Decreased Insulin Sensitivity Research Articles

Inhibition of CILP2 Improves Glucose Metabolism and Mitochondrial Dysfunction in Sarcopenia via the Wnt Signalling Pathway.

Skeletal muscle is the primary organ involved in insulin-mediated glucose metabolism. Elevated levels of CILP2 are a significant indicator of impaired glucose tolerance and are predominantly expressed in skeletal muscle. It remains unclear whether CILP2 contributes to age-related muscle atrophy through regulating the glucose homeostasis and insulin sensitivity. Initially, the expression levels of CILP2 were assessed in elderly mice and patients with sarcopenia. Lentiviral vectors were used to induce either silencing or overexpression of CILP2 in C2C12 myoblast cells. The effects of CILP2 on proliferation, myogenic differentiation, insulin sensitivity and glucose uptake were evaluated using immunofluorescence, western blotting, real-time quantitative polymerase chain reaction, RNA sequencing, glucose uptake experiments, dual-luciferase reporter assays and co-immunoprecipitation (CO-IP). An adeno-associated virus-9 containing a muscle-specific promoter was injected into SAMP8 senile mice to observe the efficacy of CILP2 knockout. We found that there was more CLIP2 expressed in the skeletal muscle of ageing mice (+1.1-fold, p < 0.01) and in patients with sarcopenia (+2.5-fold, p < 0.01) compared to the control group. Following the overexpression of CILP2, Ki67 (-65%, p < 0.01), PCNA (-32%, p < 0.05), MyoD1 (-89%, p < 0.001), MyoG (-31%, p < 0.05) and MyHC (-85%, p < 0.001), which indicate proliferation and differentiation potential, were significantly reduced. In contrast, MuRF-1 (+59%, p < 0.05), atrogin-1 (+43%, p < 0.05) and myostatin (+31%, p < 0.05), the markers of muscular atrophy, were significantly increased. Overexpression of CILP2 decreased insulin sensitivity, glucose uptake (-18%, p < 0.001), GLUT4 translocation to the membrane and the maximum respiratory capacity of mitochondria. Canonical Wnt signalling was identified through RNA sequencing as a potential pathway for CILP2 regulation in C2C12, and Wnt3a was confirmed as an interacting protein of CILP2 in the CO-IP assay. The addition of recombinant Wnt3a protein reversed the inhibitory effects on myogenesis and glucose metabolism caused by CILP2 overexpression. Conversely, CILP2 knockdown promoted myogenesis and glucose metabolism. CILP2 knockdown improved muscle atrophy in mice, characterized by significant increases in time to exhaustion (+42%, p < 0.001), grip strength (+19%, p < 0.01), muscle mass (+15%, p < 0.001) and mean muscle cross-sectional area (+37%, p < 0.01). CILP2 knockdown enhanced glycogen synthesis (+83%, p < 0.001) and the regeneration of oxidative and glycolytic muscle fibres in SAMP8 ageing mice via the Wnt/β-catenin signalling pathway. Our results indicate that CILP2 interacts with Wnt3a to suppress the Wnt/β-catenin signalling pathway and its downstream cascade, leading to impaired insulin sensitivity and glucose metabolism in skeletal muscle. Targeting CILP2 inhibition could offer potential therapeutic benefits for sarcopenia.

Oxidised phosphatidylcholine induces sarcolemmal ceramide accumulation and insulin resistance in skeletal muscle.

Intracellular ceramide accumulation in specific cellular compartments is a potential mechanism explaining muscle insulin resistance in the pathogenesis of type 2 diabetes. Muscle sarcolemmal ceramide accumulation negatively impacts insulin sensitivity in humans, but the mechanism explaining this localised accumulation is unknown. Previous reports revealed that circulating oxidised LDL is elevated in serum of individuals with obesity and type 2 diabetes. Oxidised phosphatidylcholine, which is present in oxidised LDL, has previously been linked to ceramide pathway activation, and could contribute to localised ceramide accumulation in skeletal muscle. We hypothesised that oxidised phosphatidylcholine inversely correlates with insulin sensitivity in serum, and induces sarcolemmal ceramide accumulation and decreases insulin sensitivity in muscle. We used LC-MS/MS to quantify specific oxidised phosphatidylcholine species in serum from a cross-sectional study of 58 well-characterised individuals spanning the physiological range of insulin sensitivity. We also performed in vitro experiments in rat L6 myotubes interrogating the role of specific oxidised phosphatidylcholine species in promoting sarcolemmal ceramide accumulation, inflammation and insulin resistance in skeletal muscle cells. Human serum oxidised phosphatidylcholine levels are elevated in individuals with obesity and type 2 diabetes, inversely correlated with insulin sensitivity, and positively correlated with sarcolemmal C18:0 ceramide levels in skeletal muscle. Specific oxidised phosphatidylcholine species, particularly 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC), increase total ceramide and dihydroceramide and decrease total sphingomyelin in the sarcolemma of L6 myotubes by de novo ceramide synthesis and sphingomyelinase activation. POVPC also increases inflammatory signalling and causes insulin resistance in L6 myotubes. These data suggest that circulating oxidised phosphatidylcholine species promote ceramide accumulation and decrease insulin sensitivity in muscle, help explain localised sphingolipid accumulation and muscle inflammatory response, and highlight oxidised phosphatidylcholine species as potential targets to combat insulin resistance.

