Molecular and histological responses in rat skin exposed to m-xylene

Solvents, surfactants, cutting fluids, hydrocarbons, and oils cause skin irritation by incompletely understood mechanisms. This study examined histological and molecular changes in rodent skin caused by brief topical exposures to m-xylene. At 0, 1, 2, 4, and 6 h after 1-h exposure, skin samples were removed and analyzed for histopathological changes and interleukin-1 alpha (IL-1 alpha) and inducible nitric oxide synthase (iNOS) protein levels. Histopathological changes (epidermal-dermal separation and granulocyte infiltration) and increases in IL-1 alpha and iNOS protein expression occurred during our observation period. IL-1 alpha levels increased by 80% immediately after exposure and iNOS levels increased about 60% 4 hours after exposure. Our study demonstrates that dermal exposure to m-xylene promotes IL-1 alpha and iNOS production in skin and these proteins may serve as early indicators of skin irritation.