Update on the synergistic effect of HSL and insulin in the treatment of metabolic disorders

Exploring the Biological Effects of Anti-Diabetic Vanadium Compounds in the Liver, Heart and Brain

The prevalence of diabetes mellitus and diabetes-related complications is rapidly increasing worldwide, placing a substantial financial burden on healthcare systems. Approximately 537 million adults are currently diagnosed with type 1 or type 2 diabetes globally. However, interestingly, the increasing morbidity rate is primarily influenced by the effects of long-term hyperglycemia on vital organs such as the brain, the liver and the heart rather than the ability of the body to use glucose effectively. This can be attributed to the summation of the detrimental effects of excessive glucose on major vascular systems and the harmful side effects attributed to the current treatment associated with managing the disease. These drugs have been implicated in the onset and progression of cardiovascular disease, hepatocyte injury and cognitive dysfunction, thereby warranting extensive research into alternative treatment strategies. Literature has shown significant progress in utilizing metal-based compounds, specifically those containing transition metals such as zinc, magnesium and vanadium, in managing hyperglycaemia. Amongst these metals, research carried out on vanadium reflected the most promising anti-diabetic efficacy in cell culture and animal studies. This was attributed to the ability to improve glucose management in the bloodstream by enhancing its uptake and metabolism in the kidney, brain, skeletal muscle, heart and liver. Despite this, organic vanadium was considered toxic due to its accumulative characteristics. To alleviate vanadium's toxic nature while subsequently manipulating its therapeutic properties, vanadium complexes were synthesized using either vanadate or vanadyl as a base compound. This review attempts to evaluate organic vanadium salts' therapeutic and toxic effects, highlight vanadium complexes' research and provide insight into the novel dioxidovanadium complex synthesized in our laboratory to alleviate hyperglycaemia-associated macrovascular complications in the brain, heart and liver.

Spaceflight induces changes in gene expression profiles linked to insulin and estrogen

Organismal adaptations to spaceflight have been characterized at the molecular level in model organisms, including Drosophila and C. elegans. Here, we extend molecular work to energy metabolism and sex hormone signaling in mice and humans. We found spaceflight induced changes in insulin and estrogen signaling in rodents and humans. Murine changes were most prominent in the liver, where we observed inhibition of insulin and estrogen receptor signaling with concomitant hepatic insulin resistance and steatosis. Based on the metabolic demand, metabolic pathways mediated by insulin and estrogen vary among muscles, specifically between the soleus and extensor digitorum longus. In humans, spaceflight induced changes in insulin and estrogen related genes and pathways. Pathway analysis demonstrated spaceflight induced changes in insulin resistance, estrogen signaling, stress response, and viral infection. These data strongly suggest the need for further research on the metabolic and reproductive endocrinologic effects of space travel, if we are to become a successful interplanetary species.

Ketosis Suppression and Ageing (KetoSAge): The Effects of Suppressing Ketosis in Long Term Keto-Adapted Non-Athletic Females

Most studies on ketosis have focused on short-term effects, male athletes, or weight loss. Hereby, we studied the effects of short-term ketosis suppression in healthy women on long-standing ketosis. Ten lean (BMI 20.5 ± 1.4), metabolically healthy, pre-menopausal women (age 32.3 ± 8.9) maintaining nutritional ketosis (NK) for > 1 year (3.9 years ± 2.3) underwent three 21-day phases: nutritional ketosis (NK; P1), suppressed ketosis (SuK; P2), and returned to NK (P3). Adherence to each phase was confirmed with daily capillary D-beta-hydroxybutyrate (BHB) tests (P1 = 1.9 ± 0.7; P2 = 0.1 ± 0.1; and P3 = 1.9 ± 0.6 pmol/L). Ageing biomarkers and anthropometrics were evaluated at the end of each phase. Ketosis suppression significantly increased: insulin, 1.78-fold from 33.60 (± 8.63) to 59.80 (± 14.69) pmol/L (p = 0.0002); IGF1, 1.83-fold from 149.30 (± 32.96) to 273.40 (± 85.66) µg/L (p = 0.0045); glucose, 1.17-fold from 78.6 (± 9.5) to 92.2 (± 10.6) mg/dL (p = 0.0088); respiratory quotient (RQ), 1.09-fold 0.66 (± 0.05) to 0.72 (± 0.06; p = 0.0427); and PAI-1, 13.34 (± 6.85) to 16.69 (± 6.26) ng/mL (p = 0.0428). VEGF, EGF, and monocyte chemotactic protein also significantly increased, indicating a pro-inflammatory shift. Sustained ketosis showed no adverse health effects, and may mitigate hyperinsulinemia without impairing metabolic flexibility in metabolically healthy women.

