Hazenberg M P, de Herder W W, Visser T J
Department of Medical Microbiology, Medical Faculty, Erasmus University, Rotterdam, The Netherlands.
FEMS Microbiol Rev. 1988 Feb;4(1):9-16. doi: 10.1111/j.1574-6968.1988.tb02709.x-i1.
Glucuronide and sulfate conjugation are important pathways in the peripheral metabolism of thyroid hormone. These reactions occur predominantly in the liver, and especially the glucuronides are excreted in the bile. Although an enterohepatic circulation after intestinal hydrolysis of iodothyronine conjugates is suggested by several authors, substantial proof has not been presented so far. In the present paper experimental work from our group is reviewed. The studies showed that fecal suspensions of human or rat origin hydrolysed iodothyronine conjugates, whereas oral administration of antibiotics to rats strongly reduced this capacity. Obligately anaerobic intestinal bacteria were found to be responsible for the hydrolysis and several species belonging to the major residents of the intestinal flora of man and rat could be isolated and identified. Recent studies with conventional and decontaminated rats produced strong support for the existence of an enterohepatic circulation of thyroid hormone. Our findings are discussed in connection with other relevant studies on this subject.
葡萄糖醛酸化和硫酸化结合是甲状腺激素外周代谢的重要途径。这些反应主要发生在肝脏，尤其是葡萄糖醛酸结合物经胆汁排泄。尽管几位作者提出了碘甲状腺原氨酸结合物在肠道水解后存在肝肠循环，但迄今为止尚未提供确凿证据。本文综述了我们小组的实验工作。研究表明，人源或大鼠源的粪便悬液可水解碘甲状腺原氨酸结合物，而给大鼠口服抗生素则会显著降低这种能力。发现专性厌氧肠道细菌是水解的原因，并且可以分离和鉴定出属于人和大鼠肠道菌群主要成员的几种细菌。最近对常规大鼠和无菌大鼠的研究有力地支持了甲状腺激素肝肠循环的存在。我们的研究结果结合关于该主题的其他相关研究进行了讨论。
