Lipidomics Study of Type 1 Diabetic Rats Using Online Phase Transition Trapping-Supercritical Fluid Extraction-Chromatography Coupled with Quadrupole Time-of-Flight Tandem Mass Spectrometry.

Chromatography-mass spectrometry-based lipidomics represents an essential tool for elucidating lipid dysfunction mechanisms and is extensively employed in investigating disease mechanisms and identifying biomarkers. However, the detection of low-abundance lipids in biological matrices, along with cumbersome operational procedures, complicates comprehensive lipidomic analyses, necessitating the development of highly sensitive, environmentally friendly, and automated methods. In this study, an online phase transition trapping-supercritical fluid extraction-chromatography-mass spectrometry (PTT-SFEC-MS/MS) method was developed and successfully applied to plasma lipidomics analysis in Type 1 diabetes (T1D) rats. The PTT strategy captured entire extracts at the column head by converting CO2 from a supercritical state to a gaseous state, thereby preventing peak spreading, enhancing peak shape for precise quantification, and boosting sensitivity without any sample loss. This method utilized only 5 µL of plasma and accomplished sample extraction, separation, and detection within 27 min. Ultimately, 77 differential lipids were identified, including glycerophospholipids, sphingolipids, and glycerolipids, in T1D rat plasma. The results indicated that the progression of the disease might be linked to alterations in glycerophospholipid and sphingolipid metabolism. Our findings demonstrated a green, highly efficient, and automated method for the lipidomics analysis of biological samples, providing a scientific foundation for understanding the pathogenesis and diagnosis of T1D.

Mogroside Alleviates Diabetes Mellitus and Modulates Intestinal Microflora in Type 2 Diabetic Mice.

Mogroside, the main component of Siraitia grosvenorii (Swingle) C. Jeffrey (Cucurbitaceae) is a natural product with hypoglycemic and intestinal microbiota regulating properties. However, whether the alteration of intestinal microbiota is associated with the antidiabetic effect of mogroside remains poorly understood. This study investigated the mechanism underlying the hypoglycemic effect of mogroside in regulating intestinal flora and attenuating metabolic endotoxemia. Kunming mice with type 2 diabetes mellitus (T2DM) induced by high-fat diet and intraperitoneal injection of streptozotocin were randomly divided into model, pioglitazone (2.57 mg/kg) and mogroside (200, 100, and 50 mg/kg) groups. After 28 d of administration, molecular changes related to glucose metabolism and metabolic endotoxemia in mice were evaluated. The levels of insulin receptor substrate-1 (IRS-1), cluster of differentiation 14 (CD14) and toll-like receptor 4 (TLR4) mRNAs were measured, and the composition of intestinal microflora was determined by 16s ribosomal DNA (rDNA) sequencing. The results showed that mogroside treatment significantly improved hepatic glucose metabolism in T2DM mice. More importantly, mogroside treatment considerably reduced plasma endotoxin (inhibition rate 65.93%, high-dose group) and inflammatory factor levels, with a concomitant decrease in CD14 and TLR4 mRNA levels. Moreover, mogroside treatment reduced the relative abundance of Firmicutes and Proteobacteria (the inhibition rate of Proteobacteria was 85.17% in the low-dose group) and increased the relative abundance of Bacteroidetes (growth rate up to 40.57%, high-dose group) in the intestines of diabetic mice. This study reveals that mogroside can relieve T2DM, regulating intestinal flora and improving intestinal mucosal barrier, indicating that mogroside can be a potential therapeutic agent or intestinal microbiota regulator in the treatment of T2DM.

Effects of 3.5-GHz radiofrequency radiation on energy-regulatory hormone levels in the blood and adipose tissue.

