An Increased Dietary Supply of Medium-Chain Fatty Acids during Early Weaning in Rodents Prevents Excessive Fat Accumulation in Adulthood

Diarrhea induced by insufficient fat absorption in weaned piglets: Causes and nutrition regulation

Fat is one of the three macronutrients and a significant energy source for piglets. It plays a positive role in maintaining intestinal health and improving production performance. During the weaning period, physiological, stress and diet-related factors influence the absorption of fat in piglets, leading to damage to the intestinal barrier, diarrhea and even death. Signaling pathways, such as fatty acid translocase (CD36), pregnane X receptor (PXR), and AMP-dependent protein kinase (AMPK), are responsible for regulating intestinal fat uptake and maintaining intestinal barrier function. Therefore, this review mainly elaborates on the reasons for diarrhea induced by insufficient fat absorption and related signaling pathways in weaned-piglets, with an emphasis on the intestinal fat absorption disorder. Moreover, we focus on introducing nutritional strategies that can promote intestinal fat absorption in piglets with insufficient fat absorption-related diarrhea, such as lipase, amino acids, and probiotics.

Novel trends and challenges in fat modification of next-generation infant formula: Considering the structure of milk fat globules to improve lipid digestion and metabolism of infants

Differences in the composition and structure of lipid droplets in infant formula (IF) and human milk (HM) can affect the fat digestion of infants, leading to high risk of metabolic diseases during later stages of growth. Recently, interest in simulating HM fat (HMF) has gradually increased due to its beneficial functions for infants. Much research focuses on the simulation of fatty acids and triacylglycerols. Enzymatic combined with new technologies such as carbodiimide coupling immobilization enzymes, solvent-free synthesis, and microbial fermentation can improve the yield of simulated HMF. Furthermore, fat modification in next-generation IF requires attention to the impact on the structure and function of milk fat globules (MFG). This review also summarizes the latest reports on MFG structure simulation, mainly related to the addition method and sequence of membrane components, and other milk processing steps. Although some of the simulated HMF technologies and products have been applied to currently commercially available IF, the cost is still high. Furthermore, understanding the fat decomposition of simulated HMF during digestion and assessing its nutritional effects on infants later in life is also a huge challenge. New process development and more clinical studies are needed to construct and evaluate simulated HMF in the future.

Tricaprylin, a medium-chain triglyceride, aggravates high-fat diet-induced fat deposition but improves intestinal health

Medium-chain triglycerides (MCTs) are absorbed and metabolized more rapidly than long-chain triglycerides (LCTs) and therefore are considered to have obesity-prevention potential in foods. The effect of adding tricaprylin, an MCT, to food on fat deposition and intestinal health is uncharted. In this study, mice were randomly divided into four groups and fed a normal diet (ND), ND with tricaprylin, a high-fat diet (HFD), or HFD with tricaprylin. Supplementation of 2% tricaprylin in HFD significantly increased the body weight, fat mass, liver weight, adipocyte size in adipose tissue and liver, and upregulated genes related to fat deposition. Metabolomic analysis of serum and adipose tissue revealed that tricaprylin significantly increased the contents of metabolites related to lipid metabolism, triglyceride storage, and fat deposition related signaling pathways. In vitro experiments and molecular docking analysis suggest that octanoic acid, a primary decomposition product of tricaprylin, may promote adipogenic differentiation of preadipocytes by acting as a PPARγ ligand to activate the expression of lipogenesis-related genes. Although supplementation with 2% tricaprylin in HFD cannot reduce fat deposition, it has a beneficial effect on intestinal health. Tricaprylin improved intestinal morphology, digestive enzyme activity, short-chain fatty acid concentration, and intestinal barrier function-related protein expression, while reducing inflammatory factor levels and the abundance of harmful intestinal microorganisms.

