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L Starka - One of the best experts on this subject based on the ideXlab platform.
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sex and age related changes in Epitestosterone in relation to pregnenolone sulfate and testosterone in normal subjects
The Journal of Clinical Endocrinology and Metabolism, 2002Co-Authors: Helena Havlikova, R Hampl, Martin Hill, L StarkaAbstract:Epitestosterone has been demonstrated to act at various levels as a weak antiandrogen. So far, its serum levels have been followed up only in males. Epitestosterone and its major circulating precursor pregnenolone sulfate and T were measured in serum from 211 healthy women and 386 men to find out whether serum concentrations of Epitestosterone are sufficient to exert its antiandrogenic actions. In women, Epitestosterone exhibited a maximum around 20 yr of age, followed by a continuous decline up to menopause and by a further increase in the postmenopause. In men, maximum Epitestosterone levels were detected at around 35 yr of age, followed by a continuous decrease. Pregnenolone sulfate levels in women reached their maximum at about age 32 yr and then declined continuously, and in males the maximum was reached about 5 yr earlier and then remained nearly constant. Epitestosterone correlated with pregnenolone sulfate only in males. In both sexes a sharp decrease of the Epitestosterone/T ratio around puberty ...
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allopregnanolone pregnenolone sulfate and Epitestosterone in breast cyst fluid
Steroids, 2001Co-Authors: Marie Bicikova, Martin Hill, Irene Szamel, Jaroslava Tallova, L StarkaAbstract:Abstract The risk of breast cancer is 2 to 5 times higher in patients suffering from gross cystic disease. Breast cysts are categorized into two groups (type I and type II) according to the concentration of electrolytes in the cyst fluid. The two types also differ with respect to accumulation of steroids and steroidogenic enzyme activity. In type I cysts a higher risk of breast carcinoma could be expected. Here, we studied a possible relationship between the type of cyst and levels of Epitestosterone (an endogenous antiandrogen), allopregnanolone (a product of 5α-reductase activity), and pregnenolone-sulfate (an activator of N -methyl- d -asparate receptors). We have found five times higher levels of Epitestosterone in BCF in comparison with the circulation. Allopregnanolone levels were similar to those in plasma of women in the luteal phase of the menstrual cycle. Pregnenolone-sulfate levels in BCF were about two orders of magnitude higher when compared with the circulation. No differences were found in concentrations of the steroids studied between the types of cysts.
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the effect of Epitestosterone on estrogen biosynthesis in vitro
Hormone and Metabolic Research, 2000Co-Authors: Marie Bicikova, J Klak, Martin Hill, L StarkaAbstract:OBJECTIVE: The concentrations of Epitestosterone in human serum correlates negatively with that of estradiol. The possible explanation of this relation was addressed, and the influence of Epitestosterone on kinetics of estradiol formation in vitro was evaluated. METHODS: The concentration of Epitestosterone was measured in serum of 54 men participating in a screening program for prostate disease. Epitestosterone inhibition of aromatase and 17beta-hydroxysteroid dehydrogenase activities was tested in vitro in the system consisting of human placental microsomes, NADPH or NAD and NADP respectively, and Epitestosterone in increasing concentrations. Testosterone, androstenedione, estrone and 17beta-estradiol were utilized as substrates. RESULTS: A significant negative correlation between Epitestosterone and estradiol levels in human male serum was found. No inhibition of aromatase activity was observed; however, inhibition of 17beta-hydroxysteroid dehydrogenase was found preferentially in the direction leading to oxidation of the C-17 hydroxy group. The inhibitory effect of Epitestosterone was more pronounced with androgens as substrates. CONCLUSION: Epitestosterone could influence the formation of estradiol in vitro rather by inhibition of 17beta-hydroxysteroid dehydrogenase than by blocking aromatase activity.
