High dietary cholesterol intake during lactation promotes development of fatty liver in offspring of mice

Bioactive compounds in mothers milk affecting offspring outcomes: A narrative review

BACKGROUND

Compared to the exhaustive study of transgenerational programming of obesity and diabetes through exposures in the prenatal period, postnatal programming mechanisms are understudied, including the potential role of breast milk composition linking maternal metabolic status (body mass index and diabetes) and offspring growth, metabolic health and future disease risk.

METHODS

This narrative review will principally focus on four emergent bioactive compounds [microRNA's (miRNA), lipokines/signalling lipids, small molecules/metabolites and fructose] that, until recently were not known to exist in breast milk. The objective of this narrative review is to integrate evidence across multiple fields of study that demonstrate the importance of these compositional elements of breast milk during lactation and the subsequent effect of breast milk components on the health of the infant.

RESULTS

Current knowledge on the presence of miRNA's, lipokines/signalling lipids, small molecules/metabolites and fructose in breast milk and their associations with infant outcomes is compelling, but far from resolved. Two themes emerge: (1) maternal metabolic phenotypes are associated with these bioactives and (2) though existing in milk at low concentrations, they are also associated with offspring growth and body composition.

CONCLUSION

Breast milk research is gaining momentum though we must remain focused on understanding how non-nutritive bioactive components are affected by the maternal phenotype, how they subsequently impact infant outcomes. Though early, there is evidence to suggest fructose is associated with fat mass in the 1st months of life whereas 12,13 diHOME (brown fat activator) and betaine are negatively associated with early adiposity and growth.

Gestational hypercholesterolemia programs hepatic steatosis in a sex-specific manner in ApoE-deficient mice

Maternal hypercholesterolemia (MHC), a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during pregnancy, may influence offspring hepatic lipid metabolism and increase the risk of nonalcoholic fatty liver disease (NAFLD). As NAFLD is characterized by a sexual dimorphic response, we assessed whether early-life exposure to excessive cholesterol influences the development of NAFLD in offspring and whether this occurs in a sex-specific manner. Female apoE-/- mice were randomly assigned to a control (CON) or a high cholesterol (CH; 0.15%) diet prior to breeding. At parturition, a cross-fostering approach was used to establish three groups: (1) normal cholesterol exposure throughout gestation and lactation (CON-CON); (2) excessive cholesterol exposure throughout gestation and lactation (CH-CH); and (3) excessive cholesterol exposure in the gestation period only (CH-CON). Adult male offspring (PND 84) exposed to excessive cholesterol during gestation only (CH-CON) demonstrated hepatic triglyceride (TG) accumulation and reduced lipogenic gene expression. However, male mice with a prolonged cholesterol exposure throughout gestation and lactation (CH-CH) had a similar, but not exacerbated hepatic response. Further, with the exception of higher serum TG in adult CH-CH females, evidence for a programming effect in female offspring was largely absent in comparison with males. These results indicate a sexual dimorphic response with respect to the effect of MHC on later life hepatic steatosis and highlight the gestation period as the most influential malprogramming window for hepatic lipid dysfunction in males.

Oxidative Stress Profile of Mothers and Their Offspring after Maternal Consumption of High-Fat Diet in Rodents: A Systematic Review and Meta-Analysis

Maternal exposure to the high-fat diet (HFD) during gestation or lactation can be harmful to both a mother and offspring. The aim of this systematic review was to identify and evaluate the studies with animal models (rodents) that were exposed to the high-fat diet during pregnancy and/or lactation period to investigate oxidative stress and lipid and liver enzyme profile of mothers and their offspring. The electronic search was performed in the PUBMED (Public/Publisher MEDLINE), EMBASE (Ovid), and Web of Science databases. Data from 77 studies were included for qualitative analysis, and of these, 13 studies were included for meta-analysis by using a random effects model. The pooled analysis revealed higher malondialdehyde levels in offspring of high-fat diet groups. Furthermore, the pooled analysis showed increased reactive oxygen species and lower superoxide dismutase and catalase in offspring of mothers exposed to high-fat diet during pregnancy and/or lactation. Despite significant heterogeneity, the systematic review shows oxidative stress in offspring induced by maternal HFD.

