Mellowing with age: older parents are less responsive to a stressor in a long-lived seabird
Mellowing with age: older parents are less responsive to a stressor in a long-lived seabird
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DOI：
10.1111/j.1365-2435.2010.01733.x
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发表时间：
2010-10-01
影响因子：
5.2
通讯作者：
Ketterson, Ellen D.
中科院分区：
文献类型：
--
作者：
Heidinger, Britt J.;Chastel, Olivier;Ketterson, Ellen D.
生殖成功率通常随着年龄的增长而增加；然而，这种普遍观察到的模式背后的机制却鲜为人知。一种可能很重要的机制是一套生理反应(应激反应)，它允许有机体逃避和应对应激源，但通常会抑制繁殖。如果年长的父母对压力源的反应不如年轻父母强烈，这种与年龄相关的压力反应差异可能有助于更高的生育成功率，这通常是年长父母的特征。通常情况下，应激反应是通过血浆糖皮质激素(CORT)浓度的增加来测量的，我们之前报道过，在普通燕鸥(Sterna Hirundo)中，应激诱导的CORT水平随着年龄的增长而下降。另一种荷尔蒙，催乳素(PRL)，据报道在繁育的鸟类中会因应激源而减少，并且通常与父母的行为呈正相关。我们预测，与皮质醇应激反应一样，催乳素应激反应也会随着年龄的增长而受到抑制。为了验证这一预测，我们捕获了孵化年龄从3岁到29岁的普通燕鸥，并在同一个体中测量了压力诱导的催乳素和皮质醇水平的变化。我们发现，与年轻父母相比，年龄较大的父母在应对捕获和约束压力时，催乳素水平下降的速度较慢。在这些鸟类中，我们还发现，应激诱导的最大皮质醇水平随着年龄的增长而下降，这与我们之前对该物种的报告一致。然而，催乳素和皮质醇的测量在个体内没有相关性。综上所述，这些结果支持这样的假设，即PRL和CORT应激反应的调节是灵活的激素机制，有助于解释随年龄增长的生殖成功率的增加。
P>1. Reproductive success often increases with age; however the mechanisms underlying this commonly observed pattern are poorly understood. One mechanism that may be important is a set of physiological responses (the stress response) that allows organisms to evade and cope with stressors, but often inhibits reproduction.2. If older parents respond less strongly to stressors than younger parents, this age-related difference in the stress response may contribute to the higher reproductive success that often characterizes older parents.3. Typically the stress response is measured as an increase in plasma glucocorticoid (CORT) concentration, and we have previously reported that stress-induced CORT levels decline with age in the common tern (Sterna hirundo). Another hormone, prolactin (PRL), has been reported to decrease in response to stressors in breeding birds and is often positively associated with parental behaviour. We predicted that like the CORT stress response, the PRL stress response would also be suppressed with age.4. To test this prediction, we captured known-age, incubating common terns ranging in age from 3 to 29 years and measured stress-induced changes in PRL and CORT levels within the same individuals.5. We found that PRL levels decreased less rapidly in response to capture and restraint stress in older than in younger parents. In these same birds, we also found that stress-induced maximum CORT levels decreased with age, which is consistent with what we have previously reported for this species. Measures of PRL and CORT were not, however, correlated within individuals.6. Taken together, these results support the hypothesis that modulations of both the PRL and CORT stress response are flexible hormonal mechanisms that help to account for the increase in reproductive success that occurs with age.