Data from: Neuroendocrine correlates of sex-role reversal in barred buttonquails

Sex differences in brain structure and behaviour are well-documented among vertebrates. An excellent model exploring the neural mechanisms of sex differences in behaviour represent sex-role reversed species. In the majority of bird species males compete over access to mates and resources more strongly than do females. It is thought that the responsible brain regions are, therefore, more developed in males than in females. Because these behaviours and brain regions are activated by androgens, males usually have increased testosterone levels during breeding. Therefore, in species with sex-role reversal, certain areas of the female brain should be more developed or steroid hormone profiles should be sexually reversed. Here I studied circulating hormone levels and gene expression of steroid hormone receptors and aromatase in a captive population of barred buttonquails (Turnix suscitator). While females performed courtship and agonistic behaviours, there was no evidence for sexually reversed hormone profiles. However, I found female-biased sex differences in gene expression of androgen receptors in several hypothalamic and limbic brain regions that were already in place at hatching. Such sex differences are not known from non-sex-role reversed species. These data suggest that increased neural sensitivity to androgens could be involved in the mechanisms mediating sex-role reversed behaviours.脊椎动物脑结构与行为的性别差异已有充分文献记载。性角色反转（sex-role reversed）物种是探究行为性别差异神经机制的绝佳模型。在多数鸟类类群中，雄性争夺配偶与资源的竞争强度远高于雌性，因此学界普遍认为，介导这类竞争行为的脑区在雄性体内发育更为充分。由于此类行为与对应脑区均由雄激素（androgens）激活，雄性在繁殖期通常会出现睾酮（testosterone）水平升高的现象。据此，在性角色反转物种中，雌性脑内的特定区域理应更为发达，或是其类固醇激素谱（steroid hormone profiles）出现性别反转。本研究以圈养种群的斑翅三趾鹑（Turnix suscitator）为实验对象，检测了其循环激素水平，以及类固醇激素受体与芳香化酶（aromatase）的基因表达情况。尽管雌性斑翅三趾鹑会展现求偶与争斗行为，但未观测到其类固醇激素谱存在性别反转的迹象。然而，本研究在下丘脑（hypothalamic）与边缘脑区（limbic brain regions）的多个区域中，发现雄激素受体的基因表达存在雌性偏倚的性别差异，且该差异在个体孵化出壳时便已确立。这类性别差异在非性角色反转物种中尚未见报道。上述研究结果表明，神经组织对雄激素的敏感性增强，可能参与介导性角色反转行为的调控机制。