Early postnatal protein malnutrition impairs recognition memory in rats (Rattus norvegicus)

ABSTRACT

The initial period of postnatal life is critical for brain development in both rodents and humans. Protein malnutrition imposed during this period produces irreversible consequences that include structural, neurochemical, and functional changes in the central nervous system, leading to long-term alterations in behavioral and cognitive parameters, such as memory. In this work, previously malnourished rats were evaluated in recognition memory procedures. Male Wistar rats (n = 132) were given isocaloric diets that contained 6% (malnourished) or 16% (control) protein until 49 days of life. A nutritional recovery period with standard lab chow was imposed from 50 to 70 days of age when the experiments began. Four different procedures of recognition memory were conducted. The analysis showed that malnourished rats had lower body weight compared with control rats from the first week of life until the end of the experiments (p < .05). In the memory procedures, malnourished rats had lower recognition indices compared with controls (p < .05). Well-nourished rats had a tendency to direct their exploration toward novelty, whereas malnourished rats explored the objects in the same proportion, demonstrating that they did not recognize the novelty. Protein malnutrition imposed early in life is suggested to affect hippocampal formation, the development of which is concentrated during this developmental period, and thus impair memory consolidation...