In recent years exposure of living beings to radiofrequency radiation (RFR) emitted from wireless equipment has increased. In this study, we investigated the effects of 3.5-GHz RFR on hormones that regulate energy metabolism in the body. Twenty-eight rats were divided into four groups: healthy sham (n = 7), healthy RFR (n = 7), diabetic sham (n = 7), and diabetic RFR (n = 7). Over a month, each group spent 2 h/day in a Plexiglas carousel. The rats in the experimental group were exposed to RFR, but the sham groups were not. At the end of the experiment, blood and adipose tissues were collected from euthanized rats. Total antioxidant, total oxidant, hydrogen peroxide, ghrelin, nesfatin-1, and irisin were determined. Insulin expression in pancreatic tissues was examined by immunohistochemical analysis. Whole body specific absorption rate was 37 mW/kg. For the parameters analyzed in blood and fat, the estimated effect size varied within the ranges of 0.215-0.929 and 0.503-0.839, respectively. The blood and adipose nesfatin-1 (p = 0.002), blood and pancreatic insulin are decreased, (p = 0.001), gherelin (p = 0.020), irisin (p = 0.020), and blood glucose (p = 0.040) are increased in healthy and diabetic rats exposed to RFR. While nesfatin-1 are negatively correlated with oxidative stress, hyperglycemia and insulin, ghrelin and irisin are positively correlated with oxidative stress and hyperglycemia. Thus, RFR may have deleterious effects on energy metabolism, particularly in the presence of diabetes.

[Evaluation of efficacy of Dihuang Baoyuan Granules for diabetes mellitus and composition and in vivo distribution analysis based on UHPLC-LTQ-Orbitrap MS].

Dihuang Baoyuan Granules is a prescription endorsed by HU Tianbao, a renowned and elderly Chinese medicine practitioner from Beijing, and has demonstrated definite clinical efficacy. The composition of this prescription is intricate as it includes 7 distinct herbal medicines. This study aims to analyze the chemical composition of Dihuang Baoyuan Granules, evaluate its efficacy in the treatment of diabetes and analyze the distribution of the drug components in the plasma, liver, and kidney after administration. The findings will serve as a reference for future research on pharmacodynamic substances of this prescription. UHPLC-LTQ-Orbitrap MS was employed to analyze the main chemical components of Dihuang Baoyuan Granules. A Waters ACQUITY Premier HSS T3 column(2.1 mm×100 mm, 1.8 µm) was used for chromatographic separation with 0.1% formic acid(A)-acetonitrile(B) as the mobile phases in a gradient elution at a flow rate of 0.3 mL·min~(-1). Electrospray ionization(ESI) source was used to acquire data in positive and negative ion modes. Furthermore, a rat model of diabetes mellitus was established by feeding with a high-sugar high-fat diet, and injection with streptozocin at a dose of 35 mg·kg~(-1), and the modeled rats were then administrated with Dihuang Baoyuan Granules. The fasting blood glucose, hemoglobin A1c, and other relevant indicators were measured, and the substances present in the plasma, liver, and kidney were identified. By reference to quasi-molecular ions, MS/MS fragment ions, MS spectra of reference substances, and compound information in available reports, 191 components were identified in Dihuang Baoyuan Granules, including 29 alkaloids, 24 flavonoids, 22 organic acids, 16 amino acids, 12 terpenes, 11 steroid saponins, 9 sugars, 8 phenylethanoid glycosides, 8 nucleosides, 2 phenylpropanoids, and 49 others compounds. Eighty-three chemical components were identified in rat plasma, 109 in the liver, and 98 in the kidney. Component identification and characterization of Dihuang Baoyuan Granules in vitro and in vivo provide efficacy information and guidance for the basic research on the pharmacodynamic substances and further clinical application of this prescription.

Quantification of mangiferin in streptozotocin-induced diabetic rat plasma using UPLC-MS/MS: Pharmacokinetic assessment of Gentiana rhodantha extract after oral administration.

Mangiferin, a key bioactive constituent in Gentiana rhodantha, has a favorable impact on reducing blood sugar. A selective and sensitive UPLC MS/MS approach was developed for determining mangiferin in diabetic rats. Employing acetonitrile protein precipitation, chromatographic separation utilized a 2.1×50 mm, 3.5µm C18 column with a mobile phase of 0.1% formic acid aqueous and 5mM ammonium acetate (A, 45%) and acetonitrile (B, 55%) at a 0.5mL min-1 flow rate. Quantification, employing the multiple reaction monitoring (MRM) mode, focused on precursor-to-product ion transitions at m/z 447.1→271.1 for baicalin m/z and 421.0→301.0 for mangiferin. Calibration curves demonstrated linearity in the 1.00~100ng/mL range, with a lower quantification limit for rat plasma set at 1.00ng/mL. Inter- and intra-day accuracies spanned -9.1% to 8.5% and mangiferin mean recovery varied from 82.3% to 86.7%. The adeptly utilized UPLC-MS/MS approach facilitated the exploration of mangiferin pharmacokinetics in diabetic rats.

