Pancreatic islet response to diabetes during pregnancy in rats

Aims: The objective of this study was to assess the mechanisms underlying pancreatic islet adaptation in diabetic mothers and their pups. Additionally, the influence of pancreatic adaptations on maternal reproductive performance was also investigated. Main methods: Wistar rats were injected with streptozotocin for diabetes induction. At adulthood (3 months), all animals underwent an oral glucose tolerance test (OGTT) for glucose assessment as an inclusion criterion. Following, the animals were mated. At day 18 of pregnancy, the mothers were killed for blood collect ion to determine fasting insulin and glucagon concentrations. The pancreas was removed and processed for the immunohistochemical analysis of insulin, glucagon, somatostatin, Ki-67 and PDX-1, superoxide dismutase 1 (SOD-1), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA). The pregnant uterus was also collected for the evaluation of embryofetal loss. Key findings: The diabetic rats showed increased glucose, serum glucagon and insulin concentrations, and embryofetal loss rates. They also showed a reduction in pancreatic islets area and percentage of cells stained for insulin, increased the percentage of non-β cells (alpha e delta cells) stained for Ki-67, glucagon, and somatostatin. Moreover, the cells stained for somatostatin were spread across the islets and showed stronger staining for MDA and weaker staining for GSH-Px. Significance: Diabetes leads to adaptive responses from the endocrine pancreas in pregnancy that especially involves non-β cells, modifying the mantle-core structure. Nonetheless, these adaptations are not enough for glucose homeostasis and affect the maternal environment, which in turn impairs fetal development.