Bauer Carolyn M, Ebensperger Luis A, León Cecilia, Ramírez-Estrada Juan, Hayes Loren D, Romero L Michael
Department of Biology, Tufts University, Medford, Massachusetts.
Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
J Exp Zool A Ecol Genet Physiol. 2016 Jun;325(5):304-17. doi: 10.1002/jez.2018. Epub 2016 May 20.
Maternal stress and care significantly affect offspring's future behavior and physiology. Studies in laboratory rats have shown that maternal stress decreases maternal care and that low rates of certain maternal behaviors cause offspring to develop hyperreactive stress responses. Plurally breeding rodents that practice communal care, such as degus (Octodon degus), may be able to buffer some of these effects since offspring receive care from multiple females. Directly after parturition, 0% (Control group), 50% (Mixed group), or 100% (CORT group) per cage of pair-housed female degus were implanted with 21-day release cortisol pellets. The amount of maternal care provided by females was determined from video recordings during the next 3 weeks. Females with cortisol implants did not alter rates of maternal care. However, females recently introduced to captivity had low rates of pup contact and pup retrievals compared to females of captive origin. When pups reached 4 weeks of age, we determined their baseline and stress-induced cortisol levels, in addition to assessing their negative feedback efficacy and adrenal sensitivity. Pups from mothers recently introduced to captivity had weak negative feedback. Within captive pups, those from CORT mothers weighed less compared to pups from either Control or Mixed mothers. Captive CORT pups also had weak adrenal sensitivity compared to captive Control pups. These findings demonstrate that maternal care and glucocorticoid elevation impact certain components of the degu pup stress response, but that plural breeding with communal care may buffer some of these effects.
母体应激和照料会显著影响后代未来的行为和生理状况。对实验大鼠的研究表明，母体应激会减少母性照料，而某些母性行为发生率较低会导致后代形成高反应性应激反应。进行群体照料的多雌繁殖啮齿动物，如八齿鼠（Octodon degus），可能能够缓冲其中一些影响，因为后代会得到多只雌鼠的照料。分娩后，每笼成对饲养的雌性八齿鼠中，0%（对照组）、50%（混合组）或100%（CORT组）被植入了可释放21天的皮质醇缓释丸。通过接下来3周的视频记录来确定雌鼠提供的母性照料量。植入皮质醇的雌鼠并没有改变母性照料的发生率。然而，与圈养来源的雌鼠相比，最近引入圈养的雌鼠与幼崽的接触率和找回幼崽的比率较低。当幼崽长到4周龄时，我们测定了它们的基线皮质醇水平和应激诱导的皮质醇水平，此外还评估了它们的负反馈效能和肾上腺敏感性。来自最近引入圈养的母亲的幼崽负反馈较弱。在圈养的幼崽中，来自CORT组母亲的幼崽比来自对照组或混合组母亲的幼崽体重更轻。与圈养的对照组幼崽相比，圈养的CORT组幼崽的肾上腺敏感性也较弱。这些发现表明，母性照料和糖皮质激素升高会影响八齿鼠幼崽应激反应的某些组成部分，但群体照料的多雌繁殖可能会缓冲其中一些影响。
