Insulin Sensitivity Test Research Articles

Dietary Pectin from Premna microphylla Turcz Leaves Prevents Obesity by Regulating Gut Microbiota and Lipid Metabolism in Mice Fed High-Fat Diet.

The present study was designed to investigate the protective effects of pectin extracted from Premna microphylla Turcz leaves (PTP) against high-fat-diet (HFD)-induced lipid metabolism disorders and gut microbiota dysbiosis in obese mice. PTP was made using the acid extraction method, and it was found to be an acidic pectin that had relative mole percentages of 32.1%, 29.2%, and 26.2% for galacturonic acid, arabinose, and galactose, respectively. The administration of PTP in C57BL/6J mice inhibited the HFD-induced abnormal weight gain, visceral obesity, and dyslipidemia, and also improved insulin sensitivity, as revealed by the improved insulin tolerance and the decreased glucose levels during an insulin sensitivity test. These effects were linked to increased energy expenditure, as demonstrated by the upregulation of thermogenesis-related protein UCP1 expression in the brown adipose tissue (BAT) of PTP-treated mice. 16S rRNA gene sequencing revealed that PTP dramatically improved the HFD-induced gut dysbiosis by lowering the ratio of Firmicutes to Bacteroidetes and the quantity of potentially harmful bacteria. These findings may provide a theoretical basis for us to understand the functions and usages of PTP in alleviating obesity.

Chronic oral LPS administration does not increase inflammation or induce metabolic dysregulation in mice fed a western-style diet.

Lipopolysaccharides (LPS) present in the intestine are suggested to enter the bloodstream after consumption of high-fat diets and cause systemic inflammation and metabolic dysregulation through a process named "metabolic endotoxemia." This study aimed to determine the role of orally administered LPS to mice in the early stage of chronic low-grade inflammation induced by diet. We supplemented the drinking water with E. coli derived LPS to mice fed either high-fat Western-style diet (WSD) or standard chow (SC) for 7 weeks (n = 16-17). Body weight was recorded weekly. Systemic inflammatory status was assessed by in vivo imaging of NF-κB activity at different time points, and glucose dysregulation was assessed by insulin sensitivity test and glucose tolerance test near the end of the study. Systemic LPS exposure was estimated indirectly via quantification of LPS-binding protein (LBP) and antibodies against LPS in plasma, and directly using an LPS-sensitive cell reporter assay. Our results demonstrate that weight development and glucose regulation are not affected by LPS. We observed a transient LPS dependent upregulation of NF-κB activity in the liver region in both diet groups, a response that disappeared within the first week of LPS administration and remained low during the rest of the study. However, WSD fed mice had overall a higher NF-κB activity compared to SC fed mice at all time points independent of LPS administration. Our findings indicate that orally administered LPS has limited to no impact on systemic inflammation and metabolic dysregulation in mice fed a high-fat western diet and we question the capability of intestinally derived LPS to initiate systemic inflammation through a healthy and uncompromised intestine, even when exposed to a high-fat diet.

