Age-related decrease in ultraviolet induced DNA repair in neurons but not in lymph node cells of inbred mice.

DNA repair capacity was measured, as UV induced, unscheduled DNA synthesis (UDS), in cells of the nervous and immune system of three mouse strains, as a function of age. The strains examined were DBA/1J, C57B1/6J and SJL/J. For dorsal root ganglion neurons of strain DBA/1J, aged 97-98 weeks, a significant decline in UDS of 53% at 20 J/m2 and 73% at 40 J/m2, respectively, was measured, when compared to mice aged 17-18 weeks. Similarly, neurons from C57B1/6J mice, aged 115-116 weeks, showed significant, age dependent decreases of 31% at 20 J/m2 and 40% at 40 J/m2, respectively, compared to mice aged 7-8 weeks. In lymph node cells of all three strains employed, no significant age related decreases in UDS were detected. While the complexity of processes involved in DNA repair makes conclusive interpretation of the results precarious, the results obtained for post-mitotic cells of the nervous system, may be viewed as compatible with the DNA repair hypothesis of ageing.