The early postnatal period is a time of tremendous change for the dam and her offspring. During this time, environmental insults such as repeated stress exposure can have detrimental effects. In research that has focused on the effect of postnatal stress exposure on the dams, conflicting changes in maternal care and anxiety‐like behaviour have been reported. Additionally, changes to hypothalamic neuropeptides that are crucially involved in the transition to motherhood and stress regulation, namely oxytocin and corticotrophin‐releasing factor (CRF), have not been examined. Accordingly, the present study aimed to determine (i) whether repeated postpartum stress increases engagement in maternal care behaviours and anxiety‐like behaviour and (ii) whether these behavioural changes correspond with changes to CRF‐ or oxytocin‐immunoreactive (‐IR) cells in the paraventricular nucleus (PVN) of the hypothalamus. A non‐lactating group was also included to control for the effects of lactation on anxiety and the hypothalamic neuroendocrine system. Following the birth of their litters, Long‐Evans dams were separated from their pups from postnatal day (PND) 1 to PND21 for either 15 minutes (maternal separation [MS]15) or 6 hours (MS360). Maternal behaviours were recorded for 30 minutes on select PNDs following the separation. On PND22, dams were exposed to the elevated plus maze, brains were collected, and immunofluorescence analysis of PVN oxytocin‐ and CRF‐IR cells was conducted. Our findings demonstrate that prolonged maternal separation altered typical maternal behaviours and reduced anxiety relative to MS15 dams. At the cellular level, oxytocin‐IR cells in the caudal PVN were reduced in MS360 dams to a level similar to that in non‐lactating controls, and PVN CRF‐IR cells were reduced relative to both MS15 and non‐lactating controls. Taken together, these data reveal the behavioural and neuronal changes that occur in the mother dam following repeated postnatal stress exposure.

中文翻译：

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母体分离会改变哺乳期大鼠的母体保健，焦虑样行为以及室旁催产素和促肾上腺皮质激素释放因子的免疫反应性。

产后早期是水坝及其后代发生巨大变化的时期。在这段时间内，诸如反复暴露于压力之下的环境侮辱可能具有有害影响。在专注于产后压力暴露对大坝的影响的研究中，已经报道了产妇护理和焦虑症行为发生矛盾的变化。此外，尚未检查下丘脑神经肽的变化，这些变化与母性和压力调节的过渡至关重要，即催产素和促肾上腺皮质激素释放因子（CRF）。因此，本研究旨在确定（i）产后反复应激是否会增加对孕产妇护理行为和焦虑样行为的参与，以及（ii）这些行为变化是否与心室旁CRF或催产素免疫反应性（IR）细胞的变化相对应下丘脑核（PVN）。还包括一个非泌乳组来控制泌乳对焦虑和下丘脑神经内分泌系统的影响。产仔后，长埃文斯水坝从产后第1天（PND）到PND21从幼崽中分离15分钟（母体分离[MS] 15）或6小时（MS360）。分离后，在选定的PND上记录30分钟的产妇行为。在PND22上，水坝暴露于高架迷宫中，收集了大脑，对PVN催产素和CRF-IR细胞进行了免疫荧光分析。我们的发现表明，相对于MS15大坝，延长的产妇间隔改变了典型的产妇行为并减少了焦虑。在细胞水平上，MS360大坝中尾PVN中的催产素-IR细胞减少至与非泌乳对照组相似的水平，相对于MS15和非泌乳对照，PVN CRF-IR细胞有所减少。综上所述，这些数据揭示了在反复产后应激暴露后母坝中发生的行为和神经元变化。MS360大坝中尾部PVN中的催产素IR细胞减少至与非泌乳对照组相似的水平，相对于MS15和非泌乳对照，PVN CRF-IR细胞有所减少。综上所述，这些数据揭示了在反复产后应激暴露后母坝中发生的行为和神经元变化。MS360大坝中尾部PVN中的催产素IR细胞减少至与非泌乳对照组相似的水平，相对于MS15和非泌乳对照，PVN CRF-IR细胞有所减少。综上所述，这些数据揭示了在反复产后应激暴露后母坝中发生的行为和神经元变化。