Potential Impact of Metabolic and Gut Microbial Response to Pregnancy and Lactation in Lean and Diet-Induced Obese Rats on Offspring Obesity Risk

Maternal obesity and offspring health: Adapting metabolic changes through autophagy and mitophagy

Maternal obesity leads to obstetric complications and a high prevalence of metabolic anomalies in the offspring. Among various contributing factors for maternal obesity-evoked health sequelae, developmental programming is considered as one of the leading culprit factors for maternal obesity-associated chronic comorbidities. Although a unified theory is still lacking to systematically address multiple unfavorable postnatal health sequelae, a cadre of etiological machineries have been put forward, including lipotoxicity, inflammation, oxidative stress, autophagy/mitophagy defect, and cell death. Hereinto, autophagy and mitophagy play an essential housekeeping role in the clearance of long-lived, damaged, and unnecessary cell components to maintain and restore cellular homeostasis. Defective autophagy/mitophagy has been reported in maternal obesity and negatively impacts fetal development and postnatal health. This review will provide an update on metabolic disorders in fetal development and postnatal health issues evoked by maternal obesity and/or intrauterine overnutrition and discuss the possible contribution of autophagy/mitophagy in metabolic diseases. Moreover, relevant mechanisms and potential therapeutic strategies will be discussed in an effort to target autophagy/mitophagy and metabolic disturbances in maternal obesity.

The Benefits of Switching to a Healthy Diet on Metabolic, Cognitive, and Gut Microbiome Parameters Are Preserved in Adult Rat Offspring of Mothers Fed a High-Fat, High-Sugar Diet

SCOPE

Maternal obesity increases the risk of health complications in children, highlighting the need for effective interventions. A rat model of maternal obesity to examine whether a diet switch intervention could reverse the adverse effects of an unhealthy postweaning diet is used.

METHODS AND RESULTS

Male and female offspring born to dams fed standard chow or a high-fat, high-sugar "cafeteria" (Caf) diet are weaned onto chow or Caf diets until 22 weeks of age, when Caf-fed groups are switched to chow for 5 weeks. Adiposity, gut microbiota composition, and place recognition memory are assessed before and after the switch. Body weight and adiposity fall in switched groups but remain significantly higher than chow-fed controls. Nonetheless, the diet switch improves a deficit in place recognition memory observed in Caf-fed groups, increases gut microbiota species richness, and alters β diversity. Modeling indicate that adiposity most strongly predicts gut microbiota composition before and after the switch.

CONCLUSION

Maternal obesity does not alter the effects of switching diet on metabolic, microbial, or cognitive measures. Thus, a healthy diet intervention lead to major shifts in body weight, adiposity, place recognition memory, and gut microbiota composition, with beneficial effects preserved in offspring born to obese dams.

Maternal obesity during pregnancy leads to derangements in one-carbon metabolism and the gut microbiota: implications for fetal development and offspring wellbeing

A healthy diet before and during pregnancy is beneficial in acquiring essential B vitamins involved in 1-carbon metabolism, and in maintaining a healthy gut microbiota. Each play important roles in fetal development, immune-system remodeling, and pregnancy-nutrient acquisition. Evidence shows that there is a reciprocal interaction between the one-carbon metabolism and the gut microbiota given that dietary intake of B vitamins has been shown to influence the composition of the gut microbiota, and certain gut bacteria also synthesize B vitamins. This reciprocal interaction contributes to the individual's overall availability of B vitamins and, therefore, should be maintained in a healthy state during pregnancy. There is an emerging consensus that obese pregnant women often have derangements in 1-carbon metabolism and gut dysbiosis owing to high intake of nutritiously poor foods and a chronic systemic inflammatory state. For example, low folate and vitamin B₁₂ in obese women coincide with the decreased presence of B vitamin-producing bacteria and increased presence of inflammatory-associated bacteria from approximately mid-pregnancy. These alterations are risk factors for adverse pregnancy outcomes, impaired fetal development, and disruption of fetal growth and microbiota formation, which may lead to potential long-term offspring metabolic and neurologic disorders. Therefore, preconceptional and pregnant obese women may benefit from dietary and lifestyle counseling to improve their dietary nutrient intake, and from monitoring their B vitamin levels and gut microbiome by blood tests and microbiota stool samples. In addition, there is evidence that some probiotic bacteria have folate biosynthetic capacity and could be used to treat gut dysbiosis. Thus, their use as an intervention strategy for obese women holds potential and should be further investigated. Currently, there are many knowledge gaps concerning the relationship between one-carbon metabolism and the gut microbiota, and future research should focus on intervention strategies to counteract B vitamin deficiencies and gut dysbiosis in obese pregnant women, commencing with the use of probiotic and prebiotic supplements.

