ANTICONVULSANT AND ANTIPUNISHMENT EFFECTS OF TOLUENE

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Abstract
Toluene can have striking acute behavioral effects and is subject to abuse by inhalation. To determine if its actions resemble those of drugs used in the treatment of anxiety (anxiolytics), 2 sets of experiments were undertaken. Inasmuch as prevention of pentylenetetrazol-induced convulsions is an identifying property of this class of agents, it was first demonstrated that pretreatment with toluene injections delayed the onset of convulsive signs and prevented the tonic extension phase of the convulsant activity in a dose-related manner. Injections of another alkyl benzene, m-xylene, were of comparable potency to toluene. Toluene inhalation delayed the time to death after pentylenetetrazol injection in a manner related to the duration and concentration of exposure; at lower convulsant doses, inhalation of moderate concentrations (EC50 [median effective concentration] 1311 ppm) prevented death. Treatment with a benzodiazepine receptor antagonist (Ro 151788) failed to reduce the anticonvulsant activity of inhaled toluene. Anxiolytics also attenuate the reduction in response rate produced by punishment with electric shock. Toluene increased rates of responding suppressed by punishment when responding was maintained under a multiple fixed-interval fixed-interval punishment schedule of reinforcement. Distinct antipunishment effects were observed after 2 h of exposure to 1780 and 3000 ppm of toluene; the rate-increasing effects of toluene were related to concentration and time after the termination of exposure. Thus, toluene and m-xylene resemble in several respects clinically useful drugs such as the benzodiazepines.