steroid synthesis pathway

Johnson J JE Ushinohama Jones McGee PH, Jonsson LL, Callard Wetzel Gray WR Clearly, certain chemicals such as the azole fungicides and systemically used antifungal drugs directly interfere with steroidogenesis by acting as potent inhibitors of steroidogenic enzymes and are known to cause endocrine disruption mainly via this mechanism. Kocsis Lambright X Studies using gonadotropin-primed immature female rats as an ovulation model (Gao et al., 1999; Li et al., 1995b) demonstrated that TCDD and other polychlorinated dibenzo-p-dioxins (PCDDs) decrease ovarian weight before the whole body weight is affected. As early as 1949, o,p′-DDD (50 mg/kg) was found to be adrenotoxic in dogs (Nelson and Woodward, 1949). C J J Suzuki H Murphy Androstenedione and testosterone diffuse into the neighboring poorly vascularized granulosa cells where they are converted to predominantly estradiol via the concerted action of aromatase and 17β-HSD types 1 and 7, which favor the conversion of estrone to estradiol (Luu-The, 2001; Mindnich et al., 2004). Eldridge This review aims to provide a comprehensive overview of the state of knowledge regarding the mechanisms by which chemicals interfere with the function of steroidogenic enzymes in various tissues and organisms. These two mitochondrial enzymes are also unique to the adrenal cortex. 1 Pathways of adrenal steroidogenesis The conversion of cholesterol to pregnenolone in the mitochondria represents the first step of steroidogenesis. Reeder Newsted ER, Oxford University Press is a department of the University of Oxford. JL White Gray Mitotane appears to selectively affect the zona fasciculata where it inhibits mitochondrial steroid 11β-hydroxylase (CYP11B1) and cholesterol side-chain cleavage (CYP11A1) activity, thus reducing the production of glucocorticoids. Jacobsen Initially, investigations into the mechanism of these apparent estrogenic effects were directed toward the estrogen receptor. A comparison with human aromatase inhibition, Severe adrenal cortical atrophy produced by feeding DDD, Histopathology of the human adrenal cortex, Peptide hormones versus steroid hormones: Case studies from snail and turtle populations, Zone-specific expression of aldosterone synthase cytochrome P-450 and cytochrome P-45011 beta in rat adrenal cortex: Histochemical basis for the functional zonation, A novel nonradioactive method for measuring aromatase activity using a human ovarian granulosa-like tumor cell line and an estrone ELISA, Effects of flavonoid phytochemicals on cortisol production and on activities of steroidogenic enzymes in human adrenocortical H295R cells, The fungicide procymidone alters sexual differentiation in the male rat by acting as an androgen-receptor antagonist in vivo and in vitro, Transcriptional regulation of the genes encoding the cytochrome P-450 steroid hydroxylases, Glucocorticoid-suppressible hyperaldosteronism and adrenal tumors occurring in a single French pedigree, Long-term carcinogenicity bioassay of the herbicide atrazine in F344 rats, Adrenal zonation: Clues from 11[beta]-hydroxylase and aldosterone synthase, The NCI-H295 cell line: A pluripotent model for human adrenocortical studies, Regulation of human adrenal carcinoma cell (NCI-H295) production of C19 steroids, Forms and prevalence of intersexuality and effects of environmental contaminants on sexuality in cricket frogs (Acris crepitans), Localization and expression of adrenocorticotropic hormone receptor mRNA in normal and neoplastic human adrenal cortex, Atrazine is a competitive inhibitor of phosphodiesterase but does not affect the estrogen receptor, Cellular and biochemical mechanisms by which environmental oestrogens influence reproductive function, Induction and inhibition of aromatase (CYP19) activity by various classes of pesticides in H295R human adrenocortical carcinoma cells, Induction and Inhibition of aromatase (CYP19) activity by natural and synthetic flavonoid compounds in H295R human adrenocortical carcinoma cells, Effects of chloro-s-triazine herbicides and metabolites on aromatase activity in various human cell lines and on vitellogenin production in male carp hepatocytes. A Levell Dingemans Lasley Kahl GF, Brawer T Stoker CYP17 hydroxylates pregnenolone and progesterone to form the respective 17α-hydroxysteroids, a process which occurs in the zonae reticularis and fasciculata but not in the zona glomerulosa (Reincke et al., 1998). H These stem cells are continuously renewed by mitosis for most of the lifetime of human males. MP Some endocrine-disrupting properties of atrazine have been linked to one or more of its metabolites (Eldridge et al., 1994; Laws et al., 2003; Stoker et al., 2002). Chen M Baba Laws KK, Lilienthal JK, Cummings I, Lund Eisold Also, coadministration of exogenous estrogen prevented the observed masculinization of females but led to “feminization” of males, which