Schafer S J, Colás A E
Endocrinology. 1975 Nov;97(5):1294-9. doi: 10.1210/endo-97-5-1294.
The contribution of the adrenals, the testes, and a light/dark cycle to the regulation of hepatic steroid hydroxylases was studied in vitro by measuring transformation rates (nmol/mg protein/min) of dehydroepiandrosterone (DHA). Normal and adrenalectomized male rats were kept in 12 h light:12 h dark (12L:12D) or in constant light (CL) for 1 week. Normal and castrated rats were kept in 12L:12D for 3 weeks. Rats were killed at 4-h intervals over a 36-h period, hepatic microsomal fractions were incubated with [4-14C]DHA, and C-7 and C-16-oxygenated products were quantitated. The overall mean rate of 7alpha-hydroxylation decreased in normal rats exposed to CL. Rates of both 7alpha- and 16alpha-hydroxylation were significantly greater in normal rats than in the respective group of treated rats, except for the 7alpha-hydroxylase in castrated rats. These results indicate that 16alpha-hydroxylase activity is both gonadal- and adrenal-dependent, whereas 7alpha-hydroxylase activity is adrenal-dependent only. Both enzymes are sensitive to light/dark modulations, although a circadian rhythm could not be conclusively established.
通过测量脱氢表雄酮（DHA）的转化率（nmol/毫克蛋白/分钟），在体外研究了肾上腺、睾丸以及光/暗周期对肝脏类固醇羟化酶调节的贡献。正常和肾上腺切除的雄性大鼠在12小时光照：12小时黑暗（12L:12D）或持续光照（CL）条件下饲养1周。正常和去势大鼠在12L:12D条件下饲养3周。在36小时内每隔4小时处死大鼠，将肝脏微粒体部分与[4-14C]DHA一起孵育，并对C-7和C-16氧化产物进行定量。暴露于CL的正常大鼠中，7α-羟化的总体平均速率降低。除了去势大鼠中的7α-羟化酶外，正常大鼠中7α-和16α-羟化的速率均显著高于相应的处理组大鼠。这些结果表明，16α-羟化酶活性既依赖于性腺也依赖于肾上腺，而7α-羟化酶活性仅依赖于肾上腺。两种酶都对光/暗调节敏感，尽管昼夜节律无法最终确定。