#1316 Sirtuin 3 promotes renal gluconeogenesis in fibrotic kidneys

Abstract Background and Aims Decreased renal gluconeogenesis is currently identified as a hallmark of chronic kidney disease (CKD), which may contribute to renal fibrosis. Sirt3 is a crucial metabolic sensor that regulates ATP generation, mitochondrial adaptive response to stress, and glucose metabolism. It has been shown that Sirt3 is renal protective in fibrotic kidneys, however its underlying mechanisms is not completely known. In this study, we aimed to investigated whether Sirt3 inhibits CKD associated renal fibrosis through restoring renal gluconeogenesis. Method 1. Animal model of renal fibrosis (in vivo) For unilateral ureter obstructed (UUO) mouse model, a. Twenty-eight C57 mice were divided into four groups: sham + Vehicle, UUO + Vehicle, UUO + 3-TYP and UUO + HKL group. Mice were treated with saline or 20 mg/kg 3-TYP, an inhibitor of SIRT3 or 1 mg/kg HKL, an activator of SIRT3 daily (i.p.). b. Fourteen C57 mice were divided into two groups: Ad-Sirt 3 or Ad-LacZ (0.5 × 109 pfu/100 μL) was injected into the left renal artery before the UUO operation. Systemic glucose metabolism was evaluated by insulin and glucose tolerance tests. 7 or 14 days after operation, kidney tissues were collected and performed histopathological and molecular examination. 2. Primary murine renal tubules fibrosis (ex vivo) Primary renal tubules were isolated from C57 mouse of 4 weeks of age. 5 ng/mL TGF-β was added to culture medium for inducing fibrosis. After this Sirt3 was inhibited by 3-TYP (25 μm) or activated by HKL (2 μm) or overexpressed by adenovirus for different time periods (1, 3, 24, 48 hours). Protein or RNA samples were taken to evaluate renal fibrosis and gluconeogenesis. 3. Human renal epithelial (HK2) cells culture and treatment (in vitro) TGF-β stimulated HK2 cells were used as an in vitro model. Sirt3 was inhibited by 3-TYP or activated by HKL or overexpressed by adenovirus. Protein and RNA samples were taken to evaluate renal fibrosis and gluconeogenesis. Glucose and lactate were measured in supernatant of culture medium. Results In vivo, Masson staining showed that 3-TYP treatment increased the tubulointerstitial collagen deposition of UUO kidneys (Fig. 1A). WB results indicated that 3-TYP enhanced the increased expression of fibrotic marks (Fibronectin, Collagen-I, Vimentin) (Fig. 1B), and further reduced the expression of gluconeogenesis limitation enzyme (PCK1, FBP1) and transcription factors (PGC-1α and FOXO1) 14 days after UUO operation (Fig. 1C). Conversely, HKL treatment or overexpression of Sirt3 in UUO kidney reduced expression of fibrotic marks, increased the expression of gluconeogenesis markers (Fig. 1D-E). 3-TYP increased the lactate concentration in UUO kidneys (Fig. 1F). Insulin sensitivity and glucose clearance tests showed that treatment with 3-TYP further damaged the glucose homeostasis in UUO mice (Fig. 1G-J). Ex vivo, q-PCR results showed that the mRNA of Sirt3 was significantly decreased by time after TGF-β stimulation while the mRNA of FN, Snail was up-regulated and PCK1 and FBP1 were down-regulated (Fig. 2A-D). WB showed that 3-TYP treatment inhibited the expression of PCK1, FBP1 and PGC-1α, FOXO1 (Fig. 2E), however, HKL treatment or overexpressed of Sirt3 by adenovirus increased the expression of gluconeogenesis markers respectively in primary renal tubules (Fig. 2F). In vitro, WB showed that transfection of Sirt3 increased the expression of gluconeogenesis markers and decreased the expression of fibrotic marks of HK2 cells in a fibrotic condition (Fig. 3A-B). Moreover, 3-TYP treatment further decreased the mRNA expression of PCK1 and FBP1 in TGF-β stimulated HK2 cells (Fig. 3C-D). The increased lactate concentration and decreased glucose concentration in the culture medium of TGF-β stimulated HK2 cells were further escalated after 3-TYP treatment (Fig. 3E-F) while reversed after overexpression of Sirt3 (Fig. 3G-H). Conclusion Sirt 3 promotes renal gluconeogenesis in fibrotic kidneys through up-regulation of renal gluconeogenic enzyme PCK1 and FBP1 expression, which is associated with activation of renal metabolic transcription factors PGC-1α and FOXO1.

265-LB: Human Skeletal Muscle Mitochondrial Dynamics across the Insulin-Sensitivity Spectrum

Introduction: There is immense dispute as to whether perturbations in skeletal muscle mitochondrial function contribute to the onset and progression of type 2 diabetes (T2D). The purpose of this study was to examine differences in mitochondrial dynamics, structure, and energetic function in humans across the spectrum of insulin sensitivity. Methods: 58 sedentary adults (37±12 years) were enrolled into one of three groups based upon the following criteria: (1) healthy weight without T2D (HW; BMI: 22.6±1.8 kg/m2 and HbA1c: 5.0±1.1 %); (2) overweight/obesity without T2D (Ov/Ob; BMI: 32.6±3.3 kg/m2 and HbA1c: 5.6±0.4 %); or (3) overweight/obesity with T2D (T2D; BMI: 36.1±6.5 kg/m2 and HbA1c: 6.9±0.9 %). Participants underwent a 3-day inpatient stay consisting of body composition (DXA), aerobic capacity (VO2MAX), and insulin sensitivity (hyperinsulinemic euglycemic clamp). Prior to insulin sensitivity testing, a skeletal muscle biopsy was obtained for determination of mitochondrial dynamics (Western blot), DNA content (qPCR), ultrastructure (electron microscopy), and respiratory capacity (respirometry). Comparisons were made using a one-way ANOVA with contrasts. Results: Insulin sensitivity and aerobic capacity were lower in Ov/Ob and T2D compared to HW. Markers of mitochondrial fission were higher in T2D (Drp1Ser616, MiD49), and fusion lower in T2D and Ov/Ob (Mfn2). The mitophagy marker Parkin was higher in T2D only while Pink1 was lower in T2D relative to Ov/Ob but not HW. The autophagy marker LC3II was higher in Ov/Ob. Mitochondrial content was lower in Ov/Ob and T2D relative to HW. Mitochondrial respiratory capacity was similar between groups. Conclusions: T2D is associated with heightened expression of proteins required for mitochondrial quality control and reduced mitochondrial volume despite intact respiratory function. These data support the notion that mitochondria adapt to progressive insulin resistance by increasing fragmentation to maintain bioenergetic capacity. Disclosure C. L. Axelrod: None. C. Fealy: Employee; Mission Therapeutics. C. L. Hoppel: None. J. P. Kirwan: None. W. S. Dantas: None. E. R. M. Zunica: None. K. Belmont: None. E. C. Heintz: None. G. Davuluri: None. J. T. Mey: None. M. Erickson: None. H. Fujioka: None. Funding National Institutes of Health (DK108089, GM104940)

