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VISUAL FUNCTION CHANGES AFTER SUBCHRONIC TOLUENE INHALATION IN LONG-EVANS RATS.
Citation:
BOYES, W. K., L. DEGN, M. S. BERCEGEAY, J. MWANZA, C. PINCKNEY, T. E. SAMSAM, A. M. GELLER, AND P. J. BUSHNELL. VISUAL FUNCTION CHANGES AFTER SUBCHRONIC TOLUENE INHALATION IN LONG-EVANS RATS. Presented at Society of Toxicology, Charlotte, NC, March 25 - 29, 2007.
Description:
Chronic exposure to volatile organic compounds, including toluene, has been associated with visual deficits such as reduced visual contrast sensitivity or impaired color discrimination in studies of occupational or residential exposure. These reports remain controversial, however, in part due to a lack of confirmation from controlled laboratory experiments. This study examined rats following exposure to 0, 10, 100 or 1000 ppm toluene by inhalation (6 hr/d, 5 d/wk, 13 wk) as described in Bushnell et al., (SOT, 2007). The week following exposure, rats (n=10/dose group) were surgically implanted with indwelling electrodes over visual cortex. The next week, pattern elicited visual evoked potentials (VEP) were recorded over a range of visual pattern contrasts. Four weeks after exposure, rats were anesthetized, evaluated ophthalmologically, and electroretinograms (ERG) were recorded. No significant changes were observed in VEP amplitudes or contrast thresholds derived from VEP contrast-amplitude functions. There were no dose-related ophthalmologic findings. The latencies of the ERG A- and B-waves were unchanged by toluene treatment. There was, however, a significant dose x intensity interaction for the amplitudes of A- and B-waves. The amplitudes of B-waves were reduced only at stimulus luminance values higher than the apparent rod/cone break in rats treated with 1000 ppm toluene. The ERG results are consistent with a selective deficit in cone photoreceptor function following subchronic toluene exposure. These data provide experimental confirmation that repeated exposure to toluene may lead to subtle changes in visual function.