EFFECTS OF S-TRIAZINE HERBICIDES ON HORMONE-RECEPTOR COMPLEX-FORMATION, 5-ALPHA-REDUCTASE AND 3-ALPHA-HYDROXYSTEROID DEHYDROGENASE-ACTIVITY AT THE ANTERIOR-PITUITARY LEVEL

Experiments were performed to study the effects of s-triazine herbicides, atrazine* and prometryne, on 5α-dihydrotestosterone (5α-DHT) receptor complex formation and on the activity of the 5α-reductase and 3α-hydroxysteroid dehydrogenase system in the anterior pituitary of male rats. By sucrose density gradient separation, it was found that in the presence of 0.4 mmol of atrazine or prometryne, 5α-DHT binding to receptor proteins in pituitary tissue was decreased by 27% and 17%, respectively. In in vitro experiments, the addition of atrazine or prometryne decreases the conversion of testosterone to 5α-DHT and the conversion of 5α-DHT to 5α-androstan-3α,17β-diol (3α-diol) in the anterior pituitary. The concentration in the range of 0.6 to 12 mmol of both herbicides, inhibited the 5α-reductase and 3α-hydroxysteroid dehydrogenase activity from 7-92%. in vivo subcutaneous (s.c.) administration of atrazine and prometryne reduced the 5α-reductase activity in the anterior pituitary. A single dose (0.1 mg/100 g b.w.) of atrazine decreases the amount of the 5α-reduced metabolite by 34%, while the same dose injected twice or a double dose (0.2 mg/100 g b.w.) inhibited by 46%. A single dose of prometryne (0.1 mg/100 g b.w.) does not affect the enzymic activity, while two injections of a single dose or a single injection of a double dose (0.2 mg/100 g b.w.) decreased the 5α-reductase activity by 17%. © 1979.