Anti-Obesity Effect and Mechanism of Chitooligosaccharides Were Revealed Based on Lipidomics in Diet-Induced Obese Mice

Chitooligosaccharide (COS) is a natural product from the ocean, and while many studies have reported its important role in metabolic diseases, no study has systematically elaborated the anti-obesity effect and mechanism of COS. Herein, COSM (MW ≤ 3000 Da) was administered to diet-induced obese mice by oral gavage once daily for eight weeks. The results show that COSM administration reduced body weight; slowed weight gain; reduced serum Glu, insulin, NEFA, TC, TG, and LDL-C levels; increased serum HSL and HDL-C levels; improved inflammation; and reduced lipid droplet size in adipose tissue. Further lipidomic analysis of adipose tissue revealed that 31 lipid species are considered to be underlying lipid biomarkers in COS therapy. These lipids are mainly enriched in pathways involving insulin resistance, thermogenesis, cholesterol metabolism, glyceride metabolism and cyclic adenosine monophosphate (cAMP), which sheds light on the weight loss mechanism of COS. The Western blot assay demonstrated that COSM intervention can improve insulin resistance, inhibit de novo synthesis, and promote thermogenesis and β-oxidation in mitochondria by the AMPK pathway, thereby alleviating high-fat diet-induced obesity. In short, our study can provide a more comprehensive direction for the application of COS in obesity based on molecular markers.

Predictive value of the Framingham steatosis index for cardiovascular risk: a nationwide population-based cohort study

Background

Non-alcoholic fatty liver disease (NAFLD) is common and is associated with cardiovascular (CV) disease and mortality. The Framingham steatosis index (FSI) was recently proposed as a diagnostic marker of NAFLD and was calculated from age, body mass index, triglyceride, aspartate aminotransferase, alanine aminotransferase, diabetes history, and hypertension status. We aimed to evaluate the predictive ability of FSI for CV risk using a large-scale population dataset from the Korean National Health Insurance Service-National Health Screening Cohort (NHIS-HEALS).

Methods

Among 514,866 individuals in the NHIS-HEALS, we excluded those who died, had a history of admission due to a CV event, and were heavy drinkers. The final study cohort comprised 283,427 participants. We employed both unadjusted and covariate-adjusted models in Cox proportional hazards regression analyses to determine the association between FSI and major adverse cardiovascular events (MACEs), CV events, and CV mortality.

Results

During a median follow-up of 5.9 years, we documented 9,674, 8,798, and 1,602 cases of MACEs, CV events, and CV mortality, respectively. The incidence of MACEs was 1.28%, 2.99%, 3.94%, and 4.82% in the first to fourth quartiles of FSI, respectively. The adjusted hazard ratios (95% confidence interval) for MACEs gradually and significantly increased with the FSI quartiles [1.302 (1.215-1.395) in Q2, 1.487 (1.390-1.590) in Q3, and 1.792 (1.680-1.911) in Q4], following an adjustment for conventional CV risk factors, including age, sex, smoking, drinking, physical activities, low-density lipoprotein cholesterol, estimated glomerular filtration rate, and waist circumference. Participants in the higher quartiles of FSI exhibited a noteworthy increase in the occurrence of CV event. However, upon adjusting for relevant risk factors, the association between FSI and CV mortality did not reach statistical significance.

Conclusion

Our study suggests that the FSI, which is a surrogate marker of NAFLD, has a prognostic value for detecting individuals at higher risk of CV events.

Validation and Functional Analysis of Reference and Tissue-Specific Genes in Adipose Tissue of Freshwater Drum, Aplodinotus grunniens, under Starvation and Hypothermia Stress

Adipose tissue is critical to the growth, development, and physiological health of animals. Reference genes play an essential role in normalizing the expression of mRNAs. Tissue-specific genes are preferred for their function and expression in specific tissues or cell types. Identification of these genes contributes to understanding the tissue-gene relationship and the etiology and discovery of new tissue-specific targets. Therefore, reference genes and tissue-specific genes in the adipose tissue of Aplodinotus grunniens were identified to explore their function under exogenous starvation (1 d, 2 w, 6 w) and hypothermic stress (18 °C and 10 °C for 2 d and 8 d) in this study. Results suggest that 60SRP was the most stable reference gene in adipose tissue. Meanwhile, eight genes were validated as tissue-specific candidates from the high-throughput sequencing database, while seven of them (ADM2, β₂GP1, CAMK1G, CIDE3, FAM213A, HSL, KRT222, and NCEH1) were confirmed in adipose tissue. Additionally, these seven tissue-specific genes were active in response to starvation and hypothermic stress in a time- or temperature-dependent manner. These results demonstrate that adipose-specific genes can be identified using stable internal reference genes, thereby identifying specific important functions under starvation and hypothermic stress, which provides tissue-specific targets for adipose regulation in A. grunniens.