Effects of Cucumis melo and Citrullus lanatus extracts on glucose level, lipid profile and hepato-renal performance of streptozotocin-induced diabetic albino rats.

Diabetes mellitus, recognized by elevated glucose level in the body fluids is commonly caused by less insulin production or its action. To overcome the complications of diabetes, chemical drugs are never preferred over herbal medicines. Present study was designed to find out the anti-diabetic and health-promoting effects of ethanolic leaf extracts of Cucumis melo and Citrullus lanatus in induced-diabetic albino rats. Thirty male albino rats were bought from the animal house of the university and divided randomly into five feeding groups (n=6). Diabetes was induced in rats of groups A, B, C & D by a single dose of intra-peritoneal injection of streptozotocin (55 mg/Kg), whereas, the rats of group E were considered as control. The rats of groups A, B & C were fed basal diet supplemented with plant extracts (150mg/Kg body weight), whereas; only basal diet was offered to rats of groups D & E. After 28 days of the experiment, blood was collected for biochemical analysis. Results revealed that body weight, glucose, AST, ALB, GGT, HDL, cholesterol, triglyceride, urea and creatinine level differed significantly among treatment groups. It was therefore concluded that ethanolic leaf extracts of Cucumis melo and Citrullus lanatus can be used separately or in combination for the management of diabetes.

In-vitro and in-vivo antidiabetic activity of aerial parts of Aitchisonia rosea supported by phytochemical and GC-MS analysis.

Medicinal plants contain a wide variety of bioactive phytoconstituents which can serve as new therapeutic agents for several diseases. This study examines the antidiabetic potential of Aitchisonia rosea in alloxan-induced diabetic rats and identifies its bioactive phytoconstituents using GC-MS. In vitro, antidiabetic potential was established using the α-amylase inhibition assay. In vivo, antidiabetic potential was investigated by employing the oral glucose tolerance test (OGTT). GC-MS analysis was used to identify the bioactive phytoconstituents. The in vitro and in vivo tests showed that the aqueous extract of A. rosea possesses better antidiabetic potential. The α-amylase inhibition assay highlighted an IC50 value of 134.87µg/ml. In an oral glucose tolerance test, rats given an aqueous A. rosea extract significantly lowered their blood sugar levels significant reduction in the blood glucose concentration was observed in the oral glucose tolerance test in rats treated with the aqueous A. rosea extract. GC-MS investigation revealed many phytoconstituents, with serverogenin acetate and cycloheptasiloxane tetradecamethyl being important antidiabetic agents. This study found anti-diabetic properties in A. rosea extract. The phytochemical and GC-MS investigation also found serverogenin acetate and cycloheptasiloxane tetradecamethyl, which could be used to develop new antidiabetic drugs.

Therapeutic effect of ginger garlic powder in rats with induced diabetes.

The purpose of this study was to examine the potential hypoglycemic effects of administering ginger (Zingiber officinale) and garlic (Allium sativum) to rats with induced type 2 diabetes. A total of forty-five male adult albino rats were randomly assigned to five groups. The groups were named Normal Control, Diabetic Control, Ginger group, Garlic group and a combination group of ginger and garlic. Diabetes was produced in all groups, except the normal control group, using an intraperitoneal injection of streptozotocin at a dosage of 60 mg/body weight. During the course of two months, rats were administered varying amounts of ginger and garlic powders as part of their treatment After the experiment concluded, measurements were taken for glycated hemoglobin, serum glucose, insulin, cholesterol, high density protein, low density protein and liver glycogen levels. These groups exhibited considerably greater serum insulin and high-density lipoprotein concentrations (P<0.05) compared to the diabetic control group. Conversely, body weight, fasting blood glucose, total cholesterol, low density lipoprotein, and glycated hemoglobin levels were significantly lower (P<0.05) in all groups compared to the diabetic control group. A statistically significant increase (P<0.05) increase shown in liver glycogen levels. This study proposes that the utilization of ginger and garlic powders improve the condition of type 2 diabetes and maybe reduce the risk of subsequent diabetic complications.

Evaluation of the combination of black rice bran ethanol extract and glimepiride in reducing blood glucose and protecting kidney, liver and pancreatic cells.

