The divergent effect of maternal protein restriction during pregnancy and postweaning high-fat diet feeding on blood pressure and adiposity in adult mouse offspring

Obesity is a growing health crisis of pandemic proportions. Numerous animal and human studies have confirmed that obesity and related metabolic abnormalities, such as insulin resistance and cardiovascular disease, may be programmed during development by adverse maternal nutrition. We previously documented that offspring of female mice who were protein-restricted during pregnancy alone had no alterations to their body weights, but did display a considerable reduction in food intake, a finding which was linked to reduced expression levels of appetite regulatory genes in the hypothalamus. Whether such observations were accompanied by changes in metabolic and phenotypic parameters remained to be determined. Female pregnant MF-1 mice were fed, exclusively during the pregnancy period, a normal protein diet containing 18% casein (C) or an isocaloric protein-restricted diet containing 9% casein (PR). From birth, the lactating dams were fed a normal protein diet. At weaning, offspring were fed either the standard chow which contain 7% kcal fat (C) or high-fat diet (HF, 45% kcal fat). This yielded 4 experimental groups denoted by maternal diet/offspring diet: C/C, C/HF, PR/C, PR/HF. Our results showed that offspring adiposity was significantly increased in HF-fed offspring, and was not affected by the 50% reduction in protein content of the maternal diet fed during pregnancy. Similarly, blood glucose levels were higher in HF-fed offspring, regardless of protein content of the maternal diet. Systolic blood pressure, on the other hand, was significantly increased in both male and female offspring of dams fed the PR diet, and this was exacerbated by a postweaning HF diet. Our results show that maternal protein restriction leads to elevations in systolic blood pressure, which is exacerbated by a postweaning HF-diet. Our present findings suggest that, while changes in offspring adiposity brought about by exposure to maternal protein restriction during pregnancy may be restored by adequate maternal protein content during lactation, the same may not be true for systolic blood pressure, which was similarly impaired, regardless of the timing of maternal low-protein exposure

Maternal obesity during pregnancy and lactation influences offspring obesogenic adipogenesis but not developmental adipogenesis in mice

Obesity is an escalating health crisis of pandemic proportions and by all accounts it has yet to reach its peak. Growing evidence suggests that obesity may have its origins in utero. Recent studies have shown that maternal obesity during pregnancy may promote adipogenesis in offspring. However, these studies were largely based on cell culture models. Whether or not maternal obesity impacts on offspring adipogenesis in vivo remains to be fully established. Furthermore, in vivo adipogenic differentiation has been shown to happen at distinct time periods, one during development (developmental adipogenesis—which is complete by 4 weeks of age in mice) and another in adulthood in response to feeding a high-fat (HF) diet (obesogenic adipogenesis). We therefore set out to determine whether maternal obesity impacted on offspring adipocyte hyperplasia in vivo and whether maternal obesity impacted on developmental or obesogenic adipogenesis, or both. Our findings reveal that maternal obesity is associated with enhanced obesogenic adipogenesis in HF-fed offspring. Interestingly, in newly weaned (4-week-old) offspring, maternal obesity is associated with adipocyte hypertrophy, but there were no changes in adipocyte number. Our results suggest that maternal obesity impacts on offspring obesogenic adipogenesis but does not affect developmental adipogenesis

Identification of robust cardiac reference genes in a mouse model of cardiometabolic disease

Cardiovascular disease is linked to obesity, the metabolic syndrome, and altered 24hour (circadian) rhythms. Although the underlying mechanisms remain undefined, transcriptome analysis in the heart is beginning to provide important insights into the cardiometabolic pathogenesis. The reliability and accuracy of real-time quantitative PCR generated gene expression data is largely dependent on the selection of suitable reference genes (RG), which must be constitutively expressed regardless of cardio-metabolic disease state and time of day. However, many studies do not employ the appropriate selections strategies. In this study we determined the expression stability of seven candidate RGs (GAPDH, YWHAZ, B2M, EIF4A2, ATP5?, ACTB and CYC1) in a mouse model of diet-induced metabolic syndrome in both the day and night, using geNorm qBasePLUS software. RG expression varied in hearts of normal fed versus high fat fed mice, and was also dependant on the time of day. When all experimental variables were considered YWHAZ and ACTB were ranked the most stable and therefore the most suitable genes for generating comparative gene expression data in heart tissue from murine models of cardiometabolic disease. This study provides important information for reference gene selection, and will aid further transcriptome investigations into heart organ functio

Maternal high fat diet affects offspring's vitamin K-dependent proteins expression levels

Studies suggest bone growth & development and susceptibility to vascular disease in later life are influenced by maternal nutrition, during intrauterine and early postnatal life. There is evidence for a role of vitamin K-dependent proteins (VKDPs) including Osteocalcin, Matrix-gla protein, Periostin, and Gas6, in bone and vascular development. This study extends the analysis of VKDPs previously conducted in 6 week old offspring, into offspring of 30 weeks of age, to assess the longer term effects of a maternal and postnatal high fat (HF) diet on VKDP expression. Overall a HF maternal diet and offspring diet exacerbated the bone changes observed. Sex specific and tissue specific differences were observed in VKDP expression for both aorta and femoral tissues. In addition, significant correlations were observed between femoral OCN, Periostin Gas6, and Vkor expression levels and measures of femoral bone structure. Furthermore, MGP, OCN, Ggcx and Vkor expression levels correlated to mass and fat volume, in both sexes. In summary the current study has highlighted the importance of the long-term effects of maternal nutrition on offspring bone development and the correlation of VKDPs to bone structure