Effects of a genetic variant rs13266634 in the zinc transporter 8 gene (SLC30A8) on insulin and lipid levels before and after a high-fat mixed macronutrient tolerance test in U.S. adults

BACKGROUND

The common C-allele of rs13266634 (c.973C>T or p.Arg325Trp) in SLC30A8 (ZNT8) is associated with increased risk of type 2 diabetes. While previous studies have examined the correlation of the variant with insulin and glucose metabolism, the effects of this variant on insulin and lipid responses after a lipid challenge in humans remain elusive. The goal of this study was to determine whether the C-allele had an impact on an individual's risk to metabolic syndromes in U.S. adults.

METHOD

We studied the genotypes of rs13266634 in 349 individuals aged between 18 and 65 y with BMI ranging from 18.5 to 45 kg/m². The subjects were evaluated for insulin, glucose, HbA1c, ghrelin, and lipid profiles before and after a high-fat mixed macronutrient tolerance test (MMTT).

RESULTS

We found that the effects of variants rs13266634 on glucose and lipid metabolism were sex-dimorphic, greater impact on males than on females. Insulin incremental area under the curve (AUC) after MMTT was significantly decreased in men with the CC genotype (p < 0.05). Men with the CC genotype also had the lowest fasting non-esterified fatty acid (NEFA) concentrations. On the other hand, the TT genotype was associated with a slower triglyceride removal from the circulation in men after MMTT. The reduced triglyceride removal was also observed in subjects with BMI ≥ 30 carrying either the heterozygous or homozygous T-allele. Nevertheless, the SNP had little effect on fasting or postprandial blood glucose and cholesterol concentrations.

CONCLUSION

We conclude that the CC genotype negatively affects insulin response after MMTT while the T-allele may negatively influence lipolysis during fasting and postprandial blood triglyceride removal in men and obese subjects, a novel finding in this study.

Changes in Lipid Metabolism Enzymes in Rat Epididymal Fat after Chronic Central Leptin Infusion Are Related to Alterations in Inflammation and Insulin Signaling

Leptin inhibits food intake and reduces the size of body fat depots, changing adipocyte sensitivity to insulin to restrain lipid accrual. This adipokine may modulate the production of cytokines that could diminish insulin sensitivity, particularly in visceral adipose tissue. To explore this possibility, we examined the effects of chronic central administration of leptin on the expression of key markers of lipid metabolism and its possible relationship with changes in inflammatory- and insulin-signaling pathways in epididymal adipose tissue. Circulating non-esterified fatty acids and pro- and anti-inflammatory cytokines were also measured. Fifteen male rats were divided into control (C), leptin (L, icv, 12 μg/day for 14 days), and pair-fed (PF) groups. We found a decrease in the activity of glucose-6-phosphate dehydrogenase and malic enzyme in the L group, with no changes in the expression of lipogenic enzymes. A reduction in the expression of lipoprotein lipase and carnitine palmitoyl-transferase-1A, together with a decrease in the phosphorylation of insulin-signaling targets and a low-grade inflammatory pattern, were detected in the epididymal fat of L rats. In conclusion, the decrease in insulin sensitivity and increased pro-inflammatory environment could regulate lipid metabolism, reducing epididymal fat stores in response to central leptin infusion.

Steatosis in metabolic diseases: A focus on lipolysis and lipophagy

Fatty acids (FAs), as part of lipids, are involved in cell membrane composition, cellular energy storage, and cell signaling. FAs can also be toxic when their concentrations inside and/or outside the cell exceed physiological levels, which is called "lipotoxicity", and steatosis is a form of lipotoxity. To facilitate the storage of large quantities of FAs in cells, they undergo a process called lipolysis or lipophagy. This review focuses on the effects of lipolytic enzymes including cytoplasmic "neutral" lipolysis, lysosomal "acid" lipolysis, and lipophagy. Moreover, the impact of related lipolytic enzymes on lipid metabolism homeostasis and energy conservation, as well as their role in lipid-related metabolic diseases. In addition, we describe how they affect lipid metabolism homeostasis and energy conservation in lipid-related metabolic diseases with a focus on hepatic steatosis and cancer and the pathogenesis and therapeutic targets of AMPK/SIRTs/FOXOs, PI3K/Akt, PPARs/PGC-1α, MAPK/ERK1/2, TLR4/NF-κB, AMPK/mTOR/TFEB, Wnt/β-catenin through immune inflammation, oxidative stress and autophagy-related pathways. As well as the current application of lipolytic enzyme inhibitors (especially Monoacylglycerol lipase (MGL) inhibitors) to provide new strategies for future exploration of metabolic programming in metabolic diseases.

