Limits to sustained energy intake. XXX. Constraint or restraint? Manipulations of food supply show peak food intake in lactation is constrained
Limits to sustained energy intake. XXX. Constraint or restraint? Manipulations of food supply show peak food intake in lactation is constrained
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DOI：
10.1242/jeb.208314
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发表时间：
2020-01
影响因子：
2.8
通讯作者：
Zhijun Zhao;Davina Derous;Abby Gerrard;Jing Wen;Xue Liu;Song Tan;C. Hambly;J. Speakman
中科院分区：
文献类型：
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作者：
Zhijun Zhao;Davina Derous;Abby Gerrard;Jing Wen;Xue Liu;Song Tan;C. Hambly;J. Speakman
哺乳期小鼠的摄食量增加4- 5倍，在哺乳后期达到渐近线。一个关键的问题是，这个渐近线是否反映了生理约束，或母亲的投资策略（“限制”）。我们将哺乳期小鼠暴露于食物限制期，假设如果限制反映了限制，则它们在重新喂食时会通过违反渐近线来补偿。相反，如果这是一个限制，他们将根据定义无法增加他们的摄入量再喂养的日子。使用同位素方法，我们发现在食物限制期间，雌性关闭了产奶，影响了后代的生长。在再喂养期间，食物摄入量和产奶量再次上升，但并未明显高于不受限制的对照组。这些数据提供了有力的证据，渐近摄入量在哺乳期反映了生理/物理约束，而不是限制。由于下丘脑神经肽Y（Npy）在两种限制状态下都上调，这表明限制并不是由上调饥饿信号的能力限制（饱和神经能力假设）所施加的。了解遗传基础的限制将是一个关键的未来目标，并将为我们提供更多的信息的性质限制因素的繁殖输出，其潜在的联系，生活史的战略。总结：哺乳期的渐近摄入反映了小鼠的生理/身体限制。这种限制可能不是由下丘脑饥饿信号，已经最大限度地刺激哺乳。
ABSTRACT Lactating mice increase food intake 4- to 5-fold, reaching an asymptote in late lactation. A key question is whether this asymptote reflects a physiological constraint, or a maternal investment strategy (a ‘restraint’). We exposed lactating mice to periods of food restriction, hypothesizing that if the limit reflected restraint, they would compensate by breaching the asymptote when refeeding. In contrast, if it was a constraint, they would by definition be unable to increase their intake on refeeding days. Using isotope methods, we found that during food restriction, the females shut down milk production, impacting offspring growth. During refeeding, food intake and milk production rose again, but not significantly above unrestricted controls. These data provide strong evidence that asymptotic intake in lactation reflects a physiological/physical constraint, rather than restraint. Because hypothalamic neuropeptide Y (Npy) was upregulated under both states of restriction, this suggests the constraint is not imposed by limits in the capacity to upregulate hunger signalling (the saturated neural capacity hypothesis). Understanding the genetic basis of the constraint will be a key future goal and will provide us additional information on the nature of the constraining factors on reproductive output, and their potential links to life history strategies. Summary: Asymptotic intake in lactation reflects a physiological/physical constraint in mice. This constraint is probably not defined by hypothalamic hunger signalling, being already maximally stimulated by lactation.