Regulation of epididymal glutathione S-transferases: effects of orchidectomy and androgen replacement.

Glutathione S-transferases, a family of enzymes that catalyze the conjugation of glutathione to a variety of substrates, are present in rat epididymis. In order to study the hormonal regulation of these enzymes in this tissue, adult rats were orchidectomized and implanted with empty or androgen-filled polydimethylsiloxane capsules. Orchidectomy alone significantly decreased caput-corpus epididymal glutathione S-transferase activity toward 2 substrates, 1-chloro-2,4-dinitrobenzene and trans-4-phenylbut-3-en-2-one, but had no effect on transferase activity toward the third substrate, 1,2-dichloro-4-nitrobenzene. In contrast to these results, orchidectomy did not alter glutathione S-transferase activity towards these substrates in the cauda epididymidis. Androgen replacement with testosterone prevented the orchidectomy-induced decrease in caput-corpus glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene and trans-4-phenylbut-3-en-2-one and had no effect on transferase activity toward 1,2-dichloro-4-nitrobenzene. The effects of 5 alpha-reduced metabolites of testosterone were also studied. Both dihydrotestosterone and 5 alpha-androstan-3 alpha, 17 beta-diol maintained caput-corpus glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene, although a lower dose of dihydrotestosterone was sufficient; these 1 androgens were unable to maintain activity toward trans-4-phenylbut-3-en-2-one and caused a suprastimulation of activity toward 1,2-dichloro-4-nitrobenzene above control values. The third 5 alpha-reduced androgen studied, 5 alpha-androstan-3 beta, 17 beta-diol had no effect on the transferase activity toward any of the 3 substrates. These results demonstrate that the epididymal glutathione S-transferases are under separate control and are differentially regulated by testosterone and its 5 alpha-reduced metabolites.