Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
Gen Comp Endocrinol. 2009 Nov-Dec;164(2-3):142-50. doi: 10.1016/j.ygcen.2009.03.020. Epub 2009 Mar 31.
The physiological responses to stressors, including hormonal profiles and associated tissue responsiveness have been extensively studied in teleosts, but the molecular mechanisms associated with this adaptive response are not well understood. The advent of cDNA microarray technology has transformed the field of functional genomics by revealing global gene expression changes in response to stressor exposures even in non-mammalian vertebrates, including fish. A unifying response in studies related to stressor exposure is activation of the hypothalamus-pituitary-interrenal (HPI) axis in fish, leading to cortisol release into the circulation. Here we will discuss the implications of some of the gene expression changes observed in response to acute stress in fish, while highlighting a role for cortisol in this adaptive stress response. As liver is a key organ for metabolic adjustments to stressors and also is a major target for cortisol action, the genomic studies pertaining to stress and glucocorticoid regulation have focused mainly on this tissue. The studies have identified several genes that are altered transiently after an acute stressor exposure in fish. A number of these stress-responsive genes were also modulated by glucocorticoid receptor activation, suggesting that elevation in cortisol levels during stressor exposure may be a key signal for target tissue molecular programming, essential for stress adaptation. The identification of regulatory gene networks that are stress activated, and modulated by cortisol, both in hepatic and extra-hepatic tissues, including gonads, brain, immune cells and gills, will provide a mechanistic framework to characterize the multifaceted role of cortisol during stress adaptation.
鱼类等硬骨鱼类的应激反应包括激素谱和相关组织反应性已经得到了广泛的研究,但与这种适应反应相关的分子机制还不是很清楚。cDNA 微阵列技术的出现改变了功能基因组学领域,它揭示了即使在非哺乳动物脊椎动物(包括鱼类)中,应激暴露引起的全基因表达变化。在与应激暴露相关的研究中,一个统一的反应是鱼类下丘脑-垂体-肾上腺(HPI)轴的激活,导致皮质醇释放到循环中。在这里,我们将讨论一些鱼类急性应激反应中观察到的基因表达变化的意义,同时强调皮质醇在这种适应性应激反应中的作用。由于肝脏是对应激进行代谢调整的关键器官,也是皮质醇作用的主要靶器官,因此与应激和糖皮质激素调节相关的基因组研究主要集中在该组织上。这些研究已经确定了一些在鱼类急性应激暴露后会发生短暂变化的基因。许多这些应激反应基因也受到糖皮质激素受体激活的调节,这表明应激暴露期间皮质醇水平的升高可能是靶组织分子编程的关键信号,对适应应激至关重要。鉴定应激激活的调控基因网络,以及在肝外组织(包括性腺、大脑、免疫细胞和鳃)中被皮质醇调节,将为描述皮质醇在应激适应中的多方面作用提供一个机制框架。