Expression of the Type 1 and Type 2 Steroid 5α-Reductases in Human Fetal Tissues

Abstract Androgens play a key role in human fetal development. Therefore, it is important to understand the distibution of the isozymes of 5α-reductase, the enzyme that converts testosterone to the more potent androgen, dihydrotestosterone. The expression of the two isozymes of 5α-reductase was studied in human fetal skin and fetal prostate by measuring the in vitro enzyme activity in crude preparations. Low levels of the type 1 5α-reductase were found in fetal scalp and back skin. Studies with fetal prostate samples confirmed that the type 2 enzyme is expressed in levels similar to those found in adult tissues. These results provide the first evidence that both isozymes of 5α-reductase are expressed during human fetal development.