The effect of the mitochondria-targeted, plastoquinone-containing antioxidant SkQ1 on the lifespan of outbred mice and of three strains of inbred mice was studied. To this end, low pathogen (LP) or specific pathogen free (SPF) vivaria in St. Petersburg, Moscow, and Stockholm were used. For comparison, we also studied mole-voles and dwarf hamsters, two wild species of small rodents kept under simulated natural conditions. It was found that substitution of a LP vivarium for a conventional (non-LP) one doubled the lifespan of female outbred mice, just as SkQ1 did in a non-LP vivarium. SkQ1 prevented age-dependent disappearance of estrous cycles of outbred mice in both LP and non-LP vivaria. In the SPF vivarium in Moscow, male BALB/c mice had shorter lifespan than females, and SkQ1 increased their lifespan to the values of the females. In the females, SkQ1 retarded development of such trait of aging as heart mass increase. Male C57Bl/6 mice housed individually in the SPF vivarium in Stockholm lived as long as females. SkQ1 increased the male lifespan, the longevity of the females being unchanged. SkQ1 did not change food intake by these mice. Dwarf hamsters and mole-voles kept in outdoor cages or under simulated natural conditions lived longer if treated with SkQ1. The effect of SkQ1 on longevity of females is assumed to mainly be due to retardation of the age-linked decline of the immune system. For males under LP or SPF conditions, SkQ1 increased the lifespan, affecting also some other system(s) responsible for aging.

Eusocial subterranean rodents of the Bathyergidae family have enormous longevity. The long lifespan of these species is associated with negligible senescence, that is, an absence of the signs of age-related deterioration in physical condition. The question arises as to whether these features are unique to eusocial Bathyergids or typical of other social subterranean rodents as well. In the present study, we analysed data from observations of a social subterranean Microtinae rodent, the northern mole vole (Ellobius talpinus Pall.), which, like mole-rats, has reproductive skew. Among the individuals captured in the wild and maintained in captivity, females that reproduced lived significantly longer than non-breeding females. We did not find any changes in muscle strength with age in any of the demographic groups studied. Faecal glucocorticoid concentrations before death were significantly higher in non-breeding females than in breeding females and males. Increased adrenocortical activity may be one mechanism responsible for the decreased lifespan of non-reproducing individuals of social subterranean rodents. We conclude that the patterns of aging, although different in some respects, are generally common for social subterranean rodents of different taxonomic groups.

No abstract

Social subterranean rodents of the Bathyergidae family are known to have extended longevity and some signs of negligible senescence, although the manifestation of these traits depends on the reproductive status of individuals. Such enormous life history peculiarities are usually explained by the specificity of a subterranean way of life. If so, all subterranean rodents, regardless of their taxonomic position, are expected to have higher maximum lifespans and shorter senescence periods than the related above-ground species. In this study we compared the mortality rates and age-related reproductive activity and physical conditions in two sympatric rodents of the Cricetidae family: subterranean mole voles and above-ground dwarf hamsters. Mole voles have a maximum lifespan that is as high as two times the maximum lifespan of the dwarf hamsters; however, only a few mole voles outlasted the maximum lifespan of dwarf hamsters. Dwarf hamsters were generally more fecund than mole voles, which manifests both in a higher number of litters and larger litter sizes. Neither species demonstrated a significant age-related decline in litter size or muscle strength, although there were negative trends for dwarf hamsters. We conclude that some evidence of extended longevity and slow ageing do occur in mole voles, but due to the relatively short "subterranean" phylogenetic history of the species, this evidence is not as pronounced as in the social species of Bathyergidae family.

In animal populations inhabiting ecologically suboptimal environmental conditions, phenotypical shifts in physiological traits responsible for coping with environmental challenges can be expected. If such variations are of heritable origin, then they will manifest themselves even in individuals bred in captivity. In laboratory-born red-backed voles (Myodes rutilus (Pallas, 1779)) originating from a population with constantly low density, maximum cold-induced metabolic rates were higher than in voles from a high-density population, similar to the data obtained on wild-caught individuals from the same populations. However, unlike wild-caught voles, in laboratory-born individuals maintained under comfortable conditions, we revealed no interpopulation differences either in basal plasma corticosterone level or in corticosterone response to acute cooling. These data confirm the suggestion about the heritable origin of increased maximum cold-induced metabolic rate in a red-backed vole population with relatively low density.