Perinatal Undernutrition Modifies the Immobility Behavior Induced by Forced Swim: Neuroendocrine Correlates

Abstract

The present work sought to study the onset and expression of behavioral immobility in the forced swim test in adult rats, undernourished at perinatal age. Rats were undernourished with a hypoproteic diet containing 8% casein from Day 14 of gestation until 50 days of age. Rats were thereafter fed a balanced chow until 140 days of age, when the experiments started. The time course of changes in serum corticosterone concentration in individual rats after their behavioral performance in a 15-min forced swim test and a 5-min retest 24h later, each were evaluated. During the test, control rats displayed a progressive increase in the immobility time during the three periods assessed and during the retest these animals remained 81–83% of the time in immobility. Conversely, undernourished rats showed a significantly shorter immobility time than control rats, both in test and retest. The serum basal corticosterone levels and the patterns of the time course of serum corticosterone concentration changes were similar between control and undernourished rats after the test. On the other hand, the increase in serum corticosterone concentration post-retest was significantly reduced as compared to control rats. No differences were found in the corticosterone secretion profile when animals were submitted to a shorter duration—5-min forced swim period—during 2 consecutive days. A possible functional relationship between the behavioral performance of perinatally undernourished animals and an impaired control of the pituitary—adrenocortical axis activity is discussed.