Julie A. Owens

Chronic high-fat diet in fathers programs β-cell dysfunction in female rat offspring

The global prevalence of obesity is increasing across most ages in both sexes. This is contributing to the early emergence of type 2 diabetes and its related epidemic. Having either parent obese is an independent risk factor for childhood obesity. Although the detrimental impacts of diet-induced maternal obesity on adiposity and metabolism in offspring are well established, the extent of any contribution of obese fathers is unclear, particularly the role of non-genetic factors in the causal pathway. Here we show that paternal high-fat-diet (HFD) exposure programs β-cell ‘dysfunction’ in rat F1 female offspring. Chronic HFD consumption in Sprague–Dawley fathers induced increased body weight, adiposity, impaired glucose tolerance and insulin sensitivity. Relative to controls, their female offspring had an early onset of impaired insulin secretion and glucose tolerance that worsened with time, and normal adiposity. Paternal HFD altered the expression of 642 pancreatic islet genes in adult female offspring (P < 0.01); genes belonged to 13 functional clusters, including cation and ATP binding, cytoskeleton and intracellular transport. Broader pathway analysis of 2,492 genes differentially expressed (P < 0.05) demonstrated involvement of calcium-, MAPK- and Wnt-signalling pathways, apoptosis and the cell cycle. Hypomethylation of the Il13ra2 gene, which showed the highest fold difference in expression (1.76-fold increase), was demonstrated. This is the first report in mammals of non-genetic, intergenerational transmission of metabolic sequelae of a HFD from father to offspring.

Paternal obesity initiates metabolic disturbances in two generations of mice with incomplete penetrance to the F2 generation and alters the transcriptional profile of testis and sperm microRNA content

Obesity is highly prevalent, and its incidence is increasing. The previous study showing a major effect of paternal obesity on metabolic health of offspring is confounded by comorbidity with diabetes. Therefore, we investigated the effect of diet‐induced paternal obesity, in the absence of diabetes, on the metabolic health of two resultant generations and the molecular profiles of the testes and sperm. Founder (F0) male C57BL6 mice were fed either a high‐fat diet (HFD) or a control diet (CD); n = 10/diet for a period of 10 wk. Testis expression of mRNA/microRNAs was analyzed by microarray and qPCR and sperm microRNA abundance by qPCR Two subsequent generations were generated by mating F0 and then F1 mice to CD mice, and their metabolic health was investigated. All mice, other than F0 males, were maintained on a CD. HFD feeding induced paternal obesity with a 21% increase in adiposity, but not overt diabetes, and initiated intergenerational transmission of obesity and insulin resistance in two generations of offspring. This distinct phenotypic constellation is either partially or fully transmitted to both female and male F1 offspring and further transmitted through both parental lineages to the F2 generation, with a heightened effect on female F1 offspring (+67% in adiposity) and their F2 sons (+24% in adiposity). Founder male obesity altered the testes expression of 414 mRNAs by microarray and 11 microRNAs by qPCR, concomitant with alterations in sperm microRNA content and a 25% reduction in global methylation of germ cell DNA Diet‐induced paternal obesity modulates sperm microRNA content and germ cell methylation status, which are potential signals that program offspring health and initiate the transmission of obesity and impaired metabolic health to future generations. This study implicates paternal obesity in the transgenerational amplification of obesity and type 2 diabetes in humans.—Fullston, T., Ohlsson Teague, E. M. C., Palmer, N. O., DeBlasio, M. J., Mitchell, M., Corbett, M., Print, C. G., Owens, J. A., Lane, M., Paternal obesity initiates metabolic disturbances in two generations of mice with incomplete penetrance to the F2 generation and alters the transcriptional profile of testis and sperm microRNA content. FASEBJ. 27, 4226‐4243 (2013). www.fasebj.org

Antenatal lifestyle advice for women who are overweight or obese: LIMIT randomised trial

