Post-weaning diet determines metabolic risk in mice exposed to overnutrition in early life

King et al. Reproductive Biology and Endocrinology 2014, 12:73 http://www.rbej.com/content/12/1/73 SHORT COMMUNICATION Open Access Post-weaning diet determines metabolic risk in mice exposed to overnutrition in early life Vicky King1, Jane E Norman1, Jonathan R Seckl2 and Amanda J Drake2* Abstract Background: Maternal overnutrition during pregnancy is associated with an increased risk of obesity and cardiometabolic disease in the offspring; a phenomenon attributed to ‘developmental programming’. The post-weaning development of obesity may associate with exacerbation of the programmed metabolic phenotype. In mice, we have previously shown that exposure to maternal overnutrition causes increased weight gain in offspring before weaning, but exerts no persistent effects on weight or glucose tolerance in adulthood. In order to determine whether post-weaning exposure to a cafeteria diet might lead to an exacerbation of programmed effects, offspring born and raised by mothers on control (CON) or cafeteria (DIO) diets were transferred onto either CON or DIO diets at weaning. Findings: Post-weaning DIO caused the development of obesity, with hyperglycaemia and hyperinsulinaemia in males; and obesity with hyperinsulinaemia in females and with increased cholesterol levels in both sexes. Exposure to maternal overnutrition during pregnancy and lactation caused only subtle additional effects on offspring phenotype. Conclusions: These results suggest that post-weaning exposure to a high-fat high-sugar diet has a more profound effect on offspring weight gain and glucose tolerance than exposure to maternal overnutrition. These data emphasise the importance of optimising early life nutrition in offspring of both obese and lean mothers. Keywords: Maternal overnutrition, Obesity, Developmental programming Findings Human and animal studies have shown that the environment in early life can increase the risk of later metabolic disease [1]. There is increasing interest in the role of maternal obesity in the ‘programming’ of offspring disease risk [2] and recent studies have shown that maternal obesity and gestational weight gain are independently associated with offspring cardiometabolic risk and with all-cause mortality [3,4]. This is of substantial importance given the increasing prevalence of obesity worldwide, including amongst women of childbearing age [5]. In order to understand the mechanisms by which exposure to maternal obesity leads to programming of offspring phenotype, animal models have been developed, many of which recapitulate the findings in human studies, showing effects on offspring adiposity, glucose-insulin homeostasis, blood pressure and appetite [6-8]. Using a mouse model, we recently reported remarkably few effects of maternal overnutrition on body weight and metabolism in the directly exposed (F1) offspring [9]. Despite this, there were effects on birthweight and metabolism in a second generation, suggesting that there were persistent effects in F1 offspring leading to the transmission of effects [9]. Since in humans, postnatal obesity appears to be an important determinant of metabolic disease [10], and post-weaning exposure to a highfat diet is associated with amplification of effects in some animal models [8], we hypothesised that post-weaning exposure to a cafeteria diet would result in amplification of the phenotype in both male and female F1 offspring of overnourished mothers. * Correspondence: 2 Endocrinology Unit, University/BHF Centre for Cardiovascular Science, University of Edinburgh, QMRI, 47 Little France Crescent, Edinburgh EH16 4TJ, UK Full list of author information is available at the end of the article Methods Animal studies were conducted as previously reported [9] under approval by the UK Home Office, under the Animals (Scientific Procedures) Act. The experiments were set up as previously described, using a new cohort Background © 2014 King et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. King et al. Reproductive Biology and Endocrinology 2014, 12:73 http://www.rbej.com/content/12/1/73 of mice. From 5 weeks, female C57BL/6 mice were allowed free access to cafeteria (DIO: 58 kcal% fat, 25.5 kcal% carbohydrate as sucrose) or matched control diets (Con: 10.5 kcal% fat and 73.1 kcal% carbohydrate as corn-starch) (Diets D12331 and D12328, Research Diets, New Brunswick, USA). At 17 weeks, females were timemated with chow-fed C57BL/6 males (RMI 801002, Special Diets Services, Witham, UK). Females remained on experimental diets through pregnancy and lactation. At postnatal day 1, litters were weighed and reduced to five pups; animals remained with their biological mothers until weaning at 3 weeks. Groups of F1 male and female pups were selected randomly from each litter and weaned onto cafeteria (D12331) or control diets (D12328). This gave four groups of F1 offspring (n = 7-8/ group): 1) offspring of Con mothers weaned onto control diet (CON/CON) 2) offspring of Con mothers weaned onto cafeteria diet (CON/DIO) 3) offspring of DIO mothers weaned onto control diet (DIO/CON) and 4) offspring of DIO mothers weaned onto cafeteria diet (DIO/DIO). Intraperitoneal glucose tolerance testing (GTT) and lipid measurements were performed at 3 and 6 months following a 6-hour fast. A fasting tail blood sample was taken immediately prior to glucose injection after which mice received an intraperitoneal injection of glucose (2 g/kg body weight). Tail blood samples were collected at 15, 30, 60 and 90 minutes, placed on ice, centrifuged at 2.3 × g for 10 minutes at 4°C and the supernatant plasma stored at −20°C. Plasma glucose levels were determined by the hexokinase/glucose-6-phosphate dehydrogenase method (Thermo Fisher Scientific, UK) and plasma insulin by ELISA (Crystal Chem Inc., Downers Grove, IL, USA). We calculated homoeostasis model assessment of insulin resistance (HOMA-IR; fasting plasma glucose [mmol/L] × fasting insulin [mU/L])/22·5). Fasting plasma cholesterol and triglyceride levels were measured by an enzymatic assay following the manufacturer’s instructions (Infinity kits; Thermo Fisher Scientific, UK). Data are expressed as mean ± SEM. Groups were compared by independent t-tests, Area under Curve, repeated measures ANOVA and two-way ANOVA as appropriate. Data for plasma parameters and organ weights were compared by with pre-weaning and post-weaning diet as the main factors using Statistica (Statsoft) or Graphpad prism version 5. Results Females weaned onto cafeteria diets were heavier than controls at ma (...truncated)