Interactive effects of oligofructose and obesity predisposition on gut hormones and microbiota in diet-induced obese rats

Impact of Plant-Based Dietary Fibers on Metabolic Homeostasis in High-Fat Diet Mice via Alterations in the Gut Microbiota and Metabolites

BACKGROUND

The gut microbiota contributes to metabolic disease, and diet shapes the gut microbiota, emphasizing the need to better understand how diet impacts metabolic disease via gut microbiota alterations. Fiber intake is linked with improvements in metabolic homeostasis in rodents and humans, which is associated with changes in the gut microbiota. However, dietary fiber is extremely heterogeneous, and it is imperative to comprehensively analyze the impact of various plant-based fibers on metabolic homeostasis in an identical setting and compare the impact of alterations in the gut microbiota and bacterially derived metabolites from different fiber sources.

OBJECTIVES

The objective of this study was to analyze the impact of different plant-based fibers (pectin, β-glucan, wheat dextrin, resistant starch, and cellulose as a control) on metabolic homeostasis through alterations in the gut microbiota and its metabolites in high-fat diet (HFD)-fed mice.

METHODS

HFD-fed mice were supplemented with 5 different fiber types (pectin, β-glucan, wheat dextrin, resistant starch, or cellulose as a control) at 10% (wt/wt) for 18 wk (n = 12/group), measuring body weight, adiposity, indirect calorimetry, glucose tolerance, and the gut microbiota and metabolites.

RESULTS

Only β-glucan supplementation during HFD-feeding decreased adiposity and body weight gain and improved glucose tolerance compared with HFD-cellulose, whereas all other fibers had no effect. This was associated with increased energy expenditure and locomotor activity in mice compared with HFD-cellulose. All fibers supplemented into an HFD uniquely shifted the intestinal microbiota and cecal short-chain fatty acids; however, only β-glucan supplementation increased cecal butyrate concentrations. Lastly, all fibers altered the small-intestinal microbiota and portal bile acid composition.

CONCLUSIONS

These findings demonstrate that β-glucan consumption is a promising dietary strategy for metabolic disease, possibly via increased energy expenditure through alterations in the gut microbiota and bacterial metabolites in mice.

Maternal inulin alleviates high-fat diet-induced lipid disorder in offspring by epigenetically modulating hypothalamus feeding circuit-related genes

Increasing evidence supports the existence of fetal-originated adult diseases. Recent research indicates that the intrauterine environment affects the fetal hypothalamic energy intake center. Inulin is a probiotic that can moderate metabolic disorders, but whether maternal inulin intervention confers long-term metabolic benefits to lipid metabolism in offspring in their adult lives and the mechanism involved are unknown. Here, we used a maternal overnutrition model that was induced by excess energy intake before and during pregnancy and lactation and maternal inulin intervention was performed during pregnancy and lactation. The hypothalamic genome methylation in offspring was analyzed using a methylation array. The results showed that maternal inulin treatment modified the maternal high-fat diet (HFD)-induced increases in body weight, adipose tissue weight, and serum insulin and leptin levels and decreases in serum adiponectin levels. Maternal inulin intervention regulated the impairments in hypothalamic leptin resistance, induced the methylation of Socs3, Npy, and Il6, and inhibited the methylation of Lepr in the hypothalamus of offspring. In conclusion, maternal inulin intervention modifies offspring lipid metabolism, and the underlying mechanism involves the methylation of genes in the hypothalamus feeding circuit.

Differential effects of plant-based flours on metabolic homeostasis and the gut microbiota in high-fat fed rats

BACKGROUND

The gut microbiome is a salient contributor to the development of obesity, and diet is the greatest modifier of the gut microbiome, which highlights the need to better understand how specific diets alter the gut microbiota to impact metabolic disease. Increased dietary fiber intake shifts the gut microbiome and improves energy and glucose homeostasis. Dietary fibers are found in various plant-based flours which vary in fiber composition. However, the comparative efficacy of specific plant-based flours to improve energy homeostasis and the mechanism by which this occurs is not well characterized.

METHODS

In experiment 1, obese rats were fed a high fat diet (HFD) supplemented with four different plant-based flours for 12 weeks. Barley flour (BF), oat bran (OB), wheat bran (WB), and Hi-maize amylose (HMA) were incorporated into the HFD at 5% or 10% total fiber content and were compared to a HFD control. For experiment 2, lean, chow-fed rats were switched to HFD supplemented with 10% WB or BF to determine the preventative efficacy of flour supplementation.

RESULTS

In experiment 1, 10% BF and 10% WB reduced body weight and adiposity gain and increased cecal butyrate. Gut microbiota analysis of WB and BF treated rats revealed increases in relative abundance of SCFA-producing bacteria. 10% WB and BF were also efficacious in preventing HFD-induced obesity; 10% WB and BF decreased body weight and adiposity, improved glucose tolerance, and reduced inflammatory markers and lipogenic enzyme expression in liver and adipose tissue. These effects were accompanied by alterations in the gut microbiota including increased relative abundance of Lactobacillus and LachnospiraceaeUCG001, along with increased portal taurodeoxycholic acid (TDCA) in 10% WB and BF rats compared to HFD rats.

CONCLUSIONS

Therapeutic and preventative supplementation with 10%, but not 5%, WB or BF improves metabolic homeostasis, which is possibly due to gut microbiome-induced alterations. Specifically, these effects are proposed to be due to increased concentrations of intestinal butyrate and circulating TDCA.

The associations of gut microbiota, endocrine system and bone metabolism

Gut microbiota is of great importance in human health, and its roles in the maintenance of skeletal homeostasis have long been recognized as the "gut-bone axis." Recent evidence has indicated intercorrelations between gut microbiota, endocrine system and bone metabolism. This review article discussed the complex interactions between gut microbiota and bone metabolism-related hormones, including sex steroids, insulin-like growth factors, 5-hydroxytryptamine, parathyroid hormone, glucagon-like peptides, peptide YY, etc. Although the underlying mechanisms still need further investigation, the regulatory effect of gut microbiota on bone health via interplaying with endocrine system may provide a new paradigm for the better management of musculoskeletal disorders.

Combined effects of yacon flour and probiotic yogurt on the metabolic parameters and inflammatory and insulin signaling proteins in high-fat-diet-induced obese mice

BACKGROUND

Prebiotics and probiotics may be effective dietary components that can alter the gut microbiota of the host and, consequently, overcome imbalances associated with obesity. This work aimed to evaluate the synergistic and isolated effects and mechanisms by which probiotic yogurt containing Bifidobacterium animalis and/or Lactobacillus acidophilus and yacon flour alter metabolic parameters and inflammatory and insulin signaling proteins in diet-induced obese mice. Swiss mice were fed a high-fat diet (n = 48) or a standard diet (control; n = 6) for 56 days. The 42 mice that gained the most weight were selected and divided into seven groups that received different combinations of probiotic yogurt and yacon flour. After 30 days, biochemical parameters (blood glucose, serum total cholesterol, and triacylglycerols), crude fat excretion in feces, and periepididymal fat were assessed and an immunoblotting analysis of insulin signaling proteins and interleukin-1β was conducted.

RESULTS

The combination of yacon flour and a yogurt with two strains of probiotics exerted positive effects on the parameters evaluated, such as decreased body weight (-6.5%; P < 0.05), fasting glucose (-23.1%; P < 0.05), and triacylglycerol levels (-21.4%; P < 0.05) and decreased periepididymal fat accumulation (-44.2%; P < 0.05). There was a decrease in inflammatory markers (P < 0.001) and an improvement in insulin signaling (P < 0.001).

CONCLUSIONS

The combination of a prebiotic with two strains of probiotics in a food matrix may exert a protective effect against obesity-associated inflammation, improving insulin resistance, even in the short term. © 2022 Society of Chemical Industry.

