Undernutrition during either the pre- or immediate post-weaning period does not affect longevity in Quackenbush mice.

Diet restriction of rodents during a lengthy period of adult life, can lead to a marked increase in their life-span. However, undernutrition during gestation and/or the suckling period is, paradoxically, known to cause long-lasting 'deleterious' deficits in body and brain structure. It remains uncertain whether or not such undernourished rodents also have an altered life-span. We have now investigated whether a short period of undernutrition of mice either before or immediately after the weaning period could modulate their life-span. Female out-bred Quackenbush mice were undernourished for 40 days by standardised procedures either from conception until weaning or from weaning (day 19) till 60-days-of-age and compared to control mice that had been well-nourished throughout their lives. During the course of their life-span, some mice in each group became seriously ill and, because of ethical considerations, were required to be killed before their 'natural' death. The median age of mice at which they were required to be euthanized due to illness was significantly younger in the well-fed control group compared to the two previously undernourished groups. Of those mice that died of natural causes, it was found that about 90% died between about 300-700 (average, 552-570; median, 556-595) days-of-age irrespective of group. Any differences between groups were not statistically significant. There were no significant differences between groups in the numbers of mice that survived beyond the 90th percentile of maximum life-span. Our results provided no evidence that a short period of undernutrition of Quackenbush mice either before or immediately after weaning has significant effects on their life-span. However, there was some evidence that, if it occurred, serious illness happened at a younger age in the well-nourished mice than those in the two diet-restricted groups.