Deficiency of S100 calcium binding protein A9 attenuates vascular dysfunction in aged mice

BackgroundS100 calcium-binding protein A9 (S100A9) is a danger-associated molecular pattern molecule that mediates the inflammatory response. Inflammation is essential in aging-related cardiovascular diseases. However, less is known regarding the role of S100A9 in vascular aging. MethodsS100A9 null mice were used to investigate the role of S100A9 in aging-related pathologies. Artery rings were used to measure the functional characteristics of vascular with a pressurized myograph. Telomere length, Sirtuin activity, oxidative stress, and endothelial nitric oxide synthetase (eNOS) activity were used to elevate vascular senescence. Intraperitoneal glucose tolerance (IPGTT) and insulin sensitivity test (IST) were employed to investigate the effects of S100A9 on insulin resistance. Inflammation response was reflected by the concentration of inflammatory cytokines. The Toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE) inhibitors were used to identify the downstream molecular mechanisms of S100A9 in aging-induced senescence in endothelial cells. ResultsS100A9 expression in vascular increased with aging in mice and humans. Deficiency of S100A9 alleviated vascular senescence in aged mice, as evidenced by increased telomere length, Sirtuin activity, and eNOS activity. Meanwhile, S100A9 knockout improved endothelium-dependent vasodilatation and endothelial continuity in aged mice. Moreover, the increased insulin resistance, oxidative stress, and inflammation were mitigated by S100A9 deletion in aged mice. In vitro, S100A9 induced senescence in endothelial cells, and that effect was blunted by TLR4 but not RAGE inhibitors. ConclusionThe present study suggested that S100A9 may contribute to aging-related pathologies and endothelial dysfunction via the TLR4 pathway. Therefore, targeting S100A9/TLR4 signaling pathway may represent a crucial therapeutic strategy to prevent age-related cardiovascular diseases.

Optimization of identifying insulinaemic pharmacokinetic parameters using artificial neural network

Background and ObjectiveThe identification of insulinaemic pharmacokinetic parameters using the least-squares criterion approach is easily influenced by outlying data due to its sensitivity. Furthermore, the least-squares criterion has a tendency to overfit and produce incorrect results. Hence, this research proposes an alternative approach using the artificial neural network (ANN) with two hidden layers to optimize the identifying of insulinaemic pharmacokinetic parameters. The ANN is selected for its ability to avoid overfitting parameters and its faster speed in processing data. Methods18 voluntarily participants were recruited from the Canterbury and Otago region of New Zealand to take part in a Dynamic Insulin Sensitivity and Secretion Test (DISST) clinical trial. A total of 46 DISST data were collected. However, due to ambiguous and inconsistency, 4 data had to be removed. Analysis was done using MATLAB 2020a. Results and DiscussionResults show that, with 42 gathered dataset, the ANN generates higher gains, ∅P = 20.73 [12.21, 28.57] mU·L·mmol−1·min−1 and ∅D = 60.42 [26.85, 131.38] mU·L·mmol−1 as compared to the linear least square method, ∅P = 19.67 [11.81, 28.02] mU·L·mmol−1 ·min−1 and ∅D = 46.21 [7.25, 116.71] mU·L·mmol−1. The average value of the insulin sensitivity (SI) of ANN is lower with, SI = 16 × 10−4 L·mU−1 ·min−1 than the linear least square, SI = 17 × 10−4 L·mU−1 ·min−1. ConclusionAlthough the ANN analysis provided a lower SI value, the results were more dependable than the linear least square model because the ANN approach yielded a better model fitting accuracy than the linear least square method with a lower residual error of less than 5%. With the implementation of this ANN architecture, it shows that ANN able to produce minimal error during optimization process particularly when dealing with outlying data. The findings may provide extra information to clinicians, allowing them to gain a better knowledge of the heterogenous aetiology of diabetes and therapeutic intervention options.

Caryopteris odorata and its metabolite coumarin attenuate characteristic features of cardiometabolic syndrome in high-refined carbohydrate-high fat-cholesterol-loaded feed-fed diet rats.

