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Neuroendocrinology Letters incl. Psychoneuroimmunology & Chronobiology

 

NeuroendocrinologyİLetters
ISSNİ0172ñ780X Copyrightİ©İ1997 NeuroendocrinologyİLetters

NEL Vol. 18 No. 4
Original Article

1998; 18:203-213
pii: NEL182397A03

 

Testosterone is Locally Metabolized in Human Brain Tumors, with Possible Qualitative and Quantitative Changes in its Effects
by H. J. Stuerenburg, Breivik, M. J. A. Puchner, F Lohmann, and K. Kunze

Received: October 24, 1997
Accepted: November 14, 1997

Abstract

We investigated the metabolism of testosterone by human brain tumors. Activation and deactivation of steroid hormones by enzymatic transformation in the target tissue or organ is an important regulating mechanism which modifies the effects of steroid hormones. Steroid hormones can act in human brain and in brain tumors via estrogen. androgen, glucocorticoid and progestin receptors. The 5-alpha-reductase activity [metabolism of testosterone to dihydrotestosterone], the 3-alpha-hydroxysteroid oxidoreductase activity [metabolism of 5-alpha-dihydrotestosterone to 5-alpha-androstane-3-alpha.17b-diol], the aromatase activity [metabolism of testosterone to estradiol-17b], the 17b-hydroxysteroid oxidoreductase activity [metabolism of testosterone to 4-androstene-3.17-dione] and the production of 4-androstane-3.17-dione were studied in 37 brain tumors.

We detected a mean 5-alpha-reductase activity of 4 52 (± 1 91) x 10-17 Mol/mg protein/min (± standard error), a 3-alpha-hydroxysteroid oxidoreductase activity of 1.76 (±0.58) x 10 -17 Mol/mg protein/min, an aromatase activity of 3.86 (a: 0.67) x 10-18 Mol/mg protein/min, a 17b-hydroxysteroid oxidoreductase activity of 5 77 (± 1.87) x 10-17 Mol/mg protein/min and a mean synthesis of androstanedione of 1 03 (± 0 23) x 10 -18 Mol/mg protein/min. Our findings demonstrate the local transformation of testosterone in human brain tumors, and consequently the activation (5-alpha-reductase). deactivation (3-alpha-hydroxysteroid oxidoreductase) and induction of estrogenic activity (aromatase) The local enzymatic transformation of testosterone in human brain tumors described here could lead both to an activation and a deactivation of the testosterone effect. This local metabolism could be important for the local effect of testosterone. In previous reports, considerable importance has been placed on the measurement of steroid hormone receptor concentrations in brain tumors, however, in the interpretation of these data the local metabolism of steroids demonstrated here must be taken into account, or erroneous conclusions will inevitably be drawn.

 

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