Animal Models of Osteoarthritis Part 1-Preclinical Small Animal Models: Challenges and Opportunities for Drug Development

Osteoarthritis (OA) is the most common form of arthritis and a major source of pain and disability in the adult population. There is a significant unmet medical need for the development of effective pharmacological therapies for the treatment of OA. In addition to spontaneously occurring animal models of OA, many experimental animal models have been developed to provide insights into mechanisms of pathogenesis and progression. Many of these animal models are also being used in the drug development pipeline. Here, we provide an overview of commonly used and emerging preclinical small animal models of OA and highlight the strengths and limitations of small animal models in the context of translational drug development. There is limited information in the published literature regarding the technical reliability of these small animal models and their ability to accurately predict clinical drug development outcomes. The cost and complexity of the available models however is an important consideration for pharmaceutical companies, biotechnology startups, and contract research organizations wishing to incorporate preclinical models in target validation, discovery, and development pipelines. Further considerations relevant to industry include timelines, methods of induction, the key issue of reproducibility, and appropriate outcome measures needed to objectively assess outcomes of experimental therapeutics. Preclinical small animal models are indispensable tools that will shine some light on the pathogenesis of OA and its molecular endotypes in the context of drug development. This paper will focus on small animal models used in preclinical OA research. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC.

Dysregulation of intestinal flora: excess prepackaged soluble fibers damage the mucus layer and induce intestinal inflammation

Soluble fiber is commonly used as a dietary supplement to improve intestinal flora, and many prepackaged products are sold in the market. However, whether these prepared soluble fibers are harmless for intestinal flora has not been systematically evaluated. Here, we assessed the dose-effect of fructooligosaccharides (FOSs) on obesity and intestinal flora using a mouse model. Gavage of low- and medium-dose FOS improved the microbiota in high-fat diet fed mice, but high-dose FOS leads to intestinal flatulence, diarrhea and flora disorders, including an increase in Akkermansia muciniphila and Clostridium difficile, which disrupt the mucus barrier and cause intestinal inflammation. Besides, a high dose of xylooligosaccharide by gavage induces symptoms similar to those of FOS in mice. These adverse effects can be alleviated by regulating intestinal flora. In addition, we experimentally proved that supplementary probiotics protect against the negative effects of FOS in obese mice. Therefore, prepackaged soluble fiber supplements need to be taken with caution, and excessive consumption of soluble fibers results in intestinal dysfunction and even induces intestinal inflammation. Combining probiotics and soluble fiber can be considered if necessary.

Small intestinal metabolomics analysis reveals differentially regulated metabolite profiles in obese rats and with prebiotic supplementation

INTRODUCTION

Obesity occurs partly due to consumption of a high-fat, high-sugar and low fiber diet and is associated with an altered gut microbiome. Prebiotic supplementation can reverse obesity and beneficially alter the gut microbiome, evidenced by previous studies in rodents. However, the role of the small intestinal metabolome in obese and prebiotic supplemented rodents has never been investigated.

OBJECTIVES

To investigate and compare the small intestinal metabolome of healthy and obese rats, as well as obese rats supplemented with the prebiotic oligofructose (OFS).

METHODS

Untargeted metabolomics was performed on small intestinal contents of healthy chow-fed, high fat diet-induced obese, and obese rats supplemented with oligofructose using UPLC-MS/MS. Quantification of enterohepatic bile acids was performed with UPLC-MS to determine specific effects of obesity and fiber supplementation on the bile acid pool composition.

RESULTS

The small intestinal metabolome of obese rats was distinct from healthy rats. OFS supplementation did not significantly alter the small intestinal metabolome but did alter levels of several metabolites compared to obese rats, including bile acid metabolites, amino acid metabolites, and metabolites related to the gut microbiota. Further, obese rats had lower total bile acids and increased taurine-conjugated bile acid species in enterohepatic circulation; this effect was reversed with OFS supplementation in high fat-feeding.

CONCLUSION

Obesity is associated with a distinct small intestinal metabolome, and OFS supplementation reverses some metabolite levels that were altered in obese rats. Future research into the effects of specific metabolites identified in this study will provide deeper insight into the mechanism of fiber supplementation on improved body weight.

Therapeutic Benefits and Dietary Restrictions of Fiber Intake: A State of the Art Review

Throughout history, malnutrition and deficiency diseases have been a problem for our planet’s population. A balanced diet significantly influences everyone’s health, and fiber intake appears to play a more important role than previously thought. The natural dietary fibers are a category of carbohydrates in the constitution of plants that are not completely digested in the human intestine. High-fiber foods, such as fruits, vegetables and whole grains, have consistently been highly beneficial to health and effectively reduced the risk of disease. Although the mode of action of dietary fiber in the consumer body is not fully understood, nutritionists and health professionals unanimously recognize the therapeutic benefits. This paper presents the fiber consumption in different countries, the metabolism of fiber and the range of health benefits associated with fiber intake. In addition, the influence of fiber intake on the intestinal microbiome, metabolic diseases (obesity and diabetes), neurological aspects, cardiovascular diseases, autoimmune diseases and cancer prevention are discussed. Finally, dietary restrictions and excess fiber are addressed, which can cause episodes of diarrhea and dehydration and increase the likelihood of bloating and flatulence or even bowel obstruction. However, extensive studies are needed regarding the composition and required amount of fiber in relation to the metabolism of saprotrophic microorganisms from the enteral level and the benefits of the various pathologies with which they can be correlated.

Coffee Chlorogenic Acids Incorporation for Bioactivity Enhancement of Foods: A Review

The demand of foods with high antioxidant capacity have increased and research on these foods continues to grow. This review is focused on chlorogenic acids (CGAs) from green coffee, which is the most abundant source. The main CGA in coffee is 5-O-caffeoylquinic acid (5-CQA). Coffee extracts are currently the most widely used source to enhance the antioxidant activity of foods. Due to the solubility of CGAs, their extraction is mainly performed with organic solvents. CGAs have been associated with health benefits, such as antioxidant, antiviral, antibacterial, anticancer, and anti-inflammatory activity, and others that reduce the risk of cardiovascular diseases, type 2 diabetes, and Alzheimer's disease. However, the biological activities depend on the stability of CGAs, which are sensitive to pH, temperature, and light. The anti-inflammatory activity of 5-CQA is attributed to reducing the proinflammatory activity of cytokines. 5-CQA can negatively affect colon microbiota. An increase in anthocyanins and antioxidant activity was observed when CGAs extracts were added to different food matrices such as dairy products, coffee drinks, chocolate, and bakery products. The fortification of foods with coffee CGAs has the potential to improve the functionality of foods.

Current Research on the Effects of Non-Digestible Carbohydrates on Metabolic Disease

Metabolic diseases (MDs), including cardiovascular diseases (CVDs) and diabetes, occur when the body’s normal metabolic processes are disrupted. Behavioral risk factors such as obesity, physical inactivity, and dietary habits are strongly associated with a higher risk of MD. However, scientific evidence strongly suggests that balanced, healthy diets containing non-digestible carbohydrates (NDCs), such as dietary fiber and resistant starch, can reduce the risk of developing MD. In particular, major properties of NDCs, such as water retention, fecal bulking, viscosity, and fermentation in the gut, have been found to be important for reducing the risk of MD by decreasing blood glucose and lipid levels, increasing satiety and insulin sensitivity, and modifying the gut microbiome. Short chain fatty acids produced during the fermentation of NDCs in the gut are mainly responsible for improvement in MD. However, the effects of NDCs are dependent on the type, source, dose, and duration of NDC intake, and some of the mechanisms underlying the efficacy of NDCs on MD remain unclear. In this review, we briefly summarize current studies on the effects of NDCs on MD and discuss potential mechanisms that might contribute to further understanding these effects.

