Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Instituto Tecnológico de Chascomús (CONICET-UNSAM), Chascomús, Buenos Aires B7130IWA, Argentina.
Gen Comp Endocrinol. 2020 Jul 1;293:113475. doi: 10.1016/j.ygcen.2020.113475. Epub 2020 Mar 30.
The vertebrate pituitary is arguably one of the most complex endocrine glands from the evolutionary, anatomical and functional perspectives. The pituitary plays a master role in endocrine physiology for the control of growth, metabolism, reproduction, water balance, and the stress response, among many other key processes. The synthesis and secretion of pituitary hormones are under the control of neurohormones produced by the hypothalamus. Under this conceptual framework, the communication between the hypophysiotropic brain and the pituitary gland is at the foundation of our understanding of endocrinology. The anatomy of the connections between the hypothalamus and the pituitary gland has been described in different vertebrate classes, revealing diverse modes of communication together with varying degrees of complexity. In this context, the evolution and variation in the neuronal, neurohemal, endocrine and paracrine modes will be reviewed in light of recent discoveries, and a re-evaluation of earlier observations. There appears to be three main hypothalamo-pituitary communication systems: 1. Diffusion, best exemplified by the agnathans; 2. Direct innervation of the adenohypophysis, which is most developed in teleost fish, and 3. The median eminence/portal blood vessel system, most conspicuously developed in tetrapods, showing also considerable variation between classes. Upon this basic classification, there exists various combinations possible, giving rise to taxon and species-specific, multimodal control over major physiological processes. Intrapituitary paracrine regulation and communication between folliculostellate cells and endocrine cells are additional processes of major importance. Thus, a more complex evolutionary picture of hypothalamo-hypophysial communication is emerging. There is currently little direct evidence to suggest which neuroendocrine genes may control the evolution of one communication system versus another. However, studies at the developmental and intergenerational timescales implicate several genes in the angiogenesis and axonal guidance pathways that may be important.
从进化、解剖和功能的角度来看，脊椎动物垂体无疑是最复杂的内分泌腺之一。垂体在控制生长、代谢、生殖、水盐平衡和应激反应等许多关键过程中起着主导作用。垂体激素的合成和分泌受下丘脑产生的神经激素控制。在这个概念框架下，下丘脑与垂体之间的通讯是我们理解内分泌学的基础。不同脊椎动物类群的下丘脑与垂体之间的连接解剖结构已经被描述，揭示了不同的通讯模式以及不同程度的复杂性。在这种情况下，将根据最近的发现以及对早期观察结果的重新评估，综述神经元、神经分泌、内分泌和旁分泌模式的进化和变异。似乎存在三种主要的下丘脑-垂体通讯系统：1. 扩散，以无颌类动物为最佳例证；2. 对腺垂体的直接神经支配，在硬骨鱼类中最为发达；3. 正中隆起/门脉血管系统，在四足动物中最为显著，在不同类群之间也存在着相当大的变异。在这个基本分类的基础上，存在着各种可能的组合，导致了主要生理过程的分类和物种特异性的多模式控制。垂体内旁分泌调节和滤泡星状细胞与内分泌细胞之间的通讯是另外两个重要的过程。因此，下丘脑-垂体通讯的进化图景变得更加复杂。目前几乎没有直接证据表明哪些神经内分泌基因可能控制一种通讯系统相对于另一种通讯系统的进化。然而，在发育和代际时间尺度上的研究表明，一些基因在血管生成和轴突导向途径中可能很重要。
