Léonhardt Marion, Matthews Stephen G, Meaney Michael J, Walker Claire-Dominique
CIHR program in Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) Douglas Hospital Research Center, Department of Psychiatry, McGill University, Montreal, Quebec, Canada H4H 1R3.
Horm Behav. 2007 Jan;51(1):77-88. doi: 10.1016/j.yhbeh.2006.08.008. Epub 2006 Oct 10.
Maternal adversity is associated with long-lasting consequences on cognitive development, behavior and physiological responses in rat offspring. Few studies have examined whether repeated maternal stress produces repeated activation of the hypothalamus-pituitary-adrenal (HPA) axis in mothers and whether it modifies maternal behavior. Here, we tested a novel model of perinatal stress using repeated exposure to "purely" psychological stressors throughout the gestation and lactation periods in rats. We first tested the diurnal influences of repeated 1-h strobe light exposure on maternal corticosterone secretion. Despite the hyporesponsiveness to stress documented in late pregnant and lactating mothers, we observed an enhanced response to strobe light in the afternoon compared to the morning in stressed mothers during lactation. Next, dams were exposed to 24-h forced foraging followed by 10-h wet bedding during the diurnal peak of corticosterone secretion. Although no corticosterone responses to forced foraging and wet bedding were observed, the combination of both stressors had a significant effect on maternal behavior. Mother-pup interactions were significantly altered during the first 8 days of lactation. Taken together, these findings suggest that lactating mothers maintain responsiveness to specific and repeated psychological stressors, in particular at the time of the diurnal peak in corticosterone secretion. Depending on the stressor applied, either neuroendocrine activation or changes in maternal behavior might be important determinants of the long-term consequences in the offspring. The combination of forced foraging, wet bedding and strobe light might represent a novel model of mild maternal adversity using "purely" psychological stressors.
母体逆境与大鼠后代的认知发展、行为及生理反应的长期后果相关。很少有研究探讨反复的母体应激是否会导致母体下丘脑-垂体-肾上腺（HPA）轴的反复激活，以及它是否会改变母性行为。在此，我们测试了一种围产期应激的新模型，即让大鼠在整个妊娠期和哺乳期反复暴露于“纯粹的”心理应激源。我们首先测试了反复1小时频闪光照对母体皮质酮分泌的昼夜影响。尽管在妊娠后期和哺乳期的母亲中记录到对应激的反应性降低，但我们观察到，在哺乳期，应激母亲下午对频闪光照的反应比上午增强。接下来，在皮质酮分泌的昼夜高峰期间，让母鼠经历24小时强制觅食，随后是10小时湿垫料处理。虽然未观察到对强制觅食和湿垫料的皮质酮反应，但这两种应激源的组合对母性行为有显著影响。在哺乳期的前8天，母婴互动显著改变。综上所述，这些发现表明，哺乳期母亲对特定的反复心理应激源保持反应性，尤其是在皮质酮分泌的昼夜高峰时。根据所施加的应激源不同，神经内分泌激活或母性行为的改变可能是后代长期后果的重要决定因素。强制觅食、湿垫料和频闪光照的组合可能代表一种使用“纯粹的”心理应激源的轻度母体逆境新模型。
