You are here:
ACUTE AND REPEATED INHALATION OF TOLUENE BY RATS PERFORMING A SIGNAL DETECTION TASK LEADS TO BEHAVIORAL TOLERANCE ON SOME PERFORMANCE MEASURES.
Citation:
Oshiro, W M. AND P J. Bushnell. ACUTE AND REPEATED INHALATION OF TOLUENE BY RATS PERFORMING A SIGNAL DETECTION TASK LEADS TO BEHAVIORAL TOLERANCE ON SOME PERFORMANCE MEASURES. Presented at Society of Toxicology, Baltimore, MD, March 21 - 25, 2004.
Impact/Purpose:
PRESENTATION
Description:
Previous work showed that trichloroethylene (TCE) impairs accuracy and latency in a signal detection task (SDT) in rats, and that these effects abate during repeated exposures if rats inhale TCE during SDT testing. The present experiment compared the effects of acute and repeated exposure to toluene, another commonly-used solvent. Sixteen male, Long-Evans rats were trained to perform the SDT. Upon completion of training, rats were divided into 2 groups (n=8) with equivalent accuracies and response latencies. In Phase 1, concentration-effect functions were determined for toluene (0, 1200, 1600, 2000, 2400 ppm) in both groups. In this phase, toluene reduced the proportion of hits, P(hit); did not affect the proportion of false alarms, P(fa); and increased response times (RT). In Phase 2, Group 1 was exposed to 1600 ppm toluene during 11 daily SDT sessions, while Group 2 performed the SDT in air. The effect of toluene on P(hit) abated in Group 1 during this phase, indicating the development of tolerance to toluene. In Phase 3, concentration-effect functions for P(hit) were re-determined and showed a shift to the right in both groups, indicating that both groups had developed tolerance to toluene. Although there was a trend for Group 1 to show more tolerance on P(hit) measures than Group 2, it was not significant. However, subsequent analysis of corrected P(hit), a measure of overall accuracy, indicated that Group 1 was less sensitive to toluene in Phase 3 than was Group 2. Thus, repeated inhalation of toluene can lead to behavioral tolerance, which can develop after as few as 4 exposures (as occurred in Group 2 during Phase 1). Unlike TCE, however, toluene did not increase P(fa), nor did tolerance develop on the RT measure, indicating a possible difference in the mode of action of these two solvents. (This abstract does not necessarily reflect EPA policy.)