AGENTS THAT CAUSE ENLARGEMENT OF SEBACEOUS GLANDS IN HAIRLESS MICE .2. ULTRAVIOLET-RADIATION

We have developed a murine model to measure the effects on sebaceous glands of ultraviolet (UV) radiation. Hairless mice were irradiated with Westinghouse FS-40 tubes filtered to attenuate the radiation below 290 nm. Emission was mainly in the UVB range (peak, 313 nm). Single and multiple exposures were given with fractions or multiples of one minimal erythemal dose (MED). Biopsies, fixed for light microscopy, were stained with H & E. Under high power, sebocytes of 30 glands per specimen were counted and the means determined. A single exposure of 1 MED caused a significant increase in sebocyte count, as did thrice-weekly exposures to 0.5 MED for 3 weeks. One 3-MED exposure produced sebocyte necrosis, yet 30 exposures at 4 MED failed to ablate the glands. In both cases there was rebound enlargement which had not returned to control levels by the end of the studies (24-30 weeks). Prolonged irradiation produced maximum enlargement in a few weeks. Thus, in a manner similar to other skin components, the response of sebaceous glands to UV radiation is one of hyperplasia.