Intrauterine growth retardation has been linked to the development of type 2 diabetes in later life. The mechanisms underlying this phenomenon are unknown. We have developed a model of uteroplacental insufficiency, a common cause of intrauterine growth retardation, in the rat. Bilateral uterine artery ligation was performed on day 19 of gestation (term is 22 days) in the pregnant rat; sham-operated pregnant rats served as controls. Birth weights of intrauterine growth–retarded (IUGR) animals were significantly lower than those of controls until ∼7 weeks of age, when IUGR rats caught up to controls. Between 7 and 10 weeks of age, the growth of IUGR rats accelerated and surpassed that of controls, and by 26 weeks of age, IUGR rats were obese (P < 0.05 vs. controls). No significant differences were observed in blood glucose and plasma insulin levels at 1 week of age. However, between 7 and 10 weeks of age, IUGR rats developed mild fasting hyperglycemia and hyperinsulinemia (P < 0.05 vs. controls). At age 26 weeks, IUGR animals had markedly elevated levels of glucose (P < 0.05 vs. controls). IUGR animals were glucose-intolerant and insulin-resistant at an early age. First-phase insulin secretion in response to glucose was also impaired early in life in IUGR rats, before the onset of hyperglycemia. There were no significant differences in β-cell mass, islet size, or pancreatic weight between IUGR and control animals at 1 and 7 weeks of age. However, in 15-week-old IUGR rats, the relative β-cell mass was 50% that of controls, and by 26 weeks of age, β-cell mass was less than one-third that of controls (P < 0.05). The data presented here support the hypothesis that an abnormal intrauterine milieu can induce permanent changes in glucose homeostasis after birth and lead to type 2 diabetes in adulthood.

Intrauterine growth retardation (IUGR) has been linked to the onset of diseases in adulthood, including type 2 diabetes, and has been proposed to result from altered gene regulation patterns due to epigenetic modifications of developmental genes. To determine whether epigenetic modifications may play a role in the development of adult diabetes following IUGR, we used a rodent model of IUGR that expresses lower levels of Pdx1, a pancreatic and duodenal homeobox 1 transcription factor critical for β cell function and development, which develops diabetes in adulthood. We found that expression of Pdx1 was permanently reduced in IUGR β cells and underwent epigenetic modifications throughout development. The fetal IUGR state was characterized by loss of USF-1 binding at the proximal promoter of Pdx1, recruitment of the histone deacetylase 1 (HDAC1) and the corepressor Sin3A, and deacetylation of histones H3 and H4. Following birth, histone 3 lysine 4 (H3K4) was demethylated and histone 3 lysine 9 (H3K9) was methylated. During the neonatal period, these epigenetic changes and the reduction in Pdx1 expression could be reversed by HDAC inhibition. After the onset of diabetes in adulthood, the CpG island in the proximal promoter was methylated, resulting in permanent silencing of the Pdx1 locus. These results provide insight into the development of type 2 diabetes following IUGR and we believe they are the first to describe the ontogeny of chromatin remodeling in vivo from the fetus to the onset of disease in adulthood.