Regulation of Adrenal Steroidogenesis in Birds

鸟类的肾上腺能够合成几种类似皮质醇的激素。其中一个负责调节机体碳水化合物代谢的某些方面，而另一个则作用于肾脏，以确保适当的盐分和水分平衡。从腺体中分离出来的细胞对含有垂体激素促肾上腺皮质激素的孵育液产生反应，产生两种皮质醇样激素。这些细胞还会对含有一种名为血管紧张素II的激素的孵育液做出反应。在这种情况下，它们会产生相对大量的盐分和水分调节激素，但不会产生碳水化合物调节激素。促肾上腺皮质激素和血管紧张素II对分离的组织样本的这些作用模拟了有机体在压力和含有不同水平盐分的饮食中的肾上腺反应。直到几年前，人们还认为这些激素的分泌完全受促肾上腺皮质激素和血管紧张素II的控制，但最近越来越多的证据表明，神经起源的因素也可能起作用，调节肾上腺类固醇激素的合成和释放。终止于肾上腺的神经细胞除了典型的肾上腺素样激素外，还含有并可能分泌多种多肽。这项拟议的研究将有助于我们理解神经细胞来源的调节剂如何影响肾上腺类固醇激素合成的总体控制。实验模型将是鸭子胚胎中发育中的肾上腺。通过使用最新的超微结构、组织化学和免疫细胞化学技术，将对肾上腺素样因子和多肽因子的性质、位置和分布进行研究。同时，将根据肾上腺类固醇生成细胞的分泌和合成特性来评估其在胚胎发育过程中的功能发育和反应。由于肾上腺产生的激素对包括人类在内的所有脊椎动物的生存都是绝对必要的，因此了解参与调节这一重要内分泌腺的控制机制的性质是很重要的。此外，了解这些腺体在鸟类中的功能不仅是生物学家的根本兴趣，而且对整个社会也很重要，因为鸟类是世界各地数百万人的重要食物来源。

The bird adrenal gland is capable of synthesizing several cortisone-like hormones. One of these is responsible for the regulation of certain aspects of carbohydrate metabolism in the organism, while another acts on the kidney to ensure proper salt and water balance. Cells isolated from the gland respond to incubation media containing the pituitary hormone, corticotropin by producing the two types of cortisone-like hormone. The cells also respond to incubation media containing a hormone called angiotensin II. Under these circumstancs, they produce relatively large amounts of the salt- and water regulating hormone, but none of the carbohydrate-regulating hormone. These effects of corticotropin and angiotensin II on isolated tissue samples simulate the responses of the adrenal gland in organisms subjected to stress and diets containing different levels of salts. Until a few years ago, it was assumed that the secretion of these hormones was controlled exclusively by corticotropin and angiotensin II but evidence has recently accumulated to indicate that factors of neural origin may also act, to regulate the synthesis and release of adrenal steroid hormones. Nerve cells terminating in the adrenal gland contain, and may secrete, a variety of polypeptides, in addition to the typical adrenalin-like hormones. The proposed studies will contribute to our understanding of the ways in which regulators derived from nerve cells influence the overall control of adrenal steroid hormone synthesis. The experimental model will be the developing adrenal gland in the duck embryo. Through the use of the latest ultrastructural, histochemical and immunocytochemical techiques the nature, the loci and the distribution of the adrenalin-like and peptide factors will be investigated. At the same time the functional development and responsiveness of the adrenal steroidogenic cells during embryonic development will be assessed in terms of their secretory and synthetic properties. Since the hormones produced by the adrenal gland are absolutely essential to the survival of all vertebrates, including Man, it is important to understand the nature of the control mechanisms involved in the regulation of this important endocrine gland. Also, knowledge of how these glands function in birds is not only of fundamental interest to the biologist, it is also important to society in general, for birds constitute an important source of food for many millions of people around the world.//