Uptake and clearance of exogenous estradiol-17β and testosterone during the early development of coho salmon (Oncorhynchus kisutch), including eggs, alevins and fry
Uptake and clearance of exogenous estradiol-17β and testosterone during the early development of coho salmon (Oncorhynchus kisutch), including eggs, alevins and fry
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银鲑鱼（Oncorhynchus kisutch）（包括卵、鱼卵和鱼苗）早期发育过程中外源雌二醇-17β和睾酮的吸收和清除
DOI：
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发表时间：
1994
影响因子：
2.9
通讯作者：
E. Donaldson
中科院分区：
文献类型：
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作者：
F. Piferrer;E. Donaldson
在银大麻哈鱼 (Oncorhynchus kisutch) 发育的初始阶段，包括有眼卵、新孵化的鱼苗和首次摄食的鱼苗，对雌二醇-17β (E2) 和睾酮 (T) 的吸收和清除进行了检查。通过水施用示踪剂剂量的放射性标记类固醇，无论是否含有非放射性形式，浓度为 400 μg l−1。无论发育阶段如何，T 总是比 E2 更早达到饱和水平，从而导致 E2 的掺入量更高。然而，两种类固醇具有相似的清除模式。吸收和清除显然取决于阶段，在鱼苗中最快，在鱼卵中中等，在卵中最慢。此外，组合的摄取和清除模式表明，E2 的类固醇暴露也高于 T，并且具有阶段依赖性，但在 alevins 中总是明显最高。随后，根据观察到的雌激素消除情况，两次浸泡在 400 μg 1−1 的 E2 中，间隔 2 天给药，以在 alevin 阶段最大限度地暴露，分析其对性逆转的影响，发现可诱导 100% 雌性的产生。我们认为，在鲑鱼发育的初始阶段大量存在的卵黄可以保留外源施用的脂溶性类固醇，从而在治疗完成后为发育中的胚胎提供延长的这些类固醇的供应和暴露。总之，这些发现有助于解释先前观察到的在早期发育过程中施用性类固醇在调节鲑鱼性腺分化方面的高效性，E2 与 T 相比的更高有效性，并阐明了银鲑鱼的 alevin 阶段对外源类固醇作用最敏感的时期的定位。
The uptake and clearance of estradiol-17β (E2) and testosterone (T) were examined during the initial stages of development of coho salmon (Oncorhynchus kisutch), including eyed-eggs, newly hatched alevins and first feeding fry. Radiolabeled steroids were administered through the water in tracer amounts with or without their nonradioactive form at 400 μg l−1. Regardless of developmental stage, saturation levels were invariably attained earlier for T than for E2, thus resulting in a higher incorporation of E2. However, both steroids had similar clearance patterns. Uptake and clearance was clearly stage-dependent, being fastest in fry, intermediate in alevins and slowest in eggs. Furthermore, combined uptake and clearance patterns showed that exposure to steroid was also higher for E2 than for T and stage-dependent, but always markedly highest in alevins. Subsequently, based on the observed elimination of the estrogen, a double immersion in E2 at 400 μg 1−1, administered 2 days apart to maximize exposure during the alevin stage, was assayed for its effect on sex reversal and found to induce the production of 100% females. We suggest that the yolk, which is present in substantial amounts during the initial stages of development in salmonids, can retain the exogenously administered liposoluble steroids, thus providing developing embryos with an extended supply of, and exposure to, these steroids well after the treatment is finished. Together, these findings help to explain the previously observed high effectiveness of sex steroids administered during early development in regulating gonadal differentiation in salmonids, the higher effectiveness of E2 compared to T, and clarify the localization of the most sensitive period to the action of exogenous steroids at the alevin stage in the coho salmon.