Maternal weight gain induced by an obesogenic diet affects adipose accumulation, liver weight, and insulin homeostasis in the rat offspring depending on the sex

Post-nursing early life macronutrient balance promotes persistent and malleable biometric and metabolic traits in mice

It is known that dietary factors within the gestational and nursing period affect early life and stably affect later life traits in animals. However, there is very little understanding of whether dietary factors within the early life period from post-nursing to adulthood affect traits in adulthood. To address this, we conducted studies on male C57Bl/6J mice fed from 3 weeks (immediately post-nursing) until 12 weeks (full maturity) using nine different diets varying in all three major macronutrients to parse out the effects of individual macronutrients. Early life macronutrient balance affected body composition and glucose homeostasis in early adulthood, with dietary protein and fat showing major effects. Despite this, mice showed rapid reversal of the effects on body composition and glucose homeostasis of early life diet feeding, upon standard diet feeding in adulthood. However, some traits were persistent, with early life low dietary protein levels stably affecting lean and muscle mass, and early life dietary fat levels stably affecting serum and liver triglyceride levels. In summary, macronutrient balance in the post-nursing early life period does not stably affect adiposity or glucose homeostasis but does impact muscle mass and lipid homeostasis in adulthood, with prominent effects of both protein and fat levels. KEY POINTS: Early life dietary low protein and high fat levels lowered and heightened body mass, respectively. These effects did not substantially persist into adulthood with rapid catch-up growth on a normal diet. Early life protein (negative) and fat (positive) levels affected fat mass. Early life low protein levels negatively affected lean mass. Low protein effects on lower lean and muscle mass persisted into adulthood. Early life macronutrient balance effects did not affect later life glucose homeostasis but early life high fat level affected later life dyslipidaemia. Effects of dietary carbohydrate levels in early and later life were minor.

Early life overnutrition impairs plasticity of non-neuronal brainstem cells and drives obesity in offspring across development in rats

BACKGROUND

The prevalence of adolescent obesity has increased dramatically, becoming a serious public health concern. While previous evidence suggests that in utero- and early postnatal overnutrition increases adult-onset obesity risk, the neurobiological mechanisms underlying this outcome are not well understood. Non-neuronal cells play an underestimated role in the physiological responses to metabolic/nutrient signals. Hypothalamic glial-mediated inflammation is now considered a contributing factor in the development and perpetuation of obesity; however, attention on the role of gliosis and microglia activation in other nuclei is still needed.

METHODS/RESULTS

Here, we demonstrate that early life consumption of high-fat/sucrose diet (HFSD) is sufficient to increase offspring body weight, hyperleptinemia and potentially maladaptive cytoarchitectural changes in the brainstem dorsal-vagal-complex (DVC), an essential energy balance processing hub, across postnatal development. Our data demonstrate that pre- and postnatal consumption of HFSD result in increased body weight, hyperleptinemia and dramatically affects the non-neuronal landscape, and therefore the plasticity of the DVC in the developing offspring.

CONCLUSIONS

Current findings are very provocative, considering the importance of the DVC in appetite regulation, suggesting that HFSD-consumption during early life may contribute to subsequent obesity risk via DVC cytoarchitectural changes.

A maternal high-fat, high-sucrose diet alters insulin sensitivity and expression of insulin signalling and lipid metabolism genes and proteins in male rat offspring: effect of folic acid supplementation

