Mark H. Vickers

Maternal nutritional history predicts obesity in adult offspring independent of postnatal diet

Significant alterations in maternal nutrition may induce long‐term metabolic consequences in offspring, in particular obesity and leptin and insulin resistance. Although maternal nutrient deprivation has been well characterized in this context, there is a relative paucity of data on how high fat (HF) nutrition impacts on the subsequent generation. The present study investigated the effects of maternal HF nutrition either throughout the mothers life up to and including pregnancy and lactation or HF nutrition restricted to pregnancy and lactation, on growth and metabolic parameters in male and female offspring. Virgin Wistar rats were assigned to one of three experimental groups: (1) controls (Cont): dams fed a standard chow diet throughout their life and throughout pregnancy and lactation; (2) maternal high fat (MHF) group: dams fed a HF diet from weaning up to and throughout pregnancy and lactation; and (3) pregnancy and lactation high fat (PLHF): dams fed a chow diet through their life until conception and then fed a HF diet throughout pregnancy and lactation. At weaning, all offspring were fed either a chow or HF diet for the remainder of the study (160 days). Litter size and sex ratios were not significantly different between the groups. MHF and PLHF offspring had significantly lower body weights and were hypoleptinaemic and hypoinsulinaemic at birth compared to Cont offspring. As adults however, chow‐fed MHF and PLHF offspring were significantly more obese than Cont offspring (DEXA scanning at day 150, P < 0.001 for maternal HF diet). As expected a postweaning HF diet resulted in increased adiposity in all groups; MHF and PLHF offspring, however, always remained significantly more obese than Cont offspring. Increased adiposity in MHF and PLHF offspring was paralleled by hyperinsulinaemia and hyperleptinaemia (P < 0.001; MHF and PLHF versus Cont). It is of interest that a lifetime of HF nutrition produced a similar offspring phenotype to HF nutrition restricted to pregnancy and lactation alone, thus suggesting that the postnatal sequelae of maternal HF nutrition occurs independent of preconceptional diet. These data further reinforce the importance of maternal nutrition during these critical windows of development and show that maternal HF feeding can induce a markedly obese phenotype in male and female offspring completely independent of postnatal nutrition.

Metabolic plasticity during mammalian development is directionally dependent on early nutritional status.

Developmental plasticity in response to environmental cues can take the form of polyphenism, as for the discrete morphs of some insects, or of an apparently continuous spectrum of phenotype, as for most mammalian traits. The metabolic phenotype of adult rats, including the propensity to obesity, hyperinsulinemia, and hyperphagia, shows plasticity in response to prenatal nutrition and to neonatal administration of the adipokine leptin. Here, we report that the effects of neonatal leptin on hepatic gene expression and epigenetic status in adulthood are directionally dependent on the animals nutritional status in utero. These results demonstrate that, during mammalian development, the direction of the response to one cue can be determined by previous exposure to another, suggesting the potential for a discontinuous distribution of environmentally induced phenotypes, analogous to the phenomenon of polyphenism.

Early Life Nutrition, Epigenetics and Programming of Later Life Disease

The global pandemic of obesity and type 2 diabetes is often causally linked to marked changes in diet and lifestyle; namely marked increases in dietary intakes of high energy diets and concomitant reductions in physical activity levels. However, less attention has been paid to the role of developmental plasticity and alterations in phenotypic outcomes resulting from altered environmental conditions during the early life period. Human and experimental animal studies have highlighted the link between alterations in the early life environment and increased risk of obesity and metabolic disorders in later life. This link is conceptualised as the developmental programming hypothesis whereby environmental influences during critical periods of developmental plasticity can elicit lifelong effects on the health and well-being of the offspring. In particular, the nutritional environment in which the fetus or infant develops influences the risk of metabolic disorders in offspring. The late onset of such diseases in response to earlier transient experiences has led to the suggestion that developmental programming may have an epigenetic component, as epigenetic marks such as DNA methylation or histone tail modifications could provide a persistent memory of earlier nutritional states. Moreover, evidence exists, at least from animal models, that such epigenetic programming should be viewed as a transgenerational phenomenon. However, the mechanisms by which early environmental insults can have long-term effects on offspring are relatively unclear. Thus far, these mechanisms include permanent structural changes to the organ caused by suboptimal levels of an important factor during a critical developmental period, changes in gene expression caused by epigenetic modifications (including DNA methylation, histone modification, and microRNA) and permanent changes in cellular ageing. A better understanding of the epigenetic basis of developmental programming and how these effects may be transmitted across generations is essential for the implementation of initiatives aimed at curbing the current obesity and diabetes crisis.

