Metabolism steroid hormones

Few studies have been conducted on other invertebrate taxa but pentach-lorophenol exposure has been shown to affect daphnid reproductive capacity and sex steroid hormone metabolism and a high incidence of intersex has been observed in harpacticoid copepods near an Edinburgh sewage outfall. " ... 

Donath J, Boland W (1994) Biosynthesis of acyclic homoterpenes in higher plants parallels steroid hormone metabolism. J Plant Physiol 143 473 78... 

Having said this, no criticism of the early researchers in the field of steroid hormone metabolism is intended they could only experiment with materials currently available to them. 

The last section, Endocrinology and Integration of Metabolism, includes chapters on hormonal regulation of energy metabolism (Type I Diabetes) and steroid hormone metabolism (Congenital Adrenal Hyperplasia). 

The mineralocorticoid aldosterone is also produced by the adrenal cortex and promotes retention of H20 and Na+ and loss of K+ by the kidney. Cortisol is also an agonist of the aldosterone receptor but the level of cortisol is kept low by type 2 11 (Thydroxysteroid dehydrogenase, which converts cortisol to the inactive cortisone (11-dehydrocortisol). Accordingly inhibition of this enzyme by 18(i>-glycyrrhetinic acid (from liquorice) elevates cortisol with consequent effects of H20 and Na+ retention, oedema and hypertension. Further potential sites of interference by plant substances with steroid hormone metabolism include enzymes involved in steroid hormone synthesis such as the cytochrome P450-linked 11 -hydroxylase that catalyses the last step of corticosterone synthesis. 

In addition to estimation on the basis of urinary metabolic studies, blood production rates of steroids can be estimated, after administration of isotopically labeled steroids, from the specific activity of the unchanged steroids in the blood. This method was extensively used by Tait and coworkers [322,324]. In 1966 a critical survey of steroid hormone metabolism was given by Baulieu [385]. 

XI. Cholesterol, Bile Salt, and Steroid Hormone Metabolism... 

XI. Cholesterol, bile salt, and steroid hormone metabolism 214... 

O Malley B, Strott CA. Steroid hormones metabolism and mechanism of action. In Yen SSC, Jafife RB, Bar-bieri RL, eds. Reproductive endocrinology Physiology, pathophysiology, and clinical management. 

The plausibility that PCB effects on reproductive function (and other functions such as neurobehavior and immunological competence) may involve PCB effects on endocrine functions has led to investigations of the estrogenic and anti-estrogenic activities of PCB mixtures and individual congeners, and the effects of PCBs or related halogenated aromatic compounds on steroid hormone metabolism via induction of Phase I or Phase n enzymes. How these PCB effects are specifically related to PCB effects on reproductive function is unknown, but the results of these investigations provide further evidence that reproductive effects from PCB mixtures may not be restricted to Ah-receptor mediation alone and are likely to involve multiple mechanisms that have yet to be elucidated. Related information on endocrine disruption is discussed in Section 3.6. 

The glycogen store normally present in liver also plays a role in elimination of poisons such as carbon tetrachloride, chloroform, p-aminobenzoic acid, sulfanilamide, alcohol, arsenic, and bacterial poisons (10, 26, 28, 32, 51, 60, 61, 75) It probably plays a role also in regulating steroid hormone metabolism and in eliminating excess sex hormones. The elimination of substances that otherwise would be carcinogenic may turn out to involve the liver and liver glycogen (62, page 14). 

LeBlanc, G.A., S.S. Sundseth, G.F. Weber, and D.J. Waxman (1992). Platinum anticancer drugs modulate P-450 mRNA levels and differentially alter hepatic drug and steroid hormone metabolism in male and female rats. Cancer Res. 52, 540-547. 

Changes in steroid hormone metabolism in rat liver microsomes following administration of 2,3,7,8-tetrachlorodibenzo-p-dioxine (TCDD). Biochem. Pharmacol. 28, 497-9. 

D. P. Lapenson (1988). Cytochrome P-450 steroid hormone metabolism catalyzed by human liver microsomes. Arch. Biochem. Biophys. 263, 424-436. 

Accordingly, Chapter 4 assesses the literature on dietary sources and intake of boron in humans, and evaluates the impact of boron on metabolism in health and disease. It was found that boron was capable of influencing steroid hormone metabolism however, the specific condition that controls the nature (and direction) of the response remains to be determined. 

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