Data and code from: How a territorial challenge changes sex steroid-related gene networks in the female brain: A field experiment with the tree swallow

Territorial competition can stimulate secretion of testosterone (T), which
is thought to act on neural circuits of aggression to promote further
aggression. Here, we test the hypothesis that competition modulates sex
steroid sensitivity and conversion in the brain, focused on the female
tree swallow (Tachycineta bicolor). In this bird species, exogenous T
enhances female aggression, but social competition for limited nesting
territories does not stimulate systemic T elevation. We exposed
free-living females to simulated territorial intrusions and sampled five
regions of the vertebrate social behavior network (SBN). Using
quantitative PCR, we measured mRNA abundance of: androgen receptor,
5-alpha reductase, estrogen receptor alpha, and aromatase. Using standard
analyses, we found essentially no treatment effect on mRNA abundance in
any one brain area; however, network analyses revealed marked
socially-induced changes in gene co-expression across the SBN. After a
territorial challenge, gene expression was more positively correlated with
T, and genes specific to the androgen-signaling pathway were also more
positively correlated with one another. The challenged brain also
exhibited stronger negative correlations among genes in the nucleus
taeniae, but stronger positive correlations between the lateral septum and
bed nucleus of the stria terminalis. Together, these findings suggest
that, in response to female-female territorial challenges, T acts on
androgen-mediated circuits of aggression, with some divergence in gene
regulation in the nucleus taeniae. The post-transcriptional consequences
of these shifts require more research, but their existence underscores
insights to be gained from analyzing the neuroendocrine properties of the
SBN using network-level perspectives.

领地竞争可刺激睾酮（testosterone, T）的分泌，学界普遍认为睾酮可作用于攻击行为的神经环路，以进一步促进攻击行为。本研究聚焦于雌性树燕（Tachycineta bicolor），旨在验证竞争可调控大脑内性类固醇的敏感性与转化过程这一假说。在该鸟类中，外源性睾酮可增强雌性个体的攻击行为，但针对有限筑巢领地的社会性竞争并不会引发循环睾酮水平升高。我们将自由活动的雌性个体暴露于模拟领地入侵环境中，并采集了脊椎动物社会行为网络（social behavior network, SBN）的五个脑区样本。通过定量聚合酶链反应（quantitative PCR），我们检测了以下基因的mRNA表达丰度：雄激素受体、5α-还原酶、雌激素受体α以及芳香化酶。通过标准分析方法，我们未在任一脑区中发现实验处理对mRNA表达丰度存在显著影响；但网络分析结果显示，脊椎动物社会行为网络内的基因共表达模式出现了显著的社会性诱导变化。在领地挑战后，基因表达与睾酮水平的正相关性显著增强，且雄激素信号通路特异性基因之间的正相关性也有所提升。经历领地挑战的大脑中，带状核（nucleus taeniae）内的基因间负相关性更强，而外侧隔核（lateral septum）与终纹床核（bed nucleus of the stria terminalis）之间的正相关性则更为显著。综合以上结果，本研究表明，在应对雌性间领地挑战时，睾酮可作用于雄激素介导的攻击行为环路，且带状核内的基因调控模式存在一定差异。这些变化所带来的转录后效应仍有待进一步研究，但这类效应的存在凸显了通过网络层面视角分析脊椎动物社会行为网络的神经内分泌特性所能获得的研究价值。