Gut microbiota in women with gestational diabetes mellitus has potential impact on metabolism in pregnant mice and their offspring

Studies have shown that gestational diabetes mellitus (GDM) is closely related to abnormalities in the gut microbiota, and the offspring of these women have an increased risk of diabetes. There is no direct evidence of whether bacteria in women with GDM colonize the intestinal tract of offspring and cause hyperglycemia. In this fecal microbiota transplantation (FMT), pregnant mouse model study, two groups of germ-free (GF) mice after FMT showed different colonization patterns of gut microbiota and phenotype. Compared with the control group (healthy-FMT), we found in the GDM-FMT group as a lower relative abundance of Akkermansia and Faecalibacterium; a lower content of short-chain fatty acids and naringenin in feces; an elevated blood glucose; an inflammatory factor expression (TNF-α, CXCL-15, and IL-6), and a hepatic fat deposition. In addition, the influence of the gut microbiota continued in offspring. The gut microbiota of the offspring of GDM-FMT mice was still different from that of the control group as a lower relative abundance of Akkermansia and Parvibacter; and a higher relative abundance of bacteria such as Oscillibacter, Romboutsia, and Harryflintia. In addition, the offspring of GDM-FMT mice had higher body weight and blood glucose levels than the control offspring.

Comparison of Cecal Microbiota and Performance Indices Between Lean-Type and Fatty-Type Pekin Ducks

Fatty-type (FT) Pekin ducks exhibit higher lipid deposition than lean-type (LT) ducks. The gut microbiota plays an important role in modulating fat metabolism. We compared the growth performance, slaughter performance, and cecal microbiota of FT and LT Pekin ducks and analyzed the role of cecal microbiota in lipid deposition in Pekin ducks. A total of 140 1-day-old FT and LT Pekin ducks with similar body weights were randomly assigned to 10 cages, with 14 ducks in each replicate. All ducks were fed commercial diets from 28 to 42 days of age. Results showed that the average body weight and feed intake of FT ducks were higher than those of LT ducks. The breast muscle and eviscerated percentages of LT ducks were higher than those of FT ducks; the abdominal fat and sebum percentages of LT ducks were lower than those of FT ducks at 6 weeks of age (P < 0.01). 16S DNA sequencing of the cecal microbiota revealed that the bacterial abundance differed between FT and LT ducks at 4 and 6 weeks of age. The abundance of Firmicutes was higher, while that of Fusobacteria and Fusobacterium was lower in LT ducks than in FT ducks at 4 weeks of age. The abundance of Spirochaetes was higher, while that of Firmicutes and Bacteroides was lower in LT ducks than in FT ducks at 6 weeks of age. The abundance of Spirochaetes and Brachyspira in LT ducks was higher at 6 weeks than at 4 weeks of age. Interestingly, the abundance of Firmicutes and Bacteroides in FT ducks was higher at 6 weeks of age than at 4 weeks of age, while that of Fusobacteria and Fusobacterium was lower at 6 weeks than at 4 weeks of age. Linear discriminant analysis effect size analysis showed that Spirochaetes, Brachyspira, Alistipes, Campylobacter, Megamonas, Butyricicoccus, and Fusobacteria may be involved in the fat metabolism pathway as specific markers. We reveal the differences in microbial abundance in the cecal microbiota between FT and LT Pekin ducks and provide an insight into the role of cecal microbiota in lipid deposition in Pekin ducks.