A maternal high-fat, high-sucrose (HFS) diet alters offspring glucose and lipid homoeostasis through unknown mechanisms and may be modulated by folic acid. We investigated the effect of a maternal HFS diet on glucose homoeostasis, expression of genes and proteins associated with insulin signalling and lipid metabolism and the effect of prenatal folic acid supplementation (HFS/F) in male rat offspring. Pregnant Sprague-Dawley rats were randomly fed control (CON), HFS or HFS/F diets. Offspring were weaned on CON; at postnatal day 70, fasting plasma insulin and glucose and liver and skeletal muscle gene and protein expression were measured. Treatment effects were assessed by one-way ANOVA. Maternal HFS diet induced higher fasting glucose in offspring v. HFS/F (P=0·027) and down-regulation (P<0·05) of genes coding for v-Akt murine thymoma viral oncogene homolog 2, resistin and v-Raf-1 murine leukaemia viral oncogene homolog 1 (Raf1) in offspring skeletal muscle and acetyl-CoA carboxylase (Acaca), fatty acid synthase and phosphatidylinositol-4,5-biphosphate 3-kinase, catalytic subunit β in offspring liver. Skeletal muscle neuropeptide Y and hepatic Kruppel-like factor 10 were up-regulated in HFS v. CON offspring (P<0·05). Compared with CON, Acaca and Raf1 protein expression levels were significantly lower in HFS offspring. Maternal HFS induced higher homoeostasis model of assessment index of insulin resistance v. CON (P=0·030) and HFS/F was associated with higher insulin (P=0·016) and lower glucose (P=0·025). Maternal HFS diet alters offspring insulin sensitivity and de novo hepatic lipogenesis via altered gene and protein expression, which appears to be potentiated by folate supplementation.

Different combinations of maternal and postnatal diet are reflected in changes of hepatic parenchyma and hepatic TNF-alpha expression in male rat offspring

Obesity is related to increased TNF-alpha production in different tissues. TNF-alpha is connected to mitochondrial dysfunction in the liver and also development of fatty infiltration of the liver. Also, postnatal change from normal to high-fat diet causes a significant increase in TNF-alpha serum levels. The aim of this research was to determine how maternal diet and switching male offspring to a different dietary regime after lactation influences rat liver. Ten female Sprague Dawley rats at nine weeks of age were randomly divided in two groups and fed either standard laboratory chow or high-fat diet during six weeks, and then mated with the same male subject. After birth and lactation male offspring from both groups were further divided into four subgroups depending on their subsequent diet. At 22 weeks of age, the animals were weighted, sacrificed and major organs were collected and weighted. Immunohistochemistry for TNF-alpha was performed on liver, and liver samples were analyzed for pathohistological changes. The group in which mothers were fed standard chow and offspring high-fat diet had the most pronounced changes: heaviest liver, poorest histopathological findings and strongest TNF-alpha immunohistochemical staining of liver parenchyma. High-fat diet during pregnancy and lactation and switching to high-fat diet postnatally affects liver weight, histological structure and TNF-alpha expression in male offspring.

Supplementation with methyl donors during lactation to high-fat-sucrose-fed dams protects offspring against liver fat accumulation when consuming an obesogenic diet

Methyl donor supplementation has been reported to prevent obesity-induced liver fat accumulation in adult rats. We hypothesized that this protection could be mediated by perinatal nutrition. For this purpose, we assessed the response to an obesogenic diet (high-fat-sucrose, HFS) during adulthood depending on maternal diet during lactation. Female Wistar rats fed control diet during pregnancy were assigned to four postpartum dietary groups: control, control supplemented with methyl donors (choline, betaine, folic acid, vitamin B12), HFS and HFS supplemented with methyl donors. At weaning, the male offspring was transferred to a chow diet and at week 12th assigned to a control or a HFS diet during 8 weeks. The offspring whose mothers were fed HFS during lactation showed increased adiposity (19%, P<0.001). When fed the HFS diet as adults, offspring whose mothers were HFS supplemented had more body fat (23%, P<0.001) than those from HFS non-supplemented. However, they showed lower liver fat accumulation (-18%, P<0.001). Srebf1, Dnmt1 and Lepr liver mRNA levels increased after adulthood HFS feeding. In those animals HFS fed during adulthood, previous maternal HFS decreased Lepr and Dnmt1 expression levels when compared with c-HFS offspring, while the supplementation of control and HFS-fed dams, respectively, induced higher hepatic Mme and Lepr mRNA levels after adult HFS intake compared with hfs-HFS offspring. In conclusion, maternal HFS diet during lactation influenced the response to an obesogenic diet in the adult progeny. Interestingly, dietary methyl donor supplementation in lactating mothers fed an obesogenic diet reduced liver fat accumulation, but increased adipose tissue storage in adult HFS-fed offspring.