Muscle glycogen unavailability and fat oxidation rate during exercise: Insights from McArdle disease

Carbohydrate availability affects fat metabolism during exercise; however, the effects of complete muscle glycogen unavailability on maximal fat oxidation (MFO) rate remain unknown. Our purpose was to examine the MFO rate in patients with McArdle disease, comprising an inherited condition caused by complete blockade of muscle glycogen metabolism, compared to healthy controls. Nine patients (three women, aged 36 ± 12 years) and 12 healthy controls (four women, aged 40 ± 13 years) were studied. Several molecular markers of lipid transport/metabolism were also determined in skeletal muscle (gastrocnemius) and white adipose tissue of McArdle (Pygm p.50R*/p.50R*) and wild-type male mice. Peak oxygen uptake ( V ̇ O 2 peak ${\dot V_{{{\rm{O}}_{\rm{2}}}{\rm{peak}}}}$ ), MFO rate, the exercise intensity eliciting MFO rate (FATmax) and the MFO rate-associated workload were determined by indirect calorimetry during an incremental cycle-ergometer test. Despite having a much lower V ̇ O 2 peak ${\dot V_{{{\rm{O}}_{\rm{2}}}{\rm{peak}}}}$ (24.7 ± 4 vs. 42.5 ± 11.4 mL kg^-1  min^-1 , respectively; P < 0.0001), patients showed considerably higher values for the MFO rate (0.53 ± 0.12 vs. 0.33 ± 0.10 g min^-1 , P = 0.001), and for the FATmax (94.4 ± 7.2 vs. 41.3 ± 9.1 % of V ̇ O 2 peak ${\dot V_{{{\rm{O}}_{\rm{2}}}{\rm{peak}}}}$ , P < 0.0001) and MFO rate-associated workload (1.33 ± 0.35 vs. 0.81 ± 0.54 W kg^-1 , P = 0.020) than controls. No between-group differences were found overall in molecular markers of lipid transport/metabolism in mice. In summary, patients with McArdle disease show an exceptionally high MFO rate, which they attained at near-maximal exercise capacity. Pending more mechanistic explanations, these findings support the influence of glycogen availability on MFO rate and suggest that these patients develop a unique fat oxidation capacity, possibly as an adaptation to compensate for the inherited blockade in glycogen metabolism, and point to MFO rate as a potential limiting factor of exercise tolerance in this disease. KEY POINTS: Physically active McArdle patients show an exceptional fat oxidation capacity. Maximal fat oxidation rate occurs near-maximal exercise capacity in these patients. McArdle patients' exercise tolerance might rely on maximal fat oxidation rate capacity. Hyperpnoea might cloud substrate oxidation measurements in some patients. An animal model revealed overall no higher molecular markers of lipid transport/metabolism.

Fatty liver index and cardiovascular outcomes in never-treated hypertensive patients: a prospective cohort

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing rapidly worldwide, affecting 25-30% of the population. Fatty liver index (FLI) is a validated marker of NAFLD and can be used as a screening tool for hepatic steatosis. The purpose of the study was to evaluate the relationship between FLI and the risk of major cardiovascular events in never treated hypertensive patients. We included 903 hypertensive patients without a history of cardiovascular disease (mean age 52.7 ± 11.4 years; men 55%; baseline clinic BP 149.8 ± 15.2/95.5 ± 10.1 mmHg). Participants were prospectively evaluated for a mean follow-up period of 5.2 ± 3.2 years with at least one annual visit. Patients were also categorized into two groups using an FLI of 60 units. The incidence of cardiovascular events during follow-up was 8.5% (n = 77). Patients with FLI < 60 (n = 625) had a better BP control compared to their counterparts with FLI ≥ 60 (n = 278) during follow up (43% vs 33%, p = 0.02). Cox-regression analysis indicated that FLI (Hazard Ratio [HR], 1.05; 95% Confidence Interval [CI], 1.03-1.07, p < 0.001), FLI z-scores (HR, 3.66; 95% CI, 2.22-6.04) and high-risk FLI (HR, 7.5; 95% CI, 3.12-18.04) were independent determinants of the outcome after adjustment for baseline and follow-up variables. Stratification by diabetes mellitus indicated that FLI predicted the outcome to a greater extent in those with than those without diabetes (P-interaction < 0.001). In conclusion, FLI has an independent prognostic value for the incidence of cardiovascular events in newly diagnosed, never-treated hypertensive patients. Therefore, FLI might identify higher-risk patients in the primary prevention of hypertension.

