Chronic placental ischemia alters amniotic fluid milieu and results in impaired glucose tolerance, insulin resistance and hyperleptinemia in young rats

Although small size at birth is associated with hypertension and associated co-morbidities such as insulin resistance and type II diabetes mellitus, many of the animal models employed to simulate this phenomenon do not closely mimic the ontogeny of growth restriction observed clinically. While intrauterine growth restriction (IUGR) is often detected near mid-pregnancy in women and persists until term, most rodent models of IUGR employ ligation of uterine arteries for a brief period during late gestation (days 19-21 of pregnancy). We hypothesized that IUGR associated with chronic reduction in uteroplacental perfusion (RUPP) and placental ischemia during the third trimester of pregnancy in the rat alters the amniotic fluid (AF) environment and results in hypertensive offspring presenting with metabolic abnormalities such as glucose intolerance and insulin resistance. Insulin-like growth factor-1 (IGF-1), IGF-2, Na⁺ concentration and oxidative stress in the AF were increased, while K⁺ concentration was decreased in the RUPP compared with normal pregnant (NP) fetuses. RUPP-offspring (RUPP-O) were smaller (6.1±0.2 versus 6.7±0.2 g; P<0.05) at birth compared with NP-offspring (NP-O) groups. At nine weeks of age, mean arterial pressure (121±3 versus 107±5 mmHg; P<0.05), fasting insulin (0.71±0.014 versus 0.30±0.08 ng/mL; P<0.05), glucose (4.4±0.2 versus 3.1±0.3 mmol/L; P<0.05), leptin (3.8±0.5 versus 2.3±0.3 ng/mL; P<0.05) and the homeostasis model assessment of insulin resistance index was greater (2.9±0.6 versus 1.0±0.3; P<0.05) in the RUPP-O compared with the NP-O rats. These data indicate that chronic placental ischemia results in numerous alterations to the fetal environment that contributes to the development of impaired glucose metabolism, insulin resistance and hyperleptinemia in young offspring.