Maternal methyl donors supplementation during lactation prevents the hyperhomocysteinemia induced by a high-fat-sucrose intake by dams

Maternal perinatal nutrition may program offspring metabolic features. Epigenetic regulation is one of the candidate mechanisms that may be affected by maternal dietary methyl donors intake as potential controllers of plasma homocysteine levels. Thirty-two Wistar pregnant rats were randomly assigned into four dietary groups during lactation: control, control supplemented with methyl donors, high-fat-sucrose and high-fat-sucrose supplemented with methyl donors. Physiological outcomes in the offspring were measured, including hepatic mRNA expression and global DNA methylation after weaning. The newborns whose mothers were fed the obesogenic diet were heavier longer and with a higher adiposity and intrahepatic fat content. Interestingly, increased levels of plasma homocysteine induced by the maternal high-fat-sucrose dietary intake were prevented in both sexes by maternal methyl donors supplementation. Total hepatic DNA methylation decreased in females due to maternal methyl donors administration, while Dnmt3a hepatic mRNA levels decreased accompanying the high-fat-sucrose consumption. Furthermore, a negative association between Dnmt3a liver mRNA levels and plasma homocysteine concentrations was found. Maternal high-fat-sucrose diet during lactation could program offspring obesity features, while methyl donors supplementation prevented the onset of high hyperhomocysteinemia. Maternal dietary intake also affected hepatic DNA methylation metabolism, which could be linked with the regulation of the methionine-homocysteine cycle.

Transgenic increase in N-3/n-6 Fatty Acid ratio reduces maternal obesity-associated inflammation and limits adverse developmental programming in mice

Maternal and pediatric obesity has risen dramatically over recent years, and is a known predictor of adverse long-term metabolic outcomes in offspring. However, which particular aspects of obese pregnancy promote such outcomes is less clear. While maternal obesity increases both maternal and placental inflammation, it is still unknown whether this is a dominant mechanism in fetal metabolic programming. In this study, we utilized the Fat-1 transgenic mouse to test whether increasing the maternal n-3/n-6 tissue fatty acid ratio could reduce the consequences of maternal obesity-associated inflammation and thereby mitigate downstream developmental programming. Eight-week-old WT or hemizygous Fat-1 C57BL/6J female mice were placed on a high-fat diet (HFD) or control diet (CD) for 8 weeks prior to mating with WT chow-fed males. Only WT offspring from Fat-1 mothers were analyzed. WT-HFD mothers demonstrated increased markers of infiltrating adipose tissue macrophages (P<0.02), and a striking increase in 12 serum pro-inflammatory cytokines (P<0.05), while Fat1-HFD mothers remained similar to WT-CD mothers, despite equal weight gain. E18.5 Fetuses from WT-HFD mothers had larger placentas (P<0.02), as well as increased placenta and fetal liver TG deposition (P<0.01 and P<0.02, respectively) and increased placental LPL TG-hydrolase activity (P<0.02), which correlated with degree of maternal insulin resistance (r = 0.59, P<0.02). The placentas and fetal livers from Fat1-HFD mothers were protected from this excess placental growth and fetal-placental lipid deposition. Importantly, maternal protection from excess inflammation corresponded with improved metabolic outcomes in adult WT offspring. While the offspring from WT-HFD mothers weaned onto CD demonstrated increased weight gain (P<0.05), body and liver fat (P<0.05 and P<0.001, respectively), and whole body insulin resistance (P<0.05), these were prevented in WT offspring from Fat1-HFD mothers. Our results suggest that reducing excess maternal inflammation may be a promising target for preventing adverse fetal metabolic outcomes in pregnancies complicated by maternal obesity.