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BEHAVIORAL ASSESSMENTS OF LONG EVANS RATS FOLLOWING A 13 WEEK SUBCHRONIC TOLUENE EXPOSURE.
Citation:
SAMSAM, T. E., W. M. OSHIRO, M. E. GILBERT, AND P. J. BUSHNELL. BEHAVIORAL ASSESSMENTS OF LONG EVANS RATS FOLLOWING A 13 WEEK SUBCHRONIC TOLUENE EXPOSURE. Presented at Society of Toxicology, Charlotte, NC, March 25 - 29, 2007.
Description:
Whereas the acute effects of volatile organic compounds (VOCs) are relatively well understood, there is some controversy regarding the potential for persistent effects following long-term exposure. The current study sought to develop an animal model of subchronic exposure to VOCs which may be used to predict effects of long-term exposure to these agents on public health. Adult, male Long-Evans rats were exposed to toluene (0, 10, 100, or 1000 ppm) 6 hr/day, 5 days/week for 13 weeks. Three cohorts of animals (N=40 per cohort) were assessed in a variety of behavioral tasks beginning 2 days after the exposure ended. Cohort 1 was tested on the elevated plus maze (EPM) and showed no differences in anxiety measures between the toluene groups. Cohort 2 was assessed for motor activity on the Figure-8 maze followed by an assessment of anxiety on the EPM. No differences in total motor activity or anxiety were seen between the toluene groups; however, indices of anxiety were significantly different from Cohort 1, presumably as a result of prior Figure-8 maze testing. Cohort 3 was tested on a trace fear conditioning task and showed no toluene-induced differences in cue learning. Conditioning to context was marginally enhanced by toluene, but with no clear dose-dependency. Training to perform a visual signal detection task to assess learning and sustained attention began in Cohort 2 12 days after the end of exposure. Acquisition of a lever-press response for food (autoshaping) was delayed in all toluene-exposed groups; all rats eventually learned the response. Learning a subsequent visual discrimination task was impaired in the 100 and 1000 ppm groups. These results indicate that subchronic exposure to toluene may cause persistent neurotoxic effects. [This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.]