title: Inhaled toluene can modulate the effects of anesthetics on the middle-ear acoustic reflex.
abstract: Toluene (Tol) is an organic solvent widely used in the industry. It is also abused as an inhaled solvent, and can have deleterious effects on hearing. Recently, it was demonstrated that Tol has both anticholinergic and antiglutamatergic effects, and that it also inhibits voltage-dependent Ca(2+) channels. This paper describes a study of the effects of inhaled Tol on rats anesthetized with isoflurane, pentobarbital, or a mixture of ketamine/xylazine. Hearing was tested using distortion product oto-acoustic emissions (DPOAEs) associated with a contralateral noise to evaluate contraction of the middle-ear muscles. This allowed us to assess the interactions between the effects of Tol and anesthesia on the central nervous system (CNS). Although both anesthetics and Tol are known to inhibit the middle-ear acoustic reflex, our data indicated that inhaled Tol counterbalances the effects of anesthetic in a dose-dependent manner. In other terms, Tol can increase the amplitude of the middle-ear reflex in anesthetized rats, whatever the nature of the anesthetic used. This indicates that inhaling Tol (a Ca(2+)-channel-blocking drug) modifies the potency of anesthesia, and thereby the amplitude of the middle-ear reflex.
authors.affiliation: Institut National de Recherche et de Sécurité, Vandœuvre Cedex, France. Pierre.campo@inrs.fr
authors.forename: Pierre
authors.initials: P
authors.lastname: Campo
authors.forename: Thomas
authors.initials: T
authors.lastname: Venet
authors.forename: Aurélie
authors.initials: A
authors.lastname: Thomas
authors.forename: Chantal
authors.initials: C
authors.lastname: Cour
authors.forename: Blandine
authors.initials: B
authors.lastname: Castel
authors.forename: Hervé
authors.initials: H
authors.lastname: Nunge
authors.forename: Frédéric
authors.initials: F
authors.lastname: Cosnier
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics; D000280:Administration, Inhalation; D000704:Analysis of Variance; D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004432:Ear, Middle / Q000187:drug effects*; D004567:Electrodes, Implanted; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects; D051381:Rats; D012022:Reflex, Acoustic / Q000187:drug effects*; D012997:Solvents / Q000008:administration & dosage* / Q000378:metabolism; D014050:Toluene / Q000008:administration & dosage* / Q000378:metabolism
chemical_list: D000777:Anesthetics; D012997:Solvents; D014050:Toluene