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Testosterone 5o:-Reductase in Rat Skin Homogenates: Measurement in the Skin at Various Anatomical Sites in Males and Females¹

Laboratory of Endocrinology and Metabolism, Laval University Hospital Center Quebec, Canada

Abstract

Experiments were designed to find suitable conditions to determine the 5-reductase activity in rat skin homogenates. The dihydrotestosterone formation was linear until 15 min. The 5-reductase was very heat labile at 37 C in absence of testosterone and NADPH since complete loss of activity occurred after one hour of preincubation. At 0 C, there was a 20 decrease after 5 hr. The enzyme activity was measured in the skin at various natomical sites. It was found to vary with each region in the following order in the male: tail > scrotum > ear > genital skin > dorsum thorax > sole of the foot. In a few tissues, the enzyme activity was higher than in the prostate. Corresponding female tissues exhibited lower reductase activity except the sole of the foot in which the contrary was found. This significant sex difference indicates that sex hormones may be involved in the control of the levels of that enzyme in rat skin. (Endocrinology 96: 235, 1975).

Footnotes

¹ This work was supported by Grant no. 4780 from the Medical Research Council of Canada.

Received January 24, 1974.