Effects of toluene vapors on signaled bar press shock avoidance performance in rats

Abstract

The effects of single exposure to toluene on signaled lever press shock avoidance behavior in rats were tested during and after exposure. The results obtained were as follows: Rats exposed to 125, 250 and 500 ppm toluene showed a decline in conditioned avoidance responses at 20 min exposure as compared to the pre-exposure baseline, although they recovered to almost the same level of performance as that before exposure. Exposure to 1,000 ppm toluene produced an exposure duration related to the increase in the number of total lever presses and the decrease in the effective response rate. The number of total lever presses increased drastically after 2,000 ppm toluene exposure. Effective avoidance response rate decreased to about 70% compared to the pre-test performance. Beginning at 4,000 ppm toluene exposure, the response rate increased, thereafter it gradually decreased and finally slight ataxia was observed. After 4,000 ppm exposure, all of the rats showed signs of excitation such as marked increase in the response rate. Acceleration of the reaction time was remarkably observed after 1,000 and 2,000 ppm exposure. As a whole, in the case of toluene exposure, concentration-related increases in lever presses and decreases in the effective avoidance response rate beginning at 1,000 ppm were observed. Animals showed excitatory response at 1,000 and 2,000 ppm toluene exposure and at other levels such as 4,000 ppm they showed depressive behavior. The effects were closely dependent on toluene concentration and exposure duration.