Abstract：
BACKGROUND: Sleep restriction is considered a stressful condition itself, causing a wide variety of physiological alterations, from cognitive and hormonal to immunological status. In addition, it is established that stress in mother rats can modify milk ejection, milk composition, and maternal care of the pups. Also, sleep disturbances during the early stages of motherhood are a common feature of all studied species. In this context, while the impacts of sleep disruption in non-lactating animals were extensively investigated, its repercussions during the initial phases of motherhood have been poorly explored. Therefore, we wonder if maternal behavior, milk ejection and its macronutrient composition would be disrupted when mother rats are subjected to an additional acute or chronic sleep restriction to the already existing sleep disturbances.
METHODS: Lactating rats were implanted with unilateral electrodes for polysomnographic recordings and for deep brain electrical stimulation into mesopontine waking-promoting area (for sleep deprivation). During the early postpartum period (postpartum day 5-9), mother rats were randomly assigned into one of three groups: chronic sleep restriction group (CSR; 6 h of sleep deprivation/day for five consecutive days), acute sleep restriction group (ASR; 6 h of sleep deprivation only for one day), or undisturbed group (control group). Active maternal behaviors (retrievals of the pups into the nest, mouthing, lickings [corporal and anogenital] and sniffing the pups) and passive maternal behaviors (kyphotic and supine nursing postures) were evaluated during a 30 min period without sleep restriction immediately after the sleep restriction or control period. The litter weight gain was assessed every day, and on the last experimental session mothers were milked for posterior macronutrients analysis (protein, carbohydrates and fat).
RESULTS: When compared to control group, CSR decreased the amount of milk ejected in the middle days of the sleep restriction period, while ASR did not affect this parameter. Moreover, ASR reduced milk protein content compared to control and CSR groups. Finally, compared to the control group, CSR reduced active maternal behaviors towards the end of the treatment days.
CONCLUSIONS: We demonstrated that not only acute but also chronic sleep restriction impacts on the postpartum period, each one affecting different aspects of maternal behavior and lactation. Our results suggest the existence of a homeostatic recovery mechanism in breastfeeding during CSR, possibly ensuring the survival of the litter, while the decline in active maternal behaviors appears to be cumulative.
METHODS: Lactating rats were implanted with unilateral electrodes for polysomnographic recordings and for deep brain electrical stimulation into mesopontine waking-promoting area (for sleep deprivation). During the early postpartum period (postpartum day 5-9), mother rats were randomly assigned into one of three groups: chronic sleep restriction group (CSR; 6 h of sleep deprivation/day for five consecutive days), acute sleep restriction group (ASR; 6 h of sleep deprivation only for one day), or undisturbed group (control group). Active maternal behaviors (retrievals of the pups into the nest, mouthing, lickings [corporal and anogenital] and sniffing the pups) and passive maternal behaviors (kyphotic and supine nursing postures) were evaluated during a 30 min period without sleep restriction immediately after the sleep restriction or control period. The litter weight gain was assessed every day, and on the last experimental session mothers were milked for posterior macronutrients analysis (protein, carbohydrates and fat).
RESULTS: When compared to control group, CSR decreased the amount of milk ejected in the middle days of the sleep restriction period, while ASR did not affect this parameter. Moreover, ASR reduced milk protein content compared to control and CSR groups. Finally, compared to the control group, CSR reduced active maternal behaviors towards the end of the treatment days.
CONCLUSIONS: We demonstrated that not only acute but also chronic sleep restriction impacts on the postpartum period, each one affecting different aspects of maternal behavior and lactation. Our results suggest the existence of a homeostatic recovery mechanism in breastfeeding during CSR, possibly ensuring the survival of the litter, while the decline in active maternal behaviors appears to be cumulative.
摘要：
背景：睡眠限制本身被认为是一种压力状态，引起各种各样的生理变化，从认知和荷尔蒙到免疫状态。此外,已经确定，母鼠的压力可以改变排奶，牛奶成分，和产妇对幼崽的照顾。此外，母亲早期的睡眠障碍是所有研究物种的共同特征。在这种情况下，虽然对非哺乳期动物睡眠中断的影响进行了广泛的研究，在母亲的初始阶段，它的影响一直没有得到充分的探索。因此,我们想知道母性行为，当母鼠对已经存在的睡眠障碍进行额外的急性或慢性睡眠限制时，排奶及其大量营养素组成将被破坏。
方法：给哺乳期大鼠植入单侧电极用于多导睡眠图记录和用于脑深部电刺激的中桥促醒区（用于睡眠剥夺）。在产后早期（产后第5至9天），将大鼠随机分为三组：慢性睡眠限制组（CSR；连续五天剥夺睡眠6小时/天），急性睡眠限制组（ASR；仅一天6小时睡眠剥夺），或未干扰组（对照组）。积极的母性行为（将幼崽检索到巢中，嘴巴,在30分钟的时间内评估了舔[身体和肛门生殖器]和嗅探幼犬）和被动母性行为（后凸和仰卧护理姿势），而在睡眠限制或控制期后立即没有睡眠限制。每天评估产仔增重，在最后一次实验中，母亲被挤奶进行后部常量营养素分析(蛋白质，碳水化合物和脂肪)。
结果：与对照组相比，CSR减少了睡眠限制期中期排出的牛奶量，而ASR不影响此参数。此外，与对照组和CSR组相比，ASR降低了乳蛋白含量。最后,与对照组相比，CSR在治疗日结束时减少了积极的母亲行为。
结论：我们证明，不仅急性睡眠限制，而且慢性睡眠限制对产后的影响，每一个影响母亲行为和哺乳的不同方面。我们的结果表明，在CSR期间母乳喂养存在一种稳态恢复机制，可能确保垃圾的生存，而积极母性行为的下降似乎是累积的。
方法：给哺乳期大鼠植入单侧电极用于多导睡眠图记录和用于脑深部电刺激的中桥促醒区（用于睡眠剥夺）。在产后早期（产后第5至9天），将大鼠随机分为三组：慢性睡眠限制组（CSR；连续五天剥夺睡眠6小时/天），急性睡眠限制组（ASR；仅一天6小时睡眠剥夺），或未干扰组（对照组）。积极的母性行为（将幼崽检索到巢中，嘴巴,在30分钟的时间内评估了舔[身体和肛门生殖器]和嗅探幼犬）和被动母性行为（后凸和仰卧护理姿势），而在睡眠限制或控制期后立即没有睡眠限制。每天评估产仔增重，在最后一次实验中，母亲被挤奶进行后部常量营养素分析(蛋白质，碳水化合物和脂肪)。
结果：与对照组相比，CSR减少了睡眠限制期中期排出的牛奶量，而ASR不影响此参数。此外，与对照组和CSR组相比，ASR降低了乳蛋白含量。最后,与对照组相比，CSR在治疗日结束时减少了积极的母亲行为。
结论：我们证明，不仅急性睡眠限制，而且慢性睡眠限制对产后的影响，每一个影响母亲行为和哺乳的不同方面。我们的结果表明，在CSR期间母乳喂养存在一种稳态恢复机制，可能确保垃圾的生存，而积极母性行为的下降似乎是累积的。
