Aversive effects and retention impairment induced by acetoxycycloheximide in an instrumental task

AXM, when subcutaneously injected during the first 3 min following the acquisition of a nondiscriminative instrumental learning task, induced an aversion for the food reinforcement which had been associated with the training situation and with the pharmacological treatment. The high number of nonreinforced responses preceding the first reinforced response(RR) that animals performed when tested 6 days after AXM treatment, was not due to forgetting of the lever significance, but to this aversion. Animals treated with AXM showed low levels of lever pressing response and long latencies for their first RR; this deficit did not seem only to be due to food reinforcement aversion; it disappeared, as well as food aversion, when food reinforcement which had been associated with the learning situation and to treatment, was added to the daily feeding regimen during treatment-test interval. It has been shown, moreover, that more than 90 percent of cerebral protein synthesis was inhibited during the 5 hr following subcutaneous AXM injection. These findings are interpreted as an indication that AXM does not affect memory consolidation of a non discriminative instrumental learning.