Effects of PLIN1 Gene Knockout on the Proliferation, Apoptosis, Differentiation and Lipolysis of Chicken Preadipocytes

Perilipin 1 (PLIN1) is one of the most abundant lipid droplet-related proteins on the surface of adipocytes. Our previous results showed that PLIN1 plays an important role in chicken lipid metabolism. To further reveal the role of PLIN1 in the growth and development of adipocytes, a chicken preadipocyte line with a PLIN1 gene knockout was established by the CRISPR/Cas9 gene editing technique, and the effects of the PLIN1 gene on the proliferation, apoptosis, differentiation and lipolysis of chicken preadipocytes were detected. The results showed that the CRISPR/Cas9 system effectively mediated knockout of the PLIN1 gene. After the deletion of PLIN1, the differentiation ability and early apoptotic activity of chicken preadipocytes decreased, and their proliferation ability increased. Moreover, knockout of PLIN1 promoted chicken preadipocyte lipolysis under basal conditions and inhibited chicken preadipocyte lipolysis under hormone stimulation. Taken together, our results inferred that PLIN1 plays a regulatory role in the process of proliferation, apoptosis, differentiation and lipolysis of chicken preadipocytes.

Nonalcoholic Fatty Liver Disease and Cardiovascular Risk: A Scientific Statement From the American Heart Association

Nonalcoholic fatty liver disease (NAFLD) is an increasingly common condition that is believed to affect >25% of adults worldwide. Unless specific testing is done to identify NAFLD, the condition is typically silent until advanced and potentially irreversible liver impairment occurs. For this reason, the majority of patients with NAFLD are unaware of having this serious condition. Hepatic complications from NAFLD include nonalcoholic steatohepatitis, hepatic cirrhosis, and hepatocellular carcinoma. In addition to these serious complications, NAFLD is a risk factor for atherosclerotic cardiovascular disease, which is the principal cause of death in patients with NAFLD. Accordingly, the purpose of this scientific statement is to review the underlying risk factors and pathophysiology of NAFLD, the associations with atherosclerotic cardiovascular disease, diagnostic and screening strategies, and potential interventions.

Omega-3 Fatty Acids and Their Interaction with the Gut Microbiome in the Prevention and Amelioration of Type-2 Diabetes

Type-2 diabetes mellitus (T2DM) is often linked with hyperglycemia, disturbed lipid profiles, inflammation, and gut dysbiosis. Omega-3 fatty acid supplementation has a vital role in the management of T2DM. As a result, a better understanding of the potential role of omega-3 fatty acids in the development and progression of T2DM by influencing the intestinal microflora will help to improve the therapeutic intervention for T2DM and related complications. Focusing on the molecular mechanisms and signaling pathways induced by omega-3 fatty acids, this paper attempts to comprehensively review and discuss the putative associations between omega-3 fatty acids, gut dysbiosis, and the pathophysiology of T2DM and its related comorbidities. In addition, we contemplate the importance of gut microbiota in T2DM prevention and treatment and ponder the role of omega-3 fatty acids in T2DM by positively modulating gut microbiota, which may lead to discovery of novel targets and therapeutic strategies thereby paving way for further comprehensive, mechanistic, and clinical studies.

Beneficial Metabolic Effects of Praliciguat, a Soluble Guanylate Cyclase Stimulator, in a Mouse Diet-Induced Obesity Model

Praliciguat is a soluble guanylate cyclase stimulator that elicits hemodynamic, anti-inflammatory, and antifibrotic effects in preclinical models of metabolic dysfunction. We assessed the metabolic effects of praliciguat in a mouse diet-induced obesity (DIO) model housed at thermoneutrality. At 6 weeks old, male C57BL/6N mice were either maintained on low-fat diet (LFD, lean mice) or placed on 60% high-fat diet (HFD, DIO mice). At 14 weeks old, the DIO mice were either maintained on HFD or switched to HFD with praliciguat (6-mg/kg). Day 28 samples were collected for biomarker analysis. In a second study under the same paradigm, indirect calorimetry was performed on days 8, 9, 20, 21, 32, and 33 and an oral lipid tolerance test (LTT) on day 38. Mice treated 28 days with praliciguat had lower levels of fasting plasma insulin, C-peptide, triglycerides, and HOMA-IR (homeostatic model assessment for insulin resistance) than DIO controls. In addition, energy expenditure was higher in praliciguat-treated than in DIO control mice on days 9, 20, 32, and 33; and day-38 triglycerides were lower. HFD-induced increases in gene expression of liver TNF-ɑ, lipoprotein lipase (Lpl), and patatin-like phospholipase domain-containing protein 3 (Pnpla3) in control DIO mice were attenuated in praliciguat-treated DIO mice. The positive metabolic effects observed in praliciguat-treated mice were associated with the restoration of liver PI3K (pAKT-Thr308) signaling, but not MAPK (pERK). In conclusion, praliciguat-treated DIO mice had increased energy utilization, improved insulin sensitivity, and lower plasma triglycerides. These results illustrate metabolic effects associated with praliciguat treatment in DIO mice.

