Effects of early postnatal malnutrition and chlordiazepoxide on experimental aversive situations

In order to study the lasting consequences of brain changes caused by early malnutrition, rats were fed a protein-deficient diet from birth until 49 days of age and a balanced diet from day 50 to day 70. At 49 and 70 days of age, independent groups of animals were tested in the locomotor activity, step-down inhibitory avoidance, and flinch-jump nociceptive tests. Also, at 49 days of age, malnourished and control rats were sacrificed in order to evaluate the weight of brain regions. Malnourished rats had lower body and brain weights (telencephalon and brain stem) than control rats. Malnourished rats also showed less locomotor activity at the beginning of the test session, lower flinch and jump thresholds, and longer step-down latencies than control animals. Chlordiazepoxide (5 mg/kg, IP) shortened step-down latency of well-nourished rats, but was ineffective in malnourished rats. These and previously reported results indicate that early protein malnutrition causes long-lasting impairment of neuronal systems underlying emotional behavior.