title: Otoprotectant minimizes hearing defects caused by Pseudomonas aeruginosa exotoxin A.
abstract: Exotoxin A, produced by Pseudomonas aeruginosa (PaExoA), penetrates from the middle ear in to the cochlea and causes sensorineural hearing loss (SNHL). In this investigation we studied electrophysiological changes in the albino rat following instillation of PaExoA and N(G)-nitro-L-arginine methyl ester (L-NAME), a known inhibitor of nitric oxide synthesis, into the middle ear. Hearing thresholds were measured by auditory brainstem response (ABR) technique. Latency/intensity curves were constructed to distinguish between cochlear and conductive components of hearing loss. PaExoA caused damage to cochleae and SNHL, mainly at high frequencies. This impairment was blocked by (L-NAME). It would appear that nitric oxide may be a significant link in the mechanism of SNHL caused by bacterial toxin. L-NAME acts as an otoprotectant against the deleterious action of PaExoA.
authors.affiliation: Department of Otolaryngology and Head and Neck Surgery, Uppsala University Hospital, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Popa
authors.forename: M
authors.initials: M
authors.lastname: Anniko
authors.forename: M
authors.initials: M
authors.lastname: Takumida
mesh_terms: D000818:Animals; D001309:Auditory Threshold / Q000502:physiology; D003051:Cochlea / Q000187:drug effects; D016291:Dizocilpine Maleate / Q000494:pharmacology / Q000627:therapeutic use; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005098:Exotoxins / Q000009:adverse effects*; D006314:Hearing Loss, Conductive / Q000175:diagnosis / Q000382:microbiology* / Q000517:prevention & control*; D006316:Hearing Loss, High-Frequency / Q000175:diagnosis / Q000382:microbiology / Q000517:prevention & control; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis / Q000382:microbiology* / Q000517:prevention & control*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology / Q000627:therapeutic use*; D009569:Nitric Oxide / Q000378:metabolism; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012720:Severity of Illness Index
chemical_list: D004791:Enzyme Inhibitors; D005098:Exotoxins; D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; D016291:Dizocilpine Maleate; D019331:NG-Nitroarginine Methyl Ester