Caryopteris odorata (D. Don) B.L. Robinson (Verbenaceae family) is an aromaric shrub traditionally used to treat diabetes and related pathologies (diabetic foot ulcer), cancer/tumors, wound healing, and inflammation. It is enriched with flavonoids and phenolics like coumarins, quercetin, gallic acid, coumaric acid, stigmasterol, α-tocopherol, and iridoids. C. odorata has been reported as having α-glucosidase, anti-inflammatory, and anti-oxidant properties. Its effectiveness in preventing cardiometabolic syndrome has not yet been assessed. This study aims to investigate the potential efficacy of C. odorata and coumarin for characteristic features of cardiometabolic syndrome (CMS), including obesity, dyslipidemia, hyperglycemia, insulin resistance, and hypertension by using high-refined carbohydrate-high fat-cholesterol (HRCHFC)-loaded feed-fed rats. Chronic administration of C. odorata and coumarin for 6weeks revealed a marked attenuation in body and organ weights, with a consistent decline in feed intake compared to HRCHFC diet fed rats. The test materials also caused a significant reduction in the blood pressure (systolic, diastolic, and mean) and heart rate of HRCHFC-diet fed rats. Improved glucose tolerance and insulin sensitivity tests were also observed in test material administered rats compare to only HRCHFC-diet fed rats. C. odorata and coumarin-treated animals produced a marked decline in serum FBG, TC, TG, LFTs, and RFTs, while an increase in serum HDL-C levels was noticed. C. odorata and coumarin also significantly modulated inflammatory biomarkers (TNFα, IL-6), adipokines (leptin, adiponectin, and chemerin), and HMG-CoA reductase levels, indicating prominent anti-inflammatory, cholesterol-lowering, and anti-hyperglycemic potential. Administration of C. odorata and coumarin exhibited a marked improvement in oxidative stress markers (CAT, SOD, and MDA). Histopathological analysis of liver, heart, kidney, pancreas, aorta, and fat tissues showed a revival of normal tissue architecture in C. odorata and coumarin-treated rats compared to only HRCHFC-diet fed rats. These results suggest that C. odorata and coumarin possess beneficial effects against the characteristic features of CMS (obesity, insulin resistance, hypertension, and dyslipidemia) in HRCHFC feed-administered rats. These effects were possibly mediated through improved adipokines, glucose tolerance, and insulin sensitivity, the attenuation of HMG-CoA reductase and inflammatory biomarkers, and modulated oxidative stress biomarkers. This study thus demonstrates a rationale for the therapeutic potential of C. odorata and coumarin in CMS.

Phenols from Potentilla anserina L. Improve Insulin Sensitivity and Inhibit Differentiation in 3T3-L1 Adipocytes in Vitro.

Potentilla anserina L., a well-known perennial herb, is widely used in traditional Tibetan medicine and used as a delicious food in humans. The present investigation reports on the activity of P. anserina phenols (PAP) in regulating glycolipid metabolism in 3T3-L1 adipocytes. Insulin sensitivity tests showed that PAP improved insulin-stimulated glucose uptake by promoting the phosphorylation of serine/threonine kinase Akt. Moreover, an assay involving the differentiation of 3T3-L1 preadipocytes demonstrated that PAP also decreased the accumulation of lipid droplets by suppressing the expression of adipokines during the differentiation process. In addition, the underlying mechanism from the aspects of energy metabolism and oxidative stress is also discussed. The improvement in energy metabolism was supported by an increase in mitochondrial membrane potential (MMP) and intracellular ATP. Amelioration of oxidative stress was supported by decreased levels of intracellular reactive oxygen species (ROS). In summary, our findings suggest that PAP can ameliorate the disorder of glycolipid metabolism in insulin resistant 3T3-L1 adipocytes by improving energy metabolism and oxidative stress and might be an attractive candidate for the treatment of diabetes.

Effects of the Seed Oil of Carica papaya Linn on Food Consumption, Adiposity, Metabolic and Inflammatory Profile of Mice Using Hyperlipidic Diet.

Background: Studies indicate that different parts of Carica papaya Linn have nutritional properties that mean it can be used as an adjuvant for the treatment of various pathologies. Methods: The fatty acid composition of the oil extracted from the seeds of Carica papaya Linn was evaluated by gas chromatography, and an acute toxicity test was performed. For the experiment, Swiss mice were fed a balanced or high-fat diet and supplemented with saline, soybean oil, olive oil, or papaya seed oil. Oral glucose tolerance and insulin sensitivity tests were performed. After euthanasia, adiposity, glycemia, total cholesterol and fractions, insulin, resistin, leptin, MCP-1, TNF-α, and IL-6 and the histology of the liver, pancreas, and adipose tissue were evaluated. Results: Papaya seed oil showed predominance of monounsaturated fatty acids in its composition. No changes were observed in the acute toxicity test. Had lower food intake in grams, and caloric intake and in the area of adipocytes without minimizing weight gain or adiposity and impacting the liver or pancreas. Reductions in total and non-HDL-c, LDL-c, and VLDL-c were also observed. The treatment had a hypoglycemic and protective effect on insulin resistance. Supplementation also resulted in higher leptin and lower insulin and cytokine resistance. Conclusions: Under these experimental conditions, papaya seed oil led to higher amounts of monounsaturated fatty acids and had hypocholesterolemic, hypotriglyceridemic, and hypoglycemic effects.