A Lard and Soybean Oil Mixture Alleviates Low-Fat-High-Carbohydrate Diet-Induced Nonalcoholic Fatty Liver Disease in Mice

Dietary habit is highly related to nonalcoholic fatty liver disease (NAFLD). Low-fat–high-carbohydrate (LFHC) diets could induce lean NAFLD in Asians. Previously, we found that a lard and soybean oil mixture reduced fat accumulation with a medium-fat diet; therefore, in this study, we evaluated the effect of a lard and soybean oil mixture (LFHC diet) on NAFLD and its underlying mechanisms. Mice in groups were fed with lard, soybean oil, or a lard and soybean oil mixture—an LFHC diet—separately. Our results showed that mixed oil significantly inhibited serum triglyceride, liver triglyceride, serum free fatty acids (FFAs), and liver FFAs compared with soybean oil or lard, and we found fewer inflammatory cells in mice fed with mixed oil. RNA-seq results indicate that mixed oil reduced FFAs transportation into the liver via decreasing liver fatty acid-binding protein 2 expression, inhibited oxidative phosphorylation via tumor necrosis factor receptor superfamily member 6 downregulation, and alleviated inflammation via downregulating inflammatory cytokine. The liquid chromatography–mass spectrometry results showed that the mixed oil promoted bile acid conjugated with taurine and glycine, thus activating G-protein-coupled bile acid receptor 1 for improved lipids metabolism. In conclusion, the lard and soybean oil mixture alleviated NAFLD.

Dietary copper supplementation enhances lipolysis in Rex rabbits

BACKGROUND

Copper is an important regulator of lipid metabolism in mammals, as a cofactor of many enzymes and is involved in the lipolysis. Copper deficiency has been considered as a significant factor in human diseases related to abnormal lipid metabolism, while adding copper to the diet seems to be the simplest and most effective way to prevent copper deficiency.

AIMS

The aim of this study was to investigate the effects of dietary copper level on lipid metabolism in Rex Rabbits.

METHODS

A total of 120 90-d-old Rex Rabbits were randomly allotted into three treatments, with 40 replicates (20 males, 20 females) in each treatment (1 rabbit per replicate). The diets included 1) control (8.4 mg/kg), normal-copper diet (39.1 mg/kg), 3) high-copper diet (67.5 mg/kg). The trial including a one-week adaptation period and a five-week experimental period.

RESULT

The results showed that copper (39.1 mg/kg) diet increased average daily feed intake (ADFI) (P＜0.05, N = 34), and tended to increase the final body weight (FBW) (P = 0.0556, N = 34). Moreover, dietary copper addition (39.1 and 67.5 mg/kg) significantly increased the foreleg and hindleg weight (P＜0.05, N = 8), and decreased the weight of Perirenal fat and the concentration of triglycerides (TG) in the liver (P＜0.05, N = 8). The concentration of triglycerides (TG), epinephrine (EPI), and glucagon (GC) in serum were obviously higher than that in control group (P＜0.05, N = 8), and the concentration of insulin (INS), and very low-density lipoprotein (VLDL) in serum were significantly decreased (P＜0.05, N = 8). The copper group (39.1 mg/kg) showed up-regulated gene expression levels of carnitine palmitoyl transferases (CPT-1 and CPT-2) and peroxisome proliferator-activated receptor (PPAR-α) in liver (P < 0.05, N = 8) and down-regulated gene expression levels of fatty acid synthase (FAS) and Acetyl-CoA carboxylase (ACC) (P < 0.05, N = 8). In skeletal muscle, CPT-1, CPT-2, PPAR-α, fatty acid transport protein (FATP), fatty acid-binding protein (FABP) and lipoprotein lipase (LPL) levels were significantly up-regulated by copper treatment (P < 0.05, N = 8). Rex Rabbits receiving copper addition had higher CPT-1, CPT-2, PPAR-a and hormone-sensitive lipase (HSL) mRNA levels in adipose tissue (P < 0.05, N = 8).

CONCLUSION

Copper diets promoted skeletal muscle growth and reduced fat accumulation by enhancing fatty acid oxidation, at the same time, dietary copper inhibited De novo lipogenesis in the liver. PPAR-α signaling in liver, skeletal muscle and adipose tissues were involved in the regulation of lipid metabolism by copper.

