Distribution of rat hepatic steroid 5 alpha-reductase 1 as shown by immunohistochemistry.

Peptide fragments of rat liver 5 alpha-reductase were synthesized according to the published primary sequence data. The peptide were used (i) in free form and (ii) linked to keyhole limpet hemocyanin (KLH), respectively, for immunization of rabbits. Resulting antisera showed positive reaction with the respective peptide-antigen in an ELISA. In Western blot experiments the antisera specifically recognized a 26,000 mol wt protein in extracts from female and male rat liver. All antisera, as well as isolated immunoglobulins, showed inhibition of 5 alpha-reductase activity in microsomes prepared from rat liver. Positive immunohistochemical reactions were observed in the perinuclear cytoplasm of hepatocytes. No reaction was seen in Kupffer- and connective tissue cells. Acinar heterogeneity of the immunoreaction was seen in the male rat liver with a gradient from the portal canal to the central vein. After androgen-deprivation a considerable increase in immunoreactivity was seen in male rat liver cells, indicating androgen-dependent suppression of the enzyme in male liver.