Lactation has persistent effects on a mother's metabolism and mitochondrial function

Human epidemiological data show that breastfeeding reduces the prevalence of numerous diseases compared to mothers that give birth but do not participate in lactation. The goal of this study was to determine if differences in metabolism, mitochondrial function, and oxidative stress underlie the protective phenotype found in lactating women. Ten-week old female Sprague-Dawley rats were divided into three groups (n = 8 per group): 1) rats that did not reproduce (NR), 2) rats that were allowed to mate and become pregnant but did not suckle their pups after giving birth (NL), and 3) rats that were allowed to mate and become pregnant and suckled their pups for 21 days before weaning (L). All animals were sacrificed at approximately 7 months of age, a time corresponding to 15 weeks after the NL and L females gave birth. Liver mitochondrial respiration was higher in L rats when using NADH-linked substrates and these rats had lower serum glucose concentration. Additionally, the L group exhibited changes in liver, skeletal muscle, and white adipose tissue PPARδ protein levels that may, in part, explain the observed lower serum glucose concentration. These novel animal findings provide evidence of differences in metabolic processes that persist months after weaning.