Effects of single exposure to toluene on shock avoidance and time estimation in rats.

Behavioral effects of a single exposure to toluene were investigated on 12 rats by means of a shock avoidance task in a shuttle box. After 10 days of acquisition training, 3 groups of 4 rats were exposed to toluene vapor for 4 hr at concentrations of 8,000, 4,000, and 2,000 ppm. The maintenance of shock avoidance and time estimation was examined immediately after, and at the 3rd and 6th hr after the 4 hr toluene exposure. No avoidance response occurred immediately after 8,000 ppm toluene exposure, but it was recovered by the 3rd hr after exposure. Both 4,000 and 2,000 ppm toluene exposures increased the percentage of avoidance response. The response latencies (RLs) were significantly shortened after toluene exposure and the relative frequency distribution of RLs was shifted toward a shorter RL. The shortening of RLs could be attributed not only to the excitatory effect of toluene but also to the acceleration of response initiation. It is possible that toluene-exposed rats estimated the time interval to be longer than the real time, and that this over-estimation of the time interval hastened the timing of response initiation.