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TEN DAY EXPOSURES TO CARBONYL SULFIDE PRODUCE BRAINSTEM LESIONS AND CHANGES IN BRAINSTEM AUDITORY EVOKED RESPONSES IN FISCHER 344N RATS.
Citation:
Herr, D W., J. E. Graff, P. B. Little, V C. Moser, P. M. Phillips, K M. Crofton, D. L. Morgan, AND R. C. Sills. TEN DAY EXPOSURES TO CARBONYL SULFIDE PRODUCE BRAINSTEM LESIONS AND CHANGES IN BRAINSTEM AUDITORY EVOKED RESPONSES IN FISCHER 344N RATS. Presented at Society of Toxicology, New Orleans, LA, March 06 - 10, 2005.
Description:
Carbonyl sulfide (COS) is a chemical intermediate in the production of pesticides and herbicides, a metabolite of carbon disulfide, a byproduct of the combustion of organic material, and a naturally occurring compound. COS was included in a Toxic Substances Control Act request for data, and has been listed as a Clean Air Act hazardous air pollutant. We have previously shown that 12-weeks exposure to 400 ppm COS produces brainstem lesions and altered brainstem auditory evoked responses (BAERs). To determine if shorter duration exposures produce similar effects, and to examine additional behavioral endpoints, male Fischer 344N rats were exposed by
inhalation to 0, 300, or 400 ppm COS for 6 h/day, 5 days/week, for 2 weeks. Animals were tested 5 - 11 days after the last exposure using a functional observational battery and white noise pre-pulse inhibition (PPI) of the startle response. Subjects were surgically implanted with screw electrodes over the cerebellum and visual cortex about 19 days after COS exposure, and were allowed to recover for one week. Unanesthetized animals were restrained and presented with auditory stimuli consisting of rarefaction clicks (50, 65, 80 dB SPL), pure tone pips (4 and 16 kHz at 80 dB SPL), and flash stimuli (15 and 146 lux-s). Rats exposed to 400 ppm COS had lower motor activity, grip strengths, a slightly altered gait, and a few animals lacked the forelimb
proprioceptive placing response. No alterations were observed in sensory responses. White noise PPI of the startle response was not altered in COS-treated animals. Exposure to COS decreased BAER amplitudes (peak P4 region). Histopathology confirmed the presence of brainstem lesions in the anterior olivary complex and posterior colliculus. Flash evoked responses were not altered by COS exposure. We have shown that short-term exposure to COS produces mild motor deficits, brainstem lesions, altered auditory electrophysiological responses (without changes in PPI of the startle response), and that the effects did not alter visual evoked responses. This is an
abstract of a proposed presentation and does not necessarily reflect EPA policy.