3β-Hydroxysteroid dehydrogenase activity was studied histochemically in human, monkey, and rat adrenal glands and in human placentae. Tissue sections were incubated separately with each of the following substrates: (1) 3β-hydroxypregn-5-en-20-one (pregnenolone); (2) sodium 3β-sulphoxypregn-5-en-20-one (pregnenolonesulphate); (3) 3β-acetoxypregn-5-en-20 one (pregnenoloneacetate); (4) 3β,16α-dihydroxypregn-5-en-20-one (16α-hydroxypregnenolone); (5) 3β,17α-dihydroxypregn-5-en-20-one (17α-hydroxypregnenolone); (6) ammonium 3β-sulphoxy-17α-hydroxypregn-5-en-20-one (17α-hydroxypregnenolone ammonium sulphate); (7) 3β-hydroxyandrost-5-en-17-one (DHA); (8) 3β-sulphoxyandrost-5-en-17-one (DHA sulphate); (9) 3β-acetoxyandrost-5-en-17-one (DHA acetate); (10) androst-5-ene-3β, 17β-diol (androstenediol).
The histochemical results obtained with pregnenolone and DHA as substrates resemble those described by other workers. Using pregnenolone sulphate and 17α-hydroxypregnenolone sulphate, a strong histochemical reaction with diformazan deposition was found in the zona fasciculata of the adrenals of all species and in the placental syntrophoblast. With DHA sulphate an extremely weak histochemical reaction was obtained with the adrenal zona fasciculata, monoformazan only being deposited. The syntrophoblast, however, showed intense 3β-hydroxysteroid dehydrogenase activity when incubated with DHA sulphate. These results accord with recent findings regarding the secretion and metabolism of 3β-sulphoxysteroids.
A strong histochemical reaction was also obtained in both adrenal and placental tissues using 17α-hydroxypregnenolone, 16α-hydroxypregnenolone, androstenediol, pregnenolone acetate, and DHA acetate. These steroids have not previously been described as substrates for the histochemical demonstration of 3β-hydroxysteroid dehydrogenase in the adrenal or placenta.