Offspring of diabetic mothers have higher risk to develop type 2 diabetes. Though exposure to hyperglycemia in-utero is an inciting event, the mechanism by which it impacts islet function and leads to increased risk of diabetes is unknown. We hypothesize that high glucose at late gestation alters pancreatic islet transcriptome during early life and impairs offspring islet function in adulthood. To test this, gestation day (GD) 20 fetal rats in left uterine horn were exposed to 48 hours of hyperglycemia (HG) by infusing 4mg/min glucose directly into maternal left uterine artery. Right uterine pups remained euglycemic as internal controls (Con). On GD22, HG and Con pups were either euthanized or cross-fostered to healthy dams. Glucose tolerance testing was performed on weaning and at 2month old (2mo) offspring. Islets of GD22 and weanling pups were isolated for RNAseq. While pregnant dams and Con fetal pups remained euglycemic during infusion, HG pups had higher blood glucose (88±9 mg/dL vs. 51±5mg/dL, p<0.05, n=20/20) and serum insulin levels (4.24±0.8 ng/mL vs. 3.04 ±0.6 ng/mL, p<0.05, 6/6 pups). HG pups also had higher beta cell area (31±12% increase, p<0.05, n=5/5 pups) but lower neonatal blood glucose level (72±9 mg/dL vs. 129±20 mg/dL, p<0.05, n=9/12 pups). Subsequently, weaning and 2mo HG offspring had impaired glucose tolerance (55±23% higher iAUC, n = 8/10 pups, p<0.05). 2mo pups also had lower insulin release during GTT. RNAseq identified 131 differentially expressed genes (DEG) in GD22 islets (fdr<0.1, n=3/3,) and 77 DEG in weanling islets (fdr<0.1, n=4/4,); with 10 common DEG. IPA analysis on these DEGs identified "cell signaling", "cellular movement", and "cell to cell signaling and interaction" as relevant biological processes. Weanling and young adult offspring exposed to late gestation hyperglycemia had impaired islet function with change expression in genes regulating critical biological processes. These genes will serve as target for future mechanistic studies.
J. Casasnovas: None. X. Rao: None. K. Kua: None.