Contribution of RAS, ROS and COX-1-derived prostanoids to the contractile profile of perivascular adipose tissue in cafeteria diet-induced obesity

AimsObesity can lead to the loss of the anticontractile properties of perivascular adipose tissue (PVAT). Given that cafeteria (CAF) diet reflects the variety of highly calorie and easily accessible foods in Western societies, contributing to obesity and metabolic disorders, we sought to investigate the impact of CAF diet on PVAT vasoactive profile and the involvement of renin-angiotensin system, oxidative stress, and cyclooxygenase pathway. Main methodsMale Balb/c mice received standard or CAF diet for 4 weeks. Oral glucose tolerance and insulin sensitivity tests were performed, and fasting serum glucose, cholesterol and triglyceride parameters were determined. Vascular reactivity, fluorescence and immunofluorescence analyzes were carried out in intact thoracic aorta in the presence or absence of PVAT. Key findingsCAF diet was effective in inducing obesity and metabolic disorders, as demonstrated by increased body weight gain and adiposity index, hyperlipidemia, hyperglycemia, glucose intolerance and insulin insensitivity. Importantly, CAF diet led to a significant decrease in aortic contractility which was restored in the presence of PVAT, exhibiting therefore a contractile profile. The contractile effect of PVAT was associated with the activation of AT1 receptor, reactive oxygen species, cyclooxygenase-1, thromboxane A2 and prostaglandin E2 receptors. SignificanceThese findings suggest that the contractile profile of PVAT involving the renin-angiotensin system activation, reactive oxygen species and cyclooxygenase-1 metabolites may be a protective compensatory adaptive response during early stage of CAF diet-induced obesity as an attempt to restore the impaired vascular contraction observed in the absence of PVAT, contributing to the maintenance of vascular tone.

Extracts and fractions of Gymnema sylvestre restore liver and kidney function by regulating tissue and serum transaminases in the type 2 diabetic rat

Diabetes mellitus usually induce kidney and liver complications, characterized by an increase in transaminases activity. The aim of this study was to evaluate the activity of Gymnema sylvestre on the variation of tissue and serum transaminases activities in high sucrose diet and dexamethasone-induced diabetic rats. The animals were fed with high sucrose diet and 20% sugar water for 12 weeks then, received an intraperitoneal injection of dexamethasone (8mg/kg) once a day for 5 days between 07 and 08 am. After induction, the insulin sensitivity test was performed and the animals were divided into 7 groups. The experimental groups received extracts (aqueous and methanolic) and fractions (methylene chloride and methanol) of G. sylvestre once a day for 14 days. At the end of experiment, the animals were sacrificed and the blood, liver and kidney were collected for evaluation of transaminases and histopathology reduced by the plant. The activity of liver and kidney transaminases of the diabetic negative control (DNC) group on days 1 and 14 had significantly elevated (P<0.001) compared with this of the normoglycemic negative control (NNC) group and the different treated groups. This trend was also observed at the serum level but only with ASAT. Histological analysis revealed hepatic leukocyte infiltrations and mesangial expansions in the urinary space in the DNC group on days 1 and 14. These tissue abnormalities were corrected in groups receiving extracts and fractions of G. sylvestre. This study suggests that the extracts and fractions of G. sylvestre restore tissue damage in diabetic rats.

A long-term anti-inflammation markedly alleviated high-fat diet-induced obesity by repeated administrations of overexpressing IL10 human umbilical cord-derived mesenchymal stromal cells

ObjectivesObesity is a chronic process and could activate various inflammatory responses, which in turn aggravates obesity and related metabolic syndrome. Here we explored whether long-term inhibition of inflammation could successfully alleviate high-fat diet (HFD)-induced obesity.MethodsWe constructed stable overexpressing interleukin 10 (IL10) human umbilical cord-derived mesenchymal stromal cells (HUCMSCs) which repeatedly were applied to obesity mice with HFD feeding to obtain a long-term anti-inflammation based on the prominent anti-inflammation effects of IL10 and immunomodulatery effects of HUCMSCs. Then we monitored the features of obesity including body weight, serum ALT, AST, and lipids. In addition, glucose homeostasis was determined by glucose tolerance and insulin sensitivity tests. The infiltrated macrophages in adipose tissues and hepatic lipid accumulation were detected, and the expressions of adipogenesis and inflammatory genes in adipose tissues were examined by real-time (RT) PCR and western blot analysis.ResultsCompared with HUCMSCs, IL10-HUCMSCs treatment had much better anti-obesity effects including body weight reduction, less hepatic lipids accumulation, lower amount and size of adipocyte, greater glucose tolerance, less systemic insulin resistance, and less adipose tissue inflammation in HFD feeding mice. Finally, IL10-HUCMSCs could decrease the activation of MAPK JNK of adipose tissue induced by HFD. The inhibition of MAPK JNK signal pathway by a small chemical molecule SP600125 in 3T3-L1 cells, a preadipocyte line, reduced the differentiation of adipocytes and lipid droplet accumulation.ConclusionA lasting anti-inflammation based on gene modified stem cell therapy is an effective strategy in preventing diet-induced obesity and obesity-related metabolic syndrome.

