Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada.
Aquat Toxicol. 2011 Oct;105(3-4):218-26. doi: 10.1016/j.aquatox.2011.06.012. Epub 2011 Jul 16.
Selenomethionine (Se-Met) is the major dietary form of selenium (Se). Detrimental effects have been associated with exposure to elevated dietary selenium. Previous studies have demonstrated effects of Se on the endocrine system, in particular effects on cortisol and thyroid hormones. However, no information is available regarding effects of Se on sex steroid hormones. In the present study, effects of dietary exposure to an environmentally relevant concentration (4.54 mg/kg wet weight (ww)) of Se-Met for 126 days on concentrations of sex steroid hormones in blood plasma of female rainbow trout were determined. Furthermore, the molecular basis for effects of Se-Met on plasma sex steroid hormone concentrations was investigated. Concentrations of androstenedione (A), estrone (E1), and estradiol (E2) were 39.5-, 3.8-, and 12.7-fold greater in plasma of treated females than the untreated controls, respectively. Testosterone (T) was detected only in plasma of treated females. The greater E2 concentration stimulated greater transcript abundance of vitellogenin (vtg) and zona-radiata protein (zrp). Female rainbow trout exposed to Se-Met had greater transcript abundance of key steroidogenic proteins and enzymes, including peripheral benzodiazepine receptor (pbr), cytochrome P450 side-chain cleavage (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-hsd). Exposure to Se-Met did not affect transcript abundance of luteinizing hormone (lh) or follicle stimulating hormone (fsh). Similarly, there was no change in transcript abundance of luteinizing hormone receptor (lhr) or follicle stimulating hormone receptor (fshr). Long-term exposure to dietary Se-Met has the potential to stimulate vitellogenesis in female rainbow trout by directly stimulating ovarian tissue steroidogenesis. This is the first study to report effects of Se on sex steroid hormone production in fish.
硒代蛋氨酸（Se-Met）是硒（Se）的主要膳食形式。与暴露于高膳食硒有关的有害影响已有报道。先前的研究表明，硒对内分泌系统有影响，特别是对皮质醇和甲状腺激素有影响。然而，关于硒对性激素的影响尚无信息。本研究旨在确定在 126 天内以环境相关浓度（4.54mg/kg 湿重（ww））摄入硒代蛋氨酸对雌性虹鳟血浆中性激素浓度的影响。此外，还研究了硒代蛋氨酸对血浆性激素浓度的影响的分子基础。处理组雌性鱼血浆中的雄烯二酮（A）、雌酮（E1）和雌二醇（E2）浓度分别比对照组高 39.5、3.8 和 12.7 倍。仅在处理组雌性鱼的血浆中检测到睾酮（T）。较高的 E2 浓度刺激了卵黄蛋白原（vtg）和透明带蛋白（zrp）的转录丰度增加。暴露于硒代蛋氨酸的雌性虹鳟的关键类固醇生成蛋白和酶的转录丰度增加，包括外周苯二氮䓬受体（pbr）、细胞色素 P450 侧链裂解酶（P450scc）和 3β-羟甾脱氢酶（3β-hsd）。暴露于硒代蛋氨酸对促黄体生成激素（lh）或促卵泡激素（fsh）的转录丰度没有影响。同样，促黄体生成激素受体（lhr）或促卵泡激素受体（fshr）的转录丰度也没有变化。长期摄入膳食硒代蛋氨酸有可能通过直接刺激卵巢组织类固醇生成来刺激雌性虹鳟的卵黄生成。这是第一项报道鱼类中硒对性激素产生影响的研究。
