particularities: a high amount of hepatic cytochrome P-450s (P-450s) and a high concentration of glutathione in the cochlea. It is therefore likely that the efficiency of both the hepatic and cochlear metabolisms plays a key role in the innocuousness of the hearing of guinea pigs to exposure to solvent. The present study was carried out to test the auditory resistance to toluene in glutathione-depleted guinea pigs whose the P-450 activity was partly inhibited. To this end, animals on a low-protein diet received a general P-450 inhibitor, namely SKF525-A. Meanwhile, they were exposed to 1750 ppm toluene for 4 weeks, 5 days/week, 6 h/day. Auditory function was tested by electrocochleography and completed by histological analyses. For the first time, a significant toluene-induced hearing loss was provoked in the P-450-inhibited guinea pigs. However, the ototoxic process caused by the solvent exposure was different from that observed in the rat. Only the stria vascularis and the spiral fibers were disrupted in the apical coil of the cochlea. The protective mechanisms developed by guinea pigs are discussed in the present publication.
authors.affiliation: Département Polluants et Santé Rue du Morvan, Institut National de Recherche et de Sécurité, 54519 Vandoeuvre Cédex, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Waniusiow
authors.forename: Pierre
authors.initials: P
authors.lastname: Campo
authors.forename: Thomas
authors.initials: T
authors.lastname: Venet
authors.forename: Benoît
authors.initials: B
authors.lastname: Cossec
authors.forename: Frédéric
authors.initials: F
authors.lastname: Cosnier
authors.forename: Dominique
authors.initials: D
authors.lastname: Beydon
authors.forename: Benoît
authors.initials: B
authors.lastname: Rieger
authors.forename: Manuella
authors.initials: M
authors.lastname: Burgart
authors.forename: Luc
authors.initials: L
authors.lastname: Ferrari
authors.forename: Cécile
authors.initials: C
authors.lastname: Parietti-Winkler
mesh_terms: D000818:Animals; D001299:Audiometry; D006168:Guinea Pigs; D034381:Hearing Loss / Q000139:chemically induced* / Q000503:physiopathology; D008297:Male; D009925:Organ of Corti / Q000187:drug effects / Q000473:pathology; D010865:Pilot Projects; D014050:Toluene / Q000097:blood / Q000633:toxicity* / Q000652:urine
chemical_list: D014050:Toluene