Maternal hypercholesterolemia programs dyslipidemia in adult male mouse progeny

As a collection of metabolic abnormalities including inflammation, insulin resistance, hypertension, hormone imbalance, and dyslipidemia, maternal obesity has been well-documented to program disease risk in adult offspring. Although hypercholesterolemia is strongly associated with obesity, less work has examined the programming influence of maternal hypercholesterolemia (MHC) independent of maternal obesity or high-fat feeding. This study was conducted to characterize how MHC per se impacts lipid metabolism in offspring. Female (n = 6/group) C57BL/6J mice were randomly assigned to: (1.) a standard chow diet (Control, CON) or (2.) the CON diet supplemented with exogenous cholesterol (CH) (0.15%, w/w) throughout mating and the gestation and lactation periods. At weaning (postnatal day (PND) 21) and adulthood (PND 84), male offspring were characterized for blood lipid and lipoprotein profile and hepatic lipid endpoints, namely cholesterol and triglyceride (TG) accumulation, fatty acid profile, TG production, and mRNA expression of lipid-regulatory genes. Both newly weaned and adult offspring from CH mothers demonstrated increased very low-density lipoprotein (VLDL) particle number and size and hepatic TG and n-6 polyunsaturated fatty acid accumulation. Further, adult CH offspring exhibited reduced fatty acid synthase (Fasn) and increased diglyceride acyltransferase (Dgat1) mRNA expression. These programming effects appear to be independent of changes in hepatic TG production and postprandial lipid clearance. Study results suggest that MHC, independent of obesity or high-fat feeding, can induce early changes to serum VLDL distribution and hepatic lipid profile that persist into adulthood.

Effects of dietary n-3 PUFA levels in early life on susceptibility to high-fat-diet-induced metabolic syndrome in adult mice

The maternal nutritional status during pregnancy and lactation was closely related to the growth and development of the fetus and infants, which had a profound impact on the health of the offspring. N-3 polyunsaturated fatty acid (PUFA) had been proved to have beneficial effects on glucolipid metabolism. However, the effects of dietary different n-3 PUFA levels for mother during pregnancy and lactation on susceptibility to high-fat-diet-induced metabolic syndrome for offspring in adulthood are still unclear. The maternal mice were fed with control, n-3 PUFA-deficient or fish oil-contained n-3 PUFA-rich diets during pregnancy and lactation, and the weaned offspring were fed with high-fat or low-fat diet for 13 weeks, then were subjected to oral glucose tolerance tests. The results showed that dietary n-3 PUFA-deficiency in early life could aggravate the high-fat-diet-induced glucolipid metabolism disorders, including glucose intolerance, insulin resistance, obesity, and dyslipidemia, thus increased the susceptibility to metabolic syndrome of adult mice. Notably, nutritional supplementation with n-3 PUFA in early life could significantly alleviate the glucose metabolism disorders by increasing insulin sensitivity, inhibiting gluconeogenesis and promoting glycogenesis. In addition, administration with n-3 PUFA in early life remarkably reduced serum and hepatic lipid profiles by mediating the expression of genes related to lipogenesis and β-oxidation of fatty acids. Dietary n-3 PUFA-deficiency in early life increases the susceptibility to metabolic syndrome of adult offspring, and nutritional supplementation with n-3 PUFA enhances the tolerance to a high-fat diet of adult offspring.

Excessive early-life cholesterol exposure may have later-life consequences for nonalcoholic fatty liver disease

The in utero and immediate postnatal environments are recognized as critical windows of developmental plasticity where offspring are highly susceptible to changes in the maternal metabolic milieu. Maternal hypercholesterolemia (MHC) is a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during pregnancy which can program metabolic dysfunction in offspring, including dysregulation of hepatic lipid metabolism. Although there is currently no established reference range MHC, a loosely defined cutoff point for total cholesterol >280 mg/dL in the third trimester has been suggested. There are several unanswered questions regarding this condition particularly with regard to how the timing of cholesterol exposure influences hepatic lipid dysfunction and the mechanisms through which these adaptations manifest in adulthood. Gestational hypercholesterolemia increased fetal hepatic lipid concentrations and altered lipid regulatory mRNA and protein content. These early changes in hepatic lipid metabolism are evident in the postweaning environment and persist into adulthood. Further, changes to hepatic epigenetic signatures including microRNA (miR) and DNA methylation are observed in utero, at weaning, and are evident in adult offspring. In conclusion, early exposure to cholesterol during critical developmental periods can predispose offspring to the early development of nonalcoholic fatty liver disease (NAFLD) which is characterized by altered regulatory function beginning in utero and persisting throughout the life cycle.