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analysis of relations between serum levels of Epitestosterone estradiol testosterone igf 1 and prostatic specific antigen in men with benign prostatic hyperplasia and carcinoma of the prostate
Physiological Research, 2000Co-Authors: Martin Hill, Radovan Bilek, L Safarik, L StarkaAbstract:: Epitestosterone competes with testosterone for androgen receptors and inhibits several enzymes of steroidogenesis. Insulin-like growth factors (IGFs) stimulate the growth of prostate cells and directly activate androgen receptors in prostatic tumor cell lines. The prostate-specific antigen (PSA) decreases the affinity of IGF-binding protein-3. The samples were collected from 71 patients suffering from various diseases of the prostate (56 patients without prostate cancer but with benign prostatic hyperplasia and 15 patients with prostate cancer). Correlations between age and IGF-1 (r = -0.281, p<0.05), age and serum Epitestosterone (r = -0.261, p<0.05), estradiol and testosterone (r = 0.367, p<0.01), and between estradiol and Epitestosterone (r = -0.414, p<0.001) were found. After age adjustment, IGF-I correlated with Epitestosterone (r = -0.277, p<0.05). The age correlated positively with PSA (r = 0.286, p<0.05) and negatively with IGF-1 (r = -0.377, p<0.01) in partial correlations. PSA levels were higher in patients with prostate cancer (p<0.00001). Epitestosterone, which is negatively correlating with estradiol and IGF-1, may modulate the development of prostate diseases.
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inhibition of rat renal and testicular 11 beta hydroxysteroid dehydrogenase by some antihypertensive drugs diuretics and Epitestosterone
Hormone and Metabolic Research, 1997Co-Authors: Marie Bicikova, R Hampl, Martin Hill, L StarkaAbstract:: With regard to previous finding of an inhibitory activity of furosemide on 11 beta-hydroxysteroid dehydrogenase, 16 other commonly used diuretics have been tested as to their ability to inhibit rat renal, and in four instances also testicular 11 beta-hydroxysteroid dehydrogenase, using glycerrhetinic acid as a standard. In addition, Epitestosterone has been tested as well, with respect to its recently demonstrated inhibitory activity on several other enzymes of androgen biosynthesis. Besides corticosterone, 11 beta-hydroxy-4-androstene-3,17-dione has been used as a substrate. Of all drugs studied, quinapril, dihydralazin, trandolapril, metipamid, methyldopa, betaxolol only appeared to be weak inhibitors of 11 beta-hydroxysteroid dehydrogenase, with an inhibitory activity 10-28% of that of glycyrrhetinic acid. Using corticosterone as a substrate, Epitestosterone displayed a weak inhibitory activity with Ki 850, 1200 nmol/l and Vmax 2420, 3900 nmol/l.min for renal and testicular enzyme, respectively. In contrast to kidneys, the testicular 11 beta-hydroxysteroid dehydrogenase accepted also 11 beta-hydroxy-4-androstene-3,17-dione as a substrate, which could be inhibited by Epitestosterone (Ki 1490 nmol/l, Vmax 1150 nmol/l.min). The results represent further evidence for different substrate specificity of renal and testicular 11 beta-hydroxysteroid dehydrogenase.
Martial Saugy - One of the best experts on this subject based on the ideXlab platform.
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Recent developments in the use of isotope ratio mass spectrometry in sports drug testing
Analytical and Bioanalytical Chemistry, 2011Co-Authors: Thomas Piper, Caroline Emery, Martial SaugyAbstract:According to the annual report of the World Anti-Doping Agency, steroids are the most frequently detected class of doping agents. Detecting the misuse of endogenously occurring steroids, i.e. steroids such as testosterone that are produced naturally by humans, is one of the most challenging issues in doping control analysis. The established thresholds for urinary concentrations or concentration ratios such as the testosterone/Epitestosterone quotient are sometimes inconclusive owing to the large biological variation in these parameters. For more than 15 years, doping control laboratories focused on the carbon isotope ratios of endogenous steroids to distinguish between naturally elevated steroid profile parameters and illicit administration of steroids. A variety of different methods has been developed throughout the last decade and the number of different steroids under investigation by isotope ratio mass spectrometry has recently grown considerably. Besides norandrosterone, boldenone was found to occur endogenously in rare cases and the misuse of corticosteroids or Epitestosterone can now be detected with the aid of carbon isotope ratios as well. In addition, steroids excreted as sulfoconjugates were investigated, and the first results regarding hydrogen isotope ratios recently became available. All of these will be presented in detail within this review together with some considerations on validation issues and on identification of parameters influencing steroidal isotope ratios in urine.
