Acute effects of polychlorinated biphenyl-containing and -free transformerfluids on rat testicular steroidogenesis

Polychlorinated biphenyl (PCB)-based transformer fluids belong to a class o f environmentally persistent mixtures with known toxic effects. Here, we st udied the acute effects of Askarel (which contains Aroclor 1260) and two su bstitute transformer fluids (the silicone oil-based DC561 and the mineral o il-based ENOL C) on rat testicular steroidogenesis. Single intraperitoneal (ip; 10 mg/kg body weight) or bilateral intratesticular (itt; 25 mug/testis ) injections of Askarel markedly decreased serum androgen levels 24 hr afte r administration. In acute testicular cultures from these animals, chorioni c gonadotropin-stimulated progesterone and androgen productions were severe ly attenuated. When itt was injected or added in vitro, Askarel inhibited 3 beta -hydroxysteroid dehydrogenase (3 beta HSD), stimulated 17 alpha -hydr oxylase/lyase (P450c17), and did not affect 17 beta -hydroxysteroid dehydro genase in testicular postmitochondrial fractions. The ip-injected Askarel d id not affect 3 beta HSD, but inhibited P450c17, suggesting that a more int ensive metabolism of peripherally injected Askarel reduces the circulating levels of active ingredients below the threshold needed for inhibition of 3 beta HSD and generates a derivative that inhibits P450c17. In contrast to Askarel, itt-injection (25 mug/testis) of DC561 and ENOL C did not affect i n vivo and in vitro steroidogenesis. These findings show the acute effects of Askarel, but not silicone and mineral oils, on testicular steroidogenesi s.