TOLUENE-INDUCED HEARING-LOSS IN RATS EVIDENCED BY THE BRAIN-STEM AUDITORY-EVOKED RESPONSE

  • 1 January 1983
    • journal article
    • research article
    • Vol. 5  (1) , 59-62
Abstract
Behavioral results showing that toluene caused hearing loss in rats precipitated an electrophysiologic study of the auditory thresholds of these rats using the brainstem auditory-evoked response (BAER). Male Fischer-344 rats (23 days old) were exposed to 1400 or 1200 ppm toluene 14 h/day, for 4 or 5 wk while a control group was exposed only to air. The rats were tested 2.5 mo. after termination of the exposures. BAER, recorded with 25 gauge needle electrodes placed over the nose and posterior skull, were evoked by 100 .mu.s duration clicks and 1 ms duration tone pips at 8 intensities. Thresholds for the appearance of BAER in the toluene-exposed rats were elevated by 13-27 dB, and latency-intensity functions were consistent with the occurrence of sensorineural hearing loss. The amplitudes of the 3rd and 5th components of the BAER were attenuated at high stimulus intensities in the toluene-exposed rats. These behavioral and electrophysiologic results were apparently the first to indicate the ototoxicity of toluene in experimental animals.