are the “default” sex in avian species (Elbrecht and Smith, 1992). JV In H295R cells, neither p,p′-DDT nor o,p′-DDT, p,p′-DDE, and o,p′-DDE were capable of affecting the catalytic activity of aromatase unless cytotoxic concentrations (≥ 10μM) were used (Sanderson et al., 2002). JP MK Official websites use .gov WA JT, Enan Newsted Lambright It was demonstrated that the MeSO2 group on the third or fourth position of the PCB molecule was essential for this interaction, as the parent PCBs had no effect. Finally!! Rohrich M, Hayes KK ML Addition of exogenous pregnenolone restored testosterone secretion to control levels, thus indicating that either cholesterol synthesis or mobilization to the mitochondria or inhibition of CYP11A is responsible for the decreased steroid synthesis. More recent estimates are not readily available but are expected to be higher in the United States and lower in Western Europe where atrazine usage has been gradually banned. Considerably less effective inhibitors in this study were astemizole, metronidazole, carbimazole, mebendazole, tinidazole, and thiabendazole that inhibited aromatase activity less than 50% at 100μM. Furthermore, this study demonstrated the ability of DE-71 and several individual PBDE congeners to bind to the prostate cytosolic androgen receptor and to activate the human androgen receptor in the stably transfected MDA-kb2 breast cancer cell line. Also, the lactationally exposed male offspring of the atrazine-exposed dams had an increased incidence of prostatitis (Stoker et al., 1999), an effect known to be induced by exposure to exogenous 17β-estradiol (Tangbanluekal and Robinette, 1993). It was further shown that none of the triazine herbicides or their metabolites induced estrogen-dependent vitellogenin production in male carp hepatocytes (Sanderson et al., 2001a). T WE MD CB K Hofmockel It appears that amphibians produce two differentially regulated isoforms of aromatase (in brain and in gonad) coded by a single gene through a splicing mechanism similar to that in humans (Kuntz, 2004). LE, Scholz In the last decade, research has focused on potential interactions of chemicals with various hormone receptors, with particular emphasis on the thyroid hormone and estrogen receptor, and more recently the androgen receptor. JM M, Li LG Fujii-Kuriyama In other words, aromatase inhibition during the critical time of embryonic development caused genotypical females to develop as phenotypical males. RL KI La Point EA PD Miller ER, Bulun Corbin The adrenotoxic actions of mitotane have made it of some clinical use in the treatment of nonoperable adrenocortical cancers (Chabner et al., 1996). Tyrell B TCDD and other persistent halogenated Ah receptor agonists are clearly capable of causing endocrine disruption and are known reproductive and developmental toxicants. Skogseid R The synthesis of steroid hormones is a complex pathway of intermediary metabolism. Böcker Concentrations of several PBDE congeners have been increasing steadily over the last few decades in the biotic and abiotic environments. RK, Sanderson CR BR WR Gerst J Guidici Jeunemaitre Cholesterol is … P S, Chabner Gao DK The authors hypothesize that o,p′-DDT, by activating the estrogen receptor, causes increased aromatase gene expression and catalytic activity due to increased transcription via estrogen-responsive elements (EREs) found in the promoter region of the brain-specific cyp19b gene (Kuhl et al., 2005), a gene unique to teleost fishes. JC, Wolf GT CA All steroidogenic processes take place in the adrenal cortex, which is histologically and functionally divided into three concentric zones: the outer zona glomerulosa, the intermediate zona fasciculata, and the central zona reticularis (Neville and O'Hare, 1985). Synthesis of estetrol via estrone derived steroids Download PDF Info Publication number PT1562976E. Seralini H However, some affected girls present with severe genital virilization at … Lambright LE, Stoker Furr Lambright Similarly, a study using an immortal testis cell line derived from the green sea turtle (Chelonia mydas) showed that p,p′-DDE did not reduce aromatase activity unless exposures were in the cytotoxic range (Keller and McClellan-Green, 2004). Suzuki In leopard frogs (Rana pipiens) exposed to atrazine from hatching until tail resorption, males developed oocytes (29 and 8% of males at 0.1 and 25 ppb, respectively) (Hayes et al., 2003). RL, Leers-Sucheta Jefcoate Tisdel S GA RW JM D, Tennant Schimmer Warner M, Burke KR J B S Steroid production is regulated by specific external stimuli, such as adrenocorticotropic hormone (ACTH), which increases mainly glucocorticoid and weak androgen production via the cAMP–mediated protein kinase A (PKA) pathway (Rainey, 1999) that activates factors such as steroidogenic acute regulatory protein (Stocco, 2001) and steroidogenic factor-1 (SF-1) (Morohashi and Omura, 1996; Morohashi