Physiological Changes and Interactions Between Microbiome and the Host During Pregnancy

In recent years, it has become clear that microbiome play a variety of essential roles in human metabolism, immunity, and overall health and that the composition of these microbiome is influenced by our environment, diet, weight, hormones, and other factors. Indeed, numerous physiological and pathological conditions, including obesity and metabolic syndrome, are associated with changes in our microbiome, referred to as dysbiosis. As a result, it is not surprising that such changes occur during pregnancy, which includes substantial weight gain and significant changes in metabolism and immune defenses. The present review relates physiological changes during pregnancy to alterations in the microbial composition at various sites, including the gut, oral cavity, and vagina. Pregnancy has been linked to such microbial changes, and we believe that, in contrast to certain disease states, these microbial changes are vital for a healthy pregnancy, probably through their influence on the mother’s immunological, endocrinological, and metabolic status.

Metabolic and Microbial Changes Associated With Diet and Obesity During Pregnancy: What Can We Learn From Animal Studies?

The intestinal microbiota changes throughout pregnancy and influences maternal metabolic adaptations to support fetal growth. Obesity induces alterations to the microbiota that include decreased microbial diversity and shifts in microbial composition, though specific species changes are inconsistent between published studies. In animal models, probiotics and exercise moderate maternal weight gain and partially correct the maternal microbiota. Supplemental Escherichia coli, however, exacerbate maternal obesity during the perinatal period, lending weight to the theory that inflammation-induced gut epithelial barrier leak influences metabolic dysregulation. Although birth weight is not always altered when offspring are exposed to an obesogenic diet during gestation, insulin resistance and lipid metabolism are impacted through adulthood in association with this exposure and can lead to increased body weight in adulthood. Postnatal offspring growth is accelerated in response to maternal overnutrition during lactation. Offspring microbiota, metabolism, and behavior are altered in response to early exposure to high fat and high sucrose diets. Consequences to this exposure include impaired glucose and insulin homeostasis, fatty liver, and neurobehavioral deficits that can be ameliorated by improving the microbial environment. In this mini review, we provide an overview of the use of translational animal models to understand the mechanisms associated with changes to the gastrointestinal microbiota due to maternal obesity and the microbial impact on the metabolic changes of pregnancy.

Paternal high protein diet modulates body composition, insulin sensitivity, epigenetics, and gut microbiota intergenerationally in rats

Mounting evidence demonstrates that paternal diet programs offspring metabolism. However, the contribution of a pre-conception paternal high protein (HP) diet to offspring metabolism, gut microbiota, and epigenetic changes remains unclear. Here we show that paternal HP intake in Sprague Dawley rats programs protective metabolic outcomes in offspring. Compared to paternal high fat/sucrose (HF/S), HP diet improved body composition and insulin sensitivity and improved circulating satiety hormones and cecal short-chain fatty acids compared to HF/S and control diet (P < .05). Further, using 16S rRNA gene sequencing to assess gut microbial composition, we observed increased alpha diversity, distinct bacterial clustering, and increased abundance of Bifidobacterium, Akkermansia, Bacteroides, and Marvinbryantia in HP fathers and/or male and female adult offspring. At the epigenetic level, DNMT1and 3b expression was altered intergenerationally. Our study identifies paternal HP diet as a modulator of gut microbial composition, epigenetic markers, and metabolic function intergenerationally.

Impact of maternal obesity and prebiotic supplementation on select maternal milk microRNA levels and correlation with offspring outcomes