Gestational hypercholesterolemia alters fetal hepatic lipid metabolism and microRNA expression in Apo-E-deficient mice

Maternal hypercholesterolemia (MHC) is a pathological condition characterized by an exaggerated rise in maternal serum cholesterol during gestation, which can alter offspring hepatic lipid metabolism. However, the extent that these maladaptations occur during gestation and the molecular mechanisms involved remain unknown. MicoRNAs (miRNA) are small, noncoding RNAs that contribute to the development and progression of nonalcoholic fatty liver disease. Therefore, we sought to determine the degree to which in utero exposure to excessive cholesterol affects fetal hepatic lipid metabolism and miRNA expression. Twelve female apoE^-/- mice were randomly assigned to two different chow-based diets throughout gestation: control (CON) or the CON diet with cholesterol (0.15%). MHC reduced maternal fecundity and reduced litter size and weight. On gestational day 18, fetuses from MHC dams possessed increased placental cholesterol and hepatic triglycerides (TG), which were accompanied by a downregulation in the expression of hepatic lipogenic and TG synthesis and transport genes. Furthermore, fetal livers from MHC mothers showed increased miRNA-27a and reduced miRNA-200c expression. In summary, in utero exposure to MHC alters fetal lipid metabolism and lends mechanistic insight that implicates early changes in miRNA expression that may link to later-life programming of disease risk.

Miso (Fermented Soybean Paste) Suppresses Visceral Fat Accumulation in Mice, Especially in Combination with Exercise

We investigated whether the difference in miso consumption between the Japanese diets of 1975 and 2010 has influenced the observed increase in diet-induced obesity. To recreate the 2010 and 1975 Japanese high-fat diets with the corresponding proportions of miso, freeze-dried miso was added to high-fat mouse feed at 1.6% and 2.6%, respectively. When 5-week-old male Institute of Cancer Research (ICR) mice were provided each of these diets ad libitum for 8 weeks, it was found that the white adipose tissue weight and adipocyte area were lower in mice receiving the 1975 diet than in those receiving the 2010 diet. Therefore, high miso consumption is one reason why the 1975 Japanese diet tended to not lead to obesity. Next, the combined effects of treadmill exercise and miso consumption were investigated. The mice were divided into three groups, which were provided either a high-fat diet (group C), a high-fat diet with exercise (group C + E), or a miso-supplemented high-fat diet with exercise (group M + E) for 8 weeks. In this experiment, the white adipose tissue weight and adipocyte area in group M + E were lower than in group C. When the mRNA expression of lipid metabolism-associated genes in adipose tissue was measured, we found that expression of Hsl (lipase, hormone sensitive), which is involved in lipolysis, and Pparγ (peroxisome proliferator activated receptor gamma), which regulates adipocyte differentiation upstream of Hsl, was increased in group M + E. These results clearly demonstrated that lipid accumulation in the adipose tissues is suppressed by miso consumption in combination with exercise.

Malprogramming of Hepatic Lipid Metabolism due to Excessive Early Cholesterol Exposure in Adult Progeny

SCOPE

The programming of hepatic lipid dysfunction in response to early cholesterol exposure and the influencing effects of postnatal diet is evaluated in apoE^-/- mice.

METHODS AND RESULTS

In two separate studies, female mice are assigned to a standard chow (S) or a cholesterol-enriched chow (C) diet during gestation and lactation. Male offspring from each dam are weaned on a postnatal S or a hypercaloric western (W) diet resulting in four experimental groups: S-S and C-S (Experiment 1) and S-W and C-W (Experiment 2). At weaning, litters from hypercholesterolemic mothers weighed less (p < 0.05) and pups had higher blood lipids, glucose, and hepatic cholesterol compared with pups from S-fed mothers. Adult C-S offspring demonstrate an atherogenic lipid profile and increased (p < 0.05) hepatic cholesterol and triglyceride content with altered lipid regulatory mRNA expression and protein content compared with S-S offspring. Alternatively, no difference (p > 0.05) is observed between S-W and C-W in serum and hepatic lipid profiles; however, serum AST and ALT are higher (p < 0.05) in C-W versus S-W offspring.

CONCLUSION

The degree of hepatic lipid deposition observed in adult offspring exposed to excessive early cholesterol is influenced by the postnatal diet.

Effects of Dietary Intake of Japanese Mushrooms on Visceral Fat Accumulation and Gut Microbiota in Mice

A lot of Japanese people are generally known for having a healthy diet, and consume a variety of mushrooms daily. Many studies have reported anti-obesity effects of mushrooms, but few have investigated the effects of consuming a variety of edible mushroom types together in realistic quantities. In this study, we investigated whether supplementation with a variety of mushroom types affects visceral fat accumulation and gut microbiota in mice. The most popular mushroom varieties in Japan were lyophilized and mixed according to their local production ratios. C57BL/6J mice were fed a normal diet, high-fat (HF) diet, HF with 0.5% mushroom mixture (equivalent to 100 g mushrooms/day in humans) or HF with 3% mushroom mixture (equivalent to 600 g mushrooms/day in humans) for 4 weeks. The mice were then sacrificed, and blood samples, tissue samples and feces were collected. Our results show that mushroom intake suppressed visceral fat accumulation and increased the relative abundance of some short chain fatty acid- and lactic acid-producing gut bacteria. These findings suggest that mushroom intake is an effective strategy for obesity prevention.