BHBA regulates the expressions of lipid synthesis and oxidation genes in sheep hepatocytes through the AMPK pathway

Pregnancy toxemia (PT) is the most frequent metabolic disease of sheep during late pregnancy, which can lead to enormous economic losses in sheep farm industry. However, the underlying mechanism of PT in sheep has not been fully elucidated. High levels of β-hydroxy butyric acid (BHBA) exist in PT sheep. The AMP-activated protein kinase (AMPK) pathway plays a major role in regulating liver function. The aim of this study was to explore the effects of gradient concentrations of BHBA on lipid metabolism of sheep hepatocytes and the underlying molecular mechanism in vitro. The results showed that 0.6, 1.2 mmol/L BHBA could activate AMPKα, promoted the expressions of peroxisome proliferator-activated receptor alpha (PPARα) and its target genes, and inhibited the expressions of sterol regulatory element binding protein-1c (SREBP-1c) as well as its downstream genes. When the concentration of BHBA was beyond 1.2 mmol/L, the expressions of the above-mentioned proteins and genes were just the opposite. However, the expressions of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) did not change significantly. The levels of very low density lipoprotein (VLDL), triglyceride (TG) and cholesterol (T-CHOL) showed a gradually increasing trend with the increase of BHBA concentration. According to the results above, it demonstrates that high levels of BHBA can inhibit the expression of the AMPK pathway and cause lipid metabolism disorders in sheep hepatocytes, which may lead to the occurrence of PT.

Role of ectopic olfactory receptors in glucose and lipid metabolism

The metabolic syndrome has become one of the major public health challenges in the world, and adjusting glucose and lipid levels to their normal values is crucial for treating the metabolic syndrome. Olfactory receptors (ORs) expressed in extra-nasal tissues participate in diverse biological processes, including the regulation of glucose and lipid metabolism. Ectopic ORs can regulate a variety of metabolic events including insulin secretion, glucagon secretion, fatty acid oxidation, lipogenesis and thermogenesis. Understanding the physiological function and deciphering the olfactory recognition code by suitable ligands make ectopic ORs potential targets for the treatment of the metabolic syndrome. In this review, we delineate the roles and mechanisms of ectopic ORs in the regulation of glucose and lipid metabolism, summarize the corresponding natural ligands, and discuss existing problems and the therapeutic potential of targeting ORs in the metabolic syndrome.

Lauric Triglyceride Ameliorates High-Fat-Diet-Induced Obesity in Rats by Reducing Lipogenesis and Increasing Lipolysis and β-Oxidation

Medium-chain triglycerides (MCTs) are found in limited foods. In these medium-chain oil resources, the abundance of lauric acid (LA) is the highest among medium-chain fatty acids (MCFAs), and its effects on lipid metabolism in obese rats have not been well-studied. This study aimed to determine the anti-obesity effects and mechanisms of lauric triglyceride (LT) in Sprague Dawley (SD) rats. LA and glycerin were used to synthesize LT, then LT was used to treat obese rats for 12 weeks. The results showed that LT significantly reduced the body weight, body mass index, and Lee's index in obese rats. The mRNA expression levels of the anorexic neuropeptide POMC in the hypothalamus between the LT group and the other groups were not different, while the gene expression levels of the orexigenic neuropeptides NPY and AGRP decreased significantly in the LT group. Except serum cholesterol, LT improved the serum triglyceride metabolism in the obese rats and reduced adipocyte and hepatic lipid deposition. Moreover, LT inhibited the expression of lipogenesis-related genes and proteins (SREBP-1c, ACC1, and FASN) and increased the expression of lipolysis (ATGL, HSL, and LPL) and β-oxidation (PPARα, CPT-1a, and PCG-1α) related genes and proteins in the white fat and liver. Furthermore, LT increased the mRNA expression of mitochondrial-biosynthesis-related genes (SIRT1, NRF1, and TFAM) in the liver. The results indicated that LT ameliorates diet-induced obesity in rats.

Combination of Metformin and Exercise in Management of Metabolic Abnormalities Observed in Type 2 Diabetes Mellitus

Excess nutrient intake and lack of exercise characterize the problem of obesity and are common factors in insulin resistance (IR). With an increasing number of prediabetic, and type 2 diabetic populations, metformin is still the most prescribed glucose-lowering drug and is often accompanied by recommendations for regular physical exercise. Metformin, by the inhibition of complex 1 of the electron transport chain, and exercise, by increasing energy expenditure, both elicit a low cellular energy state that leads to improvements in glucose control via activation of adenosine 5' monophosphate-activated protein kinase (AMPK). An augmented stimulation of the energy-sensing enzyme AMPK by either of the two modalities leads to an increase in glycogenolysis, glucose uptake, fat oxidation, a decrease in glycogen and protein synthesis, and gluconeogenesis in muscle and the liver, which are remarked as having positive effects on metabolic pathophysiology observed in IR and type 2 diabetes mellitus (T2DM). While both modalities exploit the energy-sensing enzyme AMPK to attain glucose homeostasis, the synergistic effect of these two treatments is not distinctly supported by the literature. Further, an antagonistic dynamic has been observed in cases where metformin and exercise were combined. Reduction of insulin-sensitizing effects of exercise and an overall hindrance of exercise performance and adaptations have been reported and could suggest the possible incongruity of these two modalities. The aim of this review is to elucidate the effect that metformin and exercise have on the management of the metabolic abnormalities observed in T2DM and to provide an insight into the interaction of these two modalities.