Breast milk composition varies with maternal factors including diet and confers health benefits to the neonate; however, the mechanisms mediating this protection remain incompletely understood. Our aim was to investigate the effects of supplementing a maternal high-fat/sucrose (HFS) diet with prebiotic oligofructose (OFS) on milk composition in rats and associations with offspring body composition and gut microbiota. Obese Sprague-Dawley dams consumed a control, HFS, HFS + OFS (10 % wt/wt) or HFS diet weight-matched to the HFS + OFS group (HFS-WM) during pregnancy and lactation. Pups were weaned onto a HFS diet on day 21. Milk was collected at weaning and analysed for protein, leptin and microRNA (miRNA) levels. Milk produced by HFS dams contained less protein than milk from lean controls which was normalised by OFS. Six miRNA (miR-222, miR-203a, miR-200a, miR-26a, miR-27a and miR-103) were differentially expressed in milk according to maternal diet. Milk leptin content was positively correlated with maternal body fat and faecal Enterobacteriaceae in male offspring at 24 weeks of age. Milk protein content was inversely associated with maternal body fat and body weight. miR-200a was positively associated with maternal body fat and Enterobacteriaceae in female offspring at 24 weeks of age. Correlations between milk protein and multiple milk miRNA and offspring body composition and gut microbiota differed by sex. Overall, our results suggest that obesogenic diets and prebiotic supplementation can alter the protein and miRNA levels in breast milk in rats and these milk components may explain, in part, the influence of these maternal diets on offspring body composition.

Distribution characteristics of intestinal microbiota during pregnancy and postpartum in healthy women

The characteristics of microbial community changes in pregnant women are still unclear. To investigate the changes in gut microbiota during pregnancy and after delivery in healthy women, we enrolled 47 healthy pregnant women who received obstetric care in our hospital from October 2016 to April 2017 and obtained their fecal samples at different time periods: T1 (11-13 W), T2 (23-28 W), and T3 (33-38 W) during pregnancy, and PP6W (6 weeks postpartum) and PP6M (6 months postpartum). Based on 16S rRNA gene sequencing results, there was no significant difference (p > .05) in the index of alpha-diversity between the pregnancy and postpartum periods. Principal coordinate analysis indicated that gut microbiota clustering during the postpartum period was significantly different from that during pregnancy. Phylum-level comparison of species identified using T1, T2, T3, PP6W, and PP6M samples showed higher abundance of Actinobacteria, Firmicutes, and Proteobacteria, while the abundance of Bacteroidetes decreased. At the genus level, 31 types of bacteria were found to be significantly different among these five groups. Akkermansia, Bacteroides, Subdoligranulum, Oscillospira, Ruminococcacea UCG-004), and Alistipes showed higher abundance during pregnancy, while Bifidobacterium, [Eubacterium] rectale group and Hungatella showed higher abundance after delivery. Therefore, the diversity and function of the gut microbiota in healthy pregnant women remained unchanged during pregnancy; however, the composition of the intestinal microbiota in the postpartum period changed significantly. Our results provide the basis for in-depth studies of the composition of perinatal gut microbial communities in women.

Paternal Methyl Donor Supplementation in Rats Improves Fertility, Physiological Outcomes, Gut Microbial Signatures and Epigenetic Markers Altered by High Fat/High Sucrose Diet

Increased consumption of high fat/sucrose (HF/S) diets has contributed to rising rates of obesity and its co-morbidities globally, while also negatively impacting male reproductive health. Our objective was to examine whether adding a methyl donor cocktail to paternal HF/S diet (HF/S+M) improves health status in fathers and offspring. From 3–12 weeks of age, male Sprague Dawley rats consumed a HF/S or HF/S+M diet. Offspring were followed until 16 weeks of age. Body composition, metabolic markers, gut microbiota, DNA methyltransferase (DNMT) and microRNA expression were measured in fathers and offspring. Compared to HF/S, paternal HF/S+M diet reduced fat mass in offspring (p < 0.005). HF/S+M fathers consumed 16% fewer kcal/day, which persisted in HF/S+M female offspring and was explained in part by changes in serum glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY) levels. Compared to HF/S, HF/S+M fathers had a 33% improvement in days until conception and 300% fewer stillbirths. In fathers, adipose tissue DNMT3a and hepatic miR-34a expression were reduced with HF/S+M. Adult male offspring showed upregulated miR-24, -33, -122a and -143 expression while females exhibited downregulated miR-33 expression. Fathers and offspring presented differences in gut microbial signatures. Supplementing a paternal HF/S diet with methyl-donors improved fertility, physiological outcomes, epigenetic and gut microbial signatures intergenerationally.

