Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, New York.
Center for Evolution and Medicine, Arizona State University, Tempe, Arizona.
Am J Hum Biol. 2019 Nov;31(6):e23315. doi: 10.1002/ajhb.23315. Epub 2019 Aug 30.
In humans and other mammals, maternal hormones are transferred to offspring during lactation via milk and may regulate postnatal development, including the pace of early growth. Here, we used a nonhuman primate model to test the hypotheses that milk cortisol and dehydroepiandrosterone-sulfate (DHEAS) concentrations reflect maternal characteristics, and that changes in these hormones across lactation are associated with early postnatal growth rates.
Demographic information, morphometrics, and milk samples were collected from rhesus macaque mothers and their infants at the California National Primate Research Center in Davis, California. Using linear models, we examined the relationship between maternal traits and milk hormone concentrations (N = 104 females) and explored the effect of milk hormones on the rate of offspring growth (N = 72 mother-infant dyads), controlling for available milk energy.
Contrary to previous studies, we found that milk cortisol concentrations were categorically higher in multiparous females than in primiparous females. However, milk DHEAS concentrations decreased with maternal parity. Neither milk cortisol nor DHEAS were related to maternal rank. Finally, changes in milk hormones predicted offspring growth in a sex-specific and temporal manner: increases in cortisol from peak to late lactation predicted faster female growth, and increases in DHEAS concentrations from early to peak and peak to late lactation predicted faster male growth.
Our findings shed light on how hormonal components of milk have sex-specific effects on offspring growth during early postnatal life with varying temporal windows of sensitivity.
在人类和其他哺乳动物中，母体激素通过乳汁传递给后代，并可能调节产后发育，包括早期生长速度。在这里，我们使用非人类灵长类动物模型来检验以下假设：乳汁皮质醇和脱氢表雄酮硫酸盐（DHEAS）浓度反映了母体特征，并且这些激素在哺乳期的变化与产后早期生长速度有关。
在加利福尼亚州戴维斯的加利福尼亚国家灵长类动物研究中心，收集恒河猴母亲及其婴儿的人口统计学信息、形态测量和乳汁样本。我们使用线性模型，检验了母体特征与乳汁激素浓度之间的关系（N = 104 名女性），并探讨了乳汁激素对后代生长速度的影响（N = 72 对母婴对），同时控制了可用的乳汁能量。
与之前的研究相反，我们发现，多胎母亲的乳汁皮质醇浓度明显高于初产母亲。然而，乳汁 DHEAS 浓度随母体胎次而降低。乳汁皮质醇和 DHEAS 均与母体等级无关。最后，乳汁激素的变化以性别特异性和时间特异性的方式预测后代的生长：从高峰期到后期泌乳时皮质醇的增加预测了雌性生长更快，而从早期到高峰期和高峰期到后期泌乳时 DHEAS 浓度的增加预测了雄性生长更快。
我们的研究结果揭示了乳汁中的激素成分如何以性别特异性的方式影响产后早期生活中后代的生长，并且具有不同的敏感时间窗口。
