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The enzymes, Δ45α-reductase, 3α- and 3β-hydroxysteroid oxidoreductases are present in the immature rat testis and account for its ability to produce saturated steroids from androstenedione and testosterone (Stylianou, Forchielli & Dorfman, 1961; Nayfeh, Barefoot & Baggett, 1966). Progesterone is converted to saturated C19-steroids by the immature rat testis in vitro (Steinberger & Ficher, 1969). It is assumed that androstenedione and testosterone are obligatory intermediates in their synthesis. Since it is known that 4,5-unsaturated C21-steroids are reduced in the rat testis (Bell, Vinson & Lacy, 1971) it was of interest to know whether saturated C21-steroids might also be precursors of saturated C19-steroids. To test this possibility [4-14C]5α-pregnane-3,20-dione was incubated in vitro with testicular tissue from sexually immature rats, and C19-steroids were sought among the products.
[4-14C]5α-Pregnane-3,20-dione was prepared by hydrogenation of 16 nmol (1 μCi)
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SUMMARY
A virilizing interstitial cell tumour and the attached testicular tissue from a 4-year-old boy were incubated in vitro with [7α-3H]pregnenolone and [4-14C]progesterone, or [4-14C]androstenedione and [7α-3H]5α-dihydrotestosterone. Ring A saturated steroids were produced from 4-ene precursors by the prepubertal testis, but this tissue was unable to convert pregnenolone or progesterone to 17α-hydroxylated C21 steroids, or to C19 steroids.
The virilizing interstitial cell tumour metabolized pregnenolone and progesterone to 17α-hydroxyprogesterone, androstenedione and testosterone. In addition, dehydroepiandrosterone was detected as a product of pregnenolone. The tumour lacked 4-ene-5α-steroid reductase activity.
5α-Dihydrotestosterone was metabolized to 5α-androstane-3,17-dione, androsterone, isoandrosterone, 5a-androstane-3α,17β-diol and 5α-androstane-3β,17β-diol in both the normal and tumour tissue.
The significance of these metabolic pathways is discussed.
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The syndrome of testicular feminization may occur in complete or incomplete forms, the latter being characterized by varying degrees of virilism. In the complete form, plasma concentrations of testosterone and 5α-dihydrotestosterone are usually in or above the normal male range although the metabolic clearance rates of the steroids are similar to those of the normal female and lower than those of the normal male (Tremblay, Kowarski, Park & Migeon, 1972).
The formation in vitro of androstenedione and testosterone by gonads from such subjects has been demonstrated (Griffiths, Grant & Whyte, 1963; Neher & Kahnt, 1966; Charreau & Villee, 1968), but although the formation of 5α-reduced steroids has been inferred (Tremblay et al. 1972), their biosynthesis has not previously been recorded. In view of the changes in steroid 4-ene-5α-reductase activity at puberty in animal testes (Steinberger & Ficher, 1969), the production and metabolism of C19-reduced steroids in gonads from
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SUMMARY
The metabolism of [7α-3H]dehydroepiandrosterone (DHA) and [4-14C] androstenedione in vitro was investigated in 30-day-old (prepubertal) and adult rat testicular tissue in the presence of cyanoketosteroid, a 5-ene-3β-hydroxysteroid oxidoreductase inhibitor.
Whereas both substrates were converted to 5α-reduced steroids by the prepubertal testis, 4-ene-steroid-5α-reductase activity was negligible in the adult gland. Cyanoketosteroid prevented the formation of 5α-reduced steroids from DHA by the prepubertal testis indicating testosterone and androstenedione as intermediates in their production.
