Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, United States of America; Department of Psychology, Smith College, Northampton, MA 01063, United States of America; Department of Biology, Smith College, Northampton, MA 01063, United States of America; Program in Neuroscience, Smith College, Northampton, MA 01063, United States of America; Program in Culture, Health, and Science, Five College Consortium, Amherst, MA 01002, United States of America; Neuroscience and Behavior Program, University of Massachusetts, Amherst, MA 01002, United States of America.
Department of Psychology, Smith College, Northampton, MA 01063, United States of America; Program in Culture, Health, and Science, Five College Consortium, Amherst, MA 01002, United States of America.
Horm Behav. 2023 Jul;153:105387. doi: 10.1016/j.yhbeh.2023.105387. Epub 2023 Jun 10.
The glucocorticoid hormone cortisol is an integral component of signaling pathways related to stress reactivity, energy balance, immune function, and other processes. In animal models, lactation is robustly associated with alterations in glucocorticoid signaling, and limited data suggest that similar changes may occur across human lactation. We asked whether milk letdown/secretion in breastfeeding mothers was associated with changes in cortisol, and whether such effects required presence of an infant. We measured changes in maternal salivary cortisol concentrations before and after nursing, the expression of breastmilk with an electric pump, or control activities. Participants conducted pre-session and post-session sampling (at 30 min) for all conditions, and provided a sample of pumped milk from one session. Both nursing and mechanical expression of breastmilk but not control were associated with equivalent declines in maternal cortisol concentration from pre-session values, indicating an effect of milk letdown on circulating cortisol independent of infant contact. Pre-session maternal salivary cortisol concentration was strongly and positively correlated with cortisol concentration in pumped milk samples, indicating that cortisol ingested by offspring provides a signal of maternal cortisol levels. Self-reported maternal stress was associated with higher pre-session cortisol concentrations, as well as with a larger drop in cortisol following nursing or pumping. These findings demonstrate that milk release-in the presence or absence of a suckling infant-regulates cortisol in mothers, and supports the potential for maternal signaling through breastmilk.
糖皮质激素皮质醇是与应激反应、能量平衡、免疫功能和其他过程相关的信号通路的重要组成部分。在动物模型中，哺乳期与糖皮质激素信号的改变密切相关，有限的数据表明，人类哺乳期也可能发生类似的变化。我们想知道母乳喂养的母亲在哺乳时的奶阵/分泌是否与皮质醇的变化有关，以及这种效应是否需要婴儿的存在。我们测量了母亲在哺乳前后唾液皮质醇浓度的变化，以及使用电动泵进行的母乳表达或对照活动。所有条件下，参与者都在课前和课后（30 分钟）进行了采样，并从一次课程中提供了一份泵出的母乳样本。哺乳和机械性母乳表达都与母体皮质醇浓度从课前值的同等下降有关，而对照活动则没有，这表明奶阵对循环皮质醇的影响独立于婴儿接触。课前的母亲唾液皮质醇浓度与泵出的母乳样本中的皮质醇浓度呈强烈正相关，表明婴儿摄入的皮质醇提供了母亲皮质醇水平的信号。母亲自我报告的压力与课前皮质醇浓度较高以及哺乳或泵奶后皮质醇下降幅度较大有关。这些发现表明，奶阵的释放——无论是否有吸吮的婴儿——可以调节母亲的皮质醇水平，并支持通过母乳进行母亲信号传递的潜力。
