Effect of postweaning nutritional and environmental restrictions on discrimination learning in albino rats

Charles Foster littermate albino rats (72) were randomized into 9 independent groups in a 3 x 3 factorial design by varying nutrition and environment each at three levels: normal nutrition, 25% nutritional restriction and 50% nutritional restriction; normal environment, 3-week environmental restriction and 6-week environmental restriction. The nutritional and environmental restrictions were imposed from the 30th day of life for 6 weeks. The animals were subsequently tested for black/white original learning followed by reversal discrimination learning in a T-maze. The results indicated significant main effects for nutrition and environment on indices of learning ability. However, the nutrition x environment interaction was not significant. Post hoc analysis revealed that moderate and severe nutritional restriction as well as long-term environmental restriction caused significant discrimination learning deficits. Short-term environmental restriction failed to produce significant effect on learning behaviour. The results are discussed in context of environmental stress effects, altered brain mechanisms and psychological changes such as increased drive level and emotionality of the animal.