Learning deficits on avoidance task and hippocampal lesions in area CA3 following intraperitoneal administration of...

Young adult mice of the ddN-F26 strain were given a single intraperitoneal injection of 3-acetylpyridine (3-AP) at a dosage of 200 mg/kg body weight. Two weeks after this treatment, learning on avoidance task was tested with a training apparatus called a jump-box. Each mouse was subjected to 30 trials of training per week for 3 or 4 weeks. Contrasted to untreated mice, the mean performance of the 3-AP-treated mice on avoidance training was significantly reduced in every weekly training session. However, since the learning scores of individual 3-AP-treated mice were highly varied, these mice were divided into several groups according to the characteristics of their learning patterns in order to analyze the relationships between learning ability and brain damage. It was found that there was a close association between the rate of learning deficits and the degree of destruction of the pyramidal cells in area CA3 of the hippocampus in mice treated with 3-AP. The present data suggest that the area CA3 neurons play an important role on the acquisition of avoidance task and memory formation.