Miles J. De Blasio

Improved lactational nutrition and postnatal growth ameliorates impairment of glucose tolerance by uteroplacental insufficiency in male rat offspring

Intrauterine growth restriction and accelerated postnatal growth predict increased risk of diabetes. Uteroplacental insufficiency in the rat restricts fetal growth but also impairs mammary development and postnatal growth. We used cross fostering to compare the influence of prenatal and postnatal nutritional restraint on adult glucose tolerance, insulin secretion, insulin sensitivity, and hypothalamic neuropeptide Y content in Wistar Kyoto rats at 6 months of age. Bilateral uterine vessel ligation (restricted) to induce uteroplacental insufficiency or sham surgery (control) was performed on d-18 gestation. Control, restricted, and reduced (reducing litter size of controls to match restricted) pups were cross fostered onto a control or restricted mother 1 d after birth. Restricted pups were born small compared with controls. Restricted males, but not females, remained lighter up to 6 months, regardless of postnatal environment. By 10 wk, restricted-on-restricted males ate more than controls. At 6 months restricted-on-restricted males had increased hypothalamic neuropeptide Y content compared with other groups, and together with reduced-on-restricted males had increased retroperitoneal fat weight (percent body weight) compared with control-on-controls. Restricted-on-restricted males had impaired glucose tolerance, reduced first-phase insulin secretion, but unaltered insulin sensitivity, compared with control-on-controls. In males, being born small and exposed to an impaired lactational environment adversely affects adult glucose tolerance and first-phase insulin secretion, but improving lactation partially ameliorates this condition. This study identifies early life as a target for intervention to prevent later diabetes after prenatal restraint.

Impaired β-Cell Function and Inadequate Compensatory Increases in β-Cell Mass after Intrauterine Growth Restriction in Sheep

Poor growth before birth increases the risk of non-insulin-dependent diabetes mellitus (NIDDM) and impairs insulin secretion relative to sensitivity. We investigated the effects of intrauterine growth restriction in sheep on insulin secretion, beta-cell mass, and function from before birth to young adulthood and its molecular basis. Pancreas was collected from control and placentally restricted sheep as fetuses (d 143 gestation), lambs (aged 42 d), and young adults (aged 556 d), following independent measures of in vivo insulin secretion and sensitivity. beta-Cells and islets were counted after immunohistochemical staining for insulin. In lambs, gene expression was measured by RT-PCR and expressed relative to 18S. beta-Cell mass correlated positively with fetal weight but negatively with birth weight in adult males. Glucose-stimulated insulin disposition and beta-cell function correlated negatively with fetal weight but positively with birth weight in adult males. Placental restriction increased pancreatic expression of IGF-II and IGF-I but decreased that of voltage-gated calcium channel, alpha1D subunit (CACNA1D) in lambs. In male lambs, pancreatic IGF-II and insulin receptor expression correlated strongly and positively with beta-cell mass and CACNA1D expression with glucose-stimulated insulin disposition. Restricted growth before birth in the sheep does not impair insulin secretion, relative to sensitivity, before birth or in young offspring. IGF-II and insulin receptor are implicated as key molecular regulators of beta-cell mass compensation, whereas impaired expression of the voltage-gated calcium channel may underlie impaired beta-cell function after intrauterine growth restriction. With aging, the insulin secretory capacity of the beta-cell is impaired in males, and their increases in beta-cell mass are inadequate to maintain adequate insulin secretion relative to sensitivity.

Restriction of placental growth in sheep impairs insulin secretion but not sensitivity before birth

Restricted growth before birth is associated with impaired insulin secretion but with initially enhanced insulin sensitivity in early postnatal life, which then progresses to insulin resistance and impaired glucose homeostasis by adulthood. This suggests that prenatal restraint impairs insulin secretion, but increases insulin sensitivity, before birth. Poor placental growth and function are major causes of restricted fetal growth in humans. We have therefore investigated the effects of restricted placental growth and function on plasma glucose, α‐amino nitrogen and insulin concentrations and glucose‐ and arginine‐stimulated insulin secretion in the fetal sheep at 120 and 140 days gestational age, and on insulin sensitivity, measured by hyperinsulinaemic euglycaemic clamp, at 130 days gestational age. Placental restriction decreased fetal blood pH and oxygen content, and weight in late gestation by ∼20%. Reduced fetal and placental weights and indices of poor placental function, in particular fetal hypoxia and hypoglycaemia, were associated with impaired glucose‐ and arginine‐stimulated insulin secretion, but not with changes in insulin sensitivity in the fetal sheep. We conclude that the impaired insulin secretion capacity reported in children and adults after intrauterine growth restriction, and in the neonatal and young adult sheep which is small at birth, is present in utero and persists. Whether this reflects the actions of the adverse intrauterine environment or changes to intrinsic capacity is unclear, but in utero interventions may be necessary to improve postnatal insulin secretion in the infant who is growth‐restricted before birth.