Dairy products and constituents: a review of their effects on obesity and related metabolic diseases

Obesity has become a global public health problem that seriously affects the quality of life. As an important part of human diet, dairy products contain a large number of nutrients that are essential for maintaining human health, such as proteins, peptides, lipids, vitamins, and minerals. A growing number of epidemiological investigations provide strong evidence on dairy interventions for weight loss in overweight/obese populations. Therefore, this paper outlines the relationship between the consumption of different dairy products and obesity and related metabolic diseases. In addition, we dive into the mechanisms related to the regulation of glucose and lipid metabolism by functional components in dairy products and the interaction with gut microbes. Lastly, the role of dairy products on obesity of children and adolescents is revisited. We conclude that whole dairy products exert more beneficial effect than single milk constituent on alleviating obesity and that dairy matrix has important implications for metabolic health.

Energy Homeostasis-Associated (Enho) mRNA Expression and Energy Homeostasis in the Acute Stress Versus Chronic Unpredictable Mild Stress Rat Models

The energy homeostasis-associated (Enho) gene, the transcript for the Adropin peptide, is usually linked to energy homeostasis, adiposity, glycemia, and insulin resistance. Studies on Enho expression in stressful conditions are lacking. This work aimed to investigate Enho mRNA expression and energy homeostasis in acute stress (AS) versus chronic unpredictable mild stress (CUMS) rat models. A total of thirty male Wistar rats (180-220 g) were fed a balanced diet with free access to water. Rats were divided into three equal groups (n = 10): (a) the normal control (NC) group; (b) the AS group, where one episode of stress for 2 h was applied; and (c) the CUMS group, in which rats were exposed to a variable program of mild stressors for 4 weeks. Energy homeostasis was analyzed by the PhenoMaster system for the automatic measuring of food intake (FI), respiratory O₂ volume (VO₂), CO₂ volume (VCO₂), respiratory quotient (RQ), and total energy expenditure (TEE). Finally, liver, whole brain, and adipose (WAT) tissue samples were collected, total RNA was prepared, and RT-PCR analysis of the Enho gene was performed. The CUMS group showed higher VO₂ consumption and VCO₂ production, and a higher RQ than the AS group. Furthermore, the TEE and FI were higher in the CUMS group compared to the AS group. Enho gene expression in the liver, brain, and WAT was significantly higher in the CUMS group than in the AS and NC groups. We can conclude that in the chew-fed AS rats, hypophagia was evident, with a shift in the RQ toward fat utilization, with no changes in body weight despite the increase in Enho mRNA expression in all studied tissues. In the CUMS group, the marked rise in Enho mRNA expression may have contributed to weight loss despite increased FI and TEE.

Galactose in the Post-Weaning Diet Programs Improved Circulating Adiponectin Concentrations and Skeletal Muscle Insulin Signaling

Short-term post-weaning nutrition can result in long-lasting effects in later life. Partial replacement of glucose by galactose in the post-weaning diet showed direct effects on liver inflammation. Here, we examined this program on body weight, body composition, and insulin sensitivity at the adult age. Three-week-old female C57BL/6JRccHsd mice were fed a diet with glucose plus galactose (GAL; 16 energy% (en%) each) or a control diet with glucose (GLU; 32 en%) for three weeks, and afterward, both groups were given the same high-fat diet (HFD). After five weeks on a HFD, an oral glucose tolerance test was performed. After nine weeks on a HFD, energy metabolism was assessed by indirect calorimetry, and fasted mice were sacrificed fifteen minutes after a glucose bolus, followed by serum and tissue analyses. Body weight and body composition were not different between the post-weaning dietary groups, during the post-weaning period, or the HFD period. Glucose tolerance and energy metabolism in adulthood were not affected by the post-weaning diet. Serum adiponectin concentrations were significantly higher (p = 0.02) in GAL mice while insulin, leptin, and insulin-like growth factor 1 concentrations were not affected. Expression of Adipoq mRNA was significantly higher in gonadal white adipose tissue (gWAT; p = 0.03), while its receptors in the liver and skeletal muscles remained unaffected. Irs2 expression was significantly lower in skeletal muscles (p = 0.01), but not in gWAT or Irs1 expression (in both tissues). Gene expressions of inflammatory markers in gWAT and the liver were also not affected. Conclusively, galactose in the post-weaning diet significantly improved circulating adiponectin concentrations and reduced skeletal muscle Irs2 expression in adulthood without alterations in fat mass, glucose tolerance, and inflammation.

