Maternal adaptations of pancreatic islets and glucose metabolism after lactation

Pancreatic islet adaptation in pregnancy and postpartum

Pancreatic islets, particularly insulin-producing β-cells, are central regulators of glucose homeostasis capable of responding to a variety of metabolic stressors. Pregnancy is a unique physiological stressor, necessitating the islets to adapt to the complex interplay of maternal and fetal-placental factors influencing the metabolic milieu. In this review we highlight studies defining gestational adaptation mechanisms within maternal islets and emerging studies revealing islet adaptations during the early postpartum and lactation periods. These include adaptations in both β and in 'non-β' islet cells. We also discuss insights into how gestational and postpartum adaptation may inform pregnancy-specific and general mechanisms of islet responses to metabolic stress and contribute to investigation of gestational diabetes.

Differential disruption on glucose and insulin metabolism in two rat models of diet-induced obesity, based on carbohydrates or lipids

Obesity is a relevant health public issue and is the main factor for glucose metabolism dysregulation and diabetes progression; however, the differential role of a high-fat diet or high sugar diet consumption on glucose metabolism and insulin processing is not well understood and has been scarcely described. Our research aimed to analyze the effects of chronic consumption of both high sucrose and high-fat diets on glucose and insulin metabolism regulation. Wistar rats were fed with high-sugar or high-fat diets for 12 months; after that, fasting glucose and insulin levels were measured along with a glucose tolerance test (GTT). Proteins related to insulin synthesis and secretion were quantified in pancreas homogenates, whereas islets were isolated to analyze ROS generation and size measurement. Our results show that both diets induce metabolic syndrome, linked with central obesity, hyperglycemia, and insulin resistance. We observed alterations in the expression of proteins related with insulin synthesis and secretion, along with diminution of Langerhans islets size. Interestingly, the severity and number of alterations were more evident in the high-sugar diet than in the high-fat diet group. In conclusion, obesity and glucose metabolism dysregulation induced by carbohydrate consumption, led to worst outcomes than high-fat diet.

Maternal adaptations of the pancreas and glucose homeostasis in lactation and after lactation

During lactation, the maternal physiology adapts to bear the nutritional requirements of the offspring. The exocrine and endocrine pancreas are central to nutrient handling, promoting digestion and metabolism. In concert with prolactin, insulin is a determinant factor for milk synthesis. The investigation of the pancreas during lactation has been scattered over several periods. The investigations that laid the foundation of lactating pancreatic physiology and glucose homeostasis were conducted in the decades of 1970-1980. With the development of molecular biology, newer studies have revealed the molecular mechanisms involved in the endocrine pancreas during breastfeeding. There has been a surge of information recently about unexpected changes in the pancreas at the end of the lactation period and after weaning. In this review, we aim to gather information on the changes in the pancreas and glucose homeostasis during and after lactation and discuss the outcomes derived from the current discoveries.

The adaptation of maternal energy metabolism to lactation and its underlying mechanisms

Maternal energy metabolism undergoes a singular adaptation during lactation that allows for the caloric enrichment of milk. Changes in the mammary gland, changes in the white adipose tissue, brown adipose tissue, liver, skeletal muscles and endocrine pancreas are pivotal for this adaptation. The present review details the landmark studies describing the enzymatic modulation and the endocrine signals behind these metabolic changes. We will also update this perspective with data from recent studies showing transcriptional and post-transcriptional mechanisms that mediate the adaptation of the maternal metabolism to lactation. The present text will also bring experimental and observational data that describe the long-term consequences that short periods of lactation impose to maternal metabolism.