Good Tatjana C, Harris Kendra K, Ihunnah Chioma A
Department of Ecology and Evolutionary Biology, Princeton University, USA.
Physiol Behav. 2005 Sep 15;86(1-2):96-102. doi: 10.1016/j.physbeh.2005.06.030.
Male and female mammals undergo profound hormonal changes during pregnancy, some of which are sufficiently dramatic to influence offspring survival. In order to understand the proximate mechanisms regulating the variability in reproductive success within and between individuals, we monitored changes in fecal corticosteroid concentrations over the reproductive cycle in male and female oldfield mice (Peromyscus polionotus subgriseus) to test whether corticosteroid concentrations during pregnancy were associated with offspring survival. In females that successfully raised litters to weaning, fecal corticosteroid concentrations were low until mid-gestation and increased significantly towards term; in females that did not raise their pups to weaning, fecal corticosteroid concentrations were significantly higher at mid-gestation, and remained high until late gestation. The difference in fecal corticosteroid concentrations at mid-gestation between successful and unsuccessful females can be explained by the fact that successful females were lactating. Lactation has been associated with a down-regulation of the hypothalamic-pituitary-adrenal (HPA) axis and, accordingly, a decrease in plasma corticosterone (CORT) in several species, including humans. Males that successfully raised their litters had low fecal corticosteroid concentrations throughout their partner's pregnancy. Unsuccessful males, however, had significantly higher fecal corticosteroid concentrations at term than males that raised their pups to weaning. While these preliminary data require further investigation, we suggest that pre-partum fecal corticosteroid concentrations in males were responsible for the variability in reproductive success.
雄性和雌性哺乳动物在怀孕期间会经历深刻的激素变化，其中一些变化非常显著，足以影响后代的存活。为了了解调节个体内部和个体之间生殖成功率差异的近端机制，我们监测了雄性和雌性旧域鼠（Peromyscus polionotus subgriseus）在生殖周期中粪便皮质类固醇浓度的变化，以测试怀孕期间的皮质类固醇浓度是否与后代存活有关。在成功将幼崽抚养至断奶的雌性中，粪便皮质类固醇浓度在妊娠中期之前较低，在足月时显著升高；在没有将幼崽抚养至断奶的雌性中，粪便皮质类固醇浓度在妊娠中期显著较高，并一直保持到妊娠后期。成功和未成功的雌性在妊娠中期粪便皮质类固醇浓度的差异可以用成功的雌性正在哺乳这一事实来解释。在包括人类在内的几个物种中，哺乳与下丘脑-垂体-肾上腺（HPA）轴的下调以及相应的血浆皮质酮（CORT）的降低有关。成功抚养幼崽的雄性在其伴侣整个怀孕期间粪便皮质类固醇浓度较低。然而，未成功的雄性在足月时粪便皮质类固醇浓度明显高于将幼崽抚养至断奶的雄性。虽然这些初步数据需要进一步研究，但我们认为雄性产前粪便皮质类固醇浓度是生殖成功率差异的原因。
