STEROLS OF SKIN IN THE NORMAL AND TRIPARANOL-TREATED RAT

Skin of normal rats and of rats treated with triparanol were incubated with acetate-2-H3 for 2 hr, and the sterols were extracted and separated chromatographically. Treatment with triparanol resulted in grossly visible changes (scaliness, roughness, and atrophy of the skin) and in a marked alteration in the metabolism of skin sterols. There were considerable reductions in the concentrations of compounds with saturated side chains: cholesterol, methostenol, and dihydrolanosterol; and increases in the concentrations of sterols with unsaturated side chains: desmosterol, lanosterol, and sterols tentatively identified as dehydromethostenol and Δ7,24-cholestadienol. Isotope data showed that after incubation for 2 hr, a large proportion of the counts were in squalene in skin from both normal and triparanol-treated rats. There was a reduction in the incorporation of radioactivity into the Δ5-stenol fraction and an increase in the incorporation into lanosterol and Δ7-sterols, in skin from triparanol-treated rats. Triparanol inhibits the enzyme responsible for reduction of the 24,25-double bond in the sterols of rat skin.