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short term stability of testosterone and Epitestosterone conjugates in urine samples quantification by liquid chromatography linear ion trap mass spectrometry
Journal of Chromatography B, 2006Co-Authors: C. Saudan, Norbert Baume, Patrice Mangin, Jose M Entenza, Martial SaugyAbstract:Abstract A simple method using liquid chromatography–linear ion trap mass spectrometry for simultaneous determination of testosterone glucuronide (TG), testosterone sulfate (TS), Epitestosterone glucuronide (EG) and Epitestosterone sulfate (ES) in urine samples was developed. For validation purposes, a urine containing no detectable amount of TG, TS and EG was selected and fortified with steroid conjugate standards. Quantification was performed using deuterated testosterone conjugates to correct for ion suppression/enhancement during ESI. Assay validation was performed in terms of lower limit of detection (1–3 ng/mL), recovery (89–101%), intraday precision (2.0–6.8%), interday precision (3.4–9.6%) and accuracy (101–103%). Application of the method to short-term stability testing of urine samples at temperature ranging from 4 to 37 °C during a time-storage of a week lead to the conclusion that addition of sodium azide (10 mg/mL) is required for preservation of the analytes.
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Short-term stability of testosterone and Epitestosterone conjugates in urine samples: Quantification by liquid chromatography–linear ion trap mass spectrometry
Journal of Chromatography B, 2006Co-Authors: C. Saudan, Norbert Baume, Patrice Mangin, Jose M Entenza, Martial SaugyAbstract:Abstract A simple method using liquid chromatography–linear ion trap mass spectrometry for simultaneous determination of testosterone glucuronide (TG), testosterone sulfate (TS), Epitestosterone glucuronide (EG) and Epitestosterone sulfate (ES) in urine samples was developed. For validation purposes, a urine containing no detectable amount of TG, TS and EG was selected and fortified with steroid conjugate standards. Quantification was performed using deuterated testosterone conjugates to correct for ion suppression/enhancement during ESI. Assay validation was performed in terms of lower limit of detection (1–3 ng/mL), recovery (89–101%), intraday precision (2.0–6.8%), interday precision (3.4–9.6%) and accuracy (101–103%). Application of the method to short-term stability testing of urine samples at temperature ranging from 4 to 37 °C during a time-storage of a week lead to the conclusion that addition of sodium azide (10 mg/mL) is required for preservation of the analytes.
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Testosterone and doping control
British Journal of Sports Medicine, 2006Co-Authors: C. Saudan, L. Avois, Norbert Baume, N Robinson, Patrice Mangin, Martial SaugyAbstract:BACKGROUND AND OBJECTIVES: Anabolic steroids are synthetic derivatives of testosterone, modified to enhance its anabolic actions (promotion of protein synthesis and muscle growth). They have numerous side effects, and are on the International Olympic Committee's list of banned substances. Gas chromatography-mass spectrometry allows identification and characterisation of steroids and their metabolites in the urine but may not distinguish between pharmaceutical and natural testosterone. Indirect methods to detect doping include determination of the testosterone/Epitestosterone glucuronide ratio with suitable cut-off values. Direct evidence may be obtained with a method based on the determination of the carbon isotope ratio of the urinary steroids. This paper aims to give an overview of the use of anabolic-androgenic steroids in sport and methods used in anti-doping laboratories for their detection in urine, with special emphasis on doping with testosterone. METHODS: Review of the recent literature of anabolic steroid testing, athletic use, and adverse effects of anabolic-androgenic steroids. RESULTS: Procedures used for detection of doping with endogenous steroids are outlined. The World Anti-Doping Agency provided a guide in August 2004 to ensure that laboratories can report, in a uniform way, the presence of abnormal profiles of urinary steroids resulting from the administration of testosterone or its precursors, androstenediol, androstenedione, dehydroepiandrosterone or a testosterone metabolite, dihydrotestosterone, or a masking agent, Epitestosterone. CONCLUSIONS: Technology developed for detection of testosterone in urine samples appears suitable when the substance has been administered intramuscularly. Oral administration leads to rapid pharmacokinetics, so urine samples need to be collected in the initial hours after intake. Thus there is a need to find specific biomarkers in urine or plasma to enable detection of long term oral administration of testosterone.
