Anisomycin and amnesia in the chick: state-dependent effects are not present with intracranial injections.

It has recently been suggested that intraperitoneal (IP) injection of anisomycin (ANI) in the chick produces amnesia for a one-trial passive avoidance task in a state-dependent manner. We have examined the behavioral and biochemical effects of IP and intracranial (IC) injections of ANI in chicks trained on a one-trial passive avoidance task. IC injection of ANI produced 35% brain protein synthesis inhibition whereas IP injection produced only negligible amounts of protein synthesis inhibition in the brain. IC injection of ANI produced amnesia and was not state-dependent. Patterns of behavior consistent with state-dependent effects were produced by IP injection of ANI. These experiments indicate that there are differences in the pattern of results produced by IP and IC injection of ANI and support the hypothesis that the expression of long-term memory in chicks is associated with protein synthesis.