Division of Medical Pharmacology, Leiden/Amsterdam Centre for Drug Research (LACDR)/Leiden University Medical Centre (LUMC), University of Leiden, Einsteinweg 55, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Neurosci Biobehav Rev. 2010 May;34(6):853-66. doi: 10.1016/j.neubiorev.2009.07.006. Epub 2009 Jul 23.
One of the conundrums in today's stress research is why some individuals flourish and others perish under similar stressful conditions. It is recognized that this individual variability in adaptation to stress depends on the outcome of the interaction of genetic and cognitive/emotional inputs in which glucocorticoid hormones and receptors play a crucial role. Hence one approach towards understanding individual variation in stress coping is how glucocorticoid actions can change from protective to harmful. To address this question we focus on four hypotheses that are connected and not mutual exclusive. First, the classical Glucocorticoid Cascade Hypothesis, in which the inability to cope with chronic stress causes a vicious cycle of excess glucocorticoid and downregulation of glucocorticoid receptors (GR) in the hippocampus triggering a feed-forward cascade of degeneration and disease. Second, the Balance Hypothesis, which takes also the limbic mineralocorticoid receptors (MR) into account and proposes that an integral limbic MR:GR imbalance is causal to altered processing of information in circuits underlying fear, reward, social behaviour and resilience, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and impairment of behavioural adaptation. The MR:GR balance is altered by gene variants of these receptor complexes and experience-related factors, which can induce lasting epigenetic changes in the expression of these receptors. A particular potent epigenetic stimulus is the maternal environment which is fundamental for the Maternal Mediation Hypothesis. The outcome of perinatal gene x environment interaction, and thus of MR:GR-mediated functions depends however, on the degree of 'matching' with environmental demands in later life. The Predictive Adaptation Hypothesis therefore presents a conceptual framework to examine the role of glucocorticoids in understanding individual phenotypic differences in stress-related behaviours over the lifespan.
当今应激研究中的一个难题是,为什么在相似的应激条件下,一些个体能够茁壮成长,而另一些个体却走向崩溃。人们认识到,这种个体对压力的适应能力的差异取决于遗传和认知/情绪输入的相互作用的结果,其中糖皮质激素和受体起着至关重要的作用。因此,理解个体在应激应对方面的差异的一种方法是研究糖皮质激素的作用如何从保护作用转变为有害作用。为了解决这个问题,我们专注于四个相互关联而非相互排斥的假设。首先,是经典的糖皮质激素级联假说,该假说认为,无法应对慢性应激会导致糖皮质激素过度和海马体中糖皮质激素受体(GR)下调的恶性循环,从而引发退化和疾病的前馈级联反应。其次,是平衡假说,该假说还考虑了边缘矿物质皮质激素受体(MR),并提出,完整的边缘 MR:GR 失衡是导致恐惧、奖励、社交行为和弹性、下丘脑-垂体-肾上腺(HPA)轴失调以及行为适应受损的信息处理改变的原因。这些受体复合物的基因变异和与经验相关的因素会改变 MR:GR 平衡,这些因素可以诱导这些受体表达的持久表观遗传变化。一个特别有力的表观遗传刺激是母体环境,它对母体介导假说至关重要。然而,围产期基因与环境相互作用的结果,以及因此产生的 MR:GR 介导的功能,取决于与晚年环境需求的“匹配”程度。因此,预测适应假说提供了一个概念框架,用于研究糖皮质激素在理解与压力相关的行为在整个生命周期中的个体表型差异方面的作用。