Maternal Obesity and Developmental Programming of Metabolic Disorders in Offspring: Evidence from Animal Models

The incidence of obesity and overweight has reached epidemic proportions in the developed world as well as in those countries transitioning to first world economies, and this represents a major global health problem. Concern is rising over the rapid increases in childhood obesity and metabolic disease that will translate into later adult obesity. Although an obesogenic nutritional environment and increasingly sedentary lifestyle contribute to our risk of developing obesity, a growing body of evidence links early life nutritional adversity to the development of long-term metabolic disorders. In particular, the increasing prevalence of maternal obesity and excess maternal weight gain has been associated with a heightened risk of obesity development in offspring in addition to an increased risk of pregnancy-related complications. The mechanisms that link maternal obesity to obesity in offspring and the level of gene-environment interactions are not well understood, but the early life environment may represent a critical window for which intervention strategies could be developed to curb the current obesity epidemic. This paper will discuss the various animal models of maternal overnutrition and their importance in our understanding of the mechanisms underlying altered obesity risk in offspring.

Pre- and postnatal nutritional histories influence reproductive maturation and ovarian function in the rat.

Background While prepubertal nutritional influences appear to play a role in sexual maturation, there is a need to clarify the potential contributions of maternal and childhood influences in setting the tempo of reproductive maturation. In the present study we employed an established model of nutritional programming to evaluate the relative influences of prenatal and postnatal nutrition on growth and ovarian function in female offspring. Methods Pregnant Wistar rats were fed either a calorie-restricted diet, a high fat diet, or a control diet during pregnancy and/or lactation. Offspring then were fed either a control or a high fat diet from the time of weaning to adulthood. Pubertal age was monitored and blood samples collected in adulthood for endocrine analyses. Results We report that in the female rat, pubertal timing and subsequent ovarian function is influenced by the animals nutritional status in utero, with both maternal caloric restriction and maternal high fat nutrition resulting in early pubertal onset. Depending on the offsprings nutritional history during the prenatal and lactational periods, subsequent nutrition and body weight gain did not further influence offspring reproductive tempo, which was dominated by the effect of prenatal nutrition. Whereas maternal calorie restriction leads to early pubertal onset, it also leads to a reduction in adult progesterone levels later in life. In contrast, we found that maternal high fat feeding which also induces early maturation in offspring was associated with elevated progesterone concentrations. Conclusions These observations are suggestive of two distinct developmental pathways leading to the acceleration of pubertal timing but with different consequences for ovarian function. We suggest different adaptive explanations for these pathways and for their relationship to altered metabolic homeostasis.

Offspring of Mothers Fed a High Fat Diet Display Hepatic Cell Cycle Inhibition and Associated Changes in Gene Expression and DNA Methylation

The association between an adverse early life environment and increased susceptibility to later-life metabolic disorders such as obesity, type 2 diabetes and cardiovascular disease is described by the developmental origins of health and disease hypothesis. Employing a rat model of maternal high fat (MHF) nutrition, we recently reported that offspring born to MHF mothers are small at birth and develop a postnatal phenotype that closely resembles that of the human metabolic syndrome. Livers of offspring born to MHF mothers also display a fatty phenotype reflecting hepatic steatosis and characteristics of non-alcoholic fatty liver disease. In the present study we hypothesised that a MHF diet leads to altered regulation of liver development in offspring; a derangement that may be detectable during early postnatal life. Livers were collected at postnatal days 2 (P2) and 27 (P27) from male offspring of control and MHF mothers (n = 8 per group). Cell cycle dynamics, measured by flow cytometry, revealed significant G0/G1 arrest in the livers of P2 offspring born to MHF mothers, associated with an increased expression of the hepatic cell cycle inhibitor Cdkn1a. In P2 livers, Cdkn1a was hypomethylated at specific CpG dinucleotides and first exon in offspring of MHF mothers and was shown to correlate with a demonstrable increase in mRNA expression levels. These modifications at P2 preceded observable reductions in liver weight and liver∶brain weight ratio at P27, but there were no persistent changes in cell cycle dynamics or DNA methylation in MHF offspring at this time. Since Cdkn1a up-regulation has been associated with hepatocyte growth in pathologic states, our data may be suggestive of early hepatic dysfunction in neonates born to high fat fed mothers. It is likely that these offspring are predisposed to long-term hepatic dysfunction.

Nature, nurture or nutrition? Impact of maternal nutrition on maternal care, offspring development and reproductive function

•  Maternal high fat nutrition during pregnancy and lactation significantly reduced maternal care during the early neonatal period; but reduced maternal care was not associated with an offspring phenotype. •  Maternal high fat nutrition resulted in maternal obesity characterized by increased fat mass, hyperleptinaemia, hyperinsulinaemia. •  Maternal high fat nutrition resulted in fatter offspring before puberty and advanced pubertal onset. •  Adult female offspring of high fat‐fed mothers have altered reproductive function, reflected in an increased likelihood of prolonged or persistent oestrus. •  These phenotypic effects were not related to maternal care suggesting that poor maternal nutrition, rather than inadequate maternal care, could be the primary driver of the observed alterations in offspring development and reproductive function.