Martin Hill - One of the best experts on this subject based on the ideXlab platform.
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Analysis of relations between serum levels of Epitestosterone, estradiol, testosterone, IGF-1 and prostatic specific antigen in men with benign prostatic hyperplasia and carcinoma of the prostate.
Physiological Research, 2020Co-Authors: Martin Hill, Bílek R, Safarík L, Luboslav StárkaAbstract:: Epitestosterone competes with testosterone for androgen receptors and inhibits several enzymes of steroidogenesis. Insulin-like growth factors (IGFs) stimulate the growth of prostate cells and directly activate androgen receptors in prostatic tumor cell lines. The prostate-specific antigen (PSA) decreases the affinity of IGF-binding protein-3. The samples were collected from 71 patients suffering from various diseases of the prostate (56 patients without prostate cancer but with benign prostatic hyperplasia and 15 patients with prostate cancer). Correlations between age and IGF-1 (r = -0.281, p
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sex and age related changes in Epitestosterone in relation to pregnenolone sulfate and testosterone in normal subjects
The Journal of Clinical Endocrinology and Metabolism, 2002Co-Authors: Helena Havlikova, R Hampl, Martin Hill, L StarkaAbstract:Epitestosterone has been demonstrated to act at various levels as a weak antiandrogen. So far, its serum levels have been followed up only in males. Epitestosterone and its major circulating precursor pregnenolone sulfate and T were measured in serum from 211 healthy women and 386 men to find out whether serum concentrations of Epitestosterone are sufficient to exert its antiandrogenic actions. In women, Epitestosterone exhibited a maximum around 20 yr of age, followed by a continuous decline up to menopause and by a further increase in the postmenopause. In men, maximum Epitestosterone levels were detected at around 35 yr of age, followed by a continuous decrease. Pregnenolone sulfate levels in women reached their maximum at about age 32 yr and then declined continuously, and in males the maximum was reached about 5 yr earlier and then remained nearly constant. Epitestosterone correlated with pregnenolone sulfate only in males. In both sexes a sharp decrease of the Epitestosterone/T ratio around puberty ...
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allopregnanolone pregnenolone sulfate and Epitestosterone in breast cyst fluid
Steroids, 2001Co-Authors: Marie Bicikova, Martin Hill, Irene Szamel, Jaroslava Tallova, L StarkaAbstract:Abstract The risk of breast cancer is 2 to 5 times higher in patients suffering from gross cystic disease. Breast cysts are categorized into two groups (type I and type II) according to the concentration of electrolytes in the cyst fluid. The two types also differ with respect to accumulation of steroids and steroidogenic enzyme activity. In type I cysts a higher risk of breast carcinoma could be expected. Here, we studied a possible relationship between the type of cyst and levels of Epitestosterone (an endogenous antiandrogen), allopregnanolone (a product of 5α-reductase activity), and pregnenolone-sulfate (an activator of N -methyl- d -asparate receptors). We have found five times higher levels of Epitestosterone in BCF in comparison with the circulation. Allopregnanolone levels were similar to those in plasma of women in the luteal phase of the menstrual cycle. Pregnenolone-sulfate levels in BCF were about two orders of magnitude higher when compared with the circulation. No differences were found in concentrations of the steroids studied between the types of cysts.
