Identification of a new Sertoli cell metabolite of testosterone: 5 alpha-androstane-3 alpha,16 alpha,17 beta-triol, by HPLC and GC-MS.

Testosterone metabolism by isolated rat Sertoli cells cultured in vitro was investigated using HPLC and GC-MS techniques. Monolayer cultures of Sertoli cells (greater than 90% pure and free of Leydig cells) were incubated for 3-day periods with a stable labeled [2,2,4,6,6-d5]testosterone prepared and used in a 1:1 proportion with unlabeled testosterone as the substrate (5 X 10(-7)M). After incubation, the metabolites were extracted from the media and reacted with oestradiol-antibodies. The antibody-bound components were separated on reverse phase HPLC and the fraction corresponding to oestradiol was analyzed by GC-MS in the form of TMS-ether. One of the metabolites whose mass spectrum contained d0 + d5 species was detected and interpreted to be a triol with a mol. wt of 308. Mass spectra data indicated that this testosterone metabolite is one of the sixteen possible isomers of 3,16,17-trihydroxy androstane. This substance was identified based on the Vm value (27.81) closely resembling that of 5 alpha-androstane-3 alpha,16 alpha,17 beta-triol TMS-ether (Vm reported = 27.78) [1] and when compared directly with synthesized compounds [2-3]. Recently we have demonstrated that similar Sertoli cell preparations contain two 16 alpha-hydroxylases by their ability to convert oestradiol to oestriol [4] and 5 alpha-androstane-3 alpha,17 beta-diol to 5 alpha-androstane-3 alpha,16 alpha,17 beta-triol [3], where the former conversion is not affected by FSH, the latter is significantly stimulated by the presence of FSH. Presence of this new product represents the first example of testosterone conversion to 5 alpha-androstane-3 alpha,16 alpha,17 beta-triol and confirms our previous observation that 16 alpha-hydroxylation of 5 alpha-reduced androgens can occur in the rat testis.

[3H]Oestradiol metabolism by 18-day rat interstitial cells in culture and the effect of FSH: presence of 16 alpha-hydroxylase.

The metabolism of [3H]oestradiol by interstitial cells in culture prepared from 18-day old rat testes was investigated. Interstitial cells were able to convert [3H]oestradiol to [3H]oestriol as confirmed by recrystallization of oestriol to constant specific activity from samples containing cells and not from controls. This demonstrated for the first time the presence of 16 alpha-hydroxylase in rat testicular interstitial cells. The effect of in vitro FSH treatment on the cells in culture was also investigated. FSH failed to affect 16 alpha-hydroxylase activity since we could not demonstrate a significant difference between treated and untreated preparations. The 16 alpha-hydroxylation of phenolic steroids is widely regarded as the major pathway of oestrogen metabolism in mammals. This metabolic step significantly reduces the biological activity of oestradiol. The presence of 16 alpha-hydroxylase in interstitial cells suggests that it may play a role in inactivating the oestradiol that is produced in the Leydig cells and thus prevent its intracellular accumulation. Such activity may conceivably play a role in the overall local "fine tuning" of androgen biosynthesis.

Synthesis of 5 alpha-androstane-3 alpha, 16 alpha, 17 beta-triol from 3 beta-hydroxy-5-androsten-17-one.

5 alpha-Androstane-3 alpha, 16 alpha, 17 beta-triol was synthesized from 3 beta-hydroxy-5-androsten-17-one. The procedure involved catalytic hydrogenation of 3 beta-hydroxy-5-androsten-17-one to 3 beta-hydroxy-5 alpha-androstan-17-one. This was followed by conversion of the 3 beta-hydroxy group to 3 alpha-benzoyloxy group by the Mitsunobu reaction. Further treatment with isopropenyl acetate yielded 5 alpha-androsten-16-ene-3 alpha, 17-diol 3-benzoate 17-acetate. This was then converted to 3 alpha, 17-dihydroxy-5 alpha-androstan-16-one 3-benzoate 17-acetate via the unstable epoxide intermediate after treatment with m-cloroperoxybenzoic acid. LiA1H4 reduction of this compound formed 5 alpha-androstane-3 alpha, 16 alpha, 17 beta-triol. 1H and 13C NMR of various steroids are presented to confirm the structure of this compound.

Metabolism of (3H) 5 alpha-androstane-3 alpha, 17 beta-diol by cultures of isolated rat sertoli cells and the effect of LH and FSH.

Sertoli cells from immature rats metabolized (3H) 5 alpha-androstane-3 alpha, 17 beta-diol to (3H) 5 alpha-androstane-3 alpha, 16 alpha, 17 beta-triol and (3H) 3 alpha-hydroxy-5 alpha-androstan-17-one. This is the first report of 16 alpha-hydroxylation of 5 alpha-reduced androgens in the testis. FSH significantly stimulated 16 alpha-hydroxylation while LH significantly decreased this activity. 3 alpha-Hydroxy-5 alpha-androstan-17-one was the major metabolite formed and its production was significantly increased in the presence of both LH and FSH, although FSH stimulation was significantly more than LH. The possible role of 16 alpha-hydroxylase in androgen metabolism by immature rat Sertoli cells is discussed.

Metabolism of the carcinogen 1,2-dimethylhydrazine by isolated human colon microsomes and human colon tumor cells in culture.

Human colon microsomes catalyze the metabolism of the model colon carcinogen 1,2-dimethylhydrazine. Activity appears to be distributed in a gradient towards the lower end of the colon. Highest activities were observed for microsomes prepared from the descending segment of the colon with the transverse segment exhibiting lower activities, while the ascending segment showed the lowest rate of metabolism. Dimethylhydrazine metabolism in each segment is inhibited significantly by inhibitors of the cytochrome P-450-dependent mixed function oxidase system. Microsomes prepared from a human colon tumor cell also catalyze the metabolism of 1,2-dimethylhydrazine. Metabolic activity in the cell line can be induced two-fold by treatment of cells with phenobarbital and three-fold by treatment of the cells with phenobarbital plus hydrocortisone. These results show that human colon activates 1,2-dimethylhydrazine and suggest that the human colon may be capable of activating other carcinogens in situ.