title: Transient cognitive deficits and high-frequency hearing loss in weanling rats exposed to toluene.
abstract: In a previous experiment we found that weanling rats subchronically exposed to toluene by inhalation were deficient in learning a multisensory conditioned avoidance response (CAR) task and a tone-intensity discrimination task when trained several hours after each daily 14-hour exposure ended. The present experiment was done to determine whether this deficit represented a residual pharmacologic effect or more persisting nervous system damage. Independent groups of rats were trained on the CAR task either during the last week of a 5-week exposure to 1400 or to 1200 pm toluene (14 hr/day, 7 days/week) or during the first or third weeks after the exposures ended. None of the three groups of toluene-exposed rats were able to acquire the auditory CAR, whereas it had been 4 kHz in the previous experiment. Subsequent tests, in which the frequency and intensity of the tone were varied, revealed that hearing in these rats was unimpaired at 4 kHz, slightly impaired at 8 kHz, and markedly impaired at 12 kHz and above. Thus, although toluene has been shown to be relatively innocuous as a toxicant, this new finding suggests that this solvent should be examined further in terms of its potential hazard, especially with regard to its frequent abuse.
mesh_terms: D000818:Animals; D001299:Audiometry; D001362:Avoidance Learning / Q000187:drug effects; D003072:Cognition Disorders / Q000139:chemically induced*; D003213:Conditioning, Psychological / Q000187:drug effects; D034381:Hearing Loss / Q000139:chemically induced*; D006316:Hearing Loss, High-Frequency / Q000139:chemically induced*; D006801:Humans; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D014050:Toluene / Q000633:toxicity*; D014886:Weaning
chemical_list: D014050:Toluene