Litter size is negatively correlated with corticosterone levels in weanling and juvenile laboratory rats
Litter size is negatively correlated with corticosterone levels in weanling and juvenile laboratory rats
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DOI：
10.1016/j.physbeh.2010.01.032
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发表时间：
2010-04-19
影响因子：
2.9
通讯作者：
Hudson, Robyn
中科院分区：
文献类型：
--
作者：
Roedel, Heiko G.;Meyer, Susann;Hudson, Robyn
动物在生命早期的环境会强烈影响其生理发育。例如，先前已经显示，窝仔数，即窝仔兄弟姐妹的数量，强烈影响许多小型哺乳动物物种（包括实验室大鼠）的早期生长。在本研究中，我们测试了是否自然，未经处理的产仔数也与应激激素水平的差异在年轻的Long-Evans实验室大鼠。我们发现，血清皮质酮（CORT）浓度和产仔数在两个不同阶段的少年生活呈负相关。在出生后第17天，断奶前不久，这种关系是明显的基础CORT值。然而，在第33天，断奶后两周，我们发现这种关系，只有当动物受到挑战的10分钟测试高架十字迷宫，而不是在对照组动物（基础值）。虽然这些差异的生理基础尚不清楚，我们讨论了两个主要的，不相互排斥的可能性：（a）延迟的HPA轴在典型的低体重的幼崽大窝，和（B），这样的幼崽，遇到更大的竞争，为母亲的资源，调整到这个可能更紧张的发展环境下调HPA轴的反应。总之，我们的研究提供的证据表明，自然变化的功能的发育环境中的许多altricial哺乳动物数量的同窝仔可能有助于个体差异的压力相关的生理。此外，这表明在研究动物应激反应的差异时需要考虑窝仔数的影响。(C)2010年爱思唯尔公司All rights reserved.
An animal's environment during early life can strongly affect its physiological development. For example, litter size, i.e. the number of litter siblings, has been previously shown to strongly affect early growth in many small mammal species including laboratory rats. In the present study we tested whether natural, unmanipulated litter size is also associated with differences in stress hormone levels in young Long-Evans laboratory rats. We found a negative correlation between serum corticosterone (CORT) concentrations and litter size during two different stages of juvenile life. On postnatal day 17, shortly before weaning, this relationship was apparent with respect to basal CORT values. On day 33, however, two weeks after weaning, we found this relationship only when animals were challenged by a 10-min test on an elevated plus maze, but not in control animals (basal values). Although the physiological basis of these differences is not clear, we discuss two main, not mutually exclusive possibilities: (a) delayed maturation of the HPA axis in typically lower body mass pups of large litters, and (b) that such pups, encountering greater competition for maternal resources, adjust to this presumably more stressful developmental environment by down-regulating responsiveness of the HPA axis. In conclusion, our study provides evidence that a naturally varying feature of the developmental environment of many altricial mammals number of littermates may contribute to individual differences in stress-related physiology. Furthermore, it suggests the need to consider litter-size effects when investigating differences in animals' stress responses. (C) 2010 Elsevier Inc. All rights reserved.