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1.
  • 1.1. Metabolism of 4-14C-testosterone was investigated in human, rat and rabbit fetal lung subcellular fractions and also in rabbit neonatal lungs. Androst-4-ene-3,17-dione, 17β-hydroxy-5α-androstan-3-one and both 5α- and 5β-androstane-3α,17β-diols were identified as metabolites of testosterone.
  • 2.2. The microsomal fraction produced mainly 5α-reduced epimers while the cytosol incubations resulted in 5β-reduced metabolites.
  • 3.3. No conjugation was found.
  • 4.4. The amounts of polar metabolites in the microsomal incubations and the amounts of dihydroxy-lated metabolites in the soluble fraction incubations were statistically significantly greater in the neonatal rabbit lung incubations compared with those of fetal lungs.
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2.
Following the incubation of human sperm and seminal plasma with 13C2-labelled testosterone, the main metabolite, identified by gas chromatography-mass spectrometry (GC-MS), was 4-androstene-3,17-dione. In addition, 6 alpha- and 6 beta-hydroxytestosterone were identified. The more common metabolites of testosterone were not detected, and it is possible that the high substrate-tissue ratio influenced the result. Incubation of individual sperm and seminal plasma specimens with [14C]testosterone resulted in the identification, by specific activity measurements, of 4-androstene-3,17-dione in almost every specimen but with a widely varying conversion rate. Dihydrotestosterone, which on general grounds was considered a likely metabolite, could not be positively confirmed as such, although in some samples its presence was suspected. Gas chromatography-mass spectrometry was also used to identify steroids in sperm and seminal plasma extracts. Some, but not all the steroids identified as present in such extracts by other investigators, were found. During the course of this work C18 Sep-Pak cartridges were successfully used to prepare fractions suitable for SP-Sephadex and TEAP-Lipidex chromatography and subsequent analysis by GC-MS. Their use eliminated the need for purification steps otherwise necessary.  相似文献   

3.
Two human placentas in mid-pregnancy were perfused in situ with a combination of 3H-labelled retrotestosterone and 14C-labelled testosterone.14C-labelled oestrone, 17β-oestradiol, androstenedione and testosterone and 3H-labelled retrostestosterone and retroandrostenedione were isolated in a radio-chemically homogeneous form from the placentas and perfusates.Neither the oestrone and 17β-oestradiol isolated from the placentas and perfusates, nor the urinary oestrone, 17β-oestradiol and oestriol fractions contained any 3H-labelled material.Almost 70% of the 3H-labelled material recovered from the placentas and perfusates was isolated as retrotestosterone and retroandrostenedione. Only 14% of the 14C-labelled material recovered from the same sources was present as testosterone and androstenedione. Furthermore, whereas only 3·5% of the 14C-labelled material recovered from the placentas and perfusates was testosterone, more than 32% of the 3H-labelled material was isolated as retrotesterone.It is concluded that steroids with a 9β,10α configuration cannot be aromatised and that the placental metabolism of retrotestosterone is much more limited than that of testosterone.  相似文献   

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In view of the uterine action of androgens we have investigated in vitro the metabolism of [4-14C]-testosterone in uterine tissue of ovariectomized rats. After purification of the extracts on Amberlite XAD-2 the metabolites have been isolated by gel. Five metabolites were isolated and identified during these incubation studies: 4-androstene 3,17-dione, 17beta-hydroxy-5alpha-androstan-3-one, 5 alpha-androstane-3alpha17beta-diol, 4-androstene-3 beta, 17beta-diol and 4-androstene-3alpha, 17beta-diol. Furthermore, two polar C19O3-metabolites and one isopolar to 5 alpha-androstane-3, 17-dione have also been detected. The metabolites were characterized by radioactive gas chromatogrphy, and determination of the relative specific activity in the eluates of Sephadex column chromatography. The identification of allylic alcohols was complemented by their oxidation to 4-androstene-3,17-dione. The present data show that activity of 17beta,3alpha- and 3beta-hydroxysteroid-oxidoreductase and 5alpha-ring-reductase are involved in the metabolism of testosterone in vitro in the rat uterus. The very low 5 alpha-reductase activity under the experimental conditions used in this work explains the formation of allylalcohols as the principal metabolites of testosterone in the rat uterus.  相似文献   

