Learned and emotional behavior in chronically malnourished rats.

Weanling male and female Wistar rats, whose mothers received low protein diet (6.8%) during pregnancy and lactation, were fed on the same diet of their mothers and trained in an active avoidance situation at the ages of 60, 90 or 120 days. Control animals fed on a 20% protein diet of the same age groups were submitted to similar training. The consolidation and performance of the conditioned avoidance response and other behavioral reactions were studied. The malnourished animals showed delay of consolidation and lower frequency of conditioned avoidance responses, escape responses and holdings as well as higher frequency of anticipatory reactions, vocalization, riddance attempts and touching of surroundings. The results show that chronic malnutrition impairs the active avoidance response. They also show that chronic malnutrition affects the emotional behavior more markedly than early malnutrition. Chronic malnutrition also enhances the exploratory activity, in contrast to early malnutrition, and this is attributed to an alimentary drive-dependent mechanism.