Data from: Evolutionary conserved neural signature of early life stress affects animal social competence

In vertebrates the early social environment can persistently influence behaviour and social competence later in life. However, the molecular mechanisms underlying variation in animal social competence are largely unknown. In rats, high-quality maternal care causes an upregulation of hippocampal glucocorticoid receptors (gr) and reduces offspring stress responsiveness. This identifies gr regulation as a candidate mechanism for maintaining variation in animal social competence. We tested this hypothesis in a highly-social cichlid fish, Neolamprologus pulcher, reared with or without caring parents. We find that the molecular pathway translating early social experience into later-life alterations of the stress axis is homologous across vertebrates: fish reared with parents expressed the glucocorticoid receptor gr1 more in the telencephalon. Furthermore, expression levels of the transcription factor egr-1 (early growth response 1) were associated with gr1 expression in the telencephalon and hypothalamus. When blocking glucocorticoid receptors (GR) with an antagonist, mifepristone (RU486), parent-reared individuals showed more socially appropriate, submissive behaviour when intruding a larger conspecific's territory. Remarkably, mifepristone-treated fish were less attacked by owners and had a higher likelihood of territory takeover. Our results indicate that early social-environment effects on stress axis programming are mediated by an evolutionary conserved molecular pathway, which is causally involved in environmentally-induced variation of animal social competence.

在脊椎动物中，早期社会环境可对个体成年后的行为与社会能力产生持久影响。然而，目前学界对介导动物社会能力个体差异的分子机制仍知之甚少。在大鼠模型中，亲代提供的高质量抚育可上调海马体糖皮质激素受体（glucocorticoid receptors, GR）的表达，并降低子代的应激响应性。这表明糖皮质激素受体的调控或许是维持动物社会能力个体差异的潜在机制。我们以高度社会化的慈鲷物种燕尾鮨丽鱼（Neolamprologus pulcher）为实验对象，设置有亲代抚育与无亲代抚育两种饲养条件，对该假说进行验证。研究发现，将早期社会经验转化为成年后应激轴改变的分子通路在脊椎动物间具有同源性：有亲代抚育的慈鲷端脑内的糖皮质激素受体1（gr1）表达水平更高。此外，转录因子早期生长反应蛋白1（early growth response 1, Egr-1）的表达水平与端脑及下丘脑内的gr1表达量显著相关。当使用拮抗剂米非司酮（mifepristone, RU486）阻断糖皮质激素受体（GR）时，有亲代抚育的个体在侵入更大同种个体的领地时，会表现出更符合社会规范的顺从行为。值得注意的是，经米非司酮处理的慈鲷受到领地所有者攻击的概率更低，且成功夺取领地的可能性更高。本研究结果表明，早期社会环境对动物应激轴编程的影响由一条进化保守的分子通路所介导，且该通路直接参与了环境诱导的动物社会能力个体差异的形成。