Stress Reduction Potential in Mice Ingesting DNA from Salmon Milt

SIMPLE SUMMARY: This study was conducted to elucidate the functionality of food-derived nucleotide supplementation. DNA sodium salt derived from salmon milt (DNA-Na) was found to exhibit stress-relieving effects in a screening experiment using a stress load based on the territoriality of male mice. On the other hand, RNA from yeast showed no significant effect. The stress-relieving effect of DNA-Na was then examined in another experimental system, whereby mice were subjected to chronic crowding stress as they aged. We found that DNA-Na suppresses the inflammatory response in the hippocampus of aged mice. This suggests that the intake of dietary DNA suppresses stress-induced inflammation in the brain, which increases with aging. ABSTRACT: The functionality of food-derived nucleotides is revealed when nucleotide components are ingested in emergency situations, such as during stress loading, though it is difficult to elucidate the physiological function of dietary nucleotide supplementation. Using a stress load experimental system utilizing territoriality among male mice, we evaluated whether DNA sodium salt derived from salmon milt (DNA-Na) has stress-relieving effects. It was found that stress was reduced in mice fed a diet containing a 1% concentration of DNA-Na, but this was insignificant for yeast-derived RNA. Next, we attempted to elucidate the anti-stress effects of DNA-Na using another experimental system, in which mice were subjected to chronic crowding stress associated with aging: six mice in a cage were kept until they were 7 months of age, resulting in overcrowding. We compared these older mice with 2-month-old mice that were kept in groups for only one month. The results show that the expression of genes associated with hippocampal inflammation was increased in the older mice, whereas the expression of these genes was suppressed in the DNA-Na-fed group. This suggests that dietary DNA intake may suppress inflammation in the brain caused by stress, which increases with age.