Effects of d-lysergic acid diethylamide on operant behavior in the rat

Summary

Twelve albino rats were used to determine the effects of LSD-25 on operant behavior. Half of the subjects were trained to press a bar for food on an aperiodic schedule and half were trained with a Sidman-type avoidance procedure to press a bar to avoid shock. A latin square design was employed in which each subject served as his own control and was injected intraperitoneally with a control saline solution, 0.05, 0.10, 0.20, 0.40, and 0.80 mg/kg. The following results were obtained:

• 1. In the food-reward situation injection with 0.05 mg/kg increased the number of bar presses emitted; doses of 0.20, 0.40, and 0.80 mg/kg decreased the number of responses.

• 2. In the shock-avoidance situation there was a decrease in the number of shocks received during the first 30 min. when the subjects were treated with 0.05 mg/kg but injections of 0.40 and 0.80 mg/kg resulted in more shocks during this time period. No significant differences in number of bar presses were found for any of the dosages.

• 3. The effects of the drug were found to persist for approximately 1 hr. and 30 min. following injection.

The present results support an interpretation of central-stimulating and central-depressing effects of LSD-25 depending on the dose level.