Single-Atom Ce-N-C Nanozyme Ameliorates Type 2 Diabetes Mellitus by Improving Glucose Metabolism Disorders and Reducing Oxidative Stress.

Type 2 diabetes mellitus (T2DM) as a chronic metabolic disease has become a global public health problem. Insulin resistance (IR) is the main pathogenesis of T2DM. Oxidative stress refers to an imbalance between free radical production and the antioxidant system, causing insulin resistance and contributing to the development of T2DM via several molecular mechanisms. Besides, the reduction in hepatic glycogen synthesis also leads to a decrease in peripheral insulin sensitivity. Thus, reducing oxidative stress and promoting glycogen synthesis are both targets for improving insulin resistance and treating T2DM. The current study aims to investigate the pharmacological effects of single-atom Ce-N-C nanozyme (SACe-N-C) on the improvement of insulin resistance and to elucidate its underlying mechanisms using HFD/STZ-induced C57BL/6J mice and insulin-resistant HepG2 cells. The results indicate that SACe-N-C significantly improves hepatic glycogen synthesis and reduces oxidative stress, as well as pancreatic and liver injury. Specifically, compared to the T2DM model group, fasting blood glucose decreased by 29%, hepatic glycogen synthesis increased by 17.13%, and insulin secretion increased by 18.87%. The sod and GPx in the liver increased by 17.80% and 25.28%, respectively. In terms of mechanism, SACe-N-C modulated glycogen synthesis through the PI3K/AKT/GSK3β signaling pathway and activated the Keap1/Nrf2 pathway to alleviate oxidative stress. Collectively, this study suggests that SACe-N-C has the potential to treat T2DM.

The effect of 60days of 6° head-down-tilt bed rest on circulating adropin, irisin, retinol binding protein-4 (RBP4) and individual metabolic responses in young, healthy males.

Alterations in the circulating concentrations and target-tissue action of organokines underpin the development of insulin resistance in microgravity and gravity deprivation. The purpose of this study was to examine changes in circulating adropin, irisin, retinol binding protein-4 (RBP4), and the metabolic response of healthy young males following 60days of 6° head-down-tilt (HDT) bed rest, with and without reactive jump training (RJT), to explore links with whole-body and tissue-specific insulin sensitivity. To our knowledge, this is the first time that adropin, irisin, and RBP4 have been studied in HDT bed rest. A total of 23 male subjects (29 ± 6years, 181 ± 6cm, 77 ± 7kg) were exposed to 60days of 6° HDT bed rest and randomized to a control (CTRL, n = 11) or a RJT (JUMP, n = 12) group (48 sessions with ≤4min total training time per session). Circulating adropin, irisin, and RBP4 were quantified in fasting serum before and after HDT bed rest. A subanalysis was performed a posteriori to investigate individual metabolic responses post-HDT bed rest based on subjects that showed an increase or decrease in whole-body insulin sensitivity (Matsuda index). There were significant main effects of time, but not group, for decreases in adropin, irisin, Matsuda index, and liver insulin sensitivity following HDT bed rest (p < 0.05), whereas RBP4 did not change. The subanalysis identified that in a subgroup with decreased whole-body insulin sensitivity (n = 17), RBP4 increased significantly, whereas adropin, irisin, and liver insulin sensitivity were all decreased significantly following HDT bed rest. Conversely, in a subgroup with increased whole-body insulin sensitivity (n = 6), liver insulin sensitivity increased significantly after HDT bed rest, whereas adropin, irisin, and RBP4 did not change. Investigating individual metabolic responses has provided insights into changes in circulating adropin, irisin, RBP4, in relation to insulin sensitivity following HDT bed rest. We conclude that adropin, irisin, and RBP4 are candidate biomarkers for providing insights into whole-body and tissue-specific insulin sensitivity to track changes in physiological responsiveness to a gravity deprivation intervention in a lean male cohort.

The Relationship between Vitamin D, Inflammatory Markers, and Insulin Resistance in Children.