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The metabolism of testosterone (T) was examined during the second half of pregnancy in the rat to determine whether utilization of T for estradiol (E2) synthesis occurs via conversion of T to androstenedione (A). On Days 11, 16, and 21 of gestation (term = Day 23), rats (n = 7-9/group) were anesthetized and a constant infusion of [3H]T was initiated. At 60 min, blood was obtained from a jugular vein and the ovaries (Days 11, 16, and 21), and placentae and uterine tissue (Day 16 only) were removed. In a second study performed in rats on Day 16 of gestation (n = 8-10/group), the ovaries and/or gravid uterus were removed 15 min after initiation of [3H]T infusion, and blood was taken from a jugular vein 60 min later. Radiolabeled T and A were purified from serum and tissues by paper chromatography. In a third group of rats (n = 6), jugular vein samples were obtained sequentially on Days 11, 16 and 21 of gestation and serum concentrations of T were measured by radioimmunoassay. The metabolic clearance rate of T was constant during the study period (overall mean = 31 1/day). In contrast, the serum concentration of T (pg/ml) on Day 16 of gestation (863 +/- 108) exceeded (p less than 0.02) that on Day 11 (445 +/- 74); the latter was similar to that measured on Day 21 (592 +/- 109). Thus, the estimated production rate of T was greatest on Day 16 of gestation.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
Metabolism of testosterone in the hypothalamus of the male adult rat was studied in vitro. The whole homogenate of the hypothalamus in the presence of NADPH2 generating system converted testosterone mainly to dihydrotestosterone and 5α-androstan-3α-17β-diol. The reduction of testosterone to dihydrotestosterone was irreversible, while that of dihydrotestosterone to 5α-androstan-3α-17β-diol was reversible. Michaelis constant for the 5α-reductase in the hypothalamus was 7.4 × 10−7 M.The administration of testosterone propionate caused no significant change of the 5α-reductase activity in the hypothalamus, in contrast to the marked induction of 5α-reductase activity in the prostate. Furthermore, the 5α-reductase appeared to be widely distributed in the subcellular paniculate components in the hypothalamus, being located mainly in the nuclear fraction in the prostate.These results suggest that there is some difference in the characteristics of the metabolism of testosterone in the hypothalamus and in the prostate.  相似文献   

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Summary It is shown that at relatively high concentrations testosterone will depress the rate of mitosis in phytohaemagglutinin-stimulated human lymphocytes culturedin vitro. Therapeutic doses seem unlikely to cause this effect.I wish to thank the Smith Kline and French Foundation for financial support.  相似文献   

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Seminiferous tubules isolated from immature and adult rats were incubated with [14C] testosterone. Androstanediol and androstenedione were the major metabolites; dihydrotestosterone and androsterone were produced in lesser amounts. Cell suspensions of spermatocytes prepared from tubules of immature rats formed dihydrotestosterone as the major metabolite of testosterone. Smaller amounts of androstanediol were formed and no androsterone was detectable. The results show that spermatocytes in common with androgen responsive tissues have the capacity to metabolize testosterone to 5α-reduced products.  相似文献   

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Steroid metabolism in hepatoma tissue culture (HTC) cells derived from a male rat was investigated. Steroids in ethanol were incubated with the cells for various lengths of time. Volume of ethanol never exceeded 1% of incubation volume. Thin-layer and paper chromatography were used. Incubation was with tritiated steroids. It was demonstrated that testosterone as well as dihydrotestosterone is transformed. The main enzyme activities detected were 5alpha-reduction and 3alpha-, 3beta, and 17beta-hydroxysteroid dehydrogenation. The pattern of metabolism was reproducible and varied with time, substrate concentration, and number of cells incubated. Some steroids interfered with androgen metabolism. 17beta-estradiol, 17-epitestosterone, and progesterone competed for the 17beta-hydroxyprogesterone dehydrogenase. it is concluded that 3beta and 17beta reduction in the HTC cells may be catalyzed by the same enzyme which might differ considerably from the 3beta-hydroxysteroid dehydrogenase assayed in intact liver cells. A hepatoma derived from a female rat also produced considerable amounts of 3beta-derivatives of testosterone.  相似文献   

18.
Short-term organ cultures of peripheral lung from lung cancer patients metabolise benzo[alpha]pyrene to ethylacetate-soluble metabolites, which covalently bind to tissue macromolecules. The nature and quantities of metabolites formed and the extent of covalent binding are dependent upon the time of incubation, the substrate concentration and interindividual variability in the metabolic activity of the lung. Individuals whose lungs rapidly metabolise the carcinogen exhibit more extensive further metabolism of primary metabolites and higher levels of covalent binding. Certain striking differences in the relative retention in the tissue or release into the extra-cellular medium of different metabolites have been found as illustrated by the observation that the ratio of 7,8-dihydro-7,8-dihydroxybenzo[alpha]-pyrene to 9,10-dihydro-9,10-dihydroxybenzo[alpha]pyrene was always significantly higher in the tissue than in the extracellular medium.  相似文献   

19.
Metabolism of 14C-arachidonate was investigated in rat isolated lungs perfused via the pulmonary circulation with Krebs solution. Only 10% of the radioactivity derived from an infusion of 14C-arachidonate through the pulmonary circulation of rat isolated lungs appeared in the effluent by 10 minutes. At 10 min, the major component of effluent radioactivity and 20–40% of that retained in lung was unchanged arachidonate. Between 10 and 20 min of perfusion, a further small amount of radioactivity was lost in lung effluent and at 20 min the retained radioactivity showed a decrease in the proportion present as free arachidonate. Between 20 and 60 min, there was no further loss of radioactivity in effluent and no further change in the distribution in lung. Addition of albumin to the Krebs solution perfusate during the infusion of 14C-arachidonate increased effluent radioactivity to 80%, but albumin added after 10 min only caused the efflux of a small amount of radioactivity (10%). Treatment of labelled lung at 20 min with the calcium ionophore A23187 released biologically active metabolites of arachidonate but very little radioactivity. Metabolism of arachidonate, either during the infusion or after retention in lung, in rat lung was closer to that in human lung than to that in guinea-pig lung.  相似文献   

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