Abstract
► Dependence on maternal resources for eutherian development extends into neonatal life. ► Lactation and lactocrine communication support postnatal developmental programming. ► Lactocrine signaling affects neonatal female reproductive tract development. ► Disruption of estrogen-sensitive, lactocrine-driven uterine development has lasting effects. ► Colostrum/milk is a conduit for delivery of endocrine-disruptive chemicals to neonates.
For eutherian mammals a continuum of maternal support insures that development of progeny follows an optimal program. Beginning in utero, such support extends into the early neonatal period when bioactive factors are communicated from mother to offspring in colostrum/milk. Defined as lactocrine signaling, communication of milk-borne bioactive factors from mother to offspring as a consequence of nursing is important for development of somatic tissues, including the female reproductive tract (FRT). Data for the domestic pig indicate that lactocrine signaling contributes to the maternal continuum of factors that define the developmental program and determine the developmental trajectory of FRT tissues during early neonatal life. Both naturally occurring and manmade factors of environmental origin can be communicated to neonates in milk and affect development with lasting consequences. Here, evidence for lactocrine programming of FRT development and the potential for environmental endocrine disruption of this process are reviewed.