The Influence of Physical Activity on the Bioactive Lipids Metabolism in Obesity-Induced Muscle Insulin Resistance

High-fat diet consumption and lack of physical activity are important risk factors for metabolic disorders such as insulin resistance and cardiovascular diseases. Insulin resistance is a state of a weakened response of tissues such as skeletal muscle, adipose tissue, and liver to insulin, which causes an increase in blood glucose levels. This condition is the result of inhibition of the intracellular insulin signaling pathway. Skeletal muscle is an important insulin-sensitive tissue that accounts for about 80% of insulin-dependent glucose uptake. Although the exact mechanism by which insulin resistance is induced has not been thoroughly understood, it is known that insulin resistance is most commonly associated with obesity. Therefore, it is believed that lipids may play an important role in inducing insulin resistance. Among lipids, researchers’ attention is mainly focused on biologically active lipids: diacylglycerols (DAG) and ceramides. These lipids are able to regulate the activity of intracellular enzymes, including those involved in insulin signaling. Available data indicate that physical activity affects lipid metabolism and has a positive effect on insulin sensitivity in skeletal muscles. In this review, we have presented the current state of knowledge about the impact of physical activity on insulin resistance and metabolism of biologically active lipids.

Effects of β-glucan Rich Barley Flour on Glucose and Lipid Metabolism in the Ileum, Liver, and Adipose Tissues of High-Fat Diet Induced-Obesity Model Male Mice Analyzed by DNA Microarray

We evaluated whether intake of β-glucan-rich barley flour affects expression levels of genes related to glucose and lipid metabolism in the ileum, liver, and adipose tissues of mice fed a high-fat diet. C57BL/6J male mice were fed a high-fat diet supplemented with high β-glucan barley, for 92 days. We measured the expression levels of genes involved in glucose and lipid metabolism in the ileum, liver, and adipose tissues using DNA microarray and q-PCR. The concentration of short-chain fatty acids (SCFAs) in the cecum was analyzed by GC/MS. The metabolic syndrome indices were improved by barley flour intake. Microarray analysis showed that the expression of genes related to steroid synthesis was consistently decreased in the liver and adipose tissues. The expression of genes involved in glucose metabolism did not change in these organs. In liver, a negative correlation was showed between some SCFAs and the expression levels of mRNA related to lipid synthesis and degradation. Barley flour affects lipid metabolism at the gene expression levels in both liver and adipose tissues. We suggest that SCFAs are associated with changes in the expression levels of genes related to lipid metabolism in the liver and adipose tissues, which affect lipid accumulation.

Sleeve Gastrectomy Surgery Improves Glucose Metabolism by Downregulating the Intestinal Expression of Sodium-Glucose Cotransporter-3

AIMS

Sleeve gastrectomy (SG) has been proven effective in the treatment of obesity and type 2 diabetes. We hypothesized that SGLT3 may play an important role in the mechanism of glucose control and weight loss after SG.

MATERIALS AND METHODS

Daily body weight and food intake were measured in SG and sham-operated mice. Glucose tolerance test, SGLT3 agonist (αMG), and SGLT1 inhibitor (phlorizin) perfusion experiments were used to detect changes in intestinal SGLT3 and SGLT1 activity following SG. Expression of SGLT3a and SGLT1 was assessed at 2 weeks, 1 month after surgery by quantitative PCR and fluorescence immunoassay. Hematoxylin and eosin staining was used to detect morphological changes in the villi. SGLT3 and SGLT1 expression was measured after stimulation of human intestinal epithelial cells (HIEC).

RESULTS

Both the body weight and daily food intake of the SG-treated mice decreased within 30 days after surgery. Oral glucose absorption was significantly reduced at 30 days. The intestinal stimulation proved that SG can improve glucose metabolism, which can be reversed by αMG and enhanced by phlorizin. Villus height and surface area of the intestine in SG mice decreased after surgery. mRNA expression of SGLT3a and SGLT1 decreased at 2 weeks and 1 month after SG, immunofluorescence also confirmed these changes. HIEC stimulation confirmed that αMG could increase the expression of SGLT3 and SGLT1, but the expression of SGLT1 was down regulated when phlorizin was added to the medium.

CONCLUSION

The results suggest that reducing SGLT3 expression might contribute to lowering blood glucose and controlling body weight after SG.