Effect of age on the radiation-induced repopulation in mouse lip mucosa.

The acute macroscopic radiation reactions in mouse lip mucosa were used as a biological model to evaluate the influence of aging on the radiosensitivity and more specifically on the repopulation capacity after irradiation of rapidly proliferating epithelial tissues. No difference in the mucosa response after single dose irradiations was observed for animals ranging between one and twelve months of age. There was a trend for decreased radiosensitivity of the lip mucosa comparing 18 months old (early-senescence) with young adult mice. The repopulation experiments involved two equal sized radiation doses delivered with an interval of ten days. Again, in all age-groups, not only was the 50% incidence-dose for mucosa desquamation similar, but also the full biphasic course of radiation reactions. These data therefore demonstrate that the capacity of the lip mucosa basal cells to restore the radiation damage was not modified by the phenomenon of aging.