Dietary fiber combinations to mitigate the metabolic, microbial, and cognitive imbalances resulting from diet-induced obesity in rats

Dietary fiber promotes a healthy gut microbiome and shows promise in attenuating the unfavorable microbial changes resulting from a high-fat/sucrose (HFS) diet. High-fiber diets consisting of oligofructose alone (HFS/O) or in combination with β-glucan (HFS/OB), resistant starch (HFS/OR), or β-glucan and resistant starch (HFS/OBR) were fed to diet-induced obese rats for 8 weeks to determine if these fibers could attenuate the obese phenotype. Only the HFS/O group displayed a decrease in body weight and body fat, but all fiber interventions improved insulin sensitivity and cognitive function. The HFS/O diet was the least effective at improving cognitive function and only the HFS/OB group showed improvements in glucose tolerance, thus highlighting the differential effects of fiber types. Hippocampal cytokines (IL-6, IL-10) were more pronounced in the HFS/OB group which coincided with the most time spend in the open arms of the elevated plus maze. All fiber groups showed an increase in beneficial Bifidobacterium and Lactobacillus abundance while the HFS group showed higher abundance of Clostridium. Fecal microbiota transplant from fiber-treated rats into germ-free mice did not alter body composition in the mice but did result in a higher abundance of Bacteroides in the HFS/O and HFS/OB groups compared to HFS. The HFS/OB recipient mice also had higher insulin sensitivity compared to the other groups. This study highlights the influence of dietary fiber type on metabolic and cognitive outcomes suggesting that the type of supplementation (single or combined fibers) could be tailored to specific targeted outcomes.

Prebiotic and Exercise Do Not Alter Knee Osteoarthritis in a Rat Model of Established Obesity

OBJECTIVE

Metabolic disturbance is a known risk factor for cardiovascular disease and has been identified as a risk factor for the development of knee osteoarthritis. In this study, we sought to determine the effects of prebiotic fiber supplementation, aerobic exercise, and the combination of the 2 interventions, on the progression of knee osteoarthritis in a high-fat/high-sucrose diet-induced rat model of metabolic disturbance.

DESIGN

Twelve-week-old male CD-Sprague-Dawley rats were either fed a standard chow diet, or a high-fat/high-sucrose diet. After 12 weeks on diets, rats consuming the high-fat/high-sucrose diet were randomized into 4 subgroups: a sedentary, an aerobic exercise, a prebiotic fiber supplementation, and an aerobic exercise combined with prebiotic fiber supplementation group. The aerobic exercise intervention consisted of a progressive treadmill training program for 12 weeks, while the prebiotic fiber was added to the high-fat/high-sucrose diet at a dose of 10% by weight for 12 weeks. Outcome measures included knee joint damage, body mass, percent body fat, bone mineral density, insulin sensitivity, and serum lipid profile.

RESULTS

Aerobic exercise, or the combination of prebiotic fiber and aerobic exercise, improved select markers of metabolic disturbance, but not knee joint damage. However, these results need to be considered in view of the fact that the chow-fed rats had similar knee OA-like damage as the high-fat/high-sucrose-fed rats.

CONCLUSION

Exercise or prebiotics did not increase joint damage and might be good strategies for populations with metabolic knee osteoarthritis to alleviate other health-related problems, such as diabetes or cardiovascular disorders.

Effect of synbiotic supplementation on asprosin level in high fat diet-induced metabolic disorder in pregnant rats

Synbiotic supplementation can improve metabolic disorders. The aim of this study was to assess the impact of synbiotic supplementation on the levels of asprosin, lipid profile, glucose, and insulin resistance in pregnant rats fed a high-fat diet (HFD). Rats were divided into three groups: control group (fed base chow), HFD group, and HFD + synbiotic group. Levels of blood glucose, total cholesterol, triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), insulin, and asprosin levels were measured. Birth weight of offspring in the HFD + synbiotic group was significantly lower than in the HFD group. Similarly, serum asprosin, insulin, insulin resistance, TG and total cholesterol levels in the HFD + symbiotic group were significantly lower than in the HFD group. Asprosin levels had a significant and positive correlation between food intake in the first ten days of the experiment and gestation period, fasting blood sugar (FBS), TG, and homeostatic model assessment (HOMA) index. Moreover, asprosin levels had a significant and negative correlation with HDL and insulin levels. Results showed, synbiotic supplementation has beneficial effects on obese animals and improves weight gain during pregnancy, pup birth weight, FBS, insulin resistance and lipid profile. These advantages of synbiotic supplementation could be mediated by reducing serum asprosin levels.

Moderate aerobic exercise, but not dietary prebiotic fibre, attenuates losses to mechanical property integrity of tail tendons in a rat model of diet-induced obesity

The purpose of this study was to investigate the alterations with obesity, and the effects of moderate aerobic exercise or prebiotic dietary-fibre supplementation on the mechanical and biochemical properties of the tail tendon in a rat model of high-fat/high-sucrose (HFS) diet-induced obesity. Thirty-two male Sprague-Dawley rats were randomized to chow (n = 8) or HFS (n = 24) diets. After 12-weeks, the HFS fed rats were further randomized into sedentary (HFS sedentary, n = 8), exercise (HFS + E, n = 8) or prebiotic fibre supplementation (HFS + F, n = 8) groups. After another 12-weeks, rats were sacrificed, and one tail tendon was isolated and tested. Stress-relaxation and stretch-to-failure tests were performed to determine mechanical properties (peak, steady-state, yield and failure stresses, Young's modulus, and yield and failure strains) of the tendons. The hydroxyproline content was also analyzed. The HFS sedentary and HFS + F groups had higher final body masses and fat percentages compared to the chow and HFS + E groups. Yield strain was reduced in the HFS sedentary rats compared to the chow rats. Peak and steady-state stresses, failure strain, Young's modulus, and hydroxyproline content were not different across groups. Although the HFS + E group showed higher failure stress, yield stress, and yield strain compared to the HFS sedentary group, HFS + F animals did not produce differences in the properties of the tail tendon compared to the HFS sedentary group. These results indicate that exposure to a HFS diet led to a reduction in the yield strain of the tail tendon and aerobic exercise, but not fibre supplementation, attenuated these diet-related alterations to tendon integrity.

Therapeutic Potential of Various Plant-Based Fibers to Improve Energy Homeostasis via the Gut Microbiota

Obesity is due in part to increased consumption of a Western diet that is low in dietary fiber. Conversely, an increase in fiber supplementation to a diet can have various beneficial effects on metabolic homeostasis including weight loss and reduced adiposity. Fibers are extremely diverse in source and composition, such as high-amylose maize, β-glucan, wheat fiber, pectin, inulin-type fructans, and soluble corn fiber. Despite the heterogeneity of dietary fiber, most have been shown to play a role in alleviating obesity-related health issues, mainly by targeting and utilizing the properties of the gut microbiome. Reductions in body weight, adiposity, food intake, and markers of inflammation have all been reported with the consumption of various fibers, making them a promising treatment option for the obesity epidemic. This review will highlight the current findings on different plant-based fibers as a therapeutic dietary supplement to improve energy homeostasis via mechanisms of gut microbiota.

Gut Microbiome Composition and Metabolic Status Are Differently Affected by Early Exposure to Unhealthy Diets in a Rat Model

Childhood is a critical stage of development during which diet can have profound influence on the microbiota–host interactions, leading to potentially lifelong impacts. This study aimed to investigate whether the consumption of cafeteria diet (CAFD) and sugary drinks during early rat life alters the structure of the gut microbial community and the metabolic activity. Four-week-old male Wistar rats (n = 27) were fed a standard chow diet with ad libitum access to water (CD) or to sucrose solution (HSD), and a third group was fed with CAFD and a sucrose solution for 14 weeks. HSD and CAFD consumption induced alterations in Firmicutes to Bacteroidetes ratio, Proteobacteria, and Verrucomicrobia. HSD increased the abundance of Barnesiella, whereas CAFD induced a depletion of Saccharibacteria. CAFD increased total white adipose tissue (WAT) weight (p < 0.0005) compared to CD. When CAFD was compared to HSD, a significant difference was found only for retroperitoneal WAT (p < 0.0005). Unhealthy diet-fed groups presented higher glucose (p < 0.0005), total cholesterol and creatinine serum levels (p < 0.005) compared to the CD rats. Early-life consumption of HSD, and of CAFD even more so, can have long-lasting negative effects on metabolic function. The gut microbiota communities were distinctively perturbed by diet composition.

