Department of Psychology, 3210 Tolman Hall, MC 1650, University of California at Berkeley, Berkeley, CA 94720, USA.
Physiol Behav. 2013 Aug 15;120:156-63. doi: 10.1016/j.physbeh.2013.08.003. Epub 2013 Aug 12.
Diverse environments early in mammalian life can have profound influences on the physiology and behavior of developing offspring. Environmental factors can influence offspring development directly or through perturbations in parental care. In the current study, we wished to determine if the influence of a single environmental variable, type of bedding material used in laboratory cages, is capable of altering physiological and behavioral outcomes in offspring. Female rats were housed in cages containing wood pulp or corncob bedding and allowed to mature. These rats, while housed on assigned bedding material, were bred and allowed to give birth. At weaning, male offspring were housed on one of the two bedding conditions and tested later in adulthood on stress-sensitive behavioral measures. Postmortem analysis of glucocorticoid receptor expression and CRH mRNA levels were also measured. Maternal care directed at the pups reared in the two different bedding conditions was also recorded. Rats reared from birth on corncob bedding exhibited decreased anxiety-like behavior, as adults, in both open field and light-dark box tasks compared to wood pulp reared animals. Animals that received similar overall levels of maternal care, regardless of bedding condition, also differed in anxiety-like behaviors as adults, indicating that the bedding condition is capable of altering phenotype independent of maternal care. Despite observed behavioral differences in adult offspring reared in different bedding conditions, no changes in glucocorticoid receptor expression at the level of the hippocampus, frontal cortex, or corticotrophin releasing hormone (CRH) mRNA expression in the hypothalamus were observed between groups. These results highlight the importance of early life housing variables in programming stress-sensitive behaviors in adult offspring.
早期哺乳动物生活环境的多样性会对发育后代的生理和行为产生深远影响。环境因素可以直接或通过干扰父母的照顾来影响后代的发育。在本研究中，我们希望确定单一环境变量（实验室笼中使用的垫料类型）是否能够改变后代的生理和行为结果。雌性大鼠被安置在含有木浆或玉米芯垫料的笼子中并成熟。这些大鼠在被分配的垫料条件下饲养，并允许繁殖和分娩。在断奶时，雄性后代被安置在两种垫料条件之一中，并在成年后进行应激敏感行为测量。还测量了糖皮质激素受体表达和 CRH mRNA 水平的死后分析。也记录了针对在两种不同垫料条件下饲养的幼崽的母性照顾。与在木浆中饲养的动物相比，从出生就饲养在玉米芯垫料上的大鼠在成年后在开阔场和明暗箱任务中表现出较低的焦虑样行为。无论垫料条件如何，接受相似总体水平母性照顾的动物在成年后也表现出不同的焦虑样行为，这表明垫料条件能够改变表型，而不依赖于母性照顾。尽管在不同垫料条件下饲养的成年后代表现出行为差异，但在海马体、前额皮质或下丘脑促肾上腺皮质激素释放激素 (CRH) mRNA 表达水平上，各组之间的糖皮质激素受体表达没有变化。这些结果强调了早期生活环境变量在编程成年后代应激敏感行为中的重要性。
