Role of 11β-OH-C₁₉ and C₂₁ steroids in the coupling of 11β-HSD1 and 17β-HSD3 in regulation of testosterone biosynthesis in rat Leydig cells

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• 作者：Syed A. Latif^a ; ^{slatif@lifespan.org"" rel=""nofollow} ; Mae Shen^a ; Ren-Shan Ge^b ; Chantal M. Sottas^b ; Matthew P. Hardy^b ; ¹ ; David J. Morris^a
• 关键词：11&#x3b2 ; -Hydroxysteroid dehydrogenase ; 17&#x3b2 ; -Hydroxysteroid dehydrogenase ; Enzymatic coupling ; Adrenal ; Testis
• 刊名：Steroids
• 出版年：2011
• 出版时间：June 2011
• 年：2011
• 卷：76
• 期：7
• 页码：682-689
• 全文大小：577 K

文摘

Here we describe further experiments to support our hypothesis that bidirectional 11&#x3b2;-HSD1-dehydrogenase in Leydig cells is a NADP(H) regenerating system. In the absence of androstenedione (AD), substrate for 17&#x3b2;-HSD3, incubation of Leydig cells with corticosterone (B) or several C₁₉- and C₂₁-11&#x3b2;-OH-steroids, in the presence of [³H]-11-dehydro-corticosterone (A), stimulated 11&#x3b2;-HSD1-reductase activity. However, in presence of 30 μM AD, testosterone (Teso) synthesis is stimulated from 4 to 197 picomole/25,000 cells/30 min and concomitantly inhibited 11&#x3b2;-HSD1-reductase activity, due to competition for the common cofactor NADPH needed for both reactions. Testo production was further significantly increased (p < 0.05) to 224–267 picomole/25,000 cells/30 min when 10 μM 11&#x3b2;-OH-steroids (in addition to 30 μM AD) were also included. Similar results were obtained in experiments conducted with lower concentrations of AD (5 μM), and B or A (500 nM).

Incubations of 0.3–6.0 μM of corticosterone (plus or minus 30 μM AD) were then performed to test the effectiveness of 17&#x3b2;-HSD3 as a possible NADP⁺ regenerating system. In the absence of AD, increasing amounts (3–44 pmol/25,000 cells/30 min) of 11-dehydro-corticosterone were produced with increasing concentrations of corticosterone in the medium. When 30 μM AD was included, the rate of 11-dehydro-corticosterone formation dramatically increased 1.3–5-fold producing 4–210 pmol/25,000 cells/30 min of 11-dehydro-corticosterone. We conclude that 11&#x3b2;-HSD1 is enzymatically coupled to 17&#x3b2;-HSD3, utilizing NADPH and NADP in intermeshed regeneration systems.