Maternal Microbiota Transfer Programs Offspring Eating Behavior

Understanding the link between mother's obesity and regulation of the child's appetite is a prerequisite for the design of successful preventive strategies. Beyond the possible contributions of genetic heritage, family culture, and hormonal and metabolic environment during pregnancy, we investigate in the present paper the causal role of the transmission of the maternal microbiotas in obesity as microbiotas differ between lean and obese mothers, maternal microbiotas are the main determinants of a baby's gut colonization, and the intestinal microbiota resulting from the early colonization could impact the feeding behavior of the offspring with short- and long-term consequences on body weight. We thus investigated the potential role of vertical transfers of maternal microbiotas in programming the eating behavior of the offspring. Selectively bred obese-prone (OP)/obese-resistant (OR) Sprague-Dawley dams were used since differences in the cecal microbiota have been evidenced from males of that strain. Microbiota collected from vagina (at the end of gestation), feces, and milk (at postnatal days 1, 5, 10, and 15) of OP/OR dams were orally inoculated to conventional Fischer F344 recipient pups from birth to 15 days of age to create three groups of pups: F-OP, F-OR, and F-Sham group (that received the vehicle). We first checked microbiotal differences between inoculas. We then assessed the impact of transfer (from birth to adulthood) onto the intestinal microbiota of recipients rats, their growth, and their eating behavior by measuring their caloric intake, their anticipatory food reward responses, their preference for sweet and fat tastes in solutions, and the sensations that extend after food ingestion. Finally, we searched for correlation between microbiota composition and food intake parameters. We found that maternal transfer of microbiota differing in composition led to alterations in pups' gut microbiota composition that did not last until adulthood but were associated with specific eating behavior characteristics that were predisposing F-OP rats to higher risk of over consuming at subsequent periods of their life. These findings support the view that neonatal gut microbiotal transfer can program eating behavior, even without a significant long-lasting impact on adulthood microbiota composition.

The microbiota-gut-brain axis: A novel nutritional therapeutic target for growth retardation

Growth retardation (GR), which commonly occurs in childhood, is a major health concern globally. However, the specific mechanism remains unclear. It has been increasingly recognized that changes in the gut microbiota may lead to GR through affecting the microbiota-gut-brain axis. Microbiota interacts with multiple factors such as birth to affect the growth of individuals. Microbiota communicates with the nerve system through chemical signaling (direct entry into the circulation system or stimulation of enteroendocrine cells) and nervous signaling (interaction with enteric nerve system and vagus nerve), which modulates appetite and immune response. Besides, they may also influence the function of enteric glial cells or lymphocytes and levels of systemic inflammatory cytokines. Environmental stress may cause leaky gut through perturbing the hypothalamic-pituitary-adrenal axis to further result in GR. Nutritional therapies involving probiotics and pre-/postbiotics are being investigated for helping the patients to overcome GR. In this review, we summarize the role of microbiota in GR with human and animal models. Then, existing and potential regulatory mechanisms are reviewed, especially the effect of microbiota-gut-brain axis. Finally, we propose nutritional therapeutic strategies for GR by the intervention of microbiota-gut-brain axis, which may provide novel perspectives for the treatment of GR in humans and animals.

Polylactose Exhibits Prebiotic Activity and Reduces Adiposity and Nonalcoholic Fatty Liver Disease in Rats Fed a High-Fat Diet

BACKGROUND

Prebiotic dietary fibers change the intestinal microbiome favorably and provide a health benefit to the host.

OBJECTIVES

Polylactose is a novel fiber, synthesized by extrusion of lactose. We evaluated its prebiotic activity by determining its fermentability, effect on the microbiota, and effects on adiposity and liver lipids in a diet-induced obesity animal model.

METHODS

Male Wistar rats (4-5 wk old) were fed normal-fat (NF, 25% fat energy) or high-fat (HF, 51% fat energy) diets containing different fibers (6% fiber of interest and 3% cellulose, by weight), including cellulose (NFC and HFC, negative and positive controls, respectively), polylactose (HFPL), lactose matched to residual lactose in the HFPL diet, and 2 established prebiotic fibers: polydextrose (HFPD) and fructooligosaccharide (HFFOS). After 10 wk of feeding, organs were harvested and cecal contents collected.

RESULTS

HFPL animals had greater cecum weight (3 times greater than HFC) and lower cecal pH (∼1 pH unit lower than HFC) than all other groups, suggesting that polylactose is more fermentable than other prebiotic fibers (HFPD, HFFOS; P < 0.05). HFPL animals also had increased taxonomic abundance of the probiotic species Bifidobacterium in the cecum relative to all other groups (P < 0.05). Epididymal fat pad weight was significantly decreased in the HFPL group (29% decrease compared with HFC) compared with all other HF groups (P < 0.05) and did not differ from the NFC group. Liver lipids and cholesterol were reduced in HFPL animals when compared with HFC animals (P < 0.05).

CONCLUSIONS

Polylactose is a fermentable fiber that elicits a beneficial change in the gut microbiota as well as reducing adiposity in rats fed HF diets. These effects of polylactose were greater than those of 2 established prebiotics, fructooligosaccharide and polydextrose, suggesting that polylactose is a potent prebiotic.

Effects of microbiome changes on endocrine ghrelin signaling - A systematic review

The 28-amino acid peptide hormone ghrelin plays a unique role in the gut-brain axis: It is mainly produced peripherally in gastric X/A-like cells but stimulates food intake centrally via hypothalamic nuclei; thus, providing orexigenic communication between the gut and central food intake-regulatory centers. Another component of the gut-brain axis that gained increasing interest in recent years due to its ability to influence central signaling via metabolites is the gut microbiome. Interestingly, there is increasing evidence that changes in the microbiome are related to alterations in ghrelin expression, secretion, activation and signaling. Since ghrelin is supposedly implicated in the pathogenesis of obesity, changes in the microbiome were hypothesized to improve obesity via modulation of ghrelin abundance and receptor interaction. To shed more light on the association between the microbiome and ghrelin a systematic search of Medline, EMBASE and Web of science using the search term combination "microbiome AND ghrelin" was performed. As a result of the search, 42 publications were included into this systematic review, of which 30 publications reported preclinical and 12 manuscripts presented clinical data. In addition to a critical analysis of the present data, gaps in knowledge were highlighted in order to foster further research.

Osteopenic effects of high-fat diet-induced obesity on mechanically induced alveolar bone remodeling

OBJECTIVES

The aim of the study was to investigate the effect of obesity on the tissue and molecular reactions of alveolar bone in response to orthodontic force and its underlying mechanisms.

METHODS

Sixty-four rats were randomly divided into normal diet (ND) and high-fat diet (HFD) groups for eight weeks of dietary treatment. OTM was induced using nickel-titanium springs between the upper left first molar and incisor. After 1, 3, 7, and 14 days of OTM, the maxillary alveolar bone and gingival tissues were harvested and analyzed.

RESULTS

Compared with the ND rats, the HFD rats had greater OTM distance, serum levels of tartrate-resistant acid phosphatase (TRAP), and tumor necrosis factor α (TNF-α), as well as significant alveolar bone loss and bone architecture deterioration on both the compression and tension sides (p < .05 for all). This response was linked to the increased osteoclast numbers and functional activity and decreased osteoblast activity in the periodontal ligament, gingival tissue, and alveolar bone.

CONCLUSIONS

HFD-induced obesity promoted mechanically induced alveolar bone remodeling and detrimental changes in alveolar bone microstructure by increasing osteoclastogenesis and regulating inflammatory cytokine expression. The increased alveolar bone remodeling in the obese rats lead to an accelerated OTM.