Role Medium-Chain Fatty Acids in the Lipid Metabolism of Infants

Human breastmilk, the ideal food for healthy infants, naturally contains a high concentration of medium-chain fatty acids (MCFAs, about 15% of total fatty acids). MCFAs are an important energy source for infants due to their unique digestive and metabolic properties. MCFA-enriched oils are widely used in an infant formula, especially the formula produced for preterm infants. Recently, there has been a growing interest in the triglyceride structure of MCFAs in human milk, their metabolism, and their effects on infant health. This study summarized the MCFA composition and structure in both human milk and infant formula. Recent studies on the nutritional effects of MCFAs on infant gut microbiota have been reviewed. Special attention was given to the MCFAs digestion and metabolism in the infants. This paper aims to provide insights into the optimization of formulations to fulfill infant nutritional requirements.

Insulin-resistance in paediatric age: Its magnitude and implications

Insulin resistance (IR) is insulin failure in normal plasma levels to adequately stimulate glucose uptake by the peripheral tissues. IR is becoming more common in children and adolescents than before. There is a strong association between obesity in children and adolescents, IR, and the metabolic syndrome components. IR shows marked variation among different races, crucial to understanding the possible cardiovascular risk, specifically in high-risk races or ethnic groups. Genetic causes of IR include insulin receptor mutations, mutations that stimulate autoantibody production against insulin receptors, or mutations that induce the formation of abnormal glucose transporter 4 molecules or plasma cell membrane glycoprotein-1 molecules; all induce abnormal energy pathways and end with the development of IR. The parallel increase of IR syndrome with the dramatic increase in the rate of obesity among children in the last few decades indicates the importance of environmental factors in increasing the rate of IR. Most patients with IR do not develop diabetes mellitus (DM) type-II. However, IR is a crucial risk factor to develop DM type-II in children. Diagnostic standards for IR in children are not yet established due to various causes. Direct measures of insulin sensitivity include the hyperinsulinemia euglycemic glucose clamp and the insulin-suppression test. Minimal model analysis of frequently sampled intravenous glucose tolerance test and oral glucose tolerance test provide an indirect estimate of metabolic insulin sensitivity/resistance. The main aim of the treatment of IR in children is to prevent the progression of compensated IR to decompensated IR, enhance insulin sensitivity, and treat possible complications. There are three main lines for treatment: Lifestyle and behavior modification, pharmacotherapy, and surgery. This review will discuss the magnitude, implications, diagnosis, and treatment of IR in children.

Roles of gut microbiota and metabolites in overweight and obesity of children

The prevalence of overweight and obesity in children and adolescents is an increasing public health problem. Pediatric overweight and obesity result from multiple factors, including genetic background, diet, and lifestyle. In addition, the gut microbiota and their metabolites play crucial roles in the progression of overweight and obesity of children. Therefore, we reviewed the roles of gut microbiota in overweight/obese children. The relationship between pediatric overweight/obesity and gut metabolites, such as short-chain fatty acids, medium-chain fatty acids, amino acids, amines, and bile acids, are also summarized. Targeting gut microbiota and metabolites might be a promising strategy for interventions aimed at reducing pediatric overweight/obesity.

