Cutaneous morphometric parameters of young FVB/N mice sustained in aged mice and in calorically restricted transgenic alphaMUPA mice.

Caloric restriction (CR) extends the lifespan of diverse animal species and is currently the only therapeutic intervention known to attenuate aging and increase longevity in laboratory animals. The effect of CR on intrinsic skin aging is not well understood. To study this issue, we took advantage of transgenic alphaMUPA mice that spontaneously eat less (20-30%) when fed ad libitum and live longer compared to their wild type (WT) FVB/N control mice. Herein we determined morphometric skin parameters in young (6-7 months) and aged (17-18 months) alphaMUPA and WT mice. In addition, we transplanted skin grafts excised from the aged or young alphaMUPA and WT mice into both types of young mice, to test whether the systemic environments of alphaMUPA and WT mice could affect the grafts differently. The results have shown that the mean epidermal thickness, number of hair follicles and number of dermal blood vessels were similar in all four groups regardless of age or mouse type. In addition, the post-graft specimens of all four groups exhibited increase in all parameters measured, in particular a remarkable 6-7 fold increase in epidermal thickness. However, no significant differences were detected in the post-graft samples between the four experimental groups. Our findings indicate that, at least in FVB/N mice, parameters measured in normal or grafted skin depend primarily on the intrinsic cutaneous capacity rather than on circulating factors as determined by age or reduced calories.