Functions of the Secretory Cocktail of Chromaffin Cells in aTeleost Model

肾上腺髓质参与心血管功能的控制，特别是在应激反应中。肾上腺素和去甲肾上腺素是发挥这些作用的激素。随着被称为脑啡肽（enkephalins）的肾上腺髓肽激素的发现，这种情况发生了翻天覆地的变化，这种激素在注射时的作用类似于鸦片。当肾上腺释放这些激素时，其功能尚不清楚，但据推测它们具有欣快和镇痛作用。然而，作为多肽，这些脑啡肽不能进入中枢神经系统的几个区域（因为血脑屏障的存在）。更令人困惑的是，现在很清楚，即使是真正的阿片类药物，如可待因和吗啡，也是由肾上腺产生的。这些真正的鸦片可以进入中枢神经系统的许多区域。显然，了解这三种不同类型的物质之间的相互作用，这三种物质似乎在压力下同时释放，对于基础科学和潜在的治疗原因至关重要。不幸的是，哺乳动物的循环阿片类药物含量相当低，因此对相关研究的价值有限。然而，美洲鳗是血浆阿片类药物研究的理想模型。它的肾上腺髓质等效物含有高浓度的这三种激素，并且可以很容易地在体内和体外研究。此外，它们的血浆中可待因和吗啡的含量比哺乳动物高出好几倍。此外，在实验条件下，鳗鱼比温血动物要顽强得多，而且它的中枢神经系统也比后者容易研究得多。在这项提议中，鳗鱼被采用，因为这个物种具有独特的特征，可以研究肾上腺髓质的三种分泌物的功能和相互作用。实验方法包括：(a)体内和体外激素释放的测量；(b)分析脑啡肽和阿片类药物对心脏、呼吸、渗透调节、代谢和内分泌功能以及激动行为可能产生的生理影响。这些研究应该(1)有助于阐明嗜铬蛋白鸡尾酒的功能，特别是在应激反应中；(2)帮助理解与嗜铬细胞相关的病理；(3)为了解人类胚胎/胎儿的染色质细胞系统提供了基本的见解，该系统与鳗鲡的染色质细胞系统相似。

The adrenal medulla is involved in the control of cardiovascular functions, especially during stress reactions. Epinephrine and norepinephrine are the hormones by which it exerts these effects. This picture has changed drastically with the discovery of adrenomedullary peptide hormones, called enkephalins, that act like opiates when given via injections. The function(s) of these hormones, when released by the adrenal, are unknown though it has been speculated that they have euphoric and analgesic effects. However, being peptides, these enkephalins do not have access to several regions of the central nervous system (because of the presence of a blood-brain barrier). To make matters more confusing, it is now clear that even true opiates, codeine and morphine, are produced by the adrenal gland. These true opiates have access to many regions of the central nervous system. Obviously, an understanding of the interactions of these three different types of substances, which seem to be released simultaneously during stress, is of utmost importance for basic scientific and potentially therapeutic reasons. Unfortunately, mammals have rather low levels of circulating opiates, and are therefore only of limited value for pertinent research. However, the American eel is an ideal model for work on plasma opiates. Its adrenal medulla equivalent contains high concentrations of all three types of hormones, and it can be studied easily in vivo and in vitro. In addition, the plasma levels of codeine and morphine are several times higher than in mammals. Furthermore, the eel is much hardier under experimental conditions than warm-blooded animals, and its central nervous system is much easier to study than that of the latter. In this proposal the eel is employed because this species has unique features for research on the functions and interactions of the three types of secretions of the adrenal medulla. Experimental approaches include:(a) measurement of hormone release in vivo and in vitro; (b) analysis of the possible physiological effects of enkephalins and opiates on cardiac, respiratory, osmoregulatory, metabolic and endocrine functions, and on agonistic behavior. These studies should (1) help to clarify the functions of the chromaffin secretory cocktail, particularly during stress responses; (2) help to understand pathologies related to the chromaffin cell; and (3) provide basic insights for the understanding of the chromaffin cell system of the human embryo/fetus, which is similar to that of Anguilla rostrata.