Excretion, Metabolism and Enterohepatic Circulation Pathways and Their Role in Overall Thyroid Hormone Regulation in the Rat
Excretion, Metabolism and Enterohepatic Circulation Pathways and Their Role in Overall Thyroid Hormone Regulation in the Rat
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排泄、代谢和肠肝循环途径及其在大鼠总体甲状腺激素调节中的作用
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发表时间：
1988
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通讯作者：
J. DiStefano
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作者：
J. DiStefano
哺乳动物的主要内分泌腺分泌的甲状腺、肾上腺皮质和其他激素的调节被广泛认为主要是与垂体、下丘脑或两者的反馈控制关系，肝胆和肠机制只起被动或排泄作用。我提出了另一种观点，肠肝成分在甲状腺内分泌功能，这表明一个功能和更普遍的作用，肠道，在一个更复杂的层次系统控制甲状腺激素水平，影响和经济的大鼠，并可能在其他哺乳动物。一个中心因素是这些激素的肠肝循环的存在，或它们从尿道池重吸收到门静脉，然后是全身血液。这一过程影响了它们在整个生物体中的动态行为，而不仅仅是激素经济，因为激素在血液和肠道（包括腔内容物中的大池）之间的双向运输使全部或部分肠道位于调节甲状腺激素的系统内部。我们回顾了这一假设的证据和可能的意义，包括大鼠激素水平控制的具体方面，包括脱碘，共轭和其他代谢途径，特别是在肝脏和肠道，粪便和尿液排泄（汇）和激素生产（源）途径。据推测，甲状腺激素的肝肠子系统调节的调节剂涉及肝脏中的激素结合和降解过程及其随后在胆汁中的分泌，以及肠道的细菌解结合、重吸收和某些激素储存机制的综合作用。
Regulation of thyroid, adrenocortical and other hormones secreted by the major endocrine glands in mammals is widely attributed primarily to feedback control relationships with the pituitary, hypothalamus or both, with hepatobiliary and intestinal mechanisms having no more than a passive or excretory role. I present another view of enterohepatic components in thyroid endocrine function, suggesting a functional and more pervasive role for the intestine, in a more complex hierarchical system controlling thyroid hormone levels, effects and economy in the rat, and possibly in other mammals. A central factor is the existence of enterohepatic cycling of these hormones, or their reabsorption from intestnal pools to portal and then systemic blood. This process affects their dynamic behavior throughout the organism, not only hormone economy, because bidirectional transport of hormone between blood and intestine (including large pools in luminal contents) renders all or part of the gut internal to the system regulating thyroid hormones. We review the evidence for and possible significance of this hypothesis, covering specific aspects of hormone level control in the rat, including the deiodination, conjugation and other metabolic pathways, particularly in liver and intestine, and the fecal and urinary excretory (sink) and hormone production (source) pathways. The modulators of enterohepatic subsystem regulation of thyroid hormones are postulated to involve the combined effects of hormone conjugation and degradation processes in liver and their subsequent secretion in bile, coupled with the bacterial deconjugation, the reabsorption and certain hormone storage mechanisms of the intestine.