The Mechanistic Basis for Improved Metabolic Health in Females Following Lactation

Abstract

Human epidemiological data show that breastfeeding reduces the mother’s prevalence of many disease conditions such as obesity, type II diabetes, and hypertension compared to mothers that give birth but do not breastfeed. The current research project seeks to delineate the changes in animals at different reproductive stages, and how these may confer health benefits to mothers that lactate. Markers of metabolism, mitochondrial function, and oxidative stress were measured in skeletal muscle, liver, and white adipose tissue in three experiments. In experiment 1, Sprague- Dawley rats were randomly assigned to one of four treatment groups (n = 8 per group): 1) non-pregnant animals (NP), 2) animals sacrificed at day 20 of gestation (P), 3) animals that gave birth, but did not lactate their pups (NL), and 4) animals that gave birth, and lactated their pups for 14 days (L). In experiment 2, rats were divided into three groups and were sacrificed at a time that corresponded to 28 days following parturition (n = 8 per group): 1) non-reproductive (NR), 2) those that were gave birth, but were not allowed to suckle their pups (P), and 3) those that gave birth, and suckled their young for 21 days (L). In experiment 3, rats were divided into three groups and sacrificed at a time that corresponded to 15 weeks after parturition (n = 8 per group): 1) rats that did not reproduce (NR), 2) rats that gave birth, but did not suckle their pups (NL), and 3) rats that give birth, and suckled their pups for 21 days before weaning (L). I found that metabolism and mitochondrial function is modulated in tissues in response to iii pregnancy and lactation and that lactation improves glucose metabolism, increases peroxisome proliferator activated receptor delta (PPARδ) levels, and improves mitochondrial function in all experiments. I also found that animals that do not lactate may have a propensity for fat storage that could increase the risk of disease. These animal findings support human epidemiological data and provide systemic and tissue specific evidence of the maternal health benefits conferred via breastfeeding.