Maternal High-Fat Diet Disturbs the DNA Methylation Profile in the Brown Adipose Tissue of Offspring Mice

The prevalence of obesity has become a threatening global public health issue. The consequence of obesity is abnormal energy metabolism. Unlike white adipose tissue (WAT), brown adipose tissue (BAT) has a unique role in nonshivering thermogenesis. Lipids and glucose are consumed to maintain energy and metabolic homeostasis in BAT. Recently, accumulating evidence has indicated that exposure to excess maternal energy intake affects energy metabolism in offspring throughout their life. However, whether excess intrauterine energy intake influences BAT metabolism in adulthood is not clear. In this study, mouse dams were exposed to excess energy intake by feeding a high-fat diet (HFD) before and during pregnancy and lactation. The histology of BAT was assessed by hematoxylin and eosin staining. The genome-wide methylation profile of BAT was determined by a DNA methylation array, and specific site DNA methylation was quantitatively analyzed by methylated DNA immunoprecipitation (MeDIP) qPCR. We found that intrauterine exposure to a high-energy diet resulted in blood lipid panel disorders and impaired the BAT structure. Higher methylation levels of genes involved in thermogenesis and fatty acid oxidation (FAO) in BAT, such as Acaa2, Acsl1, and Cox7a1, were found in 16-week-old offspring from mothers fed with HFD. Furthermore, the expression of Acaa2, Acsl1, and Cox7a1 was down-regulated by intrauterine exposure to excess energy intake. In summary, our results reveal that excess maternal energy leads to a long-term disorder of BAT in offspring that involves the activation of DNA methylation of BAT-specific genes involved in fatty acid oxidation and thermogenesis.

Differential Effects of Post-Weaning Diet and Maternal Obesity on Mouse Liver and Brain Metabolomes

Nutritional changes during developmental windows are of particular concern in offspring metabolic disease. Questions are emerging concerning the role of maternal weight changes before conception, particularly for weight loss, in the development of diet-related disorders. Understanding the physiological pathways affected by the maternal trajectories in the offspring is therefore essential, but a broad overview is still lacking. We recently reported both metabolic and behavioral negative outcomes in offspring born to obese or weight-loss mothers and fed a control of high-fat diet, suggesting long-term modeling of metabolic pathways needing to be further characterized. Using non-targeted LC–HRMS, we investigated the impact of maternal and post-weaning metabolic status on the adult male offspring’s metabolome in three tissues involved in energy homeostasis: liver, hypothalamus and olfactory bulb. We showed that post-weaning diet interfered with the abundance of several metabolites, including 1,5-anhydroglucitol, saccharopine and β-hydroxybutyrate, differential in the three tissues. Moreover, maternal diet had a unique impact on the abundance of two metabolites in the liver. Particularly, anserine abundance, lowered by maternal obesity, was normalized by a preconceptional weight loss, whatever the post-weaning diet. This study is the first to identify a programming long-term effect of maternal preconception obesity on the offspring metabolome.

Human Milk Oligosaccharide Supplementation Affects Intestinal Barrier Function and Microbial Composition in the Gastrointestinal Tract of Young Sprague Dawley Rats

Human milk oligosaccharides (HMOs) are chief maternal milk constituents that feed the intestinal microbiota and drive maturation of the infant gut. Our objective was to determine whether supplementing individual HMOs to a weanling diet alters growth and gut health in rats. Healthy three-week-old Sprague Dawley rat pups were randomized to control, 2'-O-fucosyllactose (2'FL)- and 3'sialyllactose (3'SL)-fortified diets alone or in combination at physiological doses for eight weeks. Body composition, intestinal permeability, serum cytokines, fecal microbiota composition, and messenger RNA (mRNA) expression in the gastrointestinal tract were assessed. Males fed a control diet were 10% heavier and displayed elevated interleukin (IL-18) (p = 0.01) in serum compared to all HMO-fortified groups at week 11. No differences in body composition were detected between groups. In females, HMOs did not affect body weight but 2'FL + 3'SL significantly increased cecum weight. All female HMO-fortified groups displayed significant reductions in intestinal permeability compared to controls (p = 0.02). All HMO-fortified diets altered gut microbiota composition and mRNA expression in the gastrointestinal tract, albeit differently according to sex. Supplementation with a fraction of the HMOs found in breast milk has a complex sex-dependent risk/benefit profile. Further long-term investigation of gut microbial profiles and supplementation with other HMOs during early development is warranted.