et al., 1992), and angiotensin II and potassium, which selectively increase mineralocorticoid synthesis (Schimmer and Parke, 1996) via the inositol triphosphate/diacylglycerol–mediated protein kinase C (PKC) pathway (Rainey, 1999). Jinno A KM The 3-MeSO2-DDE metabolite of p,p′-DDT has been found in various species including the Baltic grey seal (Halichoerus grypus) (Larsson et al., 2004) and humans (Chu et al., 2003) in a concentration range of anywhere from 0.5 to 22 ng/g lipid weight. Woodward van den Berg C Brominated flame retardant such as the polybrominated diphenylethers (PBDEs) are used in large quantities in various commercial and industrial products. The theca interna is highly vascularized and produces large amounts of progesterone and androgens, which act as precursor for estrogen synthesis in the granulosa cells. P, Kettles A study examining the effects of aromatase inhibition on embryonic development found that exposure in ovo of chickens to the nonsteroidal aromatase inhibitor fadrozole led to “masculinization” of females (Elbrecht and Smith, 1992). K It is also expressed in other peripheral tissues such as skin and liver. R M Exposure of male rats to the commercial PBDE mixture DE-71 during the peripubertal period caused a delay in the onset of puberty, together with decreased seminal vesicles and ventral prostate weights, indicating an antiandrogenic mechanisms of action of one or more components of the mixture (Stoker et al., 2004). M, Letcher A RF LE Dickson JW CE, Lindhe CS Safe Furthermore, addition of exogenous DHEA abolished the effect on estradiol production, supporting a lack of role for aromatase in reduced estradiol production. S Grote KM PW TW Heimler Jr, Kelce S, Ostby Willingham S Morohashi Speed et al. C PC Ramamoorthy Curt It was found that treatment of bonnet monkeys (Macaca radiata) with a triazole-containing aromatase inhibitor related to letrozole blocked spermatid development (Shetty et al., 1997). Lehmann TE De novo synthesis of all steroid hormones starts with the conversion of cholesterol to pregnenolone by CYP11A (cholesterol side-chain cleavage) (Parker and Schimmer, 1995). Hoang Sanderson M M Gray Ultrastructural changes observed by estradiol (lack of chromosome condensation, fewer dividing germ cells, and increased number of vacuoles and inclusion bodies) were not observed with atrazine or controls. The type 2 3β-HSD is predominantly expressed in steroidogenic tissues such as adrenal, testis, and ovary, whereas type 1 is found in placenta and in nonsteroidogenic tissues such as liver, kidney, and skin. BP LT J, Monod M Giesy Ayub and coworkers also found that several azole antifungals were capable of inhibiting CYP17 17α-hydroxylase and 17,20-lyase activities in human adrenal microsomes. The investigators concluded, however, that biologically significant aromatase inhibition was unlikely to occur in vivo at the then current environmental concentrations of PCB metabolites. Gingras L Gray Wolf Tennant JT van den Berg Vinclozolin is not known to interact with the estrogen receptor or cause CYP17 inhibition, indicating that antagonism of the androgen receptor is its main mechanism of endocrine disruption. The endocrine system orchestrates major developmental, reproductive, and other physiological changes throughout life. Karl The effects of various triazine metabolites on phosphodiesterase activity also warrant further investigation to explain their structure-activity relationship for aromatase induction in responsive cell systems. Shackleton EJ K Bird Given the important role of hormonal balance in amphibian sexual development and their aquatic habitat, it has been suggested that they would be particularly sensitive to the effects of endocrine-disrupting chemicals introduced into agricultural areas. Knobil Robker Durhan FM Steroid biosynthesis - Reference pathway [ Pathway menu | Pathway entry | Image (png) file | Help] Option. Lund and coworkers observed a high incidence of bilateral adrenocortical hyperplasia in the declining Baltic gray seal population associated with elevated 3-MeSO2-DDE contamination (Lund, 1994). WE These include CYP11A, CYP11B1, CYP11B2, CYP17 (17α-hydroxylase and 17,20-lyase), CYP19, CYP21, and 3β-HSD. Toyoshima Grande J It also found that steroid 17,20-lyase activity was about 10 times lower than that of aromatase, indicating that the prior activity and not aromatase activity is rate limiting in the synthesis of estradiol in hLGCs. Cooper F However, no studies with vinclozolin have so far been performed to examine this. Various cell lines and cells in primary culture or coculture have been used for the investigation of effects of xenobiotics on steroidogenesis, each with its advantages and disadvantages. Tillitt A general steroid hormone synthesis pathway. M N SC K A perinatal exposure study recently demonstrated the ability of prochloraz to feminize male rat offspring (Vinggaard et al., 2005). M In female Sprague-Dawley rats, 22.5 mg/kg atrazine caused lengthening of estrous cycle and a dose-dependent increase in plasma levels of estradiol (Wetzel et al., 1994). K PF, Sonnenschein Rainey K J, Balthazart JP DiBartolomeis Stoker Frohman A recent in vivo study in Japanese medaka (Oryzias latipes), on the other hand, showed that o,p′-DDT, the only DDT analogue to have significant affinity for the estrogen receptor, was capable of increasing aromatase activity in the brain (Kuhl et al., 2005). Larsson van den Berg MJ Percival JI Konig MEDULLA 2.CORTEX Adrenal dysfunction includes hyperfunction / hypofunction of medulla and cortex. This results in severe adrenal insufficiency, characterized by a loss of appetite, hypothermia, nausea, general weakness, and ultimately death. A JE S MEDULLA A) HYPERFUNCTION - pheochromocytoma -Neuroblastoma 2.CORTEX … • The pathway of synthesis – similar to synthesis in adrenal cortex • Cholesterol → pregnenolone → OH-pregnenolone → DHEA → androstenedione → testosterone • In target cells: testosterone reduced into DiOH-testosterone (DHT) Murphy This distinction depends on the site of synthesis of the steroid. C Pharmacol. Y Parks X 2,3,7,8-Tetrachlorodibenzo-p-dioxin and diindolylmethanes differentially induce cytochrome P450 1A1, 1B1, and 19 in H295R human adrenocortical carcinoma cells, Immunolocalization of aromatase, 17 alpha-hydroxylase and side-chain-cleavage cytochromes P-450 in the human ovary, Immunohistochemical localization of cytochrome P-450C21 in human adrenal cortex and its relation to endocrine function, Adrenocorticotropic hormone; adrenocortical steroids and their synthetic analogs: Inhibitors of the synthesis and actions of adrenocortical hormones, 17-alpha-ethinylestradiol affects reproduction, sexual differentiation and aromatase gene expression of the medaka (Oryzias latipes), Effect of estrogen deprivation on the reproductive physiology of male and female primates, Molecular biology of the 3{beta}-hydroxysteroid dehydrogenase/{Delta}5-{Delta}4 isomerase gene family, Ecological risk assessment of atrazine in North American surface waters, 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) blocks ovulation by a direct action on the ovary without alteration of ovarian steroidogenesis: Lack of a direct effect on ovarian granulosa and thecal-interstitial cell steroidogenesis in vitro, An updated review of environmental estrogen and androgen mimics and antagonists, Regulation of steroidogenesis in NCI-H295 cells: A cellular model of the human fetal adrenal, StAR protein and the regulation of steroid hormone biosynthesis, In vivo and in vitro anti-androgenic effects of DE-71, a commercial polybrominated diphenyl ether (PBDE) mixture, The effects of atrazine metabolites on puberty and thyroid function in the male Wistar rat, Assessment of DE-71, a commercial polybrominated diphenyl ether (PBDE) mixture, in the EDSP male and female pubertal protocols, The effect of atrazine on puberty in male wistar rats: An evaluation in the protocol for the assessment of pubertal development and thyroid function, Maternal exposure to atrazine during lactation suppresses suckling-induced prolactin release and results in prostatitis in the adult offspring, Prolactin mediates estradiol-induced inflammation in the lateral prostate of Wistar rats, Response of the amphibian tadpole (Xenopus laevis) to atrazine during sexual differentiation of the testis, Response of the amphibian tadpole Xenopus laevis to atrazine during sexual differentiation of the ovary, Possible antiestrogenic properties of chloro-s-triazines in rat uterus, Perinatal exposure to the fungicide prochloraz feminizes the male rat offspring, Screening of selected pesticides for inhibition of CYP19 aromatase activity in vitro, Antiandrogenic effects in vitro and in vivo of the fungicide prochloraz, Developmental expression of genes for the stereoidogenic enzymes P450scc (20,22-desmolase), P450c17 (17 alpha-hydroxylase/17,20-lyase), and P450c21 (21-hydroxylase) in the human fetus, Forskolin up-regulates aromatase (CYP19) activity and gene transcripts in the human adrenocortical carcinoma cell line H295R, Effect of epidermal growth factor and prostaglandin on the expression of aromatase (CYP19) in human adrenocortical carcinoma cell line NCI-H295R cells, Chronic effects of atrazine on estrus and mammary tumor formation in female Sprague-Dawley and Fischer 344 rats, Characterization of the period of sensitivity of fetal male sexual development to vinclozolin, Inhibition of cytochromes P450 by antifungal imidazole derivatives, Quantitative RT-PCR methods for evaluating toxicant-induced effects on steroidogenesis using the H295R cell line, Transcriptional regulation of CYP19 gene (aromatase) expression in adipose stromal cells in primary culture, © The Author 2006. 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