Potential benefits of structured lipids in bulk compound chocolate: Insights on bioavailability and effect on serum lipids

The bioavailability impact of serum lipids in compound chocolate products based on structured lipids was studied. Compound chocolate products containing fat with and without structured lipids were digested in vitro under simulated gastrointestinal lipolysis conditions and were studied in vivo in healthy C57BL/6J mice. The in vitro digestion results show that products containing structured lipids, milk compound chocolate filling and white compound coating, significantly reduced the release rate of Free Fatty Acids (FFA) and improved the caloric reduction between 12.49% and 13.71% compared to products without structured lipids, suggesting that FFA were not absorbed. Animal feeding studies revealed no adverse effects on the compound products intake; in fact, these products reduced total cholesterol, LDL-c, VLDL-c and triacylglycerols. The present work shows the relevance of developing functional compound chocolate as providing a potential healthy initiative through the biological effect of the bioactive ingredients incorporated.

Protective effects of medium chain triglyceride diet in a mouse model of Dravet syndrome

OBJECTIVE

Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy with early childhood onset. Patients with DS do not respond well to antiepileptic drugs and have only a few treatment options available. Here, we evaluated the effect of medium chain triglyceride (MCT) diet therapy in a mouse model of DS.

METHODS

Scn1a^R1407X/+ DS mice were given diets supplemented with MCTs with varying ratios of decanoic (C10) and octanoic (C8) acid or a control diet for 4 weeks. Video monitoring was performed to evaluate spontaneous convulsive seizure frequency. Susceptibility to hyperthermia-induced seizures was also examined. Medium chain fatty acids, and mitochondrial and antioxidant markers were assessed in brain homogenate.

RESULTS

Dietary intervention with MCTs significantly prolonged survival and reduced convulsive seizure frequency during the critical period of highest seizure occurrence in the Scn1a^R1407X/+ DS mice. Moreover, MCT diet therapy showed protective effects against hyperthermia-induced seizures. We demonstrated that coadministration of C10/C8 was effective at reducing both seizures and mortality, whereas C10 alone only reduced mortality, suggesting that the ratio of C10 to C8 in the MCT is an important factor for efficacy. When C10 and C8 are supplemented at an 80:20 ratio in the diet, C10 accumulates in the brain in high enough concentrations to enhance brain energy metabolism by both stimulating mitochondrial enrichment and increasing its antioxidant status.

SIGNIFICANCE

The results from this study indicate that MCT diet therapy may provide therapeutic benefits in DS. Future clinical studies would elucidate whether these positive effects are mirrored in human patients.

Leptin administration during lactation leads to different nutritional, biometric, hemodynamic, and cardiac outcomes in prepubertal and adult female Wistar rats

Literature reports that insults, such as hormonal disturbances, during critical periods of development may modulate organism physiology and metabolism favoring cardiovascular diseases (CVDs) later in life. Studies show that leptin administration during lactation leads to cardiovascular dysfunction in young and adult male Wistar rats. However, there are sex differences regarding CVD. Thus, the present work aimed to investigate neonatal leptin administration's consequences on different outcomes in female rats at prepubertal and adult age. Newborn Wistar female rats were divided into two groups, Leptin and Control, receiving daily subcutaneous injections of this adipokine (8 μg/100 g) or saline for the first 10 of 21 d of lactation. Nutritional, biometric, hemodynamic, and echocardiographic parameters, as well as maximal effort ergometer performance, were determined at postnatal days (PND) 30 and 150. Leptin group presented lower food intake (p = 0.0003) and higher feed efficiency (p = 0.0058) between PND 21 and 30. Differences concerning echocardiographic parameters revealed higher left ventricle internal diameter (LVID) in systole (p = 0.0051), as well as lower left ventricle ejection fraction (LVEF) (p = 0.0111) and fractional shortening (FS) (p = 0.0405) for this group at PND 30. Older rats treated with leptin during lactation presented only higher LVID in systole (p = 0.0270). Systolic blood pressure and maximum effort ergometer test performance was similar between groups at both ages. These data suggest that nutritional, biometric, and cardiac outcomes due to neonatal leptin administration in female rats are age-dependent.