Long-lasting hyperglycemia can potentially cause damage to organs such as the kidneys, liver and pancreas. Glimepiride (GLIM), as a drug of choice in the treatment of diabetes mellitus (DM), has the risk of decreasing the functioning of organs such as the kidneys, liver and pancreas. Black rice bran ethanol extract (EEBRB) with antioxidant content has been shown to protect the kidney, liver and pancreas organs. The aim of this study was to establish the effect of EEBRB on lowering fasting blood glucose (FBG) and protecting several organs after GLIM administration in alloxan (ALX)-induced hyperglycemic rats. A total of 20 rats were divided into 4 groups and treated for 21 days treatments using following preparations: normal control (NC), diabetic group (DC), GLIM 1 mg/ kgBW and combination of glimepiride 1mg/kgBW and EEBRB 50 mg/KgBW (GLBR). The results showed that the GLBR was able to lower blood glucose levels back to normal (<126 mg/dL) and protect kidney, liver and pancreas cells by increasing the amount in normal cells.

CaMKII Serine 280 O-GlcNAcylation Links Diabetic Hyperglycemia to Proarrhythmia.

[Figure: see text].

Dual self-regulated delivery of insulin and glucagon by a hybrid patch.

Reduced ß-cell function and insulin deficiency are hallmarks of diabetes mellitus, which is often accompanied by the malfunction of glucagon-secreting α-cells. While insulin therapy has been developed to treat insulin deficiency, the on-demand supplementation of glucagon for acute hypoglycemia treatment remains inadequate. Here, we describe a transdermal patch that mimics the inherent counterregulatory effects of ß-cells and α-cells for blood glucose management by dynamically releasing insulin or glucagon. The two modules share a copolymerized matrix but comprise different ratios of the key monomers to be "dually responsive" to both hyper- and hypoglycemic conditions. In a type 1 diabetic mouse model, the hybrid patch effectively controls hyperglycemia while minimizing the occurrence of hypoglycemia in the setting of insulin therapy with simulated delayed meal or insulin overdose.

An insulin-independent mechanism for transcriptional regulation of Foxo1 in type 2 diabetic mice.

Hepatic gluconeogenesis is the major contributor to the hyperglycemia observed in both patients and animals with type 2 diabetes. The transcription factor FOXO1 plays a dominant role in stimulating hepatic gluconeogenesis. FOXO1 is mainly regulated by insulin under physiological conditions, but liver-specific disruption of Foxo1 transcription restores normal gluconeogenesis in mice in which insulin signaling has been blocked, suggesting that additional regulatory mechanisms exist. Understanding the transcriptional regulation of Foxo1 may be conducive to the development of insulin-independent strategies for the control of hepatic gluconeogenesis. Here, we found that elevated plasma levels of adenine nucleotide in type 2 diabetes are the major regulators of Foxo1 transcription. We treated lean mice with 5'-AMP and examined their transcriptional profiles using RNA-seq. KEGG analysis revealed that the 5'-AMP treatment led to shifted profiles that were similar to db/db mice. Many of the upregulated genes were in pathways associated with the pathology of type 2 diabetes including Foxo1 signaling. As observed in diabetic db/db mice, lean mice treated with 5'-AMP displayed enhanced Foxo1 transcription, involving an increase in cellular adenosine levels and a decrease in the S-adenosylmethionine to S-adenosylhomocysteine ratio. This reduced methylation potential resulted in declining histone H3K9 methylation in the promoters of Foxo1, G6Pc, and Pepck. In mouse livers and cultured cells, 5'-AMP induced expression of more FOXO1 protein, which was found to be localized in the nucleus, where it could promote gluconeogenesis. Our results revealed that adenine nucleotide-driven Foxo1 transcription is crucial for excessive glucose production in type 2 diabetic mice.

The mitochondrial-derived peptide MOTS-c relieves hyperglycemia and insulin resistance in gestational diabetes mellitus.