Modulation effects of black-vinegar-based supplement against a high-fat dietary habit: antiobesity/hypolipidemic, antioxidative, and energy-metabolism effects

BACKGROUND

An imbalanced fat or excess energy intake always results in obesity and increased serum/liver lipids, thus leading to metabolic syndromes. Given the bioactive components in black vinegar (BV), such as branched amino acids, phenolic profile, and mineral contents, we investigated the antiobesity effects of BV-based supplements in rats fed a high-fat diet (HFD).

RESULTS

HFD (30% fat, w/w) feeding increased (P < 0.05) body weight, weight gains, weights of livers and mesenteric, epididymal, and perirenal adipose tissues, and serum/liver triglyceride levels relative to those of rats fed a normal diet (4% fat, w/w; CON). These increased values were ameliorated (P < 0.05) by supplementing with BV-based supplements but were still higher (P < 0.05) than those of CON rats. The increased areas of perirenal adipocytes in rats fed with an HFD were also decreased (P < 0.05) by supplementing with BV-based supplements, which might result from an upregulation (P < 0.05) of 5'-adenosine monophosphate-activated protein kinase (AMPK), carnitine palmitoyltransferase-1 (CPT1), and uncoupling protein-2 (UCP2) in the perirenal adipose tissues. A similar effect was observed for AMPK, peroxisome proliferator-activated receptor alpha, retinoid X receptor alpha, CPT1, and UCP2 gene and protein levels in livers (P < 0.05). Generally, BV-based supplements increased the fecal triglyceride, cholesterol, and bile acid levels of rats fed with an HFD, which partially contribute to the lipid-lowering effects. Furthermore, BV-based supplements increased (P < 0.05) hepatic Trolox equivalent antioxidant capacity and lowered (P < 0.05) serum/liver thiobarbituric acid reactive substances values in HFD-fed rats.

CONCLUSION

In a chronic high-fat dietary habit, the food-grade BV-based supplement is a good daily choice to ameliorate obesity and its associated comorbidities. © 2020 Society of Chemical Industry.

Impact of age on host responses to diet-induced obesity: Development of joint damage and metabolic set points

BACKGROUND

Osteoarthritis is one of the leading causes of pain and disability worldwide, and a large percentage of patients with osteoarthritis are individuals who are also obese. In recent years, a series of animal models have demonstrated that obesity-inducing diets can result in synovial joint damage (both with and without the superimposition of trauma), which may be related to changes in percentage of body fat and a series of low-level systemic inflammatory mediators. Of note, there is a disparity between whether the dietary challenges commence at weaning, representing a weanling onset, or at skeletal maturity, representing an adult onset of obesity. We wished to evaluate the effect of the dietary exposure time and the age at which animals are exposed to a high-fat and high-sucrose (HFS) diet to determine whether these factors may result in disparate outcomes, as there is evidence suggesting that these factors result in differential metabolic disturbances. Based on dietary exposure time, we hypothesized that rats fed an HFS diet for 14 weeks from weaning (HFS Weanling) would demonstrate an increase in knee joint damage scores, whereas rats exposed to the HFS diet for 4 weeks, starting at 12 weeks of age (HFS Adult) and rats exposed to a standard chow diet (Chow) would not display an increase in knee joint damage scores.

METHODS

Male Sprague-Dawley rats were fed either an HFS diet for 14 weeks from weaning (HFS Weanling) or an HFS diet for 4 weeks, starting at 12 weeks of age (HFS Adult). At sacrifice, joints were scored using the modified Mankin Criteria, and serum was analyzed for a defined subset of inflammatory markers (Interleukin-6, leptin, monocyte chemoattractant protein-1, and tumor necrosis factor α).

