Dix C J, Habberfield A D, Sullivan M H, Cooke B A
Biochem J. 1984 Apr 15;219(2):529-37. doi: 10.1042/bj2190529.
The effect of inhibitors of the cyclo-oxygenase and lipoxygenase pathways of arachidonic acid metabolism on steroidogenesis in rat testis Leydig cells and rat tumour Leydig cells has been investigated. In the presence of nordihydroguaiaretic acid [NDGA; 4,4'-(2,3- dimethylbutan -1,4- diyl )bis[1,2- benzendiol ]], 5,8,11,14-eicosatetraynoic acid (ETYA), BW 755C [3-amino-1-[3-(trifluoromethyl)phenyl]-2-pyrazoline hydrochloride] and benoxaprofen [ Opren ; 2-(2-p-chlorophenyl- benzoxazol -5-yl)propionic acid)] (which inhibit lipoxygenase activity), but not indomethacin and aspirin (which inhibit cyclo-oxygenase activity), a dose-related inhibition of lutropin (LH)-stimulated testosterone and pregnenolone production was obtained (ID50 values of 2.5, 30, 25 and 30 microM for NDGA, ETYA, BW 755C and benoxaprofen were obtained, respectively). BW 755C and benoxaprofen had no significant effect on LH-stimulated cyclic AMP production except at the highest concentrations examined (330 and 380 microM, respectively), whereas NDGA and ETYA inhibited LH-stimulated cyclic AMP production in a dose-dependent manner (ID50 7.0 and 22 microM respectively). However, NDGA and ETYA also caused a dose-dependent inhibition of dibutyryl cyclic AMP-stimulated testosterone and pregnenolone production. The metabolism of exogenous ( 22R )-hydroxycholesterol or pregnenolone to testosterone by Leydig cells was not inhibited by either NDGA, ETYA or indomethacin. At low concentrations of NDGA and ETYA a significant increase in the conversion of both pregnenolone and ( 22R )-hydroxycholesterol to testosterone was obtained. Studies in which the metabolism of [14C]arachidonic acid by purified rat tumour Leydig cells was investigated indicate that products are formed by tumour Leydig cells that have similar mobilities in a thin layer chromatography system to 5-L-hydroxy-6,8,11,14-eicosatetraenoic acid, 12-L-hydroxy-5,8,10,14-eicosatetraenoic acid and leukotriene B4. The formation of these products was inhibited to varying degrees by NDGA, BW 755C and benoxaprofen but not by aspirin and indomethacin. These studies demonstrate for the first time that inhibition of lipoxygenase activity but not cyclo-oxygenase activity causes an inhibition of LH- and dibutyryl cyclic AMP-stimulated steroid production and suggest a stimulatory role for products of the lipoxygenase pathway of arachidonic acid metabolism in steroidogenesis. The site of this stimulation is apparently distal to the production of cyclic AMP and before the side chain cleavage of cholesterol.
研究了花生四烯酸代谢的环氧化酶和脂氧化酶途径抑制剂对大鼠睾丸间质细胞和大鼠肿瘤间质细胞类固醇生成的影响。在去甲二氢愈创木酸[NDGA；4,4'-(2,3-二甲基丁烷-1,4-二基)双[1,2-苯二酚]]、5,8,11,14-二十碳四炔酸(ETYA)、BW 755C[3-氨基-1-[3-(三氟甲基)苯基]-2-吡唑啉盐酸盐]和苯恶洛芬[奥普伦；2-(2-对氯苯基苯并恶唑-5-基)丙酸]（它们抑制脂氧化酶活性）存在的情况下，但吲哚美辛和阿司匹林（它们抑制环氧化酶活性）不存在时，获得了促黄体生成素(LH)刺激的睾酮和孕烯醇酮生成的剂量相关抑制（NDGA、ETYA、BW 755C和苯恶洛芬的ID50值分别为2.5、30、25和30 microM）。BW 755C和苯恶洛芬对LH刺激的环磷酸腺苷生成没有显著影响，除非在检测的最高浓度（分别为330和380 microM）下，而NDGA和ETYA以剂量依赖方式抑制LH刺激的环磷酸腺苷生成（ID50分别为7.0和22 microM）。然而，NDGA和ETYA也导致二丁酰环磷酸腺苷刺激的睾酮和孕烯醇酮生成的剂量相关抑制。间质细胞将外源性(22R)-羟基胆固醇或孕烯醇酮代谢为睾酮不受NDGA、ETYA或吲哚美辛的抑制。在低浓度的NDGA和ETYA下，孕烯醇酮和(22R)-羟基胆固醇向睾酮的转化均显著增加。对纯化的大鼠肿瘤间质细胞中[14C]花生四烯酸代谢的研究表明，肿瘤间质细胞形成的产物在薄层色谱系统中的迁移率与5-L-羟基-6,8,11,14-二十碳四烯酸、12-L-羟基-5,8,10,14-二十碳四烯酸和白三烯B4相似。NDGA、BW 755C和苯恶洛芬对这些产物的形成有不同程度的抑制作用，但阿司匹林和吲哚美辛没有。这些研究首次证明，抑制脂氧化酶活性而非环氧化酶活性会导致LH和二丁酰环磷酸腺苷刺激的类固醇生成受到抑制，并表明花生四烯酸代谢的脂氧化酶途径产物在类固醇生成中具有刺激作用。这种刺激的位点显然在环磷酸腺苷产生的远端且在胆固醇侧链裂解之前。
