Metabolism testosterone

Marcillo, Y., Ronis, M.J.J., and Porte, C. (1998). Effects of tributyl tin on the phase 1 testosterone metabolism and steroid titres of the clam. Aquatic Toxicology 42, 1-13. 

Horinouchi M, T Hayashi, H Koshino, T Yamamoto, T Kudo (2003a) Gene encoding the hydrolysis for the product of the mefa-cleavage reaction in testosterone metabolism by Comamonas testosteroni. Appl Environ Microbiol 69 2139-2152. 

Oberdorster, E., D. Rittschof, and G.A. LeBlanc. 1998. Alteration of [14C]-testosterone metabolism after chronic exposure of Daphnia magna to tributyltin. Arch. Environ. Contam. Toxicol. 34 21-25. 

Rosenbrock H, Hagemeyer CE, Singec I, Knoth R, Volk B. 1999. Testosterone metabolism in rat brain is differentially enhanced by phenytoin-inducible cytochrome P450 isoforms. J Neuroendocrinol 11 597-604. 

When rats were administered atrazine in drinking water at 0.1, 0.2, or 0.5 g/1 for 1 or 3 weeks, they excreted as the principal metabolite 2 -chloro-4-ethylamino-6-amino-s-triazine. Atrazine and its metabolites have been shown to alter the activity of some testosterone-metabolizing enzymes in the rat pituitary and hypothalamus and to decrease hormone-receptor binding in the prostate. ... 

Testosterone metabolism. The lipido-ste-rol extract (LSESr, Permixon) was studied in primary cultures of epithelial cells and fibroblasts separated from benign prostate hypertrophy and prostate cancer tissues. The extract inhibited the formation of the T metabolites androstenedione 5 4 and 5 a-DHT The lipophilic extracts of fruits inhibited T 5p-reductase (EC 1.3.99.5) (5(xR). For fatty acid-like 5(xR inhibition a strongly polar end-group and a molecular skeleton allowing nonpolar interactions with the enzyme were required. The result indicated that 5pR activity in prostatic tissue may be influenced by the lipid environ-... 

SR038 Delos, S., ]. L. Carsol, E. Ghazarossian, ]. P. Raynaud, and P. M. Martin. Testosterone metabolism in primary cultures of human prostate epithelial cells and fibroblasts. J Steroid Biochem Mol Biol 1995 55(3-4) 375-383. 

Nielsen, F.H., C.D. Hunt, L.M. Mullen, and J.R. Hunt. 1987. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women. EASEB Jour. 1 394-397. 

Krause W, Effendy I. Wie wirkt Ketoconazol auf den Testosteron-Stoffwechsel . [How does ketoconazole affect testosterone metabolism .] Z Hautkr 1985 60(14) 1147-55. 

Even the optimum ratio of reductase to P450 depends on the substrate and the enzyme. Whereas most reactions are saturated by a reductase/P450 ratio of 10 1, testosterone metabolism by CYP2A1 saturates at much higher reductase ratios. In contrast, essentially all reactions that have a cytochrome b5 dependence are saturated at a h5/P450 ratio of 1 1. 

Kenworthy et al. [45] proposed a model with three subsites in order to explain the binding of testosterone (TS) and diazepam (DZ). One site binds diazepam, another binds testosterone, and the third is capable of binding either diazepam or testosterone. They found that testosterone caused extensive activation of diazepam metabolism, whereas diazepam caused inhibition of testosterone metabolism. Diazepam is present in the inhibitor database used to obtain the pharmacophoric model and its inhibitory activity is well explained by the model (y-residual = 0.27 log units). The model with multiple binding sites proposed by Kenworthy helped to explain the results of the obtained pharmacophoric model if one considers that competition will occur in the catalytic site that can bind either DZ or TS and that... 

Dorfman and Ungar have given an account of the metabolism of steroid hormones [10], therefore only a few comments v/ill be made here. The comparative relative activities of testosterone metabolities on the seminal vesicle and ventral prostate of immature male rats and capon s comb are summarized in the accompanying table. 

Oettel M (2003) Testosterone metabolism, dose-response relationships and receptor polymorphisms Selected pharmacological/toxicological considerations on benefits versus risks of testosterone therapy in men. Aging Male 6 230-256. 

Morley JE, Patrick P, Perry HM III. Evaluation of assays available to measure free testosterone. Metabolism 2002 51 554-9. 

I am reluctant to use Serenoa extract because (a) It seems to reduce libido in my male patients with long-term (three-month) usage after an initial increase in libido at a dosage 5 milliliters per day (b) it induces inappropriate disruption of testosterone metabolism when prostate distress originates from mechanical and/ or postural trauma and (c) I wish to use it only when necessary. 

Genistein and daidzein directly affect testosterone metabolism, reducing the toxic metabolites of testosterone. Genistein, an isoflavone, also seems to slow or prevent the metastasis of invasive cancer cells. It is believed to work by preventing the formation of new blood vessels to cancerous tumors. Histoculture studies of genistein have shown that this phytochemical reduces the growth of prostatic cancer tissue. 

Wang, C., Catlin, D.H., Starcevic, B., Leung, A., DiStefano, E., Lucas, G., Hull, L. and Swerdloff, R.S. (2004b). Testosterone metabolic clearance and production rates determined by stable isotope dilution/tandem mass spectrometry in normal men influence of ethnicity and age. J. Clin. Endocrinol. Metab., 89, 2936-2941. 

Kenworthy, K.E., S.E. Clarke, J. Andrews, and J.B. Houston (2001). Multisite kinetic models for CYP3A4 Simultaneous activation and inhibition of diazepam and testosterone metabolism. Drug Metab. Dispos. 29, 1644-1651,... 

Johansen KL. Testosterone metabolism and replacement therapy in patients with end-stage renal disease. Semin Dial 2004 17 202-208. 

Tan SY, Antonipillai I, Murphy BE. Inhibition of testosterone metabolism in the human prostate. J Clin Endocrinol Metab 1974 39 936-941. 

In vitro skin absorption smdies often differ in the receptor fluid used. A buffered saline solution may simply be used in a study with nonviable skin however, a more physiological solution such as HEPES-buffered Hanks balanced salt solution is required to maintain the viability of skin in the diffusion cells (Collier et al., 1989). The viabihty of skin can be maintained for at least 24 h based on glucose utilization of skin, histological evaluations, and the maintenance of estadiol and testosterone metabolism (Collier et al., 1989). 

---