Maternal protein restriction during the lactation period disrupts the ontogenetic development of behavioral traits in male Wistar rat offspring.

Neonatal undernutrition in rats results in short- and long-term behavioral and hormonal alterations in the offspring. It is not clear, however, whether these effects are present since the original insult or if they develop at some specific age later in life. Here, we assessed the ontogenetic profile of behavioral parameters associated with anxiety, exploration and memory/learning of Wistar rat offspring that were subjected to protein malnutrition during lactation. Dams and respective litters were separated into two groups: (1) protein-restricted (PR), which received a hypoproteic chow (8% protein) from birth to weaning [postnatal day (PN) 21]; (2) control (C), which received normoproteic chow. Offspring's behaviors, corticosterone, catecholamines, T3 and T4 levels were assessed at PN21 (weaning), PN45 (adolescence), PN90 (young adulthood) or PN180 (adulthood). PR offspring showed an age-independent reduction in the levels of anxiety-like behaviors in the Elevated Plus Maze and better memory performance in the Radial Arm Water Maze. PR offspring showed peak exploratory activity in the Open Field earlier in life, at PN45, than C, which showed theirs at PN90. Corticosterone was reduced in PR offspring, particularly at young adulthood, while catecholamines were increased at weaning and adulthood. The current study shows that considerable age-dependent variations in the expression of the observed behaviors and hormonal levels exist from weaning to adulthood in rats, and that protein restriction during lactation has complex variable-dependent effects on the ontogenesis of the assessed parameters.