Antidiabetic Effect of Rehmanniae Radix Based on Regulation of TRPV1 and SCD1.

Purpose: This study aimed to disclose the antidiabetic mechanisms of Rehmanniae Radix (RR). Methods: The antidiabetic effect of RR was studied in Streptozocin (STZ)–induced diabetes mellitus (DM) rats and HepG2 cells with insulin resistance (IR). Antidiabetic targets and signaling pathways of RR were confirmed by the network pharmacology and transcriptome analysis as well as HK2 cells induced by high glucose (HG). Results: After the DM rats were administrated RR extract (RRE) for 4 weeks, their body weight was 10.70 ± 2.00% higher than those in the model group, and the fasting blood glucose (FBG), AUC of the oral glucose tolerance test, and insulin sensitivity test values were 73.23 ± 3.33%, 12.31 ± 2.29%, and 13.61 ± 5.60% lower in the RRE group, respectively. When compared with the model group, an increase of 45.76 ± 3.03% in the glucose uptake of HepG2 cells with IR was seen in the RRE group. The drug (RR)–components–disease (DM)–targets network with 18 components and 58 targets was established. 331 differentially expressed genes (DEGs) were identified. TRPV1 and SCD1 were important DEGs by the intersectional analysis of network pharmacology and renal transcriptome. The TRPV1 overexpression significantly inhibited apoptosis and oxidative stress of the HK2 cells induced by HG, while SCD1 overexpression induced apoptosis and oxidative stress of the HK2 cells induced by low and high glucose. When compared to the HG group, the mRNA and protein expressions of TRPV1 in the presence of RRE (100 μg/ml) increased by 3.94 ± 0.08 and 2.83 ± 0.40 folds, respectively. Conclusion: In summary, RR displayed an inspiring antidiabetic effect by reducing FBG and IR, upregulating the mRNA and protein expressions of TRPV1, and downregulating mRNA expression of SCD1. Induction of TRPV1 and inhibition of SCD1 by RR was possibly one of its antidiabetic mechanisms.

Investigation into the Role of the Skeletal Muscle BBSome in Insulin Sensitivity

The BBSome is a protein complex composed of eight Bardet‐Biedl syndrome (BBS) proteins including BBS1. Humans and mice lacking a functional BBSome display impaired insulin sensitivity, hyperglycemia, and type 2 diabetes, highlighting the importance of this protein complex in the control of insulin action and glucose homeostasis. However, the contribution of the BBSome in insulin sensitive tissues such as the skeletal muscle to the control of insulin sensitivity is not clear. We hypothesized that BBSome deficiency in the skeletal muscle will lead to insulin resistance and diabetes. To test this, we generated a novel conditional knockout mouse model lacking the Bbs1 gene specifically in the skeletal muscle. This was achieved by crossing mice expressing floxed alleles of the Bbs1 gene (Bbs1fl/fl) with mice expressing Cre‐recombinase in the skeletal muscle (MCKCre). These mice were further bred with tdTomato reporter mice to validate Cre‐recombinase using red tdTomato protein fluorescence. Body weight, glucose handling (measured using glucose tolerance test, GTT) and insulin sensitivity (measured using insulin tolerance test, ITT) of Bbs1fl/fl/MCKCre mice were compared to littermate controls. Furthermore, we used Western blot to test the ability of insulin to activate Akt, a key signaling pathway associated with the insulin receptor. We found that both male and female Bbs1fl/fl/MCKCre mice have no significant alteration in body weight relative to wild type controls (31.4±1.5 vs 31.1±1.0 g in males and 24.1±2.2 vs 23.0±1.7 g in females at 16 weeks of age). There was also no significant change in glucose handling (GTT AUC: 30608±2106 vs 30741±3480 in males and 28836±4466 vs 26530±3334 AUC in females) and insulin sensitivity (ITT AUC: 11017±1285 vs 9935±1080 in males and 8223±792 vs 5803±978 AUC in females) between Bbs1fl/fl/MCKCre mice and controls. This was further confirmed by the lack of difference in insulin‐induced Akt activation in skeletal muscle, liver, and adipose tissue. These findings suggest that BBS1 protein in skeletal muscle is not required for insulin sensitivity. Next, we assessed whether challenging the mice with high fat/high sucrose diet (HFHSD), starting at weaning, could reveal a role for the skeletal muscle BBSome in insulin sensitivity. The weight gain evoked by HFHSD was comparable between Bbs1fl/fl/MCKCre mice and controls (32.3±3.1 vs 33.3±1.0 g in males at 10 weeks of age). Once they reach 16 weeks of age, the HFHSD mice will be subject to glucose tolerance and insulin sensitivity tests to determine if obesity exaggerates hyperglycemia and insulin resistance in Bbs1fl/fl/MCKCre mice.