In this study, we investigated 25-hydroxyvitamin D (25(OH)D, vitamin D), inflammatory hematologic ratios such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), monocyte/HDL-C ratio (MHR) and plasma atherogenic index (PAI) and possible relationships with insulin resistance (IR) in children. A total of 210 individuals, including 96 children with IR and 114 children without IR, aged 6-18 years, who were admitted to the Pediatric Endocrinology Outpatient Clinic at Medicine Hospital, Istanbul Atlas University were included in our study. Compared to patients without IR, NLR, PLR, SII, and MHR were significantly higher in patients with IR. Fasting insulin, PAI, homeostasis model assessment of insulin resistance (HOMA-IR), and HOMA-β were significantly higher and quantitative insulin sensitivity check index (QUICKI) was considerably lower in patients with IR compared to those without IR. NLR, SII, and MHR were lower in normal vitamin D groups than the others (p < 0.001). PLR was lower in the group with normal vitamin D levels than the groups with insufficient or deficient levels of vitamin D (D < 21). We found that vitamin D deficiency in childhood is related to increased levels of circulating inflammatory markers (NLR, PLR, MHR, PAI), IR, and decreased insulin sensitivity. According to our results, supplementation of vitamin D may be beneficial in averting IR and enhanced systemic inflammation.

Does GLP-1 cause post-bariatric hypoglycemia: ‘Computer says no’

Background and Objective:Patients who underwent Roux-en-Y Gastric Bypass surgery for treatment of obesity or diabetes can suffer from post-bariatric hypoglycemia (PBH). It has been assumed that PBH is caused by increased levels of the hormone GLP-1. In this research, we elucidate the role of GLP-1 in PBH with a physiology-based mathematical model. Methods:The Eindhoven Diabetes Simulator (EDES) model, simulating postprandial glucose homeostasis, was adapted to include the effect of GLP-1 on insulin secretion. Parameter sensitivity analysis was used to identify parameters that could cause PBH. Virtual patient models were created by defining sets of models parameters based on 63 participants from the HypoBaria study cohort, before and one year after bariatric surgery. Results:Simulations with the virtual patient models showed that glycemic excursions can be correctly simulated for the study population, despite heterogeneity in the glucose, insulin and GLP-1 data. Sensitivity analysis showed that GLP-1 stimulated insulin secretion alone was not able to cause PBH. Instead, analyses showed the increased transit speed of the ingested food resulted in quick and increased glucose absorption in the gut after surgery, which in turn induced postprandial glycemic dips. Furthermore, according to the model post-bariatric increased rate of glucose absorption in combination with different levels of insulin sensitivity can result in PBH. Conclusions:Our model findings implicate that if initial rapid improvement in insulin sensitivity after gastric bypass surgery is followed by a more gradual decrease in insulin sensitivity, this may result in the emergence of PBH after prolonged time (months to years after surgery).

Weight gain leads to greater adverse metabolic responses in South Asian compared with white European men: the GlasVEGAS study

South Asians (SAs) develop type 2 diabetes at lower body mass index values than white Europeans (WEs). This basic human experimental study aimed to compare the metabolic consequences of weight gain in SA and WE men without overweight or obesity. Fourteen SAs and 21 WEs had assessments of body composition, metabolic responses to mixed-meal ingestion, cardiorespiratory fitness and physical activity, and a subcutaneous abdominal adipose tissue biopsy, before and after 4–6 weeks of overfeeding to induce 5–7% weight gain. Here we show that body mass index and whole-body adipose tissue volume increases similarly between ethnic groups, but SAs gain less lean tissue. SAs experience a substantially greater decrease in insulin sensitivity compared with WEs (38% versus 7% decrease, P = 0.009), have fewer small (37.1% versus 60.0%, P = 0.003) and more large (26.2% versus 9.1%, P = 0.005) adipocytes at baseline and have a smaller decrease in very small adipocytes with weight gain (−0.1% versus −1.9%, P < 0.0001). Ethnic differences in adipocyte morphology are associated with SA’s greater adverse metabolic changes with weight gain. ClinicalTrials.gov registration: NCT02399423.

Placental growth factor deficiency initiates obesity- and aging-associated metabolic syndrome

Obesity often leads to inadequate angiogenesis in expanding adipose tissue, resulting in inflammation and insulin resistance. We explored the role of placental growth factor (PlGF) in metabolic syndrome (MS) using mice models of type 2 diabetes, high-fat diet, or aging. Reduced serum PlGF levels were associated with decreased insulin sensitivity and development of MS features. PlGF was localized within endothelial cells and pericytes of adipose tissue. In vitro, low PlGF levels in hypoxic conditions worsened oxidative stress, apoptosis, and reduced autophagy. This was associated with a reduction in expression of vascular endothelial growth factor (VEGF)-A/VEGF-R1/−R2, which was influenced by a decrease and increase in PlGF/pAMPK/PI3K-pAkt/PLCγ1-iCa++/eNOS and PTEN/GSK3β axes, respectively. PlGF-knockout mice exhibited MS traits through alterations in the same signaling pathways, and these changes were mitigated by recombinant PlGF and metformin. These enhanced angiogenesis and lipid metabolism, underscoring PlGF's role in age-related MS and its potential as a therapeutic target.

Intestinal barrier function in the naked mole-rat: an emergent model for gastrointestinal insights.