Maternal Fructose Intake during Pregnancy and Lactation Alters Placental Growth and Leads to Sex-Specific Changes in Fetal and Neonatal Endocrine Function

The effects of maternal fructose intake on offspring health remain largely unknown, despite the marked increase in consumption of sweetened beverages that has paralleled the obesity epidemic. The present study investigated the impact of maternal fructose intake on placental, fetal, and neonatal development. Female Wistar rats were time-mated and allocated to receive either water [control (CONT)] or fructose solution designed to provide 20% of caloric intake from fructose (FR). FR was administered from d 1 of pregnancy until postnatal day (P) 10. All dams had ad libitum access to standard laboratory chow and water. Dams and offspring were killed at embryonic day (E) 21 and P10. FR dams demonstrated increased total caloric intake and maternal hyperinsulinemia at E21 as well as increased maternal plasma fructose levels at E21 and P10. FR intake did not alter maternal blood glucose, β-hydroxybutyrate (BHB), or electrolyte levels at either time point. Fetal weights at E21 were unchanged, although placental weights were reduced in FR female but not FR male fetuses. Plasma leptin, fructose, and blood glucose levels were increased and BHB levels decreased in FR female but not male fetuses. Plasma insulin levels were not different between CONT and FR groups. Male and female FR neonates had higher plasma fructose levels and were hypoinsulinemic but euglycemic at P10 compared with CONT. Blood BHB levels were increased in FR male neonates but not females at P10. P10 plasma leptin levels were not different between groups. Stomach content leptin levels were increased in all FR offspring at P10, but no differences in stomach content insulin or fructose levels were observed. This study reports for the first time that maternal FR intake resulted in sex-specific changes in offspring development, whereby females appear more vulnerable to metabolic compromise during neonatal life. Independent follow-up studies are essential to investigate the long-term consequences of maternal FR consumption on offspring health.

Maternal Obesity, Inflammation, and Developmental Programming

The prevalence of obesity, especially in women of child-bearing age, is a global health concern. In addition to increasing the immediate risk of gestational complications, there is accumulating evidence that maternal obesity also has long-term consequences for the offspring. The concept of developmental programming describes the process in which an environmental stimulus, including altered nutrition, during critical periods of development can program alterations in organogenesis, tissue development, and metabolism, predisposing offspring to obesity and metabolic and cardiovascular disorders in later life. Although the mechanisms underpinning programming of metabolic disorders remain poorly defined, it has become increasingly clear that low-grade inflammation is associated with obesity and its comorbidities. This review will discuss maternal metainflammation as a mediator of programming in insulin sensitive tissues in offspring. Use of nutritional anti-inflammatories in pregnancy including omega 3 fatty acids, resveratrol, curcumin, and taurine may provide beneficial intervention strategies to ameliorate maternal obesity-induced programming.

Maternal undernutrition significantly impacts ovarian follicle number and increases ovarian oxidative stress in adult rat offspring.

Background We have shown recently that maternal undernutrition (UN) advanced female pubertal onset in a manner that is dependent upon the timing of UN. The long-term consequence of this accelerated puberty on ovarian function is unknown. Recent findings suggest that oxidative stress may be one mechanism whereby early life events impact on later physiological functioning. Therefore, using an established rodent model of maternal UN at critical windows of development, we examined maternal UN-induced changes in offspring ovarian function and determined whether these changes were underpinned by ovarian oxidative stress. Methodology/Principal Findings Our study is the first to show that maternal UN significantly reduced primordial and secondary follicle number in offspring in a manner that was dependent upon the timing of maternal UN. Specifically, a reduction in these early stage follicles was observed in offspring born to mothers undernourished throughout both pregnancy and lactation. Additionally, antral follicle number was reduced in offspring born to all mothers that were UN regardless of whether the period of UN was restricted to pregnancy or lactation or both. These reductions were associated with decreased mRNA levels of genes critical for follicle maturation and ovulation. Increased ovarian protein carbonyls were observed in offspring born to mothers UN during pregnancy and/or lactation and this was associated with peroxiredoxin 3 hyperoxidation and reduced mRNA levels; suggesting compromised antioxidant defence. This was not observed in offspring of mothers UN during lactation alone. Conclusions We propose that maternal UN, particularly at a time-point that includes pregnancy, results in reduced offspring ovarian follicle numbers and mRNA levels of regulatory genes and may be mediated by increased ovarian oxidative stress coupled with a decreased ability to repair the resultant oxidative damage. Together these data are suggestive of maternal UN potentially contributing to premature ovarian ageing in offspring.