Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany; Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, BP 1303, Abidjan 01, Côte d'Ivoire.
Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany; Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, BP 1303, Abidjan 01, Côte d'Ivoire.
Psychoneuroendocrinology. 2019 Jun;104:165-173. doi: 10.1016/j.psyneuen.2019.02.007. Epub 2019 Feb 8.
The oxytocinergic system is involved in a range of functions, from attachment and social bonding to aggression and stress responses. Whether oxytocin is released in response to a stressor, shows contradictory results across species and potential contexts-dependent differences. To avoid unintended contextual changes due to experimental procedures, we tested this question non-invasively in wild chimpanzees in an ecologically valid context. We collected endogenous hormonal measures during exposure to a known natural stressor, intergroup conflict. Specifically, we tested for potential synchronous activation patterns between urinary oxytocin and cortisol in male and female chimpanzees during stressor exposure. Oxytocinergic system reactivity during chimpanzee intergroup conflict has already been established in this study population. Thus, we first investigated urinary cortisol levels during border patrol and intergroup encounter days, in comparison to another potential stressor, hunting, and control days. We found higher urinary cortisol levels during intergroup encounter days compared with control and hunting days. We then compared secretion patterns of oxytocin and cortisol in relation to increased levels of out-group contact and hostility ('out-group risk') during intergroup conflict. We found that increased 'out-group risk' was associated with higher cortisol levels, especially when involving direct visual or physical contact with rival groups. Although urinary oxytocin levels were high across intergroup conflict contexts, increasing levels of out-group risk showed no significant variation. Taken together, results indicate independent secretion of oxytocin and cortisol during chimpanzee intergroup conflict, emphasizing that stressor exposure in this context is not the main trigger of oxytocin secretion.
催产素系统参与多种功能，从依恋和社交联系到攻击和应激反应。催产素是否会对压力源产生反应，在不同物种和潜在的情境依赖差异方面存在相互矛盾的结果。为了避免由于实验程序而导致意外的情境变化，我们在一个生态有效的情境中，对野生黑猩猩进行了非侵入性测试。我们在暴露于已知自然压力源（群体间冲突）期间收集了内源性激素测量值。具体来说，我们测试了在压力源暴露期间雄性和雌性黑猩猩的尿液催产素和皮质醇之间是否存在潜在的同步激活模式。在该研究人群中，已经确定了黑猩猩群体间冲突期间的催产素系统反应性。因此，我们首先比较了边界巡逻和群体间相遇日与另一种潜在压力源狩猎日和对照日期间的尿液皮质醇水平。我们发现群体间相遇日的尿液皮质醇水平高于对照日和狩猎日。然后，我们比较了催产素和皮质醇的分泌模式与群体间冲突中与增加的外群体接触和敌意（“外群体风险”）之间的关系。我们发现，“外群体风险”增加与皮质醇水平升高有关，尤其是当涉及与敌对群体的直接视觉或身体接触时。尽管在群体间冲突的情况下，尿液催产素水平较高，但增加的“外群体风险”没有显示出显著变化。总之，结果表明在黑猩猩群体间冲突期间，催产素和皮质醇的分泌是独立的，这强调了在这种情况下，应激源暴露不是催产素分泌的主要触发因素。