The intestinal barrier plays a crucial role in homeostasis by both facilitating the absorption of nutrients and fluids and providing a tight shield to prevent the invasion by either pathogen or commensal microorganisms. Intestinal barrier malfunction is associated with systemic inflammation, oxidative stress, and decreased insulin sensitivity, which may lead to the dysregulation of other tissues. Therefore, a deeper understanding of physiological aspects related to an enhanced barrier function is of significant scientific and clinical relevance. The naked mole-rat has many unusual biological features, including attenuated colonic neuron sensitivity to acid and bradykinin and resistance to chemical-induced intestinal damage. However, insight into their intestinal barrier physiology is scarce. Here, we observed notable macroscopic and microscopic differences in intestinal tissue structure between naked mole-rats and mice. Moreover, naked mole-rats showed increased number of larger goblet cells and elevated mucus content. In measuring gut permeability, naked mole-rats showed reduced permeability compared with mice, measured as transepithelial electrical resistance, especially in ileum. Furthermore, intestinal ion secretion induced by serotonin, bradykinin, histamine, and capsaicin was significantly reduced in naked mole-rats compared with mice, despite the expression of receptors for all these agonists. In addition, naked mole-rats exhibited reduced prosecretory responses to the nonselective adenylate cyclase activator forskolin. Collectively, these findings indicate that naked mole-rats possess a robust and hard-to-penetrate gastrointestinal barrier that is resistant to environmental and endogenous irritants. Naked mole-rats may therefore provide valuable insights into the physiology of the intestinal barrier and set the stage for the development of innovative and effective therapies.NEW & NOTEWORTHY This is the first study to characterize the intestinal function of naked mole-rats. We found that these animals show a robust gut tissue structure, displaying thicker intestinal layers, longer villi, and larger crypts. Naked mole-rats showed more and larger goblet cells, with increased mucus content. Intestinal permeability, especially in the ileum, was substantially lower than that of mice. Finally, naked mole-rats showed reduced intestinal anion secretion in response to serotonin, bradykinin, histamine, capsaicin, and forskolin.

CTRP9 Promotes Brown Adipose Tissue Lipolysis in Mice Fed a High-Fat Diet.

This study aimed to elucidate the molecular mechanism through which C1q/tumor necrosis factor (TNF)-related protein 9 (CTRP9) acts in the formation and differentiation of brown adipose tissue (BAT). Adenovirus particles encoding CTRP9 and green fluorescent protein were inoculated into the scapula of C57BL/6J mice and fed a high-fat diet for 8 weeks; the body weight, lipid droplet morphology, glucose tolerance, insulin tolerance, and protein expression levels were analyzed. In addition, CTRP9 adenovirus was transfected into brown preadipocytes, and differentiation was induced to identify the effect of CTRP9 overexpression on adipocyte differentiation. CTRP9 overexpression significantly increased the weight gain of mice. Additionally, the CTRP9 overexpression group exhibited significantly increased adipose tissue weight and glucose clearance rates and decreased insulin sensitivity and serum triglyceride levels compared to the control group. Furthermore, CTRP9 overexpression significantly upregulated the adipose triglyceride lipase (ATGL) and perilipin 1 protein expression levels in BAT. The cell experiment results confirmed that CTRP9 overexpression significantly inhibited the adipogenesis of brown adipocytes as evidenced by the downregulation of uncoupling protein 1, beta-3 adrenergic receptor, ATGL, and hormone-sensitive lipase mRNA levels and the significant suppression of uncoupling protein 1, ATGL, and perilipin 1 protein levels in brown adipocytes. The finding of this study demonstrated that CTRP9 promotes lipolysis by upregulating ATGL expression in vivo and inhibits the differentiation of brown preadipocytes in vitro.

Increased Allergic Inflammation and Decreased Lung Insulin Sensitivity in Offspring of Obese Allergic Mothers.

Epidemiological studies demonstrate that maternal obesity and maternal allergy are major risk factors for asthma in offspring. However, the impact of maternal allergy and obesity on offspring lung insulin signaling and allergen responsiveness is not known. To evaluate this, allergic and non-allergic female mice were fed a high fat diet or low-fat diet from 7 weeks before pregnancy until weaning. Neonatal pups were allergen-sensitized and allergen-challenged and then were assessed for obesity, insulin signaling, and allergic inflammation. Compared to pups of non-obese non-allergic mothers, allergen-challenged pups of obese non-allergic mothers, non-obese allergic mothers and obese allergic mothers had bronchoalveolar lavage eosinophilia, with the pups of obese allergic mothers having the highest bronchoalveolar lavage eosinophilia. These pups also had lower insulin-induced lung AKT-phosphorylation, indicating a decrease in lung parenchymal insulin sensitivity. In cross-fostering experiments, allergen-challenged pups exposed to both pre- and post-natal obese allergic mothers had the highest level of BAL eosinophilia. Maternal obesity or allergy increased offspring serum allergen-specific IgE and IL-5 that was highest when the mother was both obese and allergic. Also, allergen-challenged pups exposed to both pre- and post-natal obese allergic mothers had the highest level of IL5. In summary, offspring born to obese allergic mothers have decreased lung insulin sensitivity and have increased lung allergic inflammation. Interestingly, our data also demonstrates that there is both a pregnancy and post-pregnancy aspect of maternal allergy and obesity that enhance allergen responsiveness in offspring.