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SUMMARY
The patterns of exogenous steroid metabolism by rat adrenocortical zona fasciculata and zona reticularis cells cultured together as a monolayer have been examined. In the continued presence of corticotrophin (ACTH), the cultured cells synthesized corticosterone, 18-hydroxydeoxycorticosterone and deoxycorticosterone from [3H]pregnenolone. In the prolonged absence of ACTH, however, [3H]pregnenolone was metabolized mainly to progesterone, 20α-dihydroprogesterone, 20α-hydroxy-5α-pregnan-3-one and 5α-pregnane-3β,20α-diol with small amounts of 5α-pregnane-3,20-dione, 11β-hydroxyprogesterone and 11β-hydroxy-20α-dihydroprogesterone, while virtually no corticosterone, 18-hydroxydeoxycorticosterone or deoxycorticosterone were produced. While 5-ene-3β-hydroxysteroid dehydrogenase-isomerase activity persisted at a substantial level in unstimulated cells and the 11β- and 18-hydroxylases were reduced but still present, 21-hydroxylase activity was almost completely lost when ACTH was omitted from the culture medium. These changes in enzyme activities were completely reversed by the addition of ACTH, cyclic AMP or dibutyryl cyclic AMP to unstimulated cultures for 4–5 days, during which time no proliferation of adrenal cells was observed.
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SUMMARY
Confluent monolayer cultures of cells from the zona fasciculata and zona reticularis of the normal adult rat adrenal cortex were maintained with or without corticotrophin (ACTH) for up to 4 months, without proliferation of adrenal cells. Proliferating fibroblast-like cells, however, eventually overgrew the adrenal monolayer in cultures both with and without ACTH. Adrenocortical cells in culture, maintained without ACTH, spread rapidly to form a confluent monolayer, whereas cell spreading was markedly inhibited in the presence of ACTH. Exposure of previously unstimulated cells to ACTH or cyclic AMP caused the adrenal cells to retract with loss of confluence, the process being reversed when ACTH or cyclic AMP was withdrawn. Ultrastructural features of cells cultured with ACTH were typical of normal adrenocortical cells; in cultures without ACTH they were similar to those of adrenocortical cells found in the hypophysectomized rat.
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SUMMARY
Quantitative aspects of corticosteroidogenesis were examined in monolayer cultures of cells from the zona fasciculata and zona reticularis of the adult rat adrenal cortex, maintained for up to 4 months. Corticosterone secretion continued at a steady rate in cultures maintained with corticotrophin (ACTH), the output of maximally stimulated cultures being approximately 12 μg/106 adrenocortical cells/day. In the absence of ACTH, a small amount of 20α-hydroxypregn-4-en-3-one, but no detectable corticosterone, was secreted, resulting in a fluorogenic steroid output 1/125 th of that of maximally stimulated cultures. Restimulation with ACTH of cultures maintained for up to 2 months in its absence resulted in maximum levels of corticosterone secretion after 4–5 days of continuous ACTH treatment. The levels of corticosterone secretion attained on restimulation were similar to those observed in cultures maintained with ACTH from the out set. Withdrawal of ACTH resulted in a fall in steroid output which took 10 days to reach final unstimulated levels. Trophic stimulation of corticosteroidogenesis with a similar time-course was obtained with both cyclic AMP and dibutyryl cyclic AMP, the latter being the more effective.
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SUMMARY
Incubation in vitro of homogenates of spontaneous adrenocortical tumours from gonadectomized female mice of the CE strain showed the presence of Δ5-3β-hydroxysteroid dehydrogenase systems, capable of metabolizing 3β-hydroxypregn-5-en-20-one, 3β, 17α-dihydroxypregn-5-en-20-one and 3β-hydroxyandrost-5-en-17-one. 17α-, 11β- and 21-hydroxylation of C21-Δ4-3-ketosteroids was also detected as were the enzyme systems required to form 3β-hydroxyandrost-5-ene-7,17-dione from 3β-hydroxyandrost-5-en-17-one.
After tissue culture of the tumour cells for 19 days, histochemical and incubation techniques demonstrated that the cells retained Δ5-3β-hydroxysteroid dehydrogenase, 17α-, 11β- and 21-hydroxylase activity. Autoradiography localized radioactivity in the original and newly formed cells of the tissue culture.
