Early Life Nutrition, Developmental Plasticity, and Reproductive Ecology in Filipino Males

在NSF的支持下，Chris Kuzawa博士和一个来自西北大学、北卡罗来纳大学教堂山分校和菲律宾宿务市圣卡洛斯大学的国际团队将调查胎儿和婴儿的营养和生长是否影响男性生殖生物学，这是在菲律宾参与一项长期健康研究的约1000名年轻人的测量结果。具体地说，他们将检验这样一种假设，即出生前(如出生体重或孕妇怀孕营养表明)或出生后几个月(如婴儿喂养方式或生长速度)营养不良会预测睾丸功能下降，包括与男性生育能力相关的睾丸素和其他激素的产生减少。此外，该项目还将调查睾酮的任何变化对健康的更广泛影响，例如肌肉、力量或血压的变化。这一系列问题的理论基础来自最近的研究，该研究表明，早年营养不良对老鼠和绵羊的这些特征产生了类似的长期影响。到目前为止，还没有对这些关系在人类身上进行大规模的测试。这项研究是探索这些关系的独特装备，因为所有的参与者都是在他们的母亲怀孕时(1983年)第一次参加这项研究。随着每个人年龄的增长，出生大小、生长速度、营养和其他重要特征被定期监测，为他们的生活经历提供了丰富的记录。这些人现在22岁，这使得这项研究能够评估早期测量的营养和生长是否可以预测几十年后成年后测量的生殖功能和健康。为了回答这项研究的具体假设，这些数据将通过采访中测量的成人生活方式和饮食信息以及用于测量生殖激素的生物样本(血液和唾液)来补充。所有这些补充数据和标本都是最近使用一种旨在解决这项研究的研究目标的方案收集的，这些标本现在被存放在西北大学的冷冻库中。美国国家科学基金会只需要支付分析这些样本中荷尔蒙的费用，这些荷尔蒙将在西北大学人类学系的人类生物学研究实验室进行测量。这项研究有望对一个具有相当重要理论和应用价值的问题有重要的见解。就像女性的情况一样，跨文化研究记录了男性生殖功能的大量群体差异。然而，与女性不同的是，这种生物变异性在男性身上很难解释。这项研究将通过调查早期生命营养和生长的差异是否影响男性生殖功能来解决这一悖论。这个问题的答案也可能为人类适应的一种重要模式提供洞察：在面临具有挑战性的营养环境时，减少在繁殖和肌肉质量等“昂贵”特征上的支出可能是必要的(如果不太理想的)反应。这项研究的更广泛影响包括为对获得实验室研究经验感兴趣的研究生和本科生提供培训机会。它还将加强美国和菲律宾的一个国际研究团队之间的合作关系，他们在了解男性生育的原因和后果方面有着共同的兴趣。

With NSF support, Dr. Chris Kuzawa and an international team based out of Northwestern University, the University of North Carolina, Chapel Hill, and the University of San Carlos, Cebu City (the Philippines), will investigate whether fetal and infant nutrition and growth influence male reproductive biology, as measured in roughly 1,000 young adults participating in a long-term study of health in the Philippines. Specifically, they will test the hypothesis that undernutrition prior to birth (as indicated by birth weight or maternal pregnancy nutrition) or during the months after birth (as indicated by mode of infant feeding or growth rate) will predict reduced testicular function, including lower production of testosterone and other hormones that are correlated with male fecundity. In addition, this project will also investigate the broader health effects of any changes in testosterone, such as reductions in muscle, strength or changes in blood pressure. The rationale for this series of questions comes from recent research showing similar long-term effects of early life undernutrition on these traits in rats and sheep. To date, no large scale test of these relationships have been conducted in humans.This study is uniquely equipped to explore these relationships, because all of the participants were first enrolled in the study when their mothers were pregnant with them (in 1983). Birth size, growth rate, nutrition and other important characteristics were monitored periodically as each person aged, providing a rich record of their life experiences. These individuals are now 22 years of age, allowing this study to evaluate if nutrition and growth measured early in life predict reproductive function and health measured several decades later in adulthood.To answer this study's specific hypotheses, these data will be augmented by adult information on lifestyle and diet measured in interviews, and biological specimens (blood and saliva) for the measurement of reproductive hormones. All of these supplemental data and specimens were recently collected using a protocol designed to address this study's research goals, and the specimens are now in freezer storage at Northwestern University. NSF funding will only be required to cover the costs of analyzing hormones in these samples, which will be measured in the Laboratory for Human Biology Research housed in the Department of Anthropology at Northwestern University.This study promises significant insights into an issue of considerable theoretical and applied importance. As is true for females, cross-cultural research has documented a great deal of population variation in male reproductive function. However, unlike in females, this biological variability has been difficult to explain in males. This study will address this paradox by investigating whether differences in early life nutrition and growth influence male reproduction function. The answer to this question may also provide insights into an important mode of human adaptation: reducing expenditure on "costly" traits, such as reproduction and muscle mass, might be a necessary (if less than ideal) response when faced with a challenging nutritional environment.The broader impacts of this study include training opportunities for both graduate and undergraduate students interested in gaining experience with laboratory research. It will also strengthen the collaborative ties between an international team of researchers based in the US and the Philippines, who share interests in understanding the causes and consequences of male fertility.