Ultraviolet radiation-induced histopathologic changes in the skin of the marsupial Monodelphis domestica. II. Quantitative studies of the photoreactivation of induced hyperplasia and sunburn cell formation.

Induction of sunburn cells (SBCs) and hyperplasia of the epidermis of the marsupial Monodelphis domestica by ultraviolet radiation (UVR) has been studied. A dose of 500 J/m2 (approximately 1 minimal erythemal dose) from an FS-40 sunlamp induced measurable numbers of SBCs with a peak number at 32-48 h post-UVR exposure of skin to photoreactivating light suppressed the induction of SBCs by approximately 75%. Pre-UVR exposure to photoreactivating light had no effect on the induction of SBCs. Induction of hyperplasia also was suppressed to a similar extent by post-UVR photoreactivation treatment. These studies identify pyrimidine dimers in DNA as the major photoproduct involved in the induction of SBCs and hyperplasia in M. domestica by UVR.