RESULTS

When the HFS Weanling and HFS Adult groups were compared, both groups had a similar percent of body fat, although the HFS Weanling group had a significantly greater body mass than the HFS Adult group. The HFS Weanling and HFS Adult animals had a significant increase in body mass and percentage of body fat when compared to the Chow group. Although knee joint damage scores were low in all 3 groups, we found, contrary to our hypothesis, that the HFS Adult group had statistically significant greater knee joint damage scores than the Chow and HFS Weanling groups. Furthermore, we observed that the HFS Weanling group did not have significant differences in knee joint damage scores relative to the Chow group.

CONCLUSION

These findings indicate that the HFS Weanling animals were better able to cope with the dietary challenge of an HFS diet than the HFS Adult group. Interestingly, when assessing various serum proinflammatory markers, no significant differences were detected between the HFS Adult and HFS Weanling groups. Although details regarding the mechanisms underlying an increase in knee joint damage scores in the HFS Adult group remain to be elucidated, these findings indicate that dietary exposure time maybe less important than the age at which an HFS diet is introduced. Moreover, increases in serum proinflammatory mediators do not appear to be directly linked to knee joint damage scores in the HFS Weanling group animals but may be partially responsible for the observed knee joint damage in the adults over the very short time of exposure to the HFS diet.

Microbial dysbiosis-induced obesity: role of gut microbiota in homoeostasis of energy metabolism

The global obesity epidemic has necessitated the search for better intervention strategies including the exploitation of the health benefits of some gut microbiota and their metabolic products. Therefore, we examined the gut microbial composition and mechanisms of interaction with the host in relation to homoeostatic energy metabolism and pathophysiology of dysbiosis-induced metabolic inflammation and obesity. We also discussed the eubiotic, health-promoting effects of probiotics and prebiotics as well as epigenetic modifications associated with gut microbial dysbiosis and risk of obesity. High-fat/carbohydrate diet programmes the gut microbiota to one predominated by Firmicutes (Clostridium), Prevotella and Methanobrevibacter but deficient in beneficial genera/species such as Bacteroides, Bifidobacterium, Lactobacillus and Akkermansia. Altered gut microbiota is associated with decreased expression of SCFA that maintain intestinal epithelial barrier integrity, reduce bacterial translocation and inflammation and increase expression of hunger-suppressing hormones. Reduced amounts of beneficial micro-organisms also inhibit fasting-induced adipocyte factor expression leading to dyslipidaemia. A low-grade chronic inflammation (metabolic endotoxaemia) ensues which culminates in obesity and its co-morbidities. The synergy of high-fat diet and dysbiotic gut microbiota initiates a recipe that epigenetically programmes the host for increased adiposity and poor glycaemic control. Interestingly, these obesogenic mechanistic pathways that are transmittable from one generation to another can be modulated through the administration of probiotics, prebiotics and synbiotics. Though the influence of gut microbiota on the risk of obesity and several intervention strategies have been extensively demonstrated in animal models, application in humans still requires further robust investigation.

Exposure to Amoxicillin in Early Life Is Associated With Changes in Gut Microbiota and Reduction in Blood Pressure: Findings From a Study on Rat Dams and Offspring

Background

Pediatric hypertension is recognized as an emerging global health concern. Although new guidelines are developed for facilitating clinical management, the reasons for the prevalence of hypertension in children remain unknown. Genetics and environmental factors do not fully account for the growing incidence of pediatric hypertension. Because stable bacterial flora in early life are linked with health outcomes later in life, we hypothesized that reshaping of gut microbiota in early life affects blood pressure (BP) of pediatric subjects.

Methods and Results

To test this hypothesis, we administered amoxicillin, the most commonly prescribed pediatric antibiotic, to alter gut microbiota of young, genetically hypertensive rats (study 1) and dams during gestation and lactation (study 2) and recorded their BP. Reshaping of microbiota with reductions in Firmicutes/Bacteriodetes ratio were observed. Amoxicillin treated rats had lower BP compared with untreated rats. In young rats treated with amoxicillin, the lowering effect on BP persisted even after antibiotics were discontinued. Similarly, offspring from dams treated with amoxicillin showed lower systolic BP compared with control rats. Remarkably, in all cases, a decrease in BP was associated with lowering of Veillonellaceae, which are succinate‐producing bacteria. Elevated plasma succinate is reported in hypertension. Accordingly, serum succinate was measured and found lower in animals treated with amoxicillin.

