Sylvia Kristyn E, Báez Ramos Patricia, Demas Gregory E
Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA.
Biology Department, University of Puerto Rico at Mayagüez, Mayagüez, PR 00681, USA.
Physiol Behav. 2018 Feb 1;184:68-77. doi: 10.1016/j.physbeh.2017.11.002. Epub 2017 Nov 7.
Previous work in our lab has shown that early-life infection affects female reproductive physiology and function (i.e., smaller ovaries, abnormal estrous cycles) and alters investigation and aggression towards male conspecifics in a reproductive context. Although many studies have investigated the effects of postnatal immune challenge on physiological and behavioral development, fewer studies have examined whether these changes have ultimate effects on reproduction. In the current study, we paired Siberian hamsters (Phodopus sungorus) and simulated a bacterial infection in early life by administering lipopolysaccharide (LPS) to male and female pups on pnd3 and pnd5. In adulthood, hamsters were paired with novel individuals of the same sex, and we scored an array of social behaviors (e.g., investigation, aggression). We then paired animals with individuals of the opposite sex for 5 consecutive nights, providing them with the opportunity to mate. We found that females exhibited impaired reproductive physiology and function in adulthood (i.e., smaller ovaries and abnormal estrous cycles), similar to our previous work. However, both LPS-treated males and females exhibited similar same-sex social behavior when compared with saline-treated controls, they successfully mated, and there were no significant changes in fecundity. These data suggest that the physiological changes in response to neonatal immune challenge may not have long-term effects on reproductive success in a controlled environment. Collectively, the results of this study are particularly important when investigating the relationships between physiology and behavior within an ultimate context. Animals exposed to early-life stress may in fact be capable of compensating for changes in physiology in order to survive and reproduce in some contexts.
我们实验室之前的研究表明，早期感染会影响雌性生殖生理和功能（即卵巢较小、发情周期异常），并改变在生殖背景下对雄性同种个体的探究和攻击行为。尽管许多研究调查了产后免疫挑战对生理和行为发育的影响，但较少有研究探讨这些变化是否对繁殖有最终影响。在本研究中，我们将西伯利亚仓鼠（Phodopus sungorus）配对，并通过在出生后第3天和第5天给雄性和雌性幼崽注射脂多糖（LPS）来模拟早期生活中的细菌感染。成年后，将仓鼠与新的同性个体配对，我们对一系列社会行为（如探究、攻击）进行评分。然后，我们将动物与异性个体连续配对5个晚上，为它们提供交配机会。我们发现，成年雌性表现出受损的生殖生理和功能（即卵巢较小和发情周期异常），这与我们之前的研究结果相似。然而，与生理盐水处理的对照组相比，LPS处理的雄性和雌性都表现出相似的同性社会行为，它们成功交配，繁殖力也没有显著变化。这些数据表明，在可控环境中，对新生儿免疫挑战的生理反应变化可能不会对繁殖成功产生长期影响。总体而言，在探究最终背景下生理与行为之间的关系时，本研究结果尤为重要。事实上，暴露于早期生活压力下的动物可能有能力补偿生理变化，以便在某些情况下生存和繁殖。
