Ruoff W L, Dziuk P J
University of Illinois, Department of Animal Sciences, Urbana 61801.
Domest Anim Endocrinol. 1994 Apr;11(2):197-208. doi: 10.1016/0739-7240(94)90027-2.
To determine the absorption and metabolism of 17 beta-estradiol (E2) by the stomach and liver of the pig, crystalline E2 was placed in the stomach of prepubertal gilts. Blood samples were subsequently obtained from the hepatic portal and jugular veins and plasma was assayed for E2, estrone (E1), 17 beta-estradiol-glucuronide (E2G), estrone-glucuronide (E1G) and estrone-sulfate (E1S). Concentrations of E2, E1, E2G and E1S rose in the hepatic portal vein within five min and remained elevated for several hr. Concentration of E2 represented only 6% of the total estrogen detected in the hepatic portal vein during the sampling period, indicating that most of the E2 was converted or conjugated prior to entering the hepatic portal vein. The metabolism of E2 presumably occurred in the stomach mucosa because food had been withheld for 26 hr before infusion of E2. Concentrations of E2G, E1G and E1S, but not E2 and E1, rose in the jugular vein and remained elevated for several hr. The lack of a rise in E2 and E1 in the jugular vein indicates that the E2 and E1 from the hepatic portal vein were completely converted and/or removed by the liver. Most of E2 was converted to E1 and then to E1G. The infusion of bile containing normal estrogens from pregnant gilts into the duodenum of prepubertal gilts resulted in a peak of E1G and E2G in the hepatic portal and jugular veins within a few minutes. This was followed in about 180 min by a second sustained rise. The first peak was essentially abolished by extracting E1 and E2 from the bile before infusion. The second peak failed to occur in gilts given antibiotics orally to reduce gut bacteria before infusion of bile.
为了确定猪的胃和肝脏对17β-雌二醇(E2)的吸收和代谢情况,将结晶状E2置于青春期前小母猪的胃中。随后从肝门静脉和颈静脉采集血样,并检测血浆中的E2、雌酮(E1)、17β-雌二醇葡萄糖醛酸苷(E2G)、雌酮葡萄糖醛酸苷(E1G)和硫酸雌酮(E1S)。E2、E1、E2G和E1S的浓度在5分钟内于肝门静脉中升高,并在数小时内保持升高。在采样期间,E2的浓度仅占肝门静脉中检测到的总雌激素的6%,这表明大部分E2在进入肝门静脉之前就已被转化或结合。E2的代谢可能发生在胃黏膜中,因为在注入E2之前已禁食26小时。E2G、E1G和E1S的浓度在颈静脉中升高,但E2和E1未升高,并在数小时内保持升高。颈静脉中E2和E1未升高表明来自肝门静脉的E2和E1已被肝脏完全转化和/或清除。大部分E2先转化为E1,然后再转化为E1G。将来自怀孕小母猪的含有正常雌激素的胆汁注入青春期前小母猪的十二指肠,导致肝门静脉和颈静脉中的E1G和E2G在几分钟内达到峰值。大约180分钟后出现第二次持续升高。在注入胆汁之前从胆汁中提取E1和E2基本上消除了第一个峰值。在注入胆汁之前口服抗生素以减少肠道细菌的小母猪中未出现第二个峰值。