Conclusions

Our results demonstrate a direct correlation between succinate‐producing gut microbiota and early development of hypertension and indicate that reshaping gut microbiota, especially by depleting succinate‐producing microbiota early in life, may have long‐term benefits for hypertension‐prone individuals.

Perinatal exposure to low-dose decabromodiphenyl ethane increased the risk of obesity in male mice offspring

Decabromodiphenyl Ethane (DBDPE), a kind of new brominated flame retardants (NBFRs) used to replace DecaBDE, has been frequently detected in the environment and human samples. In this study, we explored its toxic effects on male mouse offspring after perinatal exposure to DBDPE. During the perinatal period, pregnant ICR mice were exposed to DBDPE (100 μg/kg body weight) via oral gavage. After weaning, male offspring were fed on a low-fat diet and a high-fat diet, respectively. We measured and recorded body weight, liver weight, and epididymis fat mass, blood biochemical markers, metabolites changes in liver, and gene expression involved in lipid and glucose homeostasis. The results showed that perinatal exposure to DBDPE increased the risk of obesity in mouse offspring and affected triglyceride synthesis, bile secretion, purine synthesis, mitochondrial function and glucose metabolism, furthermore, the use of HFD feeding may further exacerbate these effects. All of these results show that early-life exposure to low doses of DBDPE can promote the development of metabolic dysfunction, which in turn induces obesity.

Impact of Food Ingredients (Aspartame, Stevia, Prebiotic Oligofructose) on Fertility and Reproductive Outcomes in Obese Rats

OBJECTIVE

This study aimed to investigate the interaction between obesity, low-calorie sweeteners, and prebiotic oligofructose on reproductive parameters in rats.

METHODS

Data were derived from two separate studies of female Sprague-Dawley rats with (1) Lean (n = 24), (2) Obese (n = 27), (3) Obese+Aspartame (n = 14), (4) Obese+Stevia (n = 15), and (5) Obese+Prebiotic (n = 15) groups. Obesity was induced with a high-fat/high-sucrose diet prior to pregnancy. In one study, human-approved doses of aspartame (5-7 mg/kg/d) and stevia (2-3 mg/kg/d) in drinking water were examined, and in the second, 10% prebiotics (oligofructose) in the diet was examined. Reproductive parameters, including fertility, pregnancy, and delivery indexes, were analyzed.

RESULTS

Obesity significantly reduced pregnancy index in Obese dams (60.7% successful pregnancies) compared with lean (100%). Obesity also reduced the number of pups born alive and pup survival percentage compared with those of Lean dams (P < 0.001). Only 53.3% of rats were able to conceive in the Obese+Stevia group, but if rats did become pregnant, they had 100% pregnancy and delivery index. While prebiotic administration rescued the pregnancy index, it could not remediate pup survival percentage (P = 0.025) in Obese dams.

CONCLUSIONS

Both obesity status and dietary ingredients affect the ability to conceive. Future rigorously controlled studies designed to examine reproductive outcomes in depth are needed to confirm these findings.

Epigenetic Mechanisms Link Maternal Diets and Gut Microbiome to Obesity in the Offspring

Nutrition is the most important environmental factor that can influence early developmental processes through regulation of epigenetic mechanisms during pregnancy and neonatal periods. Maternal diets or nutritional compositions contribute to the establishment of the epigenetic profiles in the fetus that have a profound impact on individual susceptibility to certain diseases or disorders in the offspring later in life. Obesity is considered a global epidemic that impairs human life quality and also increases risk of development of many human diseases such as diabetes and cardiovascular diseases. Studies have shown that maternal nutrition status is closely associated with obesity in progenies indicating obesity has a developmental origin. Maternal diets may also impact the early establishment of the fetal and neonatal microbiome leading to specific epigenetic signatures that may potentially predispose to the development of late-life obesity. This article will review the association of different maternal dietary statuses including essential nutritional quantity and specific dietary components with gut microbiome in determining epigenetic impacts on offspring susceptibility to obesity.