Impaired Hypothalamic Microglial Activation in Offspring of Antibiotic-Treated Pregnant/Lactating Rats Is Attenuated by Prebiotic Oligofructose Co-Administration

Microbial colonization of the gut early in life is crucial for the development of the immune and nervous systems, as well as influencing metabolism and weight gain. While early life exposure to antibiotics can cause microbial dysbiosis, prebiotics are non-digestible substrates that selectively promote the growth of beneficial gut microbiota. Our objective was to examine the effects of dietary prebiotic administration on the consequences of maternal antibiotic intake on offspring body weight, behavior, and neuroimmune responses later in life. Sprague-Dawley rat dams were given low-dose penicillin (LDP), prebiotic fiber (10% oligofructose), or both, during the third week of pregnancy and throughout lactation. Anxiety-like behavior, weight gain, body composition, cecal microbiota composition, and microglial responses to lipopolysaccharide (LPS) were assessed in offspring. Male and female prebiotic offspring had lower body weight compared to antibiotic offspring. Maternal antibiotic exposure resulted in lasting effects on select offspring microbiota including a lower relative abundance of Streptococcus, Lactococcus, and Eubacterium at 10 weeks of age. Maternal antibiotic use impaired microglial response to LPS in the hypothalamus compared to control, and this phenotype was reversed with prebiotic. Prebiotic fiber warrants further investigation as an adjunct to antibiotic use during pregnancy.

Effects of Nondigestible Oligosaccharides on Obesity

Obesity is a major public health concern that has almost reached the level of pandemic and is rapidly progressing. The gut microbiota has emerged as a crucial regulator involved in the etiology of obesity, and the manipulation of it by dietary intervention has been widely used for reducing the risk of obesity. Nondigestible oligosaccharides (NDOs) are attracting increasing interests as prebiotics, as the indigestible ingredients can induce compositional or metabolic improvement to the gut microbiota, thereby improving gut health and giving rise to the production of short-chain fatty acids (SCFAs) to elicit metabolic effects on obesity. In this review, the role NDOs play in obesity intervention via modification of the gut microecology, as well as the physicochemical and physiological properties and industrial manufacture of NDOs, is discussed. Our goal is to provide a critical assessment of and stimulate comprehensive research into NDO use in obesity.

Diet change affects intestinal microbiota restoration and improves vertical sleeve gastrectomy outcome in diet-induced obese rats

Purpose

Obesity, a worldwide health problem, is linked to an abnormal gut microbiota and is currently most effectively treated by bariatric surgery. Our aim was to characterize the microbiota of high-fat fed Sprague–Dawley rats when subjected to bariatric surgery (i.e., vertical sleeve gastrectomy) and posterior refeeding with either a high-fat or control diet. We hypothesized that bariatric surgery followed by the control diet was more effective in reverting the microbiota modifications caused by the high-fat diet when compared to either of the two factors alone.

Methods

Using next-generation sequencing of ribosomal RNA amplicons, we analyzed and compared the composition of the cecal microbiota after vertical sleeve gastrectomy with control groups representing non-operated rats, control fed, high-fat fed, and post-operative diet-switched animals. Rats were fed either a high-fat or control low-fat diet and were separated into three comparison groups after eight weeks comprising no surgery, sham surgery, and vertical sleeve gastrectomy. Half of the rats were then moved from the HFD to the control diet. Using next-generation sequencing of ribosomal RNA amplicons, we analyzed the composition of the cecal microbiota of rats allocated to the vertical sleeve gastrectomy group and compared it to that of the non-surgical, control fed, high-fat fed, and post-operative diet-switched groups. Additionally, we correlated different biological parameters with the genera exhibiting the highest variation in abundance between the groups.

Results

The high-fat diet was the strongest driver of altered taxonomic composition, relative microbial abundance, and diversity in the cecum. These effects were partially reversed in the diet-switched cohort, especially when combined with sleeve gastrectomy, resulting in increased diversity and shifting relative abundances. Several highly-affected genera were correlated with obesity-related parameters.

Conclusions

The dysbiotic state caused by high-fat diet was improved by the change to the lower fat, higher fiber control diet. Bariatric surgery contributed significantly and additively to the diet in restoring microbiome diversity and complexity. These results highlight the importance of dietary intervention following bariatric surgery for improved restoration of cecal diversity, as neither surgery nor change of diet alone had the same effects as when combined.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02190-8) contains supplementary material, which is available to authorized users.

Role of Dietary Nutrients in the Modulation of Gut Microbiota: A Narrative Review

Understanding how dietary nutrients modulate the gut microbiome is of great interest for the development of food products and eating patterns for combatting the global burden of non-communicable diseases. In this narrative review we assess scientific studies published from 2005 to 2019 that evaluated the effect of micro- and macro-nutrients on the composition of the gut microbiome using in vitro and in vivo models, and human clinical trials. The clinical evidence for micronutrients is less clear and generally lacking. However, preclinical evidence suggests that red wine- and tea-derived polyphenols and vitamin D can modulate potentially beneficial bacteria. Current research shows consistent clinical evidence that dietary fibers, including arabinoxylans, galacto-oligosaccharides, inulin, and oligofructose, promote a range of beneficial bacteria and suppress potentially detrimental species. The preclinical evidence suggests that both the quantity and type of fat modulate both beneficial and potentially detrimental microbes, as well as the Firmicutes/Bacteroides ratio in the gut. Clinical and preclinical studies suggest that the type and amount of proteins in the diet has substantial and differential effects on the gut microbiota. Further clinical investigation of the effect of micronutrients and macronutrients on the microbiome and metabolome is warranted, along with understanding how this influences host health.

Effect of Diet on the Gut Microbiota Associated with Obesity

Obesity is abnormal or excessive fat accumulation that is associated with progression of metabolic diseases including type 2 diabetes mellitus, cardiovascular disease, nonalcoholic fatty liver disease, and cancer. Gut microbiota (GM) have received much attention as essential factors in development and progression of obesity. The diversity, composition, and metabolic activity of GM are closely associated with nutrient intake and dietary pattern. Scientific evidence supports the idea that dietary pattern directly changes the GM profile; therefore, diet is a crucial component related to interactions between GM and obesity progression. A literature review showed that dietary factors such as probiotics, prebiotics, fat, fatty acids, and fiber dramatically alter the GM profile related to obesity. Furthermore, different dietary patterns result in different GM composition and activity that can contribute to amelioration of obesity.

The mechanical and biochemical properties of tail tendon in a rat model of obesity: Effect of moderate exercise and prebiotic fibre supplementation

The worldwide trajectory of increasing obesity rates is a major health problem precipitating a rise in the prevalence of a variety of co-morbidities and chronic diseases. Tendinopathy, in weight and non-weight bearing tendons, in individuals with overweight or obesity has been linked to metabolic dysfunction resulting from obesity. Exercise and dietary fibre supplementation (DFS) are common countermeasures to combat obesity and therefore it seems reasonable to assume that they might protect tendons from structural and mechanical damage in a diet-induced obesity (DIO) model. The purpose of this study was to determine the effects of a DIO, DIO combined with moderate exercise, DIO combined with DFS (prebiotic oligofructose), and DIO combined with moderate exercise and DFS on the mechanical and biochemical properties of the rat tail tendon. Twenty-four male Sprague-Dawley rats, fed a high-fat/high-sucrose diet were randomized into a sedentary, a moderate exercise, a DFS, or a moderate exercise combined with DFS group for 12 weeks. Additionally, six lean age-matched animals were included as a sedentary control group. DIO in combination with exercise alone and with exercise and DFS reduced the Young's Modulus but not the collagen content of the rat tail tendons compared to lean control animals. However, no differences in the mechanical and biochemical properties of the rat tail tendon were detected between the DIO and the lean control group, suggesting that DIO by itself did not impact the tail tendon. It seems that longer DIO exposure periods may be needed to develop overt differences in our DIO model.

The heart-gut axis: new target for atherosclerosis and congestive heart failure therapy

The human gut microbiota has been identified as a possible novel risk factor for cardiovascular disease. The intestinal microbiome plays a role in the pathogenesis of atherosclerosis and heart failure. Even though studies in rodents suggested that gut microbes may affect the risk of heart disease, this link has not been shown in humans. In the present study, we review several potential mechanisms by which the gut microbiome and bacterial translocation are associated with the development of cardiac disorders making them potential targets for novel therapeutic measures for these conditions. Modulation of the gut microbiota as a mechanism for altering the pathogenesis of disorders is an area of growing interest. Alteration in the gut microbiota is being explored as a method of reducing risk factors associated with cardiac diseases.