Objective To determine the effect of antenatal dietary and lifestyle interventions on health outcomes in overweight and obese pregnant women. Design Multicentre randomised trial. We utilised a central telephone randomisation server, with computer generated schedule, balanced variable blocks, and stratification for parity, body mass index (BMI) category, and hospital. Setting Three public maternity hospitals across South Australia. Participants 2212 women with a singleton pregnancy, between 10+0 and 20+0 weeks’ gestation, and BMI ≥25. Interventions 1108 women were randomised to a comprehensive dietary and lifestyle intervention delivered by research staff; 1104 were randomised to standard care and received pregnancy care according to local guidelines, which did not include such information. Main outcome measures Incidence of infants born large for gestational age (birth weight ≥90th centile for gestation and sex). Prespecified secondary outcomes included birth weight >4000 g, hypertension, pre-eclampsia, and gestational diabetes. Analyses used intention to treat principles. Results 2152 women and 2142 liveborn infants were included in the analyses. The risk of the infant being large for gestational age was not significantly different in the two groups (lifestyle advice 203/1075 (19%) v standard care 224/1067 (21%); adjusted relative risk 0.90, 95% confidence interval 0.77 to 1.07; P=0.24). Infants born to women after lifestyle advice were significantly less likely to have birth weight above 4000 g (lifestyle advice 164/1075 (15%) v standard care 201/1067 (19%); 0.82, 0.68 to 0.99; number needed to treat (NNT) 28, 15 to 263; P=0.04). There were no differences in maternal pregnancy and birth outcomes between the two treatment groups. Conclusions For women who were overweight or obese, the antenatal lifestyle advice used in this study did not reduce the risk delivering a baby weighing above the 90th centile for gestational age and sex or improve maternal pregnancy and birth outcomes. Trial registration Australian and New Zealand Clinical Trials Registry (ACTRN12607000161426).

Normal Lactational Environment Restores Nephron Endowment and Prevents Hypertension after Placental Restriction in the Rat

Uteroplacental insufficiency in the rat restricts fetal growth, impairs mammary development, compromising postnatal growth; and increases adult BP. The roles of prenatal and postnatal nutritional restraint on later BP and nephron endowment in offspring from mothers that underwent bilateral uterine vessel ligation (restricted) on day 18 of pregnancy were examined. Sham surgery (control) and a group of rats with reduced litter size (reduced; litter size reduced at birth to five, equivalent to restricted group) were used as controls. Offspring (control, reduced, and restricted) were cross-fostered on postnatal day 1 onto a control (normal lactation) or restricted (impaired lactation) mother. BP in male offspring was determined by tail cuff at 8, 12, and 20 wk of age, with glomerular number and volume (Cavalieri/Physical Dissector method) and renal angiotensin II type 1 receptor (AT(1)R) mRNA expression (real-time PCR) determined at 6 mo. Restricted-on-restricted male offspring developed hypertension (+16 mmHg) by 20 wk together with a nephron deficit (-26%) and glomerular hypertrophy (P < 0.05). In contrast, providing a normal lactational environment to restricted offspring improved postnatal growth and prevented the nephron deficit and hypertension. Reduced-on-restricted pups that were born of normal weight but with impaired growth during lactation subsequently grew faster, developed hypertension (+16 mmHg), had increased AT(1A)R and AT(1B)R mRNA expression (P < 0.05), but had no nephron deficit. Our study identifies the prenatal and postnatal nutritional environments in the programming of adult hypertension, associated with distinct renal changes. It is shown for the first time that a prenatally induced nephron deficit can be restored by correcting growth restriction during lactation.

