Dorsal Skin Responses to Subchronic Ultraviolet B Irradiation in Wistar-Derived Hypotrichotic WBN/ILA-Ht Rats

The study investigated the effects of subchronic UVB irradiation on the dorsal skin of Wistar-derived hypotrichotic WBN/ILA-Ht rats over 3 months. It found that UVB exposure led to significant epidermal changes, including hyperplasia, parakeratosis, and thickening, with epidermal ingrowths into the dermis. There was an increase in proliferating cell nuclear antigen (PCNA)-positive cells, indicating heightened cell proliferation. The upper dermis showed edema, capillary congestion, mast cell infiltration, and fibroblast proliferation, with these effects peaking at 3 months. Collagen fiber degeneration was noted, and although not statistically significant, there was a tendency for increased serum IgE levels after 2 months. The study provided insights into the skin's response to prolonged UVB exposure in this rat model.