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the effect of Epitestosterone on estrogen biosynthesis in vitro
Hormone and Metabolic Research, 2000Co-Authors: Marie Bicikova, J Klak, Martin Hill, L StarkaAbstract:OBJECTIVE: The concentrations of Epitestosterone in human serum correlates negatively with that of estradiol. The possible explanation of this relation was addressed, and the influence of Epitestosterone on kinetics of estradiol formation in vitro was evaluated. METHODS: The concentration of Epitestosterone was measured in serum of 54 men participating in a screening program for prostate disease. Epitestosterone inhibition of aromatase and 17beta-hydroxysteroid dehydrogenase activities was tested in vitro in the system consisting of human placental microsomes, NADPH or NAD and NADP respectively, and Epitestosterone in increasing concentrations. Testosterone, androstenedione, estrone and 17beta-estradiol were utilized as substrates. RESULTS: A significant negative correlation between Epitestosterone and estradiol levels in human male serum was found. No inhibition of aromatase activity was observed; however, inhibition of 17beta-hydroxysteroid dehydrogenase was found preferentially in the direction leading to oxidation of the C-17 hydroxy group. The inhibitory effect of Epitestosterone was more pronounced with androgens as substrates. CONCLUSION: Epitestosterone could influence the formation of estradiol in vitro rather by inhibition of 17beta-hydroxysteroid dehydrogenase than by blocking aromatase activity.
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analysis of relations between serum levels of Epitestosterone estradiol testosterone igf 1 and prostatic specific antigen in men with benign prostatic hyperplasia and carcinoma of the prostate
Physiological Research, 2000Co-Authors: Martin Hill, Radovan Bilek, L Safarik, L StarkaAbstract:: Epitestosterone competes with testosterone for androgen receptors and inhibits several enzymes of steroidogenesis. Insulin-like growth factors (IGFs) stimulate the growth of prostate cells and directly activate androgen receptors in prostatic tumor cell lines. The prostate-specific antigen (PSA) decreases the affinity of IGF-binding protein-3. The samples were collected from 71 patients suffering from various diseases of the prostate (56 patients without prostate cancer but with benign prostatic hyperplasia and 15 patients with prostate cancer). Correlations between age and IGF-1 (r = -0.281, p<0.05), age and serum Epitestosterone (r = -0.261, p<0.05), estradiol and testosterone (r = 0.367, p<0.01), and between estradiol and Epitestosterone (r = -0.414, p<0.001) were found. After age adjustment, IGF-I correlated with Epitestosterone (r = -0.277, p<0.05). The age correlated positively with PSA (r = 0.286, p<0.05) and negatively with IGF-1 (r = -0.377, p<0.01) in partial correlations. PSA levels were higher in patients with prostate cancer (p<0.00001). Epitestosterone, which is negatively correlating with estradiol and IGF-1, may modulate the development of prostate diseases.
C. Saudan - One of the best experts on this subject based on the ideXlab platform.
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short term stability of testosterone and Epitestosterone conjugates in urine samples quantification by liquid chromatography linear ion trap mass spectrometry
Journal of Chromatography B, 2006Co-Authors: C. Saudan, Norbert Baume, Patrice Mangin, Jose M Entenza, Martial SaugyAbstract:Abstract A simple method using liquid chromatography–linear ion trap mass spectrometry for simultaneous determination of testosterone glucuronide (TG), testosterone sulfate (TS), Epitestosterone glucuronide (EG) and Epitestosterone sulfate (ES) in urine samples was developed. For validation purposes, a urine containing no detectable amount of TG, TS and EG was selected and fortified with steroid conjugate standards. Quantification was performed using deuterated testosterone conjugates to correct for ion suppression/enhancement during ESI. Assay validation was performed in terms of lower limit of detection (1–3 ng/mL), recovery (89–101%), intraday precision (2.0–6.8%), interday precision (3.4–9.6%) and accuracy (101–103%). Application of the method to short-term stability testing of urine samples at temperature ranging from 4 to 37 °C during a time-storage of a week lead to the conclusion that addition of sodium azide (10 mg/mL) is required for preservation of the analytes.
