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 is represented by 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.

脊椎动物的大脑结构与行为性别差异已被大量文献证实。探究行为性别差异神经机制的绝佳模型，便是性角色逆转（sex-role-reversed）物种。在多数鸟类中，雄性相较于雌性会更激烈地争夺配偶与资源，因此学界普遍认为，雄性负责此类行为的脑区发育程度优于雌性。由于此类行为与脑区均由雄激素激活，雄性在繁殖期的睾酮水平通常会升高。因此，在性角色逆转物种中，要么雌性的特定脑区应更为发达，要么其类固醇激素谱应呈现性别反转状态。本研究以圈养种群的棕三趾鹑（Turnix suscitator）为对象，检测了其循环激素水平，以及类固醇激素受体与芳香化酶的基因表达情况。尽管雌性棕三趾鹑会展现求偶与争斗行为，但并未发现其类固醇激素谱存在性别反转的证据。不过，本研究在下丘脑与边缘脑的多个区域中，发现了雄激素受体基因表达的雌性偏向性性别差异，且此类差异在幼鸟孵化出壳时便已存在。此类性别差异在非性角色逆转物种中尚未见报道。上述数据表明，神经对雄激素的敏感性增强，可能参与介导性角色逆转行为的调控机制。