Growth restriction before or after birth reduces nephron number and increases blood pressure in male rats

Impaired growth in utero predicts a low nephron number and high blood pressure later in life as does slowed or accelerated growth after a normal birth weight. We measured the effects of early postnatal growth restriction, with or without prenatal growth restriction, on blood pressure and nephron number in male rat offspring. Bilateral uterine artery and vein ligation were performed to induce uteroplacental insufficiency (Restricted) on day 18 of pregnancy. Postnatal growth restriction was induced in a subset of sham operated control animals by reducing the number of pups at birth to that of the Restricted group (Reduced Litter). Compared to Controls, Restricted pups were born smaller while Reduced Litter pups weighed less by postnatal day 3 and both groups remained lighter throughout lactation. By 10 weeks of age all animals were of similar weight but the Reduced Litter rats had elevated blood pressure. At 22 weeks, Restricted but not Reduced Litter offspring were smaller and the blood pressure was increased in both groups. Restricted and Reduced Litter groups had fewer glomeruli and greater left ventricular mass than Controls. These results suggest that restriction of both perinatal and early postnatal growth increase blood pressure in male offspring. This study also demonstrates that the early postnatal period is a critical time for nephron endowment in the rat.

Restriction of placental and fetal growth in sheep alters fetal blood pressure responses to angiotensin II and captopril

1 We have measured arterial blood pressure between 115 and 145 days gestation in normally grown fetal sheep (control group; n= 16) and in fetal sheep in which growth was restricted by experimental restriction of placental growth and development (PR group; n= 13). There was no significant difference in the mean gestational arterial blood pressure between the PR (42.7 ± 2.6 mmHg) and control groups (37.7 ± 2.3 mmHg). Mean arterial blood pressure and arterial P  O 2 were significantly correlated in control animals (r= 0.53, P < 0.05, n= 16), but not in the PR group. 2 There were no changes in mean arterial blood pressure in either the PR or control groups in response to captopril (7.5 μg captopril min−1; PR group n= 7, control group n= 6) between 115 and 125 days gestation. After 135 days gestation, there was a significant decrease (P < 0.05) in the fetal arterial blood pressure in the PR group but not in the control group during the captopril infusion (15 μg captopril min−1; PR group n= 7, control group n= 6). 3 There was a significant effect (F= 14.75; P < 0.001) of increasing doses of angiotensin II on fetal diastolic blood pressure in the PR and control groups. The effects of angiotensin II were different (F= 8.67; P < 0.05) in the PR and control groups at both gestational age ranges. 4 These data indicate that arterial blood pressure may be maintained by different mechanisms in growth restricted fetuses and normally grown counterparts and suggests a role for the fetal renin‐angiotensin system in the maintenance of blood pressure in growth restricted fetuses.

Placental Restriction Alters the Functional Development of the Pituitary-Adrenal Axis in the Sheep Fetus during Late Gestation

We have experimentally restricted placental growth in the sheep to investigate the impact of reduced substrate delivery on fetal pituitary proopiomelanocortin (POMC) mRNA levels and on circulating ACTH 1-39, immunoreactive ACTH, and cortisol concentrations during late gestation. Endometrial caruncles were removed in nine ewes before mating to reduce the number of placentomes formed [placental restriction group (PR)]. Fetal arterial Po2 and O2 saturation were reduced in the PR group (2.0± 0.1 kPa and 42.8 ± 1.1%, n = 9) when compared with control fetuses (3.1 ± 0.1 kPa and 66.4 ± 0.9%, n = 10). The ratio of anterior pituitary POMC mRNA:18 S ribosomal RNA was also lower (p < 0.05) in the PR group (0.49 ± 0.05) when compared with the control group (0.80 ± 0.12) after 140 d of gestation. In contrast, plasma concentrations of ACTH 1-39 and immunoreactive ACTH were similar in the PR and control groups throughout late gestation. Plasma ACTH 1-39 concentrations increased (p < 0.006) between 128 and 134 d of gestation, in both the PR (122-128 d: 2.70 ± 0.34 pmol/L: 134-141 d; 7.07 ± 1.57 pmol/L) and control (122-128 d; 3.36 ± 0.56 pmol/L: 134-141 d; 10.78 ± 2.88 pmol/L) groups. Combined adrenal weight was higher (p < 0.005) in the PR group (130 ± 10 mg/kg) compared with controls (80 ± 1 mg/kg) at 140 d of gestation, and plasma cortisol concentrations were also higher (p < 0.02) in PR than control fetuses between 127 and 141 d of gestation. These changes imply that the fetal hypothalamopituitary-adrenal axis is operating at a new central set point in the growth-restricted fetus.

