Undernutrition without malnutrition as a protective factor to prevent DNA damage in the elderly

Recognition memory and DNA damage in undernourished young rats

This study evaluated the recognition memory and the levels of DNA damage (blood and hippocampus) in undernourished young Wistar rats. The experiment was conducted along 14-week with rodents divided in control group (CG, n=8) and undernourished group (UG, n=12) which was submitted to caloric restriction. Nutritional status for undernutrition was defined by Body Mass Index (BMI) ≤0.45g/cm2 and by weighting the organs/tissue (liver, spleen, intestine, peritoneal fat, kidney and encephalon). The Novel Object Recognition Test assessed recognition memory and the Comet Assay evaluated the levels of DNA damage. Student t test, 2-way ANOVA and Pearson's correlation analysis were used and the significance level was of p<0.05. The UG showed lower BMI and organ/tissue weights than CG (p<0.001). In short-term memory, the recognition rate was higher in the UG (p<0.05), only after 4 weeks. In the long-term memory, again recognition rate was higher in the UG than the CG, after 4 weeks (p<0.001) and 14 weeks (p<0.01). The UG showed decreased levels of DNA damage in the blood (p<0.01) and increased levels in the hippocampus (p<0.01). We concluded in this study that the undernutrition by caloric restriction did not cause impairment in recognition memory, however induced DNA damage in the hippocampus.

Malnutrition and energy restriction differentially affect viral immunity

Protein-energy malnutrition is associated with a decrease in immunity and an increase in infectious disease. Both of these effects are exacerbated in aging. Conversely, energy restriction (ER) without malnutrition extends the lifespan in animals and retards the age-related decline in various parameters of immune function. Recent evidence suggests, however, that aged ER mice exhibit an increased mortality in response to primary influenza infection compared with age-matched controls. Underweight may contribute to this outcome due to an inability to meet the energy demands associated with the immune response to primary viral infection. The energetic costs of immune responsiveness must be considered in the undernourished aging population and emerging studies of ER in humans.