Insulin and TLR4 Antagonist Improve Motor Impairments in a Rat Model of Parkinson’s Disease

Background: Insulin resistance is an important pathological hallmark of Parkinson’s disease (PD). Proinflammatory cytokines during neuroinflammation decrease insulin sensitivity by suppressing insulin signaling elements. Toll-like receptor 4 (TLR4), the main receptor involved in neuroinflammation, is also associated with the pathogenesis of PD. Objectives: The present study evaluated the effect of insulin, an insulin receptor antagonist, and a TLR4 inhibitor on behavioral deficits and insulin resistance induced by 6-hydroxydopamine (6-OHDA). Methods: Male Wistar rats were divided into nine groups: (1) sham (normal saline [NS] in the medial forebrain bundle [MFB]); (2) 6-OHDA (20 µg in the MFB); (3) 6-OHDA + NS; (4) 6-OHDA + dimethyl sulfoxide (DMSO); (5) 6-OHDA + insulin (2.5 IU/day, intracerebroventricular ([ICV]); (6) 6-OHDA + insulin (5 IU/day, intranasal [IN]); (7) 6-OHDA + insulin receptor antagonist (S961; 6.5 nM/kg, ICV); (8) 6-OHDA + TLR4 antibody (TAK242; 0.01 µg/rat, ICV); (9) 6-OHDA + insulin + TLR4 antibody. All treatments were administered for seven consecutive days. Motor performance was evaluated using apomorphine-induced rotation and cylinder tests. Gene expression and protein levels of α-synuclein, TLR4, insulin receptor substrate (IRS) 1, IRS2, and glycogen synthase kinase 3β (GSK3β) were measured by real-time PCR and western blotting, respectively, in the striatum. Results: Insulin and insulin combined with TAK242 improved motor deficits induced by 6-OHDA. Administration of the insulin receptor antagonist had no effect on motor deficits. The increased expression of α-synuclein and TLR4 following 6-OHDA was attenuated by insulin and TAK242. GSK3β levels, both mRNA and protein, were significantly increased by 6-OHDA and attenuated with insulin and TAK242. Conclusions: The findings suggest that 6-OHDA induces neurodegeneration via activation of TLR4 and GSK3β, indicating insulin resistance, and that insulin can improve these impairments. Moreover, TLR4 inhibition prevents insulin signaling dysfunction and improves behavioral and molecular impairments, highlighting the critical role of TLR4 in the development of insulin resistance in PD pathology.

The effect of statin treatment on glucose homeostasis in prediabetic individuals: A prospective, randomized, controlled trial.

This study aimed to evaluate the effects of rosuvastatin and pravastatin on glucose homeostasis and other biomarkers in individuals at high risk of developing diabetes. This prospective, randomized, open-labeled, and controlled trial included prediabetic individuals with impaired fasting glucose and impaired glucose tolerance. The participants were randomized into three groups: rosuvastatin (10 mg), pravastatin (40 mg), or control. Biomarkers of diabetes and glucose and insulin responses to oral glucose tolerance tests were assessed at baseline and after 6 months of treatment. The primary outcomes were comparisons of glucose homeostasis and biomarkers of diabetes among groups at baseline and after 6 months of treatment. A total of 141 subjects with impaired fasting glucose (IFG) were screened and 41 participants were recruited. Twenty-two subjects were randomized to either the rosuvastatin or pravastatin group and 19 subjects were assigned to the control group. After 6 months of treatment, all groups had similar cholesterol and triglyceride levels. Likewise, HbA1c levels, glucose, and insulin excursions during oral glucose tolerance test, were similar among the three groups. However, compared to the other groups, the rosuvastatin group had higher homeostasis model assessment for insulin resistance (HOMA-IR) (insulin resistance) and a lower Matsuda index (insulin sensitivity). Among prediabetic individuals with IFG, rosuvastatin treatment was associated with increased insulin resistance and decreased insulin sensitivity compared to pravastatin and control groups. Further research is needed to elucidate the underlying mechanisms and clinical implications of these findings.

Iron Overload Induces Hepatic Ferroptosis and Insulin Resistance by Inhibiting the Jak2/stat3/slc7a11 Signaling Pathway.

