Effects of scopolamine and D-amphetamine on one-way, shuttle and inhibitory avoidance: a diallel analysis in mice

The effects of scopolamine (2.0 mg/kg) and d-amphetamine (3.0 mg/kg) on one-way, shuttle and inhibitory avoidance performance were evaluated in 3 strains of mice (A/J, DBA/2J and C57BL/6J) and their 6 reciprocal F1 hybrids. In the saline condition, intermediate inheritance was observed in the inhibitory task, complete dominance for superior avoidance in the one-way task, and hybrid superiority in the shuttle situation. Administration of d-amphetamine disrupted inhibitory performance in all strains. In the shuttle task no amphetamine effect was observed in C57BL/6J mice, while improvement was seen in A/J and DBA/2J mice, as well as in all the hybrid corsses. No drug effect was seen in the one-way task. As with d-amphetamine, scopolamine disrupged performance in the inhibitory task among the inbreds, but had negligible effects in the hybrids. In the shuttle task, only the A/J mice exhibited improved performance, while a small decline in response rate was seen in one-way avoidance. Results were interpreted in terms of tha role of scopolamine and d-amphetamine in modifying non-associative factors involved in avoidance, and the interaction between associative and non-associative factors in modulating avoidance response rate.