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The ability to provision offspring with milk is a significant adaptive feature of mammals that allows for considerable maternal regulation of offspring beyond gestation, as milk provides complete nutrition for developing neonates. For mothers, lactation is a period of marked increases in energetic and nutritive demands to support milk synthesis; because of this considerable increase in demand imposed on multiple physiological systems, lactation is particularly susceptible to the effects of chronic stress. Here, we present work that explores the impact of chronic stress during lactation on maternal lactation performance (i.e. milk quality and quantity) and the expression of key milk synthesis genes in mammary tissue using a Sprague–Dawley rat model. We induced chronic stress using a well-established, ethologically relevant novel male intruder paradigm for 10 consecutive days during the postpartum period. We hypothesized that the increased energetic burden of mounting a chronic stress response during lactation would decrease lactation performance. Specifically, we predicted that chronic exposure to this social stressor would decrease either milk quality (i.e. composition of proximate components and energy density) or quantity. We also predicted that changes in proximate composition (i.e. lipid, lactose, and protein concentrations) would be associated with changes in gene expression levels of milk synthesis genes. Our results supported our hypothesis that chronic stress impairs lactation performance. Relative to the controls, chronically stressed rats had lower milk yields. We also found that milk quality was decreased; milk from chronically stressed mothers had lower lipid concentration and lower energy density, though protein and lactose concentrations were not different between treatment groups. Although there was a change in proximate composition, chronic stress did not impact mammary gland expression of key milk synthesis genes. Together, this work demonstrates that exposure to a chronic stressor impacts lactation performance, which in turn has the potential to impact offspring development via maternal effects. [ABSTRACT FROM AUTHOR]

One of the key foci of ecoimmunology is understanding the physiological interactions between reproduction and immune defense. To assess an immune challenge, investigators typically measure an immune response at a predetermined time point that was selected to represent a peak response. These time points often are based on the immunological responses of nonreproductive males. Problematically, these peaks have been applied to studies quantifying immune responses of females during reproduction, despite the fact that nonreproductive males and reproductive females display fundamentally different patterns of energy expenditure. Previous work within pharmacological research has reported that the response to the commonly-used antigen keyhole limpet hemocyanin (KLH) varies among individuals and between females and males. In this heuristic analysis, we characterize antibody responses to KLH in females with varying reproductive demands (nonreproductive, lactating, concurrently lactating, and pregnant). Serum was taken from one animal per day per group and assessed for general and specific Immunoglobulins (Igs) G and M. We then used regression analysis to characterize the antibody response curves across groups. Our results demonstrate that the antibody response curve is asynchronous among females with varying maternal demands and temporally differs from the anticipated peak responses reflected in standardized protocols. These findings highlight the importance of multiple sampling points across treatment groups for a more integrative assessment of how reproductive demand alters antibody responses in females beyond a single measurement. [ABSTRACT FROM AUTHOR]

Like many scientific disciplines, the field of reproductive biology is subject to biases in terminology and research foci. For example, females are often described as coy and passive players in reproductive behaviors and are termed "promiscuous" if they engage in extra-pair copulations. Males on the other hand are viewed as actively holding territories and fighting with other males. Males are termed "multiply mating" if they mate with multiple females. Similarly, textbooks often illustrate meiosis as it occurs in males but not females. This edition of Integrative and Comparative Biology (ICB) includes a series of papers that focus on reproduction from the female perspective. These papers represent a subset of the work presented in our symposium and complementary sessions on female reproductive biology. In this round table discussion, we use a question and answer format to leverage the diverse perspectives and voices involved with the symposium in an exploration of theoretical, cultural, pedagogical, and scientific issues related to the study of female biology. We hope this dialog will provide a stepping-stone toward moving reproductive science and teaching to a more inclusive and objective framework. [ABSTRACT FROM AUTHOR]