Recent studies showed that patients with iron overload had increased risk of insulin resistance or diabetes. Ferroptosis is a new type of cell death mainly caused by iron-dependent oxidative damage. In the present study, we investigated potential mechanisms of iron overload induced hepatic ferroptosis and insulin resistance through in vivo and in vitro experiments. In vivo, the mice models of iron overload were established by intraperitoneal injection of iron dextran. The changes of body weight, serum ferritin and blood glucose were measured. Hematoxylin-eosin (HE) and Perl's stainings were used to observe the pathological changes and iron deposition in the liver of mice. In vitro, HepG2 cells were treated with ferric ammonium citrate (FAC, 9 mmol/L, 24 h) to establish the cell models of iron overload. The labile iron pool, cell viability, glucose consumption and glycogen contents were measured. The ultrastructure of mitochondria was observed by transmission electron microscope (TEM). The malondialdehyde (MDA) and glutathione (GSH) kits were used to detect lipid peroxidation in liver tissues of mice and HepG2 cells. RT-PCR and Western blot were used to detect the mRNA and protein expression levels of ferroptosis factors and JAK2/STAT3 signaling pathway. In this study, we used the iron chelator deferasirox in mice and HepG2 cells. Iron overload caused weight loss, elevated serum ferritin, fasting blood glucose, fasting insulin, HOMA-IR, impaired glucose tolerance, and decreased insulin sensitivity in mice. HE staining and Perls staining showed clumps of iron deposition in the liver of iron overload mice. Iron overload could reduce the glucose consumption, increase MDA contents of HepG2 cells, while reduce glycogen and GSH contents in liver tissues of mice and HepG2 cells. TEM showed deletion of mitochondrial ridge and rupture of outer membrane in HepG2 cells with iron overload. Iron chelator deferasirox could significantly improve the above indicators, which might be related to the activation of JAK2/STAT3/SLC7A11 signaling pathway and hepatic ferroptosis. Iron overload could induce hepatic ferroptosis and insulin resistance by inhibiting the JAK2/STAT3/SLC7A11 signaling pathway, and the iron chelator deferasirox might improve hepatic insulin resistance induced by iron overload.

Comparison of Triglyceride–Glucose (TyG) Index and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) Index in Prediction of Male Hypogonadism

Several studies have shown the association between decreased insulin sensitivity and the risk of male hypogonadism. Homeostatic model assessment of insulin resistance (HOMA-IR) is a well-established marker of decreased insulin sensitivity. The triglyceride–glucose index (TyG), calculated as ln fasting triglyceride mg/dL× fasting glucose mg/dL/2, was recently suggested to be a cheaper and a reliable surrogate marker to detect insulin resistance (IR). Our aim was to compare the performance of those two indexes in the prediction of male hypogonadism. The data on 192 men from infertile couples (18–50 years; sperm concentration &lt;20 x 106/mL) and 199 population-based matched controls collected during the years 2009–2012 (baseline) were evaluated retrospectively. Half of these subjects (72 subfertile men and 122 controls) were reinvestigated 5–10 years later (median year (range): 7 (5–10)). The patients receiving any hormonal therapy were excluded. Hypogonadism was defined as fasting, morning serum testosterone below 12 nmol/L. In receiver operating characteristic curve analysis, the optimal diagnostic cutoff values for baseline HOMA-IR and TyG to predict MetS at re-examination were 2.68 (Area Under Curve (AUC) = 0.886, p &lt; 0.001) and 8.60 (AUC = 0.816, p &lt;0.001), respectively. Moreover, in binary logistic regression analysis performed on the whole cohort using these thresholds for high values of HOMA-IR and high TyG, the odds-ratios (ORs) for hypogonadism were 6.48 (95% Confidence Interval (CI): 3.77–11.2; p &lt;0.001) and 3.58 (95% CI: 2.17–5.94; p &lt;0.001), respectively. Even though high HOMA-IR levels provided better risk estimates, high TyG was also highly related to the risk of hypogonadism. These markers can be utilized to identify men being at high risk of hypogonadism.

High fat diet ameliorates mitochondrial cardiomyopathy in CHCHD10 mutant mice

Mutations in CHCHD10, a mitochondrial protein with undefined functions, are associated with autosomal dominant mitochondrial diseases. Chchd10 knock-in mice harboring a heterozygous S55L mutation (equivalent to human pathogenic S59L) develop a fatal mitochondrial cardiomyopathy caused by CHCHD10 aggregation and proteotoxic mitochondrial integrated stress response (mtISR). In mutant hearts, mtISR is accompanied by a metabolic rewiring characterized by increased reliance on glycolysis rather than fatty acid oxidation. To counteract this metabolic rewiring, heterozygous S55L mice were subjected to chronic high-fat diet (HFD) to decrease insulin sensitivity and glucose uptake and enhance fatty acid utilization in the heart. HFD ameliorated the ventricular dysfunction of mutant hearts and significantly extended the survival of mutant female mice affected by severe pregnancy-induced cardiomyopathy. Gene expression profiles confirmed that HFD increased fatty acid utilization and ameliorated cardiomyopathy markers. Importantly, HFD also decreased accumulation of aggregated CHCHD10 in the S55L heart, suggesting activation of quality control mechanisms. Overall, our findings indicate that metabolic therapy can be effective in mitochondrial cardiomyopathies associated with proteotoxic stress.