Variable maternal nutrition and growth hormone treatment in the second quarter of pregnancy in pigs alter semitendinosus muscle in adolescent progeny

Maternal nutrition and growth hormone (GH) treatment during early- to mid-pregnancy can each alter the subsequent growth and differentiation of muscle in progeny. We have investigated the effects of varying maternal nutrition and maternal treatment with porcine (p) GH during the second quarter of pregnancy in gilts on semitendinosus muscle cross-sectional area and fibre composition of progeny, and relationships between maternal and progeny measures and progeny muscularity. Fifty-three Large White x Landrace gilts, pregnant to Large White x Duroc boars, were fed either 2.2 kg (about 35 % ad libitum intake) or 3.0 kg commercial ration (13.5 MJ digestible energy, 150 g crude protein (N x 6.25)/kg DM)/d and injected with 0, 4 or 8 mg pGH/d from day 25 to 50 of pregnancy, then all were fed 2.2 kg/d for the remainder of pregnancy. The higher maternal feed allowance from day 25 to 50 of pregnancy increased the densities of total and secondary fibres and the secondary:primary fibre ratio in semitendinosus muscles of their female progeny at 61 d of age postnatally. The densities of secondary and total muscle fibres in semitendinosus muscles of progeny were predicted by maternal weight before treatment and maternal plasma insulin-like growth factor-II during treatment. Maternal pGH treatment from day 25 to day 50 of pregnancy did not alter fibre densities, but increased the cross-sectional area of the semitendinosus muscle; this may be partially explained by increased maternal plasma glucose. Thus, maternal nutrition and pGH treatment during the second quarter of pregnancy in pigs independently alter muscle characteristics in progeny.

Placental Restriction Reduces Insulin Sensitivity and Expression of Insulin Signaling and Glucose Transporter Genes in Skeletal Muscle, But Not Liver, in Young Sheep

Poor growth before birth is associated with impaired insulin sensitivity later in life, increasing the risk of type 2 diabetes. The tissue sites at which insulin resistance first develops after intrauterine growth restriction (IUGR), and its molecular basis, are unclear. We have therefore characterized the effects of placental restriction (PR), a major cause of IUGR, on whole-body insulin sensitivity and expression of molecular determinants of insulin signaling and glucose uptake in skeletal muscle and liver of young lambs. Whole-body insulin sensitivity was measured at 30 d by hyperinsulinaemic euglycaemic clamp and expression of insulin signaling genes (receptors, pathways, and targets) at 43 d in muscle and liver of control (n = 15) and PR (n = 13) lambs. PR reduced size at birth and increased postnatal growth, fasting plasma glucose (+15%, P = 0.004), and insulin (+115%, P = 0.009). PR reduced whole-body insulin sensitivity (-43%, P < 0.001) and skeletal muscle expression of INSR (-36%), IRS1 (-28%), AKT2 (-44%), GLUT4 (-88%), GSK3α (-35%), and GYS1 (-31%) overall (each P < 0.05) and decreased AMPKγ3 expression in females (P = 0.030). PR did not alter hepatic expression of insulin signaling and related genes but increased GLUT2 expression (P = 0.047) in males. Whole-body insulin sensitivity correlated positively with skeletal muscle expression of IRS1, AKT2, HK, AMPKγ2, and AMPKγ3 in PR lambs only (each P < 0.05) but not with hepatic gene expression in control or PR lambs. Onset of insulin resistance after PR and IUGR is accompanied by, and can be accounted for by, reduced expression of insulin signaling and metabolic genes in skeletal muscle but not liver.

