Effects of toluene, halothane and ethanol vapor on fixed-ratio performance in mice

The behavioral effects of inhalation of the vapors of volatile compounds representative of different chemical groups were studied in mice under conditions where behavior and exposure concentrations could be concurrently monitored. The magnitude and time course of the effects of toluene, halothane and ethanol inhalation on fixed-ratio (FR) responding were compared. The subjects were trained to lever-press under a FR-100 schedule of water reinforcement. Daily operant sessions took place in the exposure chambers, and solvent exposures were conducted once a week. The test exposures lasted for 20 min, and the sessions continued until the subjects resumed baseline rates of responding to give a measure of recovery. All solvents produced concentration-dependent response rate decreases, and only halothane showed any evidence of response rate increases at low concentrations. Halothane quickly produced maximal response rate-decreasing effects and recovery was rapid, while the effects of toluene became progressively greater during the exposure and recovery was prolonged. Ethanol displayed the most rapid onset and recovery of effects. Thus, these solvents produced somewhat similar effects on FR responding but displayed potency and time course differences.