Interplays between Metabolic Hormones, Metabolic Factors, Kidney Function Parameters, and Heart Rate Variability

Metabolic Syndrome (MetS) is associated with autonomic cardiac dysregulation, reflected by changes in heart rate variability (HRV) and detrimental effects on kidney function. This study aimed to 1) compare metabolic factors and hormones, kidney function profiles, and HRV parameters, including SDSD, RMSSD, pNN50, high-frequency power (HF), low-frequency power (LF), LF/HF ratio, between subjects with/without MetS or insulin resistance and 2) determine the correlations among these variables. We hypothesized that these factors differed between subjects with and without metabolic disturbances. Furthermore, we expected that metabolic factors and hormones and kidney function parameters were associated with HRV. In Thai obese subjects, characterized by BMI ≥ 25 kg/m2 for an Asian population (n = 45), fasting blood samples and spontaneous 5-minute HRV were obtained. The criteria for MetS were defined by The NCEP ATP III 2005 definition, except waist circumference which is ≥ 90 cm in men and 80 cm in women for Asians. Insulin resistance was determined by homeostatic model assessment for insulin resistance (HOMA-IR) &gt; 2.3. In subjects with MetS (n = 19), percent fat, HOMA-IR, and serum leptin were significantly higher than those without MetS (n = 26), all with P &lt; 0.05. Serum adiponectin, SDSD, RMSSD, and LF in ms2 tended to decrease in subjects with MetS. In subjects with insulin resistance (n = 30), BMI and serum leptin were significantly higher than those without insulin resistance (n = 15), all with P &lt; 0.05. HDL-cholesterol (HDL-C) was significantly lower in subjects with insulin resistance, all with P &lt; 0.05. Serum leptin exhibited positive correlations with BMI, creatinine clearance (CrCl), serum insulin, and HOMA-IR (R = 0.433-0.778) but had a negative correlation with HDL-C (R = -0.303), all with P &lt; 0.05. Serum insulin showed positive correlations with BMI, CrCl, and serum leptin (R = 0.328-0.437); while it had negative correlations with age and HDL-C (R = (-0.310)-(-0.438)), all with P &lt; 0.05. Serum adiponectin demonstrated positive correlations with HDL-C and pNN50 (R = 0.329-0.473), all with P &lt; 0.05. CrCl had positive correlations with BMI, HOMA-IR, serum insulin and leptin, and HF in normal unit (nu) (R = 0.304-0.617); and negative correlations with LFnu, and LF/HF ratio (R = (-0.317)-(-0.386)), all with P &lt; 0.05. HDL-C demonstrated significant positive correlations with serum adiponectin, SDSD, and RMSSD (R = 0.329-0.331); while showed negative correlations with the number of criteria met for MetS, BMI, triglyceride, serum insulin and leptin, and HOMA-IR (P = (-0.303)-(-0.595)), all with P &lt; 0.05. LDL-cholesterol (LDL-C) had negative correlations with percent fat and pNN50 (R = (-0.313)-(-0.340)), all with P &lt; 0.05. Subjects with metabolic syndrome tended to have decreased insulin sensitivity, serum adiponectin, as well as parasympathetic (SDSD, RMSSD) and sympathetic (LF) HRV. Those with insulin resistance showed lower level of HDL-C. Leptin and insulin were correlated with obesity, metabolic factors, insulin resistance, and kidney function parameters but not HRV. Interestingly, serum adiponectin exhibited a positive correlation with HDL-C, and both serum adiponectin and HDL-C, which are protective factors, had positive correlations with parasympathetic HRV (pNN50, SDSD, and/or RMSSD). Conversely, LDL-C showed a negative correlation with parasympathetic HRV (pNN50). Creatinine clearance was positively correlated with parasympathetic HRV (HF) and negatively correlated with sympathetic HRV (LFnu and LF/HF ratio). In conclusion, MetS was linked to shifts in HRV, with reductions in both parasympathetic and sympathetic components. HDL-C exhibited a protective role in metabolic disturbances. Parasympathetic HRV was positively correlated with protective factors but negatively with LDL-C. Deteriorating kidney function was associated with increased sympathetic HRV and decreased parasympathetic HRV. The research was funded by the Faculty of Medicine Siriraj Hospital Research Fund ((IO) R015932003, R0159333013 and R016132012. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Correlation Between Blood Urea Nitrogen and Short- and Long-Term Glycemic Variability in Elderly Patients with Type 2 Diabetes Mellitus Who Were hospitalized:A Retrospective Study.

