OBJECTIVE: The objective of the present study was to investigate the effects of early protein malnutrition on the social memory of adult rats (Rattus norvegicus) using an experimental procedure. METHODS: The animals received isocaloric diets containing 6% or 16% of protein during the lactation phase (0-21 days of age) and a commercial lab chow as from 22 days of age. The social memory test consisted of, after 2 daily habituation sessions (7minutes/session), to introduce an adult rat (100-114 days of age) and a young rat (30-44 days of age) into an acrylic cage (90cm.x.90cm.x.45cm), for two sessions separated by intervals of 30 (Experiment 1) or 15 (Experiment 2) minutes. Social contact was defined as exploration/sniffing the anogenital region of the rat. The difference in the time spent in social contact between the first and second sessions was defined as the memory index. RESULTS: No differences were observed in Experiment 1 due to the diet conditions. In Experiment 2, social contact decreased from the first to the second session in the controls (p<0.05) in contrast to the malnourished animals, who showed no differences. CONCLUSION: These results suggest that early protein malnutrition impairs the social memory in adult rats.
protein malnutrition; social behavior; rats
