REDUCTION OF ANDROGENS BY MEANS OF (17ALPHA-T)ESTRADIOL

When 17[alpha]-T oestradiol and [delta]4-androsten-3, 17-dione were incubated with liver slices of male or female rats, 10-30% of the added tritium activity was recovered in reduction products of the androstendione. In liver slices from males, the products were [I7[alpha]-T] testosterone, and trans-androstandiols with tritium in positions 4 or 5. In females, however, cis-androstandiols were formed with tritium in positions 3 or 17. The sites of incorporation of tritium were dtermined by degradation. The incorporation of tritium into reduction products, expressed as percentage of activity administered as [17[alpha]-T] estradiol, increased with a decreasing concentration of estradiol; it can still be detected after incubation with 0.3[mu] mol estradiol/l in the presence of 0.7[mu] mol androstendione/l. Since similar hydrogen-transferring processes can also be demonstrated in tissue slices of female sex organs, this reaction may be concerned in the antagonism of estradiol activity by androgens. This reaction cannot be demonstrated in male sex organs, e. g., testes, prostate and seminal vesicles. The oxidation of [17[alpha]-T] estradiol gives rise to NAD(P)T, which is oxidized to give tritium water (HTO). All the organs investigated formed relatively little HTO compared to that formed by liver tissue. Other tritium-labelled substances, e.g., [2-T] lactate and [1-T] glu-cose give rise to NAD(P)T and considerable amounts of HTO, but practically none of the tritium is incorporated into the reduction products of androstendione. Thus the positive results with [17[alpha]-T] oestra-diol indicate that there is a strict compartmentation of the cytoplasmic NAD(P) in the cell.