The lysine demethylase KDM6A regulates pancreatic β cells function

Background and ObjectiveDiabetes mellitus refers to a group of metabolic disorders characterized by impaired glucose homeostasis. Both type 1 diabetes (T1D) and type 2 diabetes (T2D) are characterized by insulin insufficiency. β cell failure in diabetes are often due to posttranslational modifications of histones and transcription factors. Lysine demethylase 6A (KDM6A) belongs to the KDM6 family of histone H3 lysine 27 (H3K27) demethylases which is important for development of various organs. The objective of this study is to investigate whether KDM6A regulates pancreatic β cell function using targeted β cell‐specific deletion of KDM6Agene.Methods and ResultsBriefly, inducible insulin 1‐cre and KDM6A‐loxp mice were bed to generate cre‐loxp mice. Injection of tamoxifen induced deletion of KDM6A gene in β cells which led to increased H3K27me3 levels. KDM6A‐KO mice exhibited reduced baseline insulin levels compared with wild‐type mice. Interestingly, despite low baseline insulin levels, KDM6A‐KO mice demonstrated enhanced glucose tolerance. Insulin release was increased in KDM6A‐KO mice vs WT mice at 15 min following glucose challenge. Furthermore, ex vivo glucose‐induced insulin secretion was increased in cultured islets isolated from KDM6A‐KO mice. In cultured Min6 β cells, knockdown of KDM6A using KDM6A shRNA largely enhanced glucose‐induced insulin release. When challenged with high‐fat diet, KDM6A‐KO mice displayed similar weight gain vs wild‐type mice. However, the insulin sensitivity test showed that KDM6A‐KO enhanced peripheral insulin sensitivity as evidenced by the delayed recovery of glucose level in KDM6A‐KO mice fed with high‐fat diet.ConclusionOur results suggest a novel role of KDM6A in the regulation of pancreatic β cell function. KDM6A may be a potential therapeutic target for β cell dysfunction.

Perinatal low-fat dietary intervention affects glucose metabolism in female adult and aging offspring.

Diabetes confers a high risk of developing poor health in later life in women. Based on the Developmental Origins of Health and Disease theory, the present study was undertaken to investigate the efficacy of perinatal fat restriction in maternal high-fat-exposed female offspring to maintain glucose homeostasis in later life between adulthood and aging. Low-fat dietary intervention during either gestation or lactation was performed using a high-fat diet-induced maternal obesity mouse model (HFD mice). Physiological metabolic parameters, including body weight and serum levels of total cholesterol and triglycerides, were monitored. Glucose tolerance test and insulin sensitivity test were performed in 12- and 70-week-old offspring. Insulin-positive islet cells were also observed using immunohistochemical staining. HFD significantly induced abnormal weight gain, hyperlipidemia and impairment of both glucose tolerance and insulin sensitivity in offspring. Standard diet intake after weaning improved weight gain, serum total cholesterol level and glucose tolerance, but not insulin sensitivity, in 70-week-old offspring. Only perinatal fat restriction during both gestation and lactation, followed by standard food intake for the rest of their life, provided adequate efficacy to restore insulin sensitivity in aging female progeny. Perinatal low-fat intervention may prevent deterioration of glucose metabolism. To improve the health status over a female's lifespan, appropriate nutritional intervention during the early developmental stage may reset the disease trajectory and prevent the onset and development of diabetes. Geriatr Gerontol Int 2022; 22: 441-448.

Loss of toll-like receptor 4 ameliorates cardiovascular dysfunction in aged mice

BackgroundToll-like receptor 4 (TLR4) is a pattern recognition receptor of the innate immune system. TLR4 contributes to many aging-related chronic diseases. However, whether TLR4 is involved in cardiovascular injury during the aging process has not been investigated.MethodsThe effects of TLR4 on the cardiovascular system of aged mice were investigated in TLR4−/− mice. An intraperitoneal glucose tolerance test (IPGTT) and insulin sensitivity test (IST) were conducted to evaluate global insulin sensitivity. Echocardiography was used to measure cardiac structure and performance. An isolated artery ring assay was used to measure the vasodilator function of the thoracic aorta. The inflammatory response was reflected by the serum concentration of cytokines.ResultsTLR4 expression increased in the hearts and aortas of mice in an age-dependent manner. Loss of TLR4 increased insulin sensitivity in aged mice. Moreover, loss of TLR4 improved cardiac performance and endothelium-dependent vascular relaxation in aged mice. Importantly, the increases in serum inflammatory cytokines and oxidative stress in the heart and aorta were also inhibited by TLR4 deficiency.ConclusionIn summary, loss of TLR4 improved cardiac performance and endothelium-dependent vascular relaxation in aged mice. The reduced inflammatory responses and oxidative stress may be the reason for the protective effects of TLR4 deficiency during aging. Our study indicates that targeting TLR4 is a potential therapeutic strategy for preventing aging-related cardiovascular disease.