Correlations of PPARα and PPARγ expressions with 1H-MRS quantified hepatic fat content in pups of rats that experienced intrauterine growth restriction

Background: Proton magnetic resonance spectroscopy (¹H-MRS) measurement of hepatic fat content in intrauterine growth restriction rats has rarely been reported. This study was to explore the association of peroxisome proliferator-activated receptor alpha and gamma (PPARα and PPARγ) expression with ¹H-MRS quantified hepatic fat content in offspring of rats that experienced intrauterine growth restriction (IUGR).Methods and findings: IUGR was established by feeding a low-protein diet to female rats during pregnancy. Male pups of IUGR rats were weighed, liver tissues were collected at the ages of 1 day and 1, 3, 8 and 12 weeks post birth. Visceral adipose tissues (VATs) were collected at 3, 8, and 12 weeks post birth. Male pups also received conventional magnetic resonance imaging and ¹H-MRS using a 3.0 T whole-body MR scanner at 3, 8, and 12 weeks post birth. The peak area ratios in the MR spectra were calculated to determine hepatic lipid content. The expression of PPARα protein was detected by Western blot. The expression of PPARα mRNA was measured by real-time quantitative PCR. Significantly lower PPARα protein and mRNA expression were observed in liver tissues of male pups of IUGR rats at 1 day and 1, 3, 8, and 12 weeks post birth compared to male pups of control rats. In contrast, significantly higher PPARγ protein and mRNA expression were observed in VATs of male pups of IUGR rats at 3, 8, and 12 weeks post birth compared to male pups of control rats. PPARα protein and mRNA expression in the liver negatively correlated with the hepatic fat content (r = -0.611, -0.607, respectively), whereas PPARγ protein and mRNA expression in VATs positively correlated with the hepatic fat content (r = 0.659, 0.668, respectively).Conclusion: ¹H-MRS allows noninvasive assessment of hepatic fat content in rats. PPARα protein and mRNA expression were significantly decreased in the livers of rats, whereas PPARγ protein and mRNA expression was significantly increased in VATs in pups of IUGR rats.

Inhibitory effect of 17β‑estradiol on triglyceride synthesis in skeletal muscle cells is dependent on ESR1 and not ESR2

The present study aimed to investigate the inhibitory effects and the mechanisms underlying 17β-estradiol (E₂) effects on triglyceride synthesis and insulin resistance in skeletal muscle tissues and cells. Ovariectomy (OVX) was performed on 6-month-old female rats treated with or without E₂. Subsequently, various serum biochemical markers were measured. Additionally, pathological alterations of the uterus, liver and skeletal muscle were analyzed, and the content of triglycerides (TG) in muscle was detected. Differentiated myotubes formed by C2C12 cells were treated with palmitic acid (PA) or pretreated with E₂, estrogen receptor (ESR) 1 agonist propylpyrazoletriol (PPT) and ESR2 agonist diarylpropionitrile (DPN). Subsequently, the mRNA or protein expression levels of ESR1/2, peroxisome proliferator activated receptor α (PPARα), CD36 molecule (CD36), fatty acid synthase (FASN), perilipin 2 (PLIN2), phosphorylated acetyl-CoA carboxylase α (p-ACACA), p-AKT serine/threonine kinase (p-AKT) and p-mitogen-activated protein kinase 8 (p-MAPK8) were analyzed in skeletal muscle or in C2C12 cells by reverse transcription-semi-quantitative polymerase chain reaction and western blotting. The present results suggested that treatment with E₂ inhibited OVX-induced body weight gain, TG accumulation and insulin resistance. The protein or mRNA expression levels of ESR1, CD36, PPARα, p-ACACA and p-AKT were decreased, whereas the protein or mRNA expression levels of ESR2, PLIN2, FASN and p-MAPK8 were increased in the OVX group. Of note, treatment with E₂ restored the expression levels of the aforementioned factors. In C2C12 cells, treatment with E₂ or PPT reversed the alterations induced by treatment with PA. In contrast, pretreatment with DPN did not influence the effect of PA. Collectively, E₂ was able to interact with ESR1, thus activating the CD36-PPARα pathway, decreasing the level of TG in the muscles and improving insulin resistance in skeletal muscles and C2C12 cells.

