Neonatal exposure to Aroclor 1254: Effects on adult hepatic testosterone hydroxylase activities

1. The effects of neonatal exposure to Aroclor 1254 (100 μmol/kg) on the metabolism of testosterone by adult male and female rats were determined by comparing their hepatic microsomal testosterone hydroxylase activities at 60, 90 and 120 days after the initial exposure.

2. The most pronounced effects in male rats were observed 90 days after treatment with Aroclor 1254, whereas in female rats the major changes in testosterone hydroxylase activities were observed after 60 days.

3. Ninety-day-old male rats neonatally treated with Aroclor 1254 exhibited decreased basal testosterone 7α-hydroxylase and increased basal testosterone 16α-, 2α- and 15β-hydroxylase activities and androstenedione formation. In addition, the Aroclor 1254-mediated induction of testosterone 7α- and 6α-hydroxylase activities and androstenedione formation was decreased, and that of testosterone 2β- and 15β-hydroxylase activities was increased.

4. Sixty-day-old female rats exposed neonatally to Aroclor 1254 exhibited increased basal testosterone 16α-, 2β-, 6α- and 15β-hydroxylase activities and androstenedione formation, and increased Aroclor 1254-induced metabolism of testosterone at all positions except 16α and 2α.

5. Changes in testosterone hydroxylase activities indicative of permanent damage (or imprinting) in androgen metabolism, i.e. altered activities in 120-day-old animals, were observed only in male rats. These activities included basal testosterone 6β-, 16α- and 2α-hydroxylase activities and androstenedione formation.