There have been some observations that low
body weight and a low level of some
hormones (e.g. IGF-1) during the first half of life are predictors of longer life in mice. However, contradictions in the available data on the
biomarkers of aging and predictors of longevity have shown that the research in these fields has become a controversial pursuit. In our study we addressed the following questions: (i) Can particular physiological parameters (
body weight, food intake, estrus function, body temperature, incidence of
chromosome aberrations in bone marrow cells) measured at the age of 3 and 12 months be a predictor of longevity and the rate of
tumor development in five strains of mice? (ii) Can a heavy
body weight at the age of 3 and 12 months be a predictor of longevity and high
tumor risk in five strains of mice? Mice of five strains-CBA, SHR, SAMR,
SAMP and transgenic HER-2/neu (FVB/N)-were under observation from the age of 2-3 months until natural death.
Body weight and temperature, food consumption, and estrous cycle were longitudinally studied in all animals.
Tumors discovered at autopsy were studied morphologically. We calculated the life span's parameters (mean, maximum, mortality rate, mortality rate doubling time) as well as their correlation with other parameters studied. The longest living CBA mice have the lowest
body weight at the ages of 3 and 12 months, the lowest food consumption, body temperature, incidence of
chromosome aberrations and spontaneous
tumor incidence. In comparison with all other mouse strains they also have the latest disturbances in estrus function and highest
body weight gain. The shortest living transgenic HER-2/neu mice have the lowest weight at the ages of 12 months, the lowest
body weight gain, maximal body temperature, the most rapid disturbances in estrus function and the highest incidence of
chromosome aberrations and
tumor incidence in comparison to all other mouse strains. Our findings have shown that heavier
body weight at the age of 12 months is a predictor of longevity in female CBA and
SAMP mice but not in SHR, SAMR and HER-2/neu mice. Excessive
body weight at the ages of 3 or 12 months is not a predictor of increased
tumor risk in the strains studied. In general, the existence and direction of a significant correlation between
body weight and life span depends upon the animals' age and genotype.