Sex differences in behavior, response to LPS, and glucose homeostasis in middle-aged mice

Sex and age have distinct influences and roles in behavior and immune reactivity; yet, most studies use adult male rodents with little attention to middle age, a time associated with key physiological transitions in both sexes. Thus, this study investigated sex differences during middle age in behavior, immune response to lipopolysaccharide (LPS), and glucose regulation in C57BL/6 mice with GFP-tagged monocytes/microglia. Behaviorally, males performed better in tests of motor function (Open Field [OF], Grip Strength, Sticker Removal, Gait, and Pole tests) and displayed less depressive- and anxiety-like behaviors across multiple mood tests (OF, Elevated Zero Maze, Sucrose Preference, and Swim test). However, females performed better in tests of cognition (Barnes Maze and Novel Object Recognition). Following behavioral assessment, mice were given LPS to characterize sex-dependent inflammagen responses. Females displayed greater sickness behavior in the OF, higher levels of peripheral cytokines, and subtle neuroinflammation in the cortex, striatum, and hippocampus. A separate middle-aged cohort was used for glucose tolerance and insulin sensitivity testing. Both sexes had excessive blood glucose rebound after insulin challenge, but displayed differences following glucose administration, where males had higher baseline glucose and females remained hyperglycemic. This study suggests that during middle-age male mice have better emotional regulation and motor function, but not cognitive ability than females. Further, males are less sensitive than females to the acute effects of LPS peripherally and centrally, but both sexes showed sex-specific impairments in blood glucose regulation. Overall, it appears that middle age is an important transition point with multiple sex differences, some of which are unique to this stage of life.

Transient effect of aerobic exercise training on insulin sensitivity

BackgroundAerobic exercise training has well established effects on increasing insulin sensitivity. However, the extent to which exercise in the absence of weight loss and/or negative energy balance results in sustained elevation in insulin sensitivity is unclear. ObjectiveThis study aimed to assess the effects of long-term aerobic exercise training on insulin sensitivity in healthy premenopausal women while controlling for energy balance. DesignFemale participants ages 20–40 (Mean BMI=27.0) trained three times per week throughout the study on a cycle ergometer under supervision of an exercise physiologist. Participants completed a pre-training evaluation and three post-training evaluations at times ranging from 8 to 20 weeks post-baseline, including insulin sensitivity and peak VO2 testing. Before each evaluation, participants stayed overnight in a room calorimeter for 23 h and food intake was adjusted to maintain energy balance. A cycle ergometer graded exercise test was completed after warm-up to determine peak oxygen uptake (VO2peak). Hyperinsulinemic-euglycemic clamp measures were conducted to determine insulin sensitivity. Adjusted and unadjusted models were performed for log insulin sensitivity and peak VO2 using linear model for repeated measures. ResultsData from 31 participants with complete data were analyzed. The models determined that mean VO2peak (F = 5.56 (3,89) p = 0.0015) and mean insulin sensitivity (F = 3.92 (3,65) p = 0.0123) differed among timepoints. Exercise training elicited an increase in VO2peak from pre-training (25.5 ± 1.15) to all three post-training evaluations (26.7 ± 1.15 vs. 27.4 ± 1.07 vs. 27.2 ± 1.17, respectively). In contrast, insulin sensitivity increased from pre-training to first post-training evaluation, but then returned to levels not different from baseline at the subsequent two evaluations. ConclusionsImprovement in insulin sensitivity resulting from exercise training appears to be transient and returns to baseline with continued training.

Maternal consumption of ɷ3 attenuates metabolic disruption elicited by saturated fatty acids-enriched diet in offspring rats

Background and aimsHigh-fat diet (HFD) intake during gestation and lactation has been associated with an increased risk of developing cardiometabolic disorders in adult offspring. We investigated whether metabolic alterations resulting from the maternal consumption of HFD are prevented by the addition of omega-3 (ɷ3) in the diet. Methods and resultsWistar rat dams were fed a control (C: 19% of lipids and ɷ6:ɷ3 = 12), HF (HF: 33% lipids and ɷ6:ɷ3 = 21), or HF enriched with ɷ3 (HFω3: 33% lipids and ɷ6:ɷ3 = 9) diet during gestation and lactation, and their offspring food consumption, murinometric measurements, serum levels of metabolic markers, insulin and pyruvate sensitivity tests were evaluated. The maternal HFD increased body weight at birth, dyslipidemia, and elevated fasting glucose levels in the HF group. The enrichment of ɷ3 in the maternal HFD led to lower birth weight and improved lipid, glycemic, and transaminase biochemical profile of the HFω3 group until the beginning of adulthood. However, at later adulthood of the offspring, there was no improvement in these biochemical parameters. ConclusionOur findings show the maternal consumption of high-fat ɷ3-rich diet is able to attenuate or prevent metabolic disruption elicited by HFD in offspring until 90 days old, but not in the long term, as observed at 300 days old of the offspring.