Protective effect of prebiotic and exercise intervention on knee health in a rat model of diet-induced obesity

Obesity, and associated metabolic syndrome, have been identified as primary risk factors for the development of knee osteoarthritis (OA), representing nearly 60% of the OA patient population. In this study, we sought to determine the effects of prebiotic fibre supplementation, aerobic exercise, and the combination of the two interventions, on the development of metabolic knee osteoarthritis in a high-fat/high-sucrose (HFS) diet-induced rat model of obesity. Twelve-week-old male Sprague-Dawley rats were randomized into five groups: a non-exercising control group fed a standard chow diet, a non-exercising group fed a HFS diet, a non-exercising group fed a HFS diet combined with prebiotic fibre supplement, an exercise group fed a HFS diet, and an exercise group fed a HFS diet combined with prebiotic fibre supplement. Outcome measures included knee joint damage, percent body fat, insulin sensitivity, serum lipid profile, serum endotoxin, serum and synovial fluid cytokines and adipokines, and cecal microbiota. Prebiotic fibre supplementation, aerobic exercise, and the combination of the two interventions completely prevented knee joint damage that is otherwise observed in this rat model of obesity. Prevention of knee damage was associated with a normalization of insulin resistance, leptin levels, dyslipidemia, gut microbiota, and endotoxemia in the HFS-fed rats.

Consumption of Chlorogenic Acids through Coffee and Health Implications

Chlorogenic acids (CGA) are the main antioxidant compounds in the Western diet, due to their high concentrations in coffee associated with the high consumption of the beverage. Until about 10 years ago, like many other phenolic compounds, CGA were thought to be poorly absorbed in the human digestive system. Along the years, large amounts of information on the absorption and metabolism of these compounds have been unveiled, and today, it is known that, on average, about one third of the consumed CGA from coffee is absorbed in the human gastrointestinal tract, although large inter-individual variation exists. Considering results from in vitro animal and human studies, it is possible to conclude that the antioxidant and anti-inflammatory effects of coffee CGA are responsible for, at least to a certain extent, the association between coffee consumption and lower incidence of various degenerative and non-degenerative diseases, in addition to higher longevity.

Intestinal Sensing by Gut Microbiota: Targeting Gut Peptides

There are more than 2 billion overweight and obese individuals worldwide, surpassing for the first time, the number of people affected by undernutrition. Obesity and its comorbidities inflict a heavy burden on the global economies and have become a serious threat to individuals' wellbeing with no immediate cure available. The causes of obesity are manifold, involving several factors including physiological, metabolic, neural, psychosocial, economic, genetics and the environment, among others. Recent advances in genome sequencing and metagenomic profiling have added another dimension to this complexity by implicating the gut microbiota as an important player in energy regulation and the development of obesity. As such, accumulating evidence demonstrate the impact of the gut microbiota on body weight, adiposity, glucose, lipid metabolism, and metabolic syndrome. This also includes the role of microbiota as a modulatory signal either directly or through its bioactive metabolites on intestinal lumen by releasing chemosensing factors known to have a major role in controlling food intake and regulating body weight. The importance of gut signaling by microbiota signaling is further highlighted by the presence of taste and nutrient receptors on the intestinal epithelium activated by the microbial degradation products as well as their role in release of peptides hormones controlling appetite and energy homeostasis. This review present evidence on how gut microbiota interacts with intestinal chemosensing and modulates the release and activity of gut peptides, particularly GLP-1 and PYY.

A mix of dietary fermentable fibers improves lipids handling by the liver of overfed minipigs

Obesity induced by overfeeding ultimately can lead to nonalcoholic fatty liver disease, whereas dietary fiber consumption is known to have a beneficial effect. We aimed to determine if a supplementation of a mix of fibers (inulin, resistant starch and pectin) could limit or alleviate overfeeding-induced metabolic perturbations. Twenty female minipigs were fed with a control diet (C) or an enriched fat/sucrose diet supplemented (O + F) or not (O) with fibers. Between 0 and 56 days of overfeeding, insulin (+88%), HOMA (+102%), cholesterol (+45%) and lactate (+63%) were increased, without any beneficial effect of fibers supplementation. However, fibers supplementation limited body weight gain (vs. O, -15% at D56) and the accumulation of hepatic lipids droplets induced by overfeeding. This could be explained by a decreased lipids transport potential (-50% FABP1 mRNA, O + F vs. O) inducing a down-regulation of regulatory elements of lipids metabolism / lipogenesis (-36% SREBP1c mRNA, O + F vs. O) but not to an increased oxidation (O + F not different from O and C for proteins and mRNA measured). Glucose metabolism was also differentially regulated by fibers supplementation, with an increased net hepatic release of glucose in the fasted state (diet × time effect, P<.05 at D56) that can be explained partially by a possible increased glycogen synthesis in the fed state (+82% GYS2 protein, O + F vs. O, P=.09). The direct role of short chain fatty acids on gluconeogenesis stimulation is questioned, with probably a short-term impact (D14) but no effect on a long-term (D56) basis.

Blueberry polyphenols extract as a potential prebiotic with anti-obesity effects on C57BL/6 J mice by modulating the gut microbiota

Polyphenols are known for their various health benefits. Blueberries are dietary sources of polyphenols with reported health benefits. However, the role of blueberry polyphenols in alleviating obesity is not completely understood. This study investigated the potential positive effect of blueberry polyphenol extract (PPE) on high-fat diet (HFD)-induced obesity in C57BL/6 J mice by modulation of the gut microbiota. Four-week-old C57BL/6 J mice were fed a normal-fat diet or HFD with or without PPE or Orlistat for 12 weeks. Mice fed HFD exhibited increased body weight and adipose tissue weight and disordered lipid metabolism. In contrast, PPE inhibited body weight gain and returned lipid metabolism to normal. Furthermore, 16S rRNA gene sequencing of the fecal microbiota suggested that PPE changed the composition of the gut microbiota in C57BL/6 J mice and modulated specific bacteria such as Proteobacteria, Deferribacteres, Actinobacteria, Bifidobacterium, Desulfovibrio, Adlercreutzia, Helicobacter, Flexispira, and Prevotella. Orlistat also improved obesity and metabolic alterations of HFD mice and modulated the composition of the gut microbiota. Our findings suggest that PPE, as a potential prebiotic agent, influences the gut microbiota to positively affect HFD-induced obesity in C57BL/6 J mice.

Prebiotic prevents impaired kidney and renal Oat3 functions in obese rats

Obesity is health issue worldwide, which can lead to kidney dysfunction. Prebiotics are non-digestible foods that have beneficial effects on health. This study aimed to investigate the effects of xylooligosaccharide (XOS) on renal function, renal organic anion transporter 3 (Oat3) and the mechanisms involved. High-fat diet was provided for 12 weeks in male Wistar rats. After that, the rats were divided into normal diet (ND); normal diet treated with XOS (NDX); high-fat diet (HF) and high-fat diet treated with XOS (HFX). XOS was given daily at a dose of 1000 mg for 12 weeks. At week 24, HF rats showed a significant increase in obesity and insulin resistance associated with podocyte injury, increased microalbuminuria, decreased creatinine clearance and impaired Oat3 function. These alterations were improved by XOS supplementation. Renal MDA level and the expression of AT1R, NOX4, p67^phox, 4-HNE, phosphorylated PKCα and ERK1/2 were significantly decreased after XOS treatment. In addition, Nrf2-Keap1 pathway, SOD2 and GCLC expression as well as renal apoptosis were also significantly reduced by XOS. These data suggest that XOS could indirectly restore renal function and Oat3 function via the reduction of oxidative stress and apoptosis through the modulating of AT1R-PKCα-NOXs activation in obese insulin-resistant rats. These attenuations were instigated by the improvement of obesity, hyperlipidemia and insulin resistance.

