Accumulating evidence suggests that intranasal oxytocin (OXT; 24 IU) reduces amygdala responses to fear-related stimuli in men, while exerting inverse effects in women. However, OXT enhances activity of the brain reward system in both sexes. Importantly, a crucial and still open question is whether there are sex-specific dose-response relationships for the amygdala and striatal regions. To address this question, a total of 90 healthy women participated in a double-blind, placebo-controlled crossover functional magnetic resonance imaging (fMRI) study and the results were compared with our previous findings from men. Participants were randomly assigned to three doses of OXT (6 IU, 12 IU, and 24 IU) and completed an emotional face recognition task including fearful and happy faces of varying emotional intensities. Across doses, OXT enhanced amygdala reactivity to low fearful faces compared to placebo and increased responses to happy faces in the dorsal striatum in women. While treatment effects on amygdala reactivity were evident at each given dose, the OXT effect on striatal responses to social stimuli was more pronounced with higher doses, but this dose-dependent effect did not survive correction for multiple comparisons. Importantly, OXT effects on amygdala and striatal activation significantly differed between sexes and striatal baseline sexual-dimorphic response patterns were diminished after administration of OXT. Our findings suggest that OXT increases the salience of social signals by strengthening the sensitivity for these signals in the amygdala and in the striatum in women, while OXT may primarily induce anxiolysis by reducing amygdala responses in men.

中文翻译：

---

催产素对杏仁核和纹状体反应性影响的动力学在女性和男性之间有所不同。

越来越多的证据表明，鼻内催产素 (OXT; 24 IU) 可减少男性杏仁核对恐惧相关刺激的反应，同时对女性产生相反的影响。然而，OXT 增强了两性大脑奖励系统的活动。重要的是，一个关键且仍然悬而未决的问题是杏仁核和纹状体区域是否存在性别特异性剂量反应关系。为了解决这个问题，共有 90 名健康女性参与了一项双盲、安慰剂对照的交叉功能磁共振成像 (fMRI) 研究，并将结果与​​我们之前对男性的研究结果进行了比较。参与者被随机分配到三个剂量的 OXT（6 IU、12 IU 和 24 IU）并完成情绪面部识别任务，包括不同情绪强度的恐惧和快乐面孔。跨剂量，与安慰剂相比，OXT 增强了杏仁核对低恐惧面孔的反应，并增加了女性背侧纹状体对快乐面孔的反应。虽然在每个给定剂量下对杏仁核反应性的治疗效果都很明显，但 OXT 对纹状体对社会刺激反应的影响在更高剂量下更为明显，但这种剂量依赖性效应在多重比较校正后无法幸免。重要的是，OXT 对杏仁核和纹状体激活的影响在性别之间存在显着差异，并且在施用 OXT 后纹状体基线性二态反应模式减少。我们的研究结果表明，OXT 通过增强女性杏仁核和纹状体对这些信号的敏感性来增加社交信号的显着性，而 OXT 可能主要通过减少男性杏仁核的反应来诱导抗焦虑。