Acute inhalation exposure to cyclohexane and schedule-controlled operant performance in rats:comparison to d-amphetamine and chlorpromazine

摘要

Adult male rats pressed a lever on a multiple fixed ratio-fixed interval (FR2O-F1120 sec) schedule of food presentation, and after attainine a stable baseline subjects received an acute inhalation exposure to cyclo-hexane vapor (0 ppm, 500 ppm, 2000 ppm, or 7000 ppm) for 6 hr. During the operant session that began 30 mm after termination of exposure. FR running rate for the 7000 ppm group decreased 11 0 o relative to perform-ance on the previous day. FR post-reinforcement pause duration and the rate and pattern of El performance were unaffected. Cyclohexane expo-sures of 500 or 2000 ppm had no detectable effects. No enduring effects of cyclohexane occurred up to 2 weeks after exposure. An independent set of rats, trained under nominally identical conditions, received various doses (i.p.) of d-amphetamine (AMPH) or chlorpromazine (CPZ) at 1-2 week intervals. Effective doses of AMPH decreased ER running rate, decreased FR post-reinforcement pause duration and increased El rate of response. AMPH also decreased the FT index of curvature, indicatine a change from an accelerating rate during the Fl to a more constant rate. Effective doses of CPZ decreased FR rate, increased FR pause duration,decreased FI rate,and decreased FI index of curvature.Thus,schedulecontrolled operant procedures that were sensitive to the effects of psychoactive drugs were able to identify only a minor and transient effect of the highest concentration (7000ppm) of cyclohexane vapor on operant performance.