Mild gestational diabetes in pregnancy and the adipoinsular axis in babies born to mothers in the ACHOIS randomised controlled trial

BackgroundMild gestational diabetes is a common complication of pregnancy, affecting up to 9% of pregnant women. Treatment of mild GDM is known to reduce adverse perinatal outcomes such as macrosomia and associated birth injuries, such as shoulder dystocia, bone fractures and nerve palsies. This study aimed to compare the plasma glucose concentrations and serum insulin, leptin and adiponectin in cord blood of babies of women (a) without gestational diabetes mellitus (GDM), (b) with mild GDM under routine care, or (c) mild GDM with treatment.Methods95 women with mild GDM on oral glucose tolerance testing (OGTT) at one tertiary level maternity hospital who had been recruited to the ACHOIS trial at one of the collaborating hospitals and randomised to either Treatment (n = 46) or Routine Care (n = 49) and Control women with a normal OGTT (n = 133) were included in the study. Women with mild GDM (treatment or routine care group) and OGTT normal women received routine pregnancy care. In addition, women with treated mild GDM received dietary advice, blood glucose monitoring and insulin if necessary.The primary outcome measures were cord blood concentrations of glucose, insulin, adiponectin and leptin.ResultsCord plasma glucose was higher in women receiving routine care compared with control, but was normalized by treatment for mild GDM (p = 0.01). Cord serum insulin and insulin to glucose ratio were similar between the three groups. Leptin concentration in cord serum was lower in GDM treated women compared with routine care (p = 0.02) and not different to control (p = 0.11). Adiponectin was lower in both mild GDM groups compared with control (Treatment p = 0.02 and Routine Care p = 0.07), while the adiponectin to leptin ratio was lower for women receiving routine care compared with treatment (p = 0.08) and control (p = 0.05).ConclusionTreatment of women with mild GDM using diet, blood glucose monitoring and insulin if necessary, influences the altered fetal adipoinsular axis characteristic of mild GDM in pregnancy.

Maternal and Neonatal Circulating Markers of Metabolic and Cardiovascular Risk in the Metformin in Gestational Diabetes (MiG) Trial: Responses to maternal metformin versus insulin treatment

OBJECTIVE This study was designed to compare glucose, lipids, and C-reactive protein (CRP) in women with gestational diabetes mellitus treated with metformin or insulin and in cord plasma of their offspring and to examine how these markers relate to infant size at birth. RESEARCH DESIGN AND METHODS Women with gestational diabetes mellitus were randomly assigned to metformin or insulin in the Metformin in Gestational Diabetes trial. Fasting maternal plasma glucose, lipids, and CRP were measured at randomization, 36 weeks’ gestation, and 6–8 weeks postpartum as well as in cord plasma. Women with available cord blood samples (metformin n = 236, insulin n = 242) were included. RESULTS Maternal plasma triglycerides increased more from randomization to 36 weeks’ gestation in women treated with metformin (21.93%) versus insulin (9.69%, P < 0.001). Maternal and cord plasma lipids, CRP, and neonatal anthropometry did not differ between treatments. In logistic regression analyses adjusted for confounders, the strongest associations with birth weight >90th centile were maternal triglycerides and measures of glucose control at 36 weeks. CONCLUSIONS There were few differences in circulating maternal and neonatal markers of metabolic status and no differences in measures of anthropometry between the offspring of women treated with metformin and the offspring of women treated with insulin. There may be subtle effects of metformin on maternal lipid function, but the findings suggest that treating gestational diabetes mellitus with metformin does not adversely affect lipids or CRP in cord plasma or neonatal anthropometric measures.

Determinants of Maternal Triglycerides in Women With Gestational Diabetes Mellitus in the Metformin in Gestational Diabetes (MiG) Study

