Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
Horm Behav. 2010 Apr;57(4-5):506-14. doi: 10.1016/j.yhbeh.2010.02.009. Epub 2010 Feb 24.
Sexual activity in mature male African elephants is predominantly associated with the occurrence of musth, a state or condition which refers to a set of physical, physiological and behavioral characteristics, including an elevation in androgen levels. Although musth appears to be energetically costly, the degree to which it is associated with changes in adrenal endocrine function (e.g., glucocorticoid output) is still unclear. To investigate the possible effect of musth on adrenocortical function, and the impact of socioecological changes on androgen and glucocorticoid levels, six adult African elephant bulls were followed for 13months in the Kruger National Park, South Africa, and observations and fecal sample collection for endocrine monitoring was carried out about twice weekly. Our data showed that the occurrence of musth was associated with reduced glucocorticoid output, suggesting that musth does not represent a physiological stress mediated by the hypothalamic-pituitary-adrenal axis. This confirms previous findings in captive-housed animals, providing evidence for a suppressive effect of the musth condition on adrenocortical activity. Furthermore, a seasonal effect on androgen and glucocorticoid levels was found, which appears to vary depending on the reproductive status of the animal. The results also indicate a relationship between the presence or absence of social partners and changes in testicular and adrenal endocrine activity. Finally, the data confirm previous findings in captive-housed elephants, that an elevation in androgen concentrations usually occurs before the onset of physical musth signs, and therefore support the idea that the change in androgen levels represents the initial stimulus for the musth condition.
成熟雄性非洲象的性行为主要与发情期有关，发情期是一种身体、生理和行为特征的集合，包括雄激素水平的升高。虽然发情期似乎需要消耗大量的能量，但它与肾上腺内分泌功能变化（如糖皮质激素的产生）的关联程度仍不清楚。为了研究发情期对肾上腺皮质功能的可能影响，以及社会生态变化对雄激素和糖皮质激素水平的影响，我们对南非克鲁格国家公园的 6 头成年非洲象公牛进行了为期 13 个月的跟踪研究，并进行了大约每周两次的观察和粪便样本采集，以进行内分泌监测。我们的数据表明，发情期的发生与糖皮质激素产生减少有关，这表明发情期并不代表下丘脑-垂体-肾上腺轴介导的生理应激。这证实了之前在圈养动物中的发现，为发情期对肾上腺皮质活动的抑制作用提供了证据。此外，我们还发现了雄激素和糖皮质激素水平的季节性变化，这似乎取决于动物的生殖状态。结果还表明，社会伙伴的存在与否与睾丸和肾上腺内分泌活动的变化有关。最后，这些数据证实了之前在圈养大象中的发现，即雄激素浓度的升高通常发生在身体发情迹象出现之前，因此支持了雄激素水平变化代表发情期初始刺激的观点。