Anxiety, Depression, and the Microbiome: A Role for Gut Peptides

The complex bidirectional communication between the gut and the brain is finely orchestrated by different systems, including the endocrine, immune, autonomic, and enteric nervous systems. Moreover, increasing evidence supports the role of the microbiome and microbiota-derived molecules in regulating such interactions; however, the mechanisms underpinning such effects are only beginning to be resolved. Microbiota-gut peptide interactions are poised to be of great significance in the regulation of gut-brain signaling. Given the emerging role of the gut-brain axis in a variety of brain disorders, such as anxiety and depression, it is important to understand the contribution of bidirectional interactions between peptide hormones released from the gut and intestinal bacteria in the context of this axis. Indeed, the gastrointestinal tract is the largest endocrine organ in mammals, secreting dozens of different signaling molecules, including peptides. Gut peptides in the systemic circulation can bind cognate receptors on immune cells and vagus nerve terminals thereby enabling indirect gut-brain communication. Gut peptide concentrations are not only modulated by enteric microbiota signals, but also vary according to the composition of the intestinal microbiota. In this review, we will discuss the gut microbiota as a regulator of anxiety and depression, and explore the role of gut-derived peptides as signaling molecules in microbiome-gut-brain communication. Here, we summarize the potential interactions of the microbiota with gut hormones and endocrine peptides, including neuropeptide Y, peptide YY, pancreatic polypeptide, cholecystokinin, glucagon-like peptide, corticotropin-releasing factor, oxytocin, and ghrelin in microbiome-to-brain signaling. Together, gut peptides are important regulators of microbiota-gut-brain signaling in health and stress-related psychiatric illnesses.

Microbial Mechanistic Insight into the Role of Inulin in Improving Maternal Health in a Pregnant Sow Model

General consumption of “western diet” characterized by high refined carbohydrates, fat and energy intake has resulted in a global obesity epidemics and related metabolic disturbance even for pregnant women. Pregnancy process is accompanied by substantial hormonal, metabolic and immunological changes during which gut microbiota is also remarkably remodeled. Dietary fiber has been demonstrated to have a striking role in shifting the microbial composition so as to improve host metabolism and health in non-pregnant individuals. The present study was conducted to investigate effects of adding a soluble dietary fiber inulin (0 or 1.5%) to low- or high- fat (0 or 5% fat addition) gestational diet on maternal and neonatal health and fecal microbial composition in a sow model. Results showed that inulin addition decreased the gestational body weight gain and fat accumulation induced by fat addition. Circulating concentrations of pro-inflammatory cytokine IL-6, adipokine leptin and chemerin were decreased by inulin supplementation. Inulin addition remarkably reduced the average BMI of newborn piglets and the within litter BMI distributions (%) ranging between 17 and 20 kg/m², and increased the BMI distribution ranging between 14 and 17 kg/m². 16S rRNA gene sequencing of the V3-V4 region showed that fecal microbial changes at different taxonomic levels triggered by inulin addition predisposed the pregnant sow to be thinner and lower inflammatory. Meanwhile, fecal microbial composition was also profoundly altered by gestation stage with distinct changes occurring at perinatal period. Most representative volatile fatty acid (VFA) producing-related genera changed dramatically when reaching the perinatal period and varied degrees of increases were detected with inulin addition. Fecal VFA concentrations failed to show any significant effect with dietary intervention, however, were markedly increased at perinatal period. Our findings indicate that positive microbial changes resulted by 1.5% soluble fiber inulin addition would possibly be the potential mechanisms under which maternal body weight, metabolic and inflammatory status and neonatal BMI were improved. Besides, distinct changes of microbial community at perinatal period indicated the mother sow is undergoing a catabolic state with increased energy loss and inflammation response at that period compared with other stages of gestation.

Chronic treatment with prebiotics, probiotics and synbiotics attenuated cardiac dysfunction by improving cardiac mitochondrial dysfunction in male obese insulin-resistant rats

PURPOSE

In metabolic syndrome, the composition of gut microbiota has been disrupted, and is associated with left ventricular (LV) dysfunction. Several types of prebiotics, probiotics, and synbiotics have been shown to exert cardioprotection by restoring gut microbiota from dysbiosis and reducing systemic inflammation. However, the effects of prebiotics such as xylooligosaccharides (XOS); probiotics such as Lactobacillus paracasei STII01 HP4, and synbiotics on metabolic and LV function in obese insulin-resistant rats have not been investigated. In this study, we hypothesized that prebiotics and probiotics improve metabolic parameters, heart rate variability (HRV), blood pressure (BP), and LV function by attenuating cardiac mitochondrial dysfunction, systemic inflammation, and oxidative stress, and that synbiotics provide greater efficacy than a single regimen in obese insulin resistance.

METHODS

Rats were fed with either normal diet or high-fat diet (HFD) for 12 weeks and then rats in each dietary group were randomly subdivided into four subgroups to receive either a vehicle, prebiotics, probiotics, or synbiotics for another 12 weeks. Metabolic parameters, BP, HRV, LV function, cardiac mitochondrial function, systemic inflammation, and oxidative stress were determined.

RESULTS

HFD-fed rats had obese insulin resistance with markedly increased systemic inflammatory marker [Serum LPS; ND; 0.6 ± 0.1 EU/ml vs. HFD; 5.7 ± 1.2 EU/ml (p < 0.05)], depressed HRV, and increased BP and LV dysfunction [%ejection fraction; ND; 93 ± 2% vs. HFD; 83 ± 2% (p < 0.05)]. Prebiotics, probiotics, and synbiotics attenuated insulin resistance by improving insulin sensitivity and lipid profiles. All interventions also improved HRV, BP, LV function [%ejection fraction; HFV; 81 ± 2% vs. HFPE; 93 ± 3%, HFPO; 92 ± 1%, HFC; 92 ± 2% (p < 0.05)] by attenuating mitochondrial dysfunction, oxidative stress, and systemic inflammation in obese insulin-resistant rats.

CONCLUSION

Prebiotics, probiotics, and synbiotics shared similar efficacy in reducing insulin resistance and LV dysfunction in obese insulin-resistant rats.

Resistant maltodextrin or fructooligosaccharides promotes GLP-1 production in male rats fed a high-fat and high-sucrose diet, and partially reduces energy intake and adiposity

PURPOSE

Increasing secretion and production of glucagon-like peptide-1 (GLP-1) by continuous ingestion of certain food components has been expected to prevent glucose intolerance and obesity. In this study, we examined whether a physiological dose (5% weight in diet) of digestion-resistant maltodextrin (RMD) has a GLP-1-promoting effect in rats fed a high-fat and high-sucrose (HFS) diet.

METHODS

Rats were fed a control diet or the HFS (30% fat, 40% sucrose wt/wt) diet supplemented with 5% RMD or fructooligosaccharides (FOS) for 8 weeks or for 8 days in separated experiments. Glucose tolerance, energy intake, plasma and tissue GLP-1 concentrations, and cecal short-chain fatty acids concentrations were assessed.

RESULTS

After 4 weeks of feeding, HFS-fed rats had significantly higher glycemic response to oral glucose than control rats, but rats fed HFS + RMD/FOS did not (approx. 50% reduction vs HFS rats). HFS + RMD/FOS-fed rats had higher GLP-1 responses (~twofold) to oral glucose, than control rats. After 8 weeks, visceral adipose tissue weight was significantly higher in HFS-fed rats than control rats, while HFS + RMD/FOS rats had a trend of reduced gain (~50%) of the tissue weight. GLP-1 contents and luminal propionate concentrations in the large intestine increased (>twofold) by adding RMD/FOS to HFS. Eight days feeding of RMD/FOS-supplemented diets reduced energy intake (~10%) and enhanced cecal GLP-1 production (~twofold), compared to HFS diet.

CONCLUSIONS

The physiological dose of a prebiotic fiber promptly (within 8 days) promotes GLP-1 production in rats fed an obesogenic diet, which would help to prevent excess energy intake and fat accumulation.

Impacts of resistant starch and wheat bran consumption on enteric inflammation in relation to colonic bacterial community structures and short-chain fatty acid concentrations in mice

Background

Identifying the connection among diet, the intestinal microbiome, and host health is currently an area of intensive research, but the potential of dietary fiber (DF) consumption to ameliorate intestinal inflammation has not been extensively studied. We examined the impacts of the DFs, wheat bran (WB) and resistant starch (RS) on host enteric health. A murine model of acute Th1/Th17 colitis (i.e. incited by Citrobacter rodentium) was used.

