Duboué Erik R, Borowsky Richard L, Keene Alex C
Department of Biology, New York University, New York, NY, USA.
Brain Behav Evol. 2012;80(4):233-43. doi: 10.1159/000341403. Epub 2012 Aug 22.
Sleep is a fundamental behavior exhibited almost universally throughout the animal kingdom. The required amount and circadian timing of sleep differs greatly between species in accordance with habitats and evolutionary history. The Mexican blind cavefish, Astyanax mexicanus, is a model organism for the study of adaptive morphological and behavioral traits. In addition to loss of eyes and pigmentation, cave populations of A. mexicanus exhibit evolutionarily derived sleep loss and increased vibration attraction behavior, presumably to cope with a nutrient-poor environment. Understanding the neural mechanisms of evolutionarily derived sleep loss in this system may reveal critical insights into the regulation of sleep in vertebrates. Here we report that blockade of β-adrenergic receptors with propranolol rescues the decreased-sleep phenotype of cavefish. This effect was not seen with α-adrenergic antagonists. Treatment with selective β1-, β2-, and β3-antagonists revealed that the increased sleep observed with propranolol could partially be explained via the β1-adrenergic system. Morphological analysis of catecholamine circuitry revealed conservation of gross catecholaminergic neuroanatomy between surface and cave morphs. Taken together, these findings suggest that evolutionarily derived changes in adrenergic signaling underlie the reduced sleep of cave populations.
睡眠是一种在动物界几乎普遍存在的基本行为。根据栖息地和进化历史的不同，不同物种所需的睡眠量和昼夜节律差异很大。墨西哥盲穴鱼（Astyanax mexicanus）是研究适应性形态和行为特征的模式生物。除了眼睛和色素沉着的丧失外，墨西哥盲穴鱼的洞穴种群还表现出进化而来的睡眠丧失和对振动吸引力增加的行为，推测这是为了应对营养匮乏的环境。了解该系统中进化而来的睡眠丧失的神经机制，可能会揭示脊椎动物睡眠调节的关键见解。在此我们报告，用普萘洛尔阻断β-肾上腺素能受体可挽救穴鱼睡眠减少的表型。α-肾上腺素能拮抗剂未观察到这种效果。用选择性β1、β2和β3拮抗剂治疗表明，普萘洛尔使睡眠增加的现象部分可通过β1-肾上腺素能系统来解释。儿茶酚胺神经回路的形态学分析显示，表层形态和洞穴形态之间的大体儿茶酚胺能神经解剖结构具有保守性。综上所述，这些发现表明，肾上腺素能信号的进化变化是穴鱼种群睡眠减少的基础。
