[Effect of sex-hormone on composition of rat skin surface lipid]

The optimum analytical conditions for studying the composition of skin surface lipid were examined by high-performance liquid chromatography equipped with a photo-diode array detector. Optimum conditions were as follows: ULTRON N-C18 (150 x 4.6 mm) as stationary phase, acetonitrile/tetrahydrofuran/water (55/35/10, V/V) as eluent at the flow rate of 1.0 ml/min, and column temperature of 40 degrees C. The peaks were detected by monitoring the absorbance at 210 nm. Effect of sex-hormone on composition of skin surface lipids was examined. Gonadectomized Sprague-Dawley rats were injected with either testosterone (50 mg/kg, s.c.) or estradiol (5 mg/kg, s.c.) for 12 days. Amount of crude lipid from the skin surface was decreased at 8 days after castration; estradiol dosing to castrated rats also decreased the amount. The other hand, in ovariectomized rats, testosterone injection increased skin surface lipids. It is recognized that sex-hormone dosing after gonadectomy changes the percentage composition of squalene and cholesterol in male rats, but does not charge them in females.