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by insulin resistance and progressively impaired insulin secretion resulting in dynamic fluctuations in glucose levels.High blood urea nitrogen (BUN) levels have been linked to decreased insulin sensitivity, suppressed insulin synthesis and increased risk of incident diabetes mellitus in humans as well as insulin use in patients with T2DM.This study characterize the association between BUN levels and short-term and long-term glycemic variability(GV) in the elderly patients with T2DM who were hospitalized. A total of 927 elderly patients with T2DM were included in the study. The short-term GV was quantified using parameters such as standard deviation (SD), coefficient of variation (CV), time in range (TIR), and mean amplitude of glycemic excursions (MAGE), based on multi-point fingertip blood glucose monitoring. The long-term GV was quantified using parameters such as SD, CV, variation independent of the mean (VIM), and average successive variability (ARV), based on fasting blood glucose(FPG). The relationship between BUN levels and short-term and long-term GV in elderly T2DM who were hospitalized was explored using methods such as Spearman correlation coefficient, linear regression analysis, logistic regression analysis, and interaction tests. In elderly patients with T2DM were hospitalized, there is a significant correlation between BUN levels and both short-term and long-term GV. BUN is negatively correlated with the GV parameter TIR (r=-0.12, P=0.000), and positively correlated with SD (r=0.12, P=0.000), CV (r=0.07, P=0.026), MAGE (r=0.11, P=0.001), FPG-SD (r=0.08, P=0.013), and FPG-CV (r=0.08, P=0.014).Furthermore, the association remains consistent across different age, gender, BMI, and haemoglobin A1c (HbA1c) subgroups (P interaction > 0.05). In elderly patients with T2DM were hospitalized, BUN levels were positively associated with GV.Therefore, monitoring BUN levels were beneficial in assessing the degree of GV.

Analysis of Associated Factors Contributing to Type 2 Diabetes Mellitus in the Coastal Community of Bahari Village, Southeast Sulawesi, Indonesia: A Cross-Sectional Study

Background Type 2 diabetes mellitus (T2DM) has become a major lifestyle disease that threatens communities in the world. The lifestyles of undiagnosed T2DM are a major issue in Indonesia. Objective This study aims to analyze the contribution of associated factors to T2DM in Bahari Village. Methods The study was conducted by cross-sectional study. Respondents included 113 men and 157 women were established through simple randomized sampling from March to May 2023. Data analysis using chi-square and logistic regression at p&lt;0.05 using SPSS 25. Results The prevalence of T2DM for women (74.2%), 45-65 years (90.9%), no education (58.7%), overweight (38.2%), heavy drinking sweet tea/coffee (77.5%), never physical activity (87.1%), diabetic father and mother (40.3%), and father’s OR 1.42 (CI 95%:0.73-2.75), significantly associated with T2DM. Gender, age, education, BMI, and occupation simultaneously influence (72.7%), and age partially affects T2DM. Discussion Decreased insulin sensitivity and increased risk of developing diabetes can be influenced by various factors, such as genetics, lifestyle, physical activity, and the environment, either partially or simultaneously. Conclusion The respondents' advanced age, obesity, lack of education, preference for sweet foods, and inactivity all contributed to their type 2 diabetes. These coastal communities need to make lifestyle changes to reduce the burden of diabetes. Classification Epidemiology; Environmental Health; Science of Nutrition MeSH.

Effects of hypertriglyceridemia with or without NEFA elevation on β-cell function and insulin clearance and sensitivity.

Hypertriglyceridemia is a risk factor for developing type 2 diabetes (T2D) and might contribute to its pathogenesis either directly or through elevation of non-esterified fatty acids (NEFAs). This study aimed at comparing the glucometabolic effects of acute hypertriglyceridemia alone or combined with NEFA elevation in non-diabetic subjects. Twenty-two healthy lean volunteers underwent two 5-h intravenous infusions of either saline or Intralipid, without (n=12) or with heparin (I+H; n=10) to activate the release of NEFAs. Oral glucose tolerance tests (OGTTs) were performed during the last 3h of infusion. Insulin sensitivity, insulin secretion rate (ISR), model-derived β-cell function, and insulin clearance were measured after 2h of lipid infusion and during the OGTTs. In fasting conditions, both lipid infusions increased plasma insulin and ISR and reduced insulin clearance, without affecting plasma glucose and insulin sensitivity. These effects on insulin and ISR were more pronounced for I+H than Intralipid alone. During the OGTT, the lipid infusions markedly impaired glucose tolerance, increased plasma insulin and ISR, and decreased insulin sensitivity and clearance, without significant group differences. Intralipid alone inhibited glucose-stimulated insulin secretion (i.e. β-cell glucose sensitivity) and increased β-cell potentiation, whereas I+H had neutral effects on these β-cell functions. In healthy non-obese subjects, mild acute hypertriglyceridemia directly reduces glucose tolerance, insulin sensitivity and clearance, and has selective and opposite effects on β-cell function that are neutralized by NEFAs. These findings provide new insight into plausible biological signals that generate and sustain insulin resistance and chronic hyperinsulinemia in the development of T2D.