Medium-chain fatty acids decrease serum cholesterol via reduction of intestinal bile acid reabsorption in C57BL/6J mice

Background

Bile acids play a pivotal role in cholesterol metabolism via the enterohepatic circulation. This study investigated the effects of medium-chain triglycerides (MCTs)/medium-chain fatty acids (MCFAs) on the reduction of bile acid absorption in the small intestine and the mechanisms of action in vivo and partially verified in vitro.

Methods

Thirty-six C57BL/6 J mice with hypercholesterolaemia were randomly divided into 3 groups: fed a cholesterol-rich diet (CR group), fed a cholesterol-rich and medium-chain triglyceride diet (CR-MCT group) and fed a cholesterol-rich and long-chain triglyceride diet (CR-LCT group). Body weights and blood lipid profiles were measured in all groups after 16 weeks of treatment. The concentrations of bile acids in bile and faeces were analysed using HPLC-MS (high-performance liquid chromatography-mass spectrometry). Gene transcription and the expression levels associated with bile acid absorption in the small intestines were determined using real-time PCR and Western blot. Ileal bile acid binding protein (I-BABP) was analysed using immunofluorescence. The effects of MCFAs on the permeability of bile acid (cholic acid, CA) in Caco-2 cell monolayers and I-BABP expression levels in Caco-2 cells treated with caprylic acid (C8:0), capric acid (C10:0), stearic acid (C18:0) and oleic acid (C18:1) were determined.

Results

Mice in the CR-MCT group exhibited lower body weights and serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels and a higher HDL-C/LDL-C ratio than the CR-LCT group (P < 0.05). The concentrations of primary bile acids (primarily CA) and secondary bile acids in faeces and secondary bile acids in bile in the CR-MCT group were significantly higher than in the CR-LCT group (P < 0.05). C8:0 and C10:0 decreased the permeability of CA in Caco-2 cell monolayers. MCT/MCFAs (C8:0 and C10:0) inhibited I-BABP gene expression in the small intestines and Caco-2 cells (P < 0.05).

Conclusions

MCT slowed the body weight increase and promoted the excretion of bile acids. MCT lowered serum cholesterol levels at least partially via reduction of bile acid absorption in the small intestine by inhibition of I-BABP expression. Our results provide the basis for clinical trials of MCT as a dietary supplement for lowering plasma cholesterol and reducing risk of CHD.

Life-long Maternal Cafeteria Diet Promotes Tissue-Specific Morphological Changes in Male Offspring Adult Rats

Here, we evaluated whether the exposure of rats to a cafeteria diet pre- and/or post-weaning, alters histological characteristics in the White Adipose Tissue (WAT), Brown Adipose Tissue (BAT), and liver of adult male offspring. Female Wistar rats were divided into Control (CTL; fed on standard rodent chow) and Cafeteria (CAF; fed with the cafeteria diet throughout life, including pregnancy and lactation). After birth, only male offspring (F1) were maintained and received the CTL or CAF diets; originating four experimental groups: CTL-CTLF1; CTL-CAFF1; CAF-CTLF1; CAF-CAFF1. Data of biometrics, metabolic parameters, liver, BAT and WAT histology were assessed and integrated using the Principal Component Analysis (PCA). According to PCA analysis worse metabolic and biometric characteristics in adulthood are associated with the post-weaning CAF diet compared to pre and post weaning CAF diet. Thus, the CTL-CAFF1 group showed obesity, higher deposition of fat in the liver and BAT and high fasting plasma levels of glucose, triglycerides and cholesterol. Interestingly, the association between pre and post-weaning CAF diet attenuated the obesity and improved the plasma levels of glucose and triglycerides compared to CTL-CAFF1 without avoiding the higher lipid accumulation in BAT and in liver, suggesting that the impact of maternal CAF diet is tissue-specific.