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Short-term stability of testosterone and Epitestosterone conjugates in urine samples: Quantification by liquid chromatography–linear ion trap mass spectrometry
Journal of Chromatography B, 2006Co-Authors: C. Saudan, Norbert Baume, Patrice Mangin, Jose M Entenza, Martial SaugyAbstract:Abstract A simple method using liquid chromatography–linear ion trap mass spectrometry for simultaneous determination of testosterone glucuronide (TG), testosterone sulfate (TS), Epitestosterone glucuronide (EG) and Epitestosterone sulfate (ES) in urine samples was developed. For validation purposes, a urine containing no detectable amount of TG, TS and EG was selected and fortified with steroid conjugate standards. Quantification was performed using deuterated testosterone conjugates to correct for ion suppression/enhancement during ESI. Assay validation was performed in terms of lower limit of detection (1–3 ng/mL), recovery (89–101%), intraday precision (2.0–6.8%), interday precision (3.4–9.6%) and accuracy (101–103%). Application of the method to short-term stability testing of urine samples at temperature ranging from 4 to 37 °C during a time-storage of a week lead to the conclusion that addition of sodium azide (10 mg/mL) is required for preservation of the analytes.
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Testosterone and doping control
British Journal of Sports Medicine, 2006Co-Authors: C. Saudan, L. Avois, Norbert Baume, N Robinson, Patrice Mangin, Martial SaugyAbstract:BACKGROUND AND OBJECTIVES: Anabolic steroids are synthetic derivatives of testosterone, modified to enhance its anabolic actions (promotion of protein synthesis and muscle growth). They have numerous side effects, and are on the International Olympic Committee's list of banned substances. Gas chromatography-mass spectrometry allows identification and characterisation of steroids and their metabolites in the urine but may not distinguish between pharmaceutical and natural testosterone. Indirect methods to detect doping include determination of the testosterone/Epitestosterone glucuronide ratio with suitable cut-off values. Direct evidence may be obtained with a method based on the determination of the carbon isotope ratio of the urinary steroids. This paper aims to give an overview of the use of anabolic-androgenic steroids in sport and methods used in anti-doping laboratories for their detection in urine, with special emphasis on doping with testosterone. METHODS: Review of the recent literature of anabolic steroid testing, athletic use, and adverse effects of anabolic-androgenic steroids. RESULTS: Procedures used for detection of doping with endogenous steroids are outlined. The World Anti-Doping Agency provided a guide in August 2004 to ensure that laboratories can report, in a uniform way, the presence of abnormal profiles of urinary steroids resulting from the administration of testosterone or its precursors, androstenediol, androstenedione, dehydroepiandrosterone or a testosterone metabolite, dihydrotestosterone, or a masking agent, Epitestosterone. CONCLUSIONS: Technology developed for detection of testosterone in urine samples appears suitable when the substance has been administered intramuscularly. Oral administration leads to rapid pharmacokinetics, so urine samples need to be collected in the initial hours after intake. Thus there is a need to find specific biomarkers in urine or plasma to enable detection of long term oral administration of testosterone.
Marie Bicikova - One of the best experts on this subject based on the ideXlab platform.
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allopregnanolone pregnenolone sulfate and Epitestosterone in breast cyst fluid
Steroids, 2001Co-Authors: Marie Bicikova, Martin Hill, Irene Szamel, Jaroslava Tallova, L StarkaAbstract:Abstract The risk of breast cancer is 2 to 5 times higher in patients suffering from gross cystic disease. Breast cysts are categorized into two groups (type I and type II) according to the concentration of electrolytes in the cyst fluid. The two types also differ with respect to accumulation of steroids and steroidogenic enzyme activity. In type I cysts a higher risk of breast carcinoma could be expected. Here, we studied a possible relationship between the type of cyst and levels of Epitestosterone (an endogenous antiandrogen), allopregnanolone (a product of 5α-reductase activity), and pregnenolone-sulfate (an activator of N -methyl- d -asparate receptors). We have found five times higher levels of Epitestosterone in BCF in comparison with the circulation. Allopregnanolone levels were similar to those in plasma of women in the luteal phase of the menstrual cycle. Pregnenolone-sulfate levels in BCF were about two orders of magnitude higher when compared with the circulation. No differences were found in concentrations of the steroids studied between the types of cysts.
