UC Riverside

Lactation brings about numerous maternal physiological and metabolic changes in order to sustain viable offspring. The liver plays a role in meeting the high energetic and metabolic needs of lactation as it is a key player in various biological processes that include lipid metabolism and homeostasis. A growing body of evidence suggests that the metabolic and physiological changes that lactation brings to the nursing mother results in a maternal profile that lowers the incidence of metabolic diseases. In this study, we examine in vivo and gene expression profiling data of fasted, age-matched virgin (V), non-lactating (NL), and lactating (L) C57Bl/6 mice in an attempt to understand the role the maternal liver plays in lactation in a global context. Our model allows us to examine the long term effects of lactation, since both the lactating and non-lactating mice have previously nursed pups. In vivo results highlight maternal adaptations to lactation that include rapid weight loss, increased liver weight, increased plasma triglyceride levels, and decreased hepatic triglyceride storage. Gene expression profiling reveals molecular signatures of different classes of genes that may explain the resulting maternal adaptations to lactation. Our model suggests a highly metabolically active liver that plays a role in supplying the energy that the lactating mammary gland needs, by synthesizing triglycerides and secreting them into the blood stream, thus making them available to the lactating mammary gland.