Department of Biology, University of Ottawa, Ontario, Canada.
Auton Neurosci. 2011 Nov 16;165(1):54-66. doi: 10.1016/j.autneu.2010.04.006. Epub 2010 Jun 12.
If severe enough, periods of acute stress in animals may be associated with the release of catecholamine hormones (noradrenaline and adrenaline) into the circulation; a response termed the acute humoral adrenergic stress response. The release of catecholamines from the sites of storage, the chromaffin cells, is under neuroendocrine control, the complexity of which appears to increase through phylogeny. In the agnathans, the earliest branching vertebrates, the chromaffin cells which are localized predominantly within the heart, lack neuronal innervation and thus catecholamine secretion in these animals is initiated solely by humoral mechanisms. In the more advanced teleost fish, the chromaffin cells are largely confined to the walls of the posterior cardinal vein at the level of the head kidney where they are intermingled with the steroidogenic interrenal cells. Catecholamine secretion from teleost chromaffin cells is regulated by a host of cholinergic and non-cholinergic pathways that ensure sufficient redundancy and flexibility in the secretion process to permit synchronized responses to a myriad of stressors. The complexity of catecholamine secretion control mechanisms continues through the amphibians, reptiles and birds although neural (cholinergic) regulation may become increasingly important in birds. Discrete adrenal glands are present in the non-mammalian tetrapods but unlike in mammals, there is no clear division of a steroidogenic cortex and a chromaffin cell enriched medulla. However, in all groups, there is an obvious intermingling of chromaffin and steroiodogenic cells. The association of the two cell types may be particularly important in the amphibians and birds because like in mammals, the enzyme catalysing the methylation of noradrenaline to adrenaline, PNMT, is under the control of the steroid cortisol.
如果严重的话，动物的急性应激期可能与儿茶酚胺激素（去甲肾上腺素和肾上腺素）释放到循环系统有关；这种反应被称为急性体液性肾上腺素应激反应。儿茶酚胺从储存部位，即嗜铬细胞释放，受神经内分泌控制，其复杂性似乎随着系统发生而增加。在无颌类动物，即最早分支的脊椎动物中，主要位于心脏内的嗜铬细胞缺乏神经元支配，因此这些动物的儿茶酚胺分泌仅由体液机制启动。在更先进的硬骨鱼中，嗜铬细胞主要局限于头部肾脏水平的后主静脉壁内，与类固醇生成的肾间细胞混合在一起。硬骨鱼嗜铬细胞的儿茶酚胺分泌受多种胆碱能和非胆碱能途径的调节，这些途径确保了分泌过程中有足够的冗余和灵活性，以允许对无数应激源做出同步反应。儿茶酚胺分泌控制机制的复杂性在两栖动物、爬行动物和鸟类中继续存在，尽管神经（胆碱能）调节在鸟类中可能变得越来越重要。非哺乳动物四足动物中存在离散的肾上腺，但与哺乳动物不同，没有明确的类固醇生成皮质和富含嗜铬细胞的髓质的划分。然而，在所有群体中，嗜铬细胞和类固醇生成细胞明显混合在一起。两种细胞类型的关联在两栖动物和鸟类中可能特别重要，因为与哺乳动物一样，催化去甲肾上腺素甲基化为肾上腺素的酶，即 PNMT，受皮质醇的类固醇控制。