The most common complication during pregnancy, gestational diabetes mellitus (GDM), can cause adverse pregnancy outcomes and result in the mother and infant having a higher risk of developing type 2 diabetes after pregnancy. However, existing therapies for GDM remain scant, with the most common being lifestyle intervention and appropriate insulin treatment. MOTS-c, a mitochondrial-derived peptide, can target skeletal muscle and enhance glucose metabolism. Here, we demonstrate that MOTS-c can be an effective treatment for GDM. A GDM mouse model was established by short term high-fat diet combined with low-dose streptozotocin (STZ) treatment while MOTS-c was administrated daily during pregnancy. GDM symptoms such as blood glucose and insulin levels, glucose and insulin tolerance, as well as reproductive outcomes were investigated. MOTS-c significantly alleviated hyperglycemia, improved insulin sensitivity and glucose tolerance, and reduced birth weight and the death of offspring induced by GDM. Similar to a previous study, MOTS-c also could activate insulin sensitivity in the skeletal muscle of GDM mice and elevate glucose uptake in vitro. In addition, we found that MOTS-c protects pancreatic ß-cell from STZ-mediated injury. Taken together, our findings demonstrate that MOTS-c could be a promising strategy for the treatment of GDM.

Apoptotic Ablation of Platelets Reduces Atherosclerosis in Mice With Diabetes.

OBJECTIVE: People with diabetes are at a significantly higher risk of cardiovascular disease, in part, due to accelerated atherosclerosis. Diabetic subjects have increased number of platelets that are activated, more reactive, and respond suboptimally to antiplatelet therapies. We hypothesized that reducing platelet numbers by inducing their premature apoptotic death would decrease atherosclerosis. Approach and Results: This was achieved by targeting the antiapoptotic protein Bcl-xL (B-cell lymphoma-extra large; which is essential for platelet viability) via distinct genetic and pharmacological approaches. In the former, we transplanted bone marrow from mice carrying the Tyr15 to Cys loss of function allele of Bcl-x (known as Bcl-xPlt20) or wild-type littermate controls into atherosclerotic-prone Ldlr+/- mice made diabetic with streptozotocin and fed a Western diet. Reduced Bcl-xL function in hematopoietic cells significantly decreased platelet numbers, exclusive of other hematologic changes. This led to a significant reduction in atherosclerotic lesion formation in Bcl-xPlt20 bone marrow transplanted Ldlr+/- mice. To assess the potential therapeutic relevance of reducing platelets in atherosclerosis, we next targeted Bcl-xL with a pharmacological strategy. This was achieved by low-dose administration of the BH3 (B-cell lymphoma-2 homology domain 3) mimetic, ABT-737 triweekly, in diabetic Apoe-/- mice for the final 6 weeks of a 12-week study. ABT-737 normalized platelet numbers along with platelet and leukocyte activation to that of nondiabetic controls, significantly reducing atherosclerosis while promoting a more stable plaque phenotype. CONCLUSIONS: These studies suggest that selectively reducing circulating platelets, by targeting Bcl-xL to promote platelet apoptosis, can reduce atherosclerosis and lower cardiovascular disease risk in diabetes. Graphic Abstract: A graphic abstract is available for this article.

Nobiletin protects against diabetes-induced testicular injury via hypophysis-gonadal axis upregulation and amelioration of oxidative stress.

BACKGROUND: Testicular injury is one of the most serious problems associated with diabetes mellitus. The present study aimed to compare the effects of two different doses of nobiletin and analyze its mechanisms of action against diabetes-induced testicular impairment in rats. METHODS AND RESULTS: Streptozotocin injection was used to induce diabetes. Diabetic rats received nobiletin orally at 10 or 25 mg/kg daily for 30 days. Diabetic rats displayed significant elevations in glucose, glycosylated hemoglobin (HbA1c), Homeostatic Model of Insulin Resistance (HOMA-IR), and pro-inflammatory cytokines, while the serum levels of insulin, testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were significantly reduced. Histological changes to positivity for caspase-3 and decreased androgen receptors (AR) immunoexpression were observed in diabetic rats. Both doses of nobiletin improved hyperglycemia, reduced pro-inflammatory cytokines, and augmented insulin, testosterone, LH, and FSH levels. LH and FSH receptors and cytochrome P450 17 α-hydroxylase (CYP17A1) were markedly downregulated in terms of both gene and protein expression in testicular tissues of the diabetic group, effects that were markedly ameliorated with both doses of nobiletin. In addition, both doses significantly reduced lipid peroxidation and caspase-3 immunoexpression and improved the activity of the antioxidant enzymes and AR in testicular tissues of the diabetic group. CONCLUSION: Both nobiletin doses showed protective effects against diabetes-induced testicular injury by reducing oxidative stress, hyperglycemia, inflammation, and caspase-3 and upregulating the hypophysis-gonadal axis and AR. The high dose of nobiletin was more effective than the lower one.