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the effect of Epitestosterone on estrogen biosynthesis in vitro
Hormone and Metabolic Research, 2000Co-Authors: Marie Bicikova, J Klak, Martin Hill, L StarkaAbstract:OBJECTIVE: The concentrations of Epitestosterone in human serum correlates negatively with that of estradiol. The possible explanation of this relation was addressed, and the influence of Epitestosterone on kinetics of estradiol formation in vitro was evaluated. METHODS: The concentration of Epitestosterone was measured in serum of 54 men participating in a screening program for prostate disease. Epitestosterone inhibition of aromatase and 17beta-hydroxysteroid dehydrogenase activities was tested in vitro in the system consisting of human placental microsomes, NADPH or NAD and NADP respectively, and Epitestosterone in increasing concentrations. Testosterone, androstenedione, estrone and 17beta-estradiol were utilized as substrates. RESULTS: A significant negative correlation between Epitestosterone and estradiol levels in human male serum was found. No inhibition of aromatase activity was observed; however, inhibition of 17beta-hydroxysteroid dehydrogenase was found preferentially in the direction leading to oxidation of the C-17 hydroxy group. The inhibitory effect of Epitestosterone was more pronounced with androgens as substrates. CONCLUSION: Epitestosterone could influence the formation of estradiol in vitro rather by inhibition of 17beta-hydroxysteroid dehydrogenase than by blocking aromatase activity.
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inhibition of rat renal and testicular 11 beta hydroxysteroid dehydrogenase by some antihypertensive drugs diuretics and Epitestosterone
Hormone and Metabolic Research, 1997Co-Authors: Marie Bicikova, R Hampl, Martin Hill, L StarkaAbstract:: With regard to previous finding of an inhibitory activity of furosemide on 11 beta-hydroxysteroid dehydrogenase, 16 other commonly used diuretics have been tested as to their ability to inhibit rat renal, and in four instances also testicular 11 beta-hydroxysteroid dehydrogenase, using glycerrhetinic acid as a standard. In addition, Epitestosterone has been tested as well, with respect to its recently demonstrated inhibitory activity on several other enzymes of androgen biosynthesis. Besides corticosterone, 11 beta-hydroxy-4-androstene-3,17-dione has been used as a substrate. Of all drugs studied, quinapril, dihydralazin, trandolapril, metipamid, methyldopa, betaxolol only appeared to be weak inhibitors of 11 beta-hydroxysteroid dehydrogenase, with an inhibitory activity 10-28% of that of glycyrrhetinic acid. Using corticosterone as a substrate, Epitestosterone displayed a weak inhibitory activity with Ki 850, 1200 nmol/l and Vmax 2420, 3900 nmol/l.min for renal and testicular enzyme, respectively. In contrast to kidneys, the testicular 11 beta-hydroxysteroid dehydrogenase accepted also 11 beta-hydroxy-4-androstene-3,17-dione as a substrate, which could be inhibited by Epitestosterone (Ki 1490 nmol/l, Vmax 1150 nmol/l.min). The results represent further evidence for different substrate specificity of renal and testicular 11 beta-hydroxysteroid dehydrogenase.
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inhibition of steroid 17α hydroxylase and c17 20 lyase in the human testis by Epitestosterone
The Journal of Steroid Biochemistry and Molecular Biology, 1993Co-Authors: Marie Bicikova, R Hampl, Martin Hill, L StarkaAbstract:Abstract Epitestosterone (17α-hydroxyl-4-androsten-3-one) inhibited competitively 17α-hydroxylation of pregnenolone and subsequent C 17,20 -side chain cleavage of resulting 17α-hydroxypregnenolone using microsomal preparations from the human testis. The inhibition constants for 17α-hydroxylase and C 17,20 -lyase with 5-ene-precursors of C 21 -steroids were 96 and 12.4 μmol/1, respectively.
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the effect of Epitestosterone on the plasma levels of lh and fsh in ovariectomized immature rats
The Journal of Steroid Biochemistry and Molecular Biology, 1993Co-Authors: Marie Bicikova, Martin Hill, O Lapcik, R Kanceva, L StarkaAbstract:Immature ovariectomized female rats primed with estradiol or without estrogen priming were treated with Epitestosterone i.p. After 7 h blood was collected and LH and FSH levels were determined. The dose-response relationship was a biphasic one. LH and less markedly FSH levels decreased under Epitestosterone treatment with doses up to 10 mg, whereas at higher doses an increase of gonadotrophins was observed.