Epigenetic priming of the metabolic syndrome

The metabolic syndrome (MetS) represents a cluster of cardiometabolic risk factors, including central obesity, insulin resistance, glucose intolerance, dyslipidemia, hypertension, hyperinsulinemia and microalbuminuria, and more recently, nonalcoholic fatty liver disease (NAFLD), polycystic ovarian syndrome (PCOS) and atherosclerosis. Although the concept of the MetS is subject to debate due to lack of a unifying underlying mechanism, the prevalence of a metabolic syndrome phenotype is rapidly increasing worldwide. Moreover, it is increasingly prevalent in children and adolescents of obese mothers. Evidence from both epidemiological and experimental animal studies now demonstrates that MetS onset is increasingly likely following exposure to suboptimal nutrition during critical periods of development, as observed in maternal obesity. Thus, the developmental priming of the MetS provides a common origin for this multifactorial disorder. Consequently, the mechanisms leading to this developmental priming have recently been the subject of intensive investigation. This review discusses recent data regarding the epigenetic modifications resulting from nutrition during early development that mediate persistent changes in the expression of key metabolic genes and contribute toward an adult metabolic syndrome phenotype. In addition, this review considers the role of the endogenous molecular circadian clock system, which has the potential to act at the interface between nutrient sensing and epigenetic processing. A continued and greater understanding of these mechanisms will eventually aid in the identification of individuals at high risk of cardiovascular disease (CVD) and type 2 diabetes, and help develop therapeutic interventions, in accordance with current global government strategy.<br/

Developmental programming of Non-Alcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disease worldwide and is present in a third of the general population and the majority of individuals with obesity and type 2 diabetes. The less severe form of the disease is relatively common and can be somewhat benign. However, in certain individuals, the disease can progress to the more severe nonalcoholic steatohepatitis (NASH), resulting in a poor health, a poor prognosis, and a significant healthcare burden. In recent years, there has been a major research effort focused on identifying the factors that promote NALFD disease progression, and as a result there has been a significant advancement in our understanding of the interaction between nutrition and the molecular mechanisms that regulate hepatic lipid homeostasis. Nonetheless, the capacity of the maternal diet to alter these fundamental metabolic pathways and thus prime the development of severe fatty liver disease in the adult liver has proved to be one of the most striking findings from this body of research. Since the prudence of the maternal diet has wavered in recent years, this may explain why NAFLD—once commonly associated with older individuals—is now increasingly common in young adults, children, and adolescents. In the following chapter, we aim to review the current hypothesis surrounding the mechanisms that underlie the developmental priming of NAFLD. We will also explore how these novel insights have facilitated the emergence of promising new pharmacological and nutritional intervention strategies

Fetal programming of adipose tissue function: an evolutionary perspective

Obesity is an escalating threat of pandemic proportions and has risen to such unrivaled prominence in such a short period of time that it has come to define a whole generation in many countries around the globe. The burden of obesity, however, is not equally shared among the population, with certain ethnicities being more prone to obesity than others, while some appear to be resistant to obesity altogether. The reasons behind this ethnic basis for obesity resistance and susceptibility, however, have remained largely elusive. In recent years, much evidence has shown that the level of brown adipose tissue thermogenesis, which augments energy expenditure and is negatively associated with obesity in both rodents and humans, varies greatly between ethnicities. Interestingly, the incidence of low birth weight, which is associated with an increased propensity for obesity and cardiovascular disease in later life, has also been shown to vary by ethnic background. This review serves to reconcile ethnic variations in BAT development and function with ethnic differences in birth weight outcomes to argue that the variation in obesity susceptibility between ethnic groups may have its origins in the in utero programming of BAT development and function as a result of evolutionary adaptation to cold environments

Sensitivity of housekeeping genes in the hypothalamus to mismatch in diets between pre- and postnatal periods in mice

Housekeeping genes are used as internal controls in gene expression studies, but their expression levels vary according to tissue types and experimental treatments. A nutritional mismatch between pre- and postnatal periods, wherein the in utero nutritional environment is suboptimal and post-weaning diet is rich in fat, results in altered hypothalamic expression levels of genes that regulate the offspring's physiology, metabolism and behavior. The present study investigated hypothalamic expression of the housekeeping genes glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-actin and 18s ribosomal RNA (18s rRNA) in offspring subjected to this pre- and postnatal dietary mismatch. Pregnant MF1 mice were fed standard chow (C, 18% casein) or protein restricted (PR, 9% casein) diet throughout pregnancy. Weaned offspring were fed to adulthood a high fat (HF, 45% kcal fat) or chow (21% kcal fat) diet to generate the C/HF, C/C, PR/HF and PR/C groups. Hypothalamic and cerebral cortex tissues were collected from these offspring at 16 weeks of age and analyzed for gene transcript levels by quantitative real time PCR. Hypothalamic GAPDH mRNA levels were higher in PR/HF male and female offspring vs. all other groups (p&lt;0.001 in males). Conversely, hypothalamic beta-actin and 18s rRNA levels were similar in all treatment groups and sex. In the cerebral cortex, GAPDH and beta-actin levels were similar in all groups and sex. The result suggests that beta-actin and 18s rRNA are suitable internal controls for gene expression studies in the hypothalamus, while the stability of GAPDH is compromised, under the condition of a nutritional mismatch between pre- and postnatal period

Vertebral Body Bone Structure at Thirty Weeks of Age.

<p>For dietary group and sex, results are shown for (A). Vertebral body bone volume. (B). Vertebral body length. (C). Bone surface to volume ratio. (D). Trabecular thickness. (E). Trabecular spacing. (F). Male whole vertebra bone density. (G). Female whole vertebra bone density. For density graphs, the bone density range 80–140 represents trabecular bone, and 140–220 represents cortical bone. For all groups, n = 5–7 per group. Graphs show mean plus 95% confidence limits.</p