Brandstätter Roland, Abraham Ute
Department of Biological Rhythms and Behaviour, Max-Planck-Research Centre for Ornithology, Andechs, Germany.
Chronobiol Int. 2003 Jul;20(4):637-55. doi: 10.1081/cbi-120023343.
In mammals, the "master clock" controlling circadian rhythmicity is located in the hypothalamic suprachiasmatic nuclei (SCN). Until now, no comparable structure has been unambiguously described in the brain of any nonmammalian vertebrate. In birds, early anatomical and lesioning studies described a SCN located in the anterior hypothalamus, but whether birds possess a nucleus equivalent to the mammalian SCN remained controversial. By reviewing the existing literature it became evident that confusion in delineation and nomenclature of hypothalamic cell groups may be one of the major reasons that no coherent picture of the avian hypothalamus exists. In this review, we attempt to clarify certain aspects of the organization of the avian hypothalamus by summarizing anatomical and functional studies and comparing them to immunocytochemical results from our laboratory. There is no single cell group in the avian hypothalamus that combines the morphological and neurochemical features of the mammalian SCN. Instead, certain aspects of anatomy and morphology suggest that at least two anatomically distinct cell groups, the SCN and the lateral hypothalamic nucleus (LHN), bear some of the characteristics of the mammalian SCN.
在哺乳动物中，控制昼夜节律的“主时钟”位于下丘脑视交叉上核（SCN）。到目前为止，在任何非哺乳动物脊椎动物的大脑中都尚未明确描述出类似的结构。在鸟类中，早期的解剖学和损伤研究描述了位于下丘脑前部的一个SCN，但鸟类是否拥有与哺乳动物SCN相当的核团仍存在争议。通过回顾现有文献，很明显下丘脑细胞群的划分和命名混乱可能是目前尚无关于鸟类下丘脑的连贯图景的主要原因之一。在本综述中，我们试图通过总结解剖学和功能研究并将其与我们实验室的免疫细胞化学结果进行比较，来阐明鸟类下丘脑组织结构的某些方面。鸟类下丘脑没有单个细胞群兼具哺乳动物SCN的形态和神经化学特征。相反，解剖学和形态学的某些方面表明，至少有两个解剖学上不同的细胞群，即SCN和下丘脑外侧核（LHN），具有哺乳动物SCN的一些特征。