Results

Diets enriched with RS increased weight gain in mice inoculated with C. rodentium compared to mice consuming a conventional control (CN) diet. Short-chain fatty acid (SCFA) quantities in the cecum and distal colon were higher in mice consuming DFs, and these mice exhibited higher butyrate concentrations in the distal colon during inflammation. Histopathologic scores of inflammation in the proximal colon on day 14 post-inoculation (p.i.) (peak infection) and 21 p.i. (late infection) were lower in mice consuming DF-enriched diets compared to the CN diet. Consumption of WB reduced the expression of Th1/Th17 cytokines. As well, the expression of bacterial recognition and response genes such as Relmβ, RegIIIγ, and Tlr4 increased in mice consuming the RS-enriched diets. Furthermore, each diet generated a region-specific bacterial community, suggesting a link between selection for specific bacterial communities, SCFA concentrations, and inflammation in the murine colon.

Conclusions

Collectively, data indicated that the consumption of DF-rich diets ameliorates the effects of C. rodentium-induced enteritis by modifying the host microbiota to increase SCFA production, and bacterial recognition and response mechanisms to promote host health.

Electronic supplementary material

The online version of this article (doi:10.1186/s13099-016-0149-6) contains supplementary material, which is available to authorized users.

The Sweetener-Sensing Mechanisms of the Ghrelin Cell

Carbohydrate administration decreases plasma levels of the 'hunger hormone' ghrelin. The ghrelin cell is co-localized with the sweet taste receptor subunit, TAS1R3, and the gustatory G-protein, gustducin, both involved in the sensing of sweeteners by entero-endocrine cells. This study investigated the role of gustducin-mediated sweet taste receptor signaling on ghrelin secretion in a gastric ghrelinoma cell line, tissue segments and mice. The monosaccharide d-glucose and low-intensity sweetener oligofructose (OFS) decreased (p < 0.001) ghrelin secretion while the high-intensity sweetener sucralose increased (p < 0.001) ghrelin secretion in vitro. These effects were not mediated via the sweet taste receptor or glucose transporters (the sodium-dependent glucose cotransporter SGLT-1 and GLUT2). The effect of these compounds was mimicked ex vivo in gastric and jejunal segments from both wild type (WT) and α-gustducin knockout (α-gust-/-) mice. In vivo, the sensing of d-glucose was polarized since intragastric but not intravenous administration of d-glucose decreased (p < 0.05) ghrelin levels in an α-gustducin independent manner which involved inhibition of duodenal ghrelin release. In contrast, neither OFS nor sucralose affected ghrelin secretion in vivo. In conclusion, α-gustducin-mediated sweet taste receptor signaling does not play a functional role in the sensing of carbohydrates, or low- or high-intensity sweeteners by the ghrelin cell.

Supplementation of oligofructose, but not sucralose, decreases high-fat diet induced body weight gain in mice independent of gustducin-mediated gut hormone release

SCOPE

Enteroendocrine cells sense nutrients through taste receptors similar to those on the tongue. Sweet and fatty acid taste receptors (FFAR) coupled to the gustatory G-protein, gustducin, on enteroendocrine cells play a role in gut hormone release. We studied if supplementation of artificial (sucralose) or prebiotic (oligofructose; OFS) sweeteners target gustducin-mediated signaling pathways to alter gut hormone release and reduce obesity-associated disorders.

METHODS AND RESULTS

Wild-type (WT) and α-gustducin knockout (α-gust^-/- ) mice were fed a high-fat diet and gavaged once daily (8 wk) with water or equisweet concentrations of sweeteners. OFS but not sucralose decreased body weight gain (-19 ± 3%, p < 0.01), fat pad mass (-55 ± 6%, p < 0.001), and insulin resistance (-39 ± 5%, p < 0.001) independent of α-gustducin. Neither sweetener improved glucose intolerance, while solely OFS improved the disturbed colonic permeability. OFS decreased (-65 ± 8%, p < 0.001) plasma glucagon-like peptide 1 (GLP-1) but not ghrelin and peptide YY (PYY) levels in WT mice. Cecal acetate and butyrate levels were reduced by OFS in both genotypes suggesting enhanced uptake of SCFAs that may target FFAR2 (upregulated expression) in adipose tissue.

CONCLUSION

OFS, but not sucralose, reduced body weight gain and decreased intestinal permeability, but not glucose intolerance. Effects were not mediated by altered gut hormone levels or gustducin-mediated signaling. Artificial sweeteners do not affect gut hormone levels and are metabolically inert in mice on a high-fat diet. In contrast, prebiotic oligosaccharides (OFS) prevent body weight gain but not glucose intolerance. Alterations in sweet and short-chain fatty acid receptors (FFAR) (studied in WT and α-gust^-/- mice) that regulate gut hormone levels are not mandatory for the positive effects of OFS. Enhanced uptake of SCFAs may favor interaction with FFAR2/3 on adipose tissue to induce weight loss.

Diet-induced changes in maternal gut microbiota and metabolomic profiles influence programming of offspring obesity risk in rats

Maternal obesity and overnutrition during pregnancy and lactation can program an increased risk of obesity in offspring. In this context, improving maternal metabolism may help reduce the intergenerational transmission of obesity. Here we show that, in Sprague-Dawley rats, selectively altering obese maternal gut microbial composition with prebiotic treatment reduces maternal energy intake, decreases gestational weight gain, and prevents increased adiposity in dams and their offspring. Maternal serum metabolomics analysis, along with satiety hormone and gut microbiota analysis, identified maternal metabolic signatures that could be implicated in programming offspring obesity risk and highlighted the potential influence of maternal gut microbiota on maternal and offspring metabolism. In particular, the metabolomic signature of insulin resistance in obese rats normalized when dams consumed the prebiotic. In summary, prebiotic intake during pregnancy and lactation improves maternal metabolism in diet-induced obese rats in a manner that attenuates the detrimental nutritional programming of offspring associated with maternal obesity. Overall, these findings contribute to our understanding of the maternal mechanisms influencing the developmental programming of offspring obesity and provide compelling pre-clinical evidence for a potential strategy to improve maternal and offspring metabolic outcomes in human pregnancy.

Postnatal prebiotic fibre intake mitigates some detrimental metabolic outcomes of early overnutrition in rats

PURPOSE

Overnutrition during early development has been linked to metabolic disease and obesity in adulthood. Interventions to ameliorate this metabolic malprogramming are needed. Our objective was to determine whether prebiotic fibre would reduce weight gain and improve satiety hormone profiles in rats overnourished during the suckling period.

METHODS

Male Sprague-Dawley rats reared in small litter (SL 3 pups) or normal litter (NL 12 pups) were randomized at weaning to AIN-93 (control) or a 10 % oligofructose (OFS) diet for 16 weeks. Body composition, an oral glucose tolerance test for glucose and gut hormones, and gut microbiota were assessed.

RESULTS

At weaning, body weight was higher in SL than in NL rats (P < 0.03). At 19 weeks, body weight was lower with OFS than control (P < 0.04). There was a diet × litter size interaction wherein OFS in SL rats reduced body fat (%) to levels seen in NL rats (P < 0.05). OFS attenuated the glucose response in SL but not in NL rats (P < 0.015). Independent of litter size, OFS decreased total AUC for glucose-dependent insulinotropic polypeptide (P < 0.002) and increased total AUC for peptide YY (P < 0.01) and glucagon-like peptide-1 (P < 0.04) when compared to control. OFS, not litter size, played the predominant role in altering gut microbiota which included increased bifidobacteria and Akkermansia muciniphila with OFS.

CONCLUSIONS

Postnatal consumption of OFS by rats raised in SL was able to attenuate body fat and glycaemia to levels seen in NL rats. OFS appears to influence satiety hormone and gut microbiota response similarly in overnourished and control rats.

Lean rats gained more body weight from a high-fructooligosaccharide diet

Lean rats gained more body weight from a high-FOS diet and increased more gut Bacteroidetes.