Winter P, Nau H, Lampen A, Kamphues J
Institute of Animal Nutrition, University of Veterinary Medicine, Hannover Foundation, Hannover, Germany.
J Anim Physiol Anim Nutr (Berl). 2008 Jun;92(3):337-44. doi: 10.1111/j.1439-0396.2007.00797.x.
There is considerable evidence that exogenous estrogenic compounds can have adverse effects on fertility. The main reason cited in literature for hyperestrogenism in pigs is contamination of feedstuffs by the mycotoxin zearalenone (Boehm, 2000), but further estrogenically active substances might also be involved in cases of impaired fertility with symptoms like enlarged, red-coloured vulvae in piglets, irregular estrus cycles and anestrus of sows (Bennetts et al., 1946; Drane et al., 1981). It is well known that soy used in diets for pigs as a main protein source contains phytoestrogens. Amongst them, isoflavones like genistein and daidzein are of particular interest. Aim of this study was to optimize and use an established bioassay (Kluczka, 2003) to determine estrogenic activity in feedstuffs for pigs related to isoflavones and further substances with estrogenic potential. This bioassay is a reporter gene assay based on stably transfected human embryonal kidney cells (HEK 293) that contains either alpha or beta estrogen receptor (alpha- or beta-HEK). The estrogenic activity measured in the luciferase assay was expressed in estradiol-equivalents (EEQ) and the results were compared with the isoflavone content (genistein, daidzein) obtained by chemical analysis using high performance liquid chromatography-Ultraviolet (HPLC-UV). Mean estrogenic activity in diets fed to sows in herds with altered fertility was 275.8 microg EEQ/kg feed in alpha-HEK cells and 295.0 microg EEQ/kg feed in beta-HEK cells. Feedstuffs from herds without any altered fertility showed an average estrogenic activity of 204.9 microg EEQ/kg feed in alpha-HEK and 213.3 microg EEQ/kg feed in beta-HEK. The estrogenic activity was strongly related to the concentration of the isoflavones (alpha-HEK, r(2)=0.9488; beta-HEK, r(2)=0.9427). Clinically relevant zearalenone concentrations (>50-150 microg/kg feed) displayed estrogenic effects in the bioassay that did not differ significantly from those caused by high isoflavone concentration because of the use of soy as protein source.
有大量证据表明，外源性雌激素化合物会对生育能力产生不利影响。文献中提到猪体内雌激素过多的主要原因是饲料被霉菌毒素玉米赤霉烯酮污染（Boehm，2000年），但在生育能力受损的情况下，如仔猪外阴肿大、发红，母猪发情周期不规律和发情停止等症状，可能也涉及其他具有雌激素活性的物质（Bennetts等人，1946年；Drane等人，1981年）。众所周知，作为猪饲料主要蛋白质来源的大豆含有植物雌激素。其中，染料木黄酮和大豆苷元等异黄酮特别受关注。本研究的目的是优化并使用一种已建立的生物测定法（Kluczka，2003年）来测定猪饲料中与异黄酮及其他具有雌激素潜力的物质相关的雌激素活性。这种生物测定法是一种基于稳定转染的人胚肾细胞（HEK 293）的报告基因测定法，该细胞含有α或β雌激素受体（α-或β-HEK）。在荧光素酶测定中测得的雌激素活性以雌二醇当量（EEQ）表示，并将结果与通过高效液相色谱-紫外（HPLC-UV）化学分析获得的异黄酮含量（染料木黄酮、大豆苷元）进行比较。在生育能力改变的猪群中，饲喂母猪的日粮在α-HEK细胞中的平均雌激素活性为275.8微克EEQ/千克饲料，在β-HEK细胞中的平均雌激素活性为295.0微克EEQ/千克饲料。来自生育能力未改变的猪群的饲料在α-HEK中的平均雌激素活性为204.9微克EEQ/千克饲料，在β-HEK中的平均雌激素活性为213.3微克EEQ/千克饲料。雌激素活性与异黄酮浓度密切相关（α-HEK，r(2)=0.9488；β-HEK，r(2)=0.9427）。由于使用大豆作为蛋白质来源，临床上相关的玉米赤霉烯酮浓度（>50-150微克/千克饲料）在生物测定中显示出的雌激素效应与高异黄酮浓度引起的效应没有显著差异。