Effect of maternal dyslipidaemia on the cardiorespiratory physiology and biochemical parameters in male rat offspring

The present study evaluated the effects of maternal dyslipidaemia on blood pressure (BP), cardiorespiratory physiology and biochemical parameters in male offspring. Wistar rat dams were fed either a control (CTL) or a dyslipidaemic (DLP) diet during pregnancy and lactation. After weaning, both CTL and DLP offspring received standard diet. On the 30th and 90th day of life, blood samples were collected for metabolic analyses. Direct measurements of BP, respiratory frequency (RF), tidal volume (VT) and ventilation (VE) under baseline condition, as well as during hypercapnia (7 % CO2) and hypoxia (KCN, 0·04 %), were recorded from awake 90-d-old male offspring. DLP dams exhibited raised serum levels of total cholesterol (TC) (4·0-fold), TAG (2·0-fold), VLDL+LDL (7·7-fold) and reduced HDL-cholesterol (2·4-fold), insulin resistance and hepatic steatosis at the end of lactation. At 30 d of age, the DLP offspring showed an increase in the serum levels of TC (P<0·05) and VLDL+LDL (P<0·05) in comparison with CTL offspring. At 90 d of age, DLP offspring exhibited higher mean arterial pressure (MAP, approximately 34 %). In the spectral analysis, the DLP group showed augmented low-frequency (LF) power and LF:high-frequency (HF) ratio when compared with CTL offspring. In addition, the DLP animals showed a larger delta variation in arterial pressure after administration of the ganglionic blocker (P=0·0003). We also found that cardiorespiratory response to hypercapnia and hypoxia was augmented in DLP offspring. In conclusion, the present data show that maternal dyslipidaemia alters cardiorespiratory physiology and may be a predisposing factor for hypertension at adulthood.

Standardisation of the Japanese diet for use in animal experiments

The aim of this study was to develop a purified diet that mimics the characteristics of the Japanese diet using readily available materials with a simpler composition and a focus on quality, with the goal of facilitating performance of studies on the Japanese diet worldwide. The utility of the new diet was examined as a mimic of the standard Japanese diet for use in animal experiments. We examined whether a key characteristic of the Japanese diet of being less likely to cause obesity could be reproduced. The mimic diet had a balance of protein, fat and carbohydrate based on the 1975 Japanese diet, which is the least likely to cause obesity, and materials chosen with reference to the National Health and Nutrition Survey (NHNS). To examine similarities of the mimic diet with the model 1975 Japanese diet, we created a menu of the 1975 diet based on the NHNS and prepared the freeze-dried and powdered diet. The mimic diet, the 1975 Japanese diet, a control AIN-93G diet and a Western diet were fed to mice for 4 weeks. As a result, the mimic diet and the 1975 diet resulted in less accumulation of visceral fat and liver fat. Mice given these two diets showed similar effects. This indicates that the mimic diet used in this study has characteristics of the 1975 Japanese diet and could be used as a standard Japanese diet in animal experiments.

Beneficial effects of exercise on offspring obesity and insulin resistance are reduced by maternal high-fat diet

SCOPE

We investigated the long-term effects of maternal high-fat consumption and post-weaning exercise on offspring obesity susceptibility and insulin resistance.

METHODS

C57BL/6J dams were fed either a high-fat (HFD, 40% kcal fat) or low-fat (LFD, 10% kcal fat) semi-synthetic diet during pregnancy and lactation. After weaning, male offspring of both maternal diet groups (mLFD; mHFD) received a LFD. At week 7, half of the mice got access to a running wheel (+RW) as voluntary exercise training. To induce obesity, all offspring groups (mLFD +/-RW and mHFD +/-RW) received HFD from week 15 until week 25.

RESULTS

Compared to mLFD, mHFD offspring were more prone to HFD-induced body fat gain and exhibited an increased liver mass which was not due to increased hepatic triglyceride levels. RW improved the endurance capacity in mLFD, but not in mHFD offspring. Additionally, mHFD offspring +RW exhibited higher plasma insulin levels during glucose tolerance test and an elevated basal pancreatic insulin production compared to mLFD offspring.

CONCLUSION

Taken together, maternal HFD reduced offspring responsiveness to the beneficial effects of voluntary exercise training regarding the improvement of endurance capacity, reduction of fat mass gain, and amelioration of HFD-induced insulin resistance.