OBJECTIVE Factors associated with increasing maternal triglyceride concentrations in late pregnancy include gestational age, obesity, preeclampsia, and altered glucose metabolism. In a subgroup of women in the Metformin in Gestational Diabetes (MiG) trial, maternal plasma triglycerides increased more between enrollment (30 weeks) and 36 weeks in those treated with metformin compared with insulin. The aim of this study was to explain this finding by examining factors potentially related to triglycerides in these women. RESEARCH DESIGN AND METHODS Of the 733 women randomized to metformin or insulin in the MiG trial, 432 (219 metformin and 213 insulin) had fasting plasma triglycerides measured at enrollment and at 36 weeks. Factors associated with maternal triglycerides were assessed using general linear modeling. RESULTS Mean plasma triglyceride concentrations were 2.43 (95% CI 2.35–2.51) mmol/L at enrollment. Triglycerides were higher at 36 weeks in women randomized to metformin (2.94 [2.80–3.08] mmol/L; +23.13% [18.72–27.53%]) than insulin (2.65 [2.54–2.77] mmol/L, P = 0.002; +14.36% [10.91–17.82%], P = 0.002). At 36 weeks, triglycerides were associated with HbA1c (P = 0.03), ethnicity (P = 0.001), and treatment allocation (P = 0.005). In insulin-treated women, 36-week triglycerides were associated with 36-week HbA1c (P = 0.02), and in metformin-treated women, they were related to ethnicity. CONCLUSIONS At 36 weeks, maternal triglycerides were related to glucose control in women treated with insulin and ethnicity in women treated with metformin. Whether there are ethnicity-related dietary changes or differences in metformin response that alter the relationship between glucose control and triglycerides requires further study.

Effect of placental restriction and neonatal exendin-4 treatment on postnatal growth, adult body composition, and in vivo glucose metabolism in the sheep.

Intrauterine growth restriction (IUGR) increases the risk of adult type 2 diabetes (T2D) and obesity. Neonatal exendin-4 treatment can prevent diabetes in the IUGR rat, but whether this will be effective in a species where the pancreas is more mature at birth is unknown. Therefore, we evaluated the effects of neonatal exendin-4 administration after experimental restriction of placental and fetal growth on growth and adult metabolic outcomes in sheep. Body composition, glucose tolerance, and insulin secretion and sensitivity were assessed in singleton-born adult sheep from control (CON; n = 6 females and 4 males) and placentally restricted pregnancies (PR; n = 13 females and 7 males) and in sheep from PR pregnancies that were treated with exendin-4 as neonates (daily sc injections of 1 nmol/kg exendin-4; PR + exendin-4; n = 11 females and 7 males). Placental restriction reduced birth weight (by 29%) and impaired glucose tolerance in the adult but did not affect adult adiposity, insulin secretion, or insulin sensitivity. Neonatal exendin-4 suppressed growth during treatment, followed by delayed catchup growth and unchanged adult adiposity. Neonatal exendin-4 partially restored glucose tolerance in PR progeny but did not affect insulin secretion or sensitivity. Although the effects on glucose tolerance are promising, the lack of effects on adult body composition, insulin secretion, and insulin sensitivity suggest that the neonatal period may be too late to fully reprogram the metabolic consequences of IUGR in species that are more mature at birth than rodents.

Neonatal exendin-4 reduces growth, fat deposition and glucose tolerance during treatment in the intrauterine growth-restricted lamb

Background IUGR increases the risk of type 2 diabetes mellitus (T2DM) in later life, due to reduced insulin sensitivity and impaired adaptation of insulin secretion. In IUGR rats, development of T2DM can be prevented by neonatal administration of the GLP-1 analogue exendin-4. We therefore investigated effects of neonatal exendin-4 administration on insulin action and β-cell mass and function in the IUGR neonate in the sheep, a species with a more developed pancreas at birth. Methods Twin IUGR lambs were injected s.c. daily with vehicle (IUGR+Veh, n = 8) or exendin-4 (1 nmol.kg-1, IUGR+Ex-4, n = 8), and singleton control lambs were injected with vehicle (CON, n = 7), from d 1 to 16 of age. Glucose-stimulated insulin secretion and insulin sensitivity were measured in vivo during treatment (d 12–14). Body composition, β-cell mass and in vitro insulin secretion of isolated pancreatic islets were measured at d 16. Principal Findings IUGR+Veh did not alter in vivo insulin secretion or insulin sensitivity or β-cell mass, but increased glucose-stimulated insulin secretion in vitro. Exendin-4 treatment of the IUGR lamb impaired glucose tolerance in vivo, reflecting reduced insulin sensitivity, and normalised glucose-stimulated insulin secretion in vitro. Exendin-4 also reduced neonatal growth and visceral fat accumulation in IUGR lambs, known risk factors for later T2DM. Conclusions Neonatal exendin-4 induces changes in IUGR lambs that might improve later insulin action. Whether these effects of exendin-4 lead to improved insulin action in adult life after IUGR in the sheep, as in the PR rat, requires further investigation.