Origins of fetal growth restriction

Regulation of growth of the fetus and its placenta begins before pregnancy. Early in pregnancy the mother sets the rate of growth of the fetus on a trajectory, which may be modified by events later in pregnancy. Low maternal weight for height, history of previous small babies, maternal undernutrition, pregnancy disorders, e.g. pre-eclampsia, are associated with low birthweight. Maternal smoking is a major factor in developed countries; infections and undernutrition in developing countries.Recently, there has been emphasis on adverse long-term outcomes including ischaemic heart disease, hypertension and diabetes associated with poor fetal growth. Experimental studies in animals show that some of these outcomes can readily be induced by restriction of fetal growth. Progress in determining successful treatments to improve the growth of the fetus has lagged behind these epidemiological and experimental findings. However, nutrient supplements improve growth in undernourished women and smoking cessation also improves fetal size and outcome.

Diet-induced paternal obesity in the absence of diabetes diminishes the reproductive health of two subsequent generations of mice

BACKGROUND Obesity and related conditions, notably subfertility, are increasingly prevalent. Paternal influences are known to influence offspring health outcome, but the impact of paternal obesity and subfertility on the reproductive health of subsequent generations has been overlooked. METHODS A high-fat diet (HFD) was used to induce obesity but not diabetes in male C57Bl6 mice, which were subsequently mated to normal-weight females. First-generation offspring were raised on a control diet and their gametes were investigated for signs of subfertility. Second-generation offspring were generated from both first generation sexes and their gametes were similarly assessed. RESULTS We demonstrate a HFD-induced paternal initiation of subfertility in both male and female offspring of two generations of mice. Furthermore, we have shown that diminished reproductive and gamete functions are transmitted through the first generation paternal line to both sexes of the second generation and via the first generation maternal line to second-generation males. Our previous findings that founder male obesity alters the epigenome of sperm, could provide a basis for the developmental programming of subfertility in subsequent generations. CONCLUSIONS This is the first observation of paternal transmission of diminished reproductive health to future generations and could have significant implications for the transgenerational amplification of subfertility observed worldwide in humans.

Uteroplacental insufficiency causes a nephron deficit, modest renal insufficiency but no hypertension with ageing in female rats

In rats, uteroplacental insufficiency induced by uterine vessel ligation restricts fetal growth and impairs mammary development compromising postnatal growth. In male offspring, this results in a nephron deficit and hypertension which can be reversed by improving lactation and postnatal growth. Here, growth, blood pressure and nephron endowment in female offspring from mothers which underwent bilateral uterine vessel ligation (Restricted) on day 18 of pregnancy were examined. Sham surgery (Control) and a reduced litter group (Reduced at birth to 5, equivalent to Restricted group) were used as controls. Offspring (Control, Reduced, Restricted) were cross‐fostered on postnatal day 1 onto a Control (normal lactation) or Restricted (impaired lactation) mother. Restricted‐on‐Restricted offspring were born small but were of similar weight to Control‐on‐Control by postnatal day 35. Blood pressure was not different between groups at 8, 12 or 20 weeks of age. Glomerular number was reduced in Restricted‐on‐Restricted offspring at 6 months without glomerular hypertrophy. Cross‐fostering a Restricted pup onto a Control dam resulted in a glomerular number intermediate between Control‐on‐Control and Restricted‐on‐Restricted. Blood pressure, along with renal function, morphology and mRNA expression, was examined in Control‐on‐Control and Restricted‐on‐Restricted females at 18 months. Restricted‐on‐Restricted offspring did not become hypertensive but developed glomerular hypertrophy by 18 months. They had elevated plasma creatinine and alterations in renal mRNA expression of transforming growth factor‐β1, collagen IV (α1) and matrix matelloproteinase‐9. This suggests that perinatally growth restricted female offspring may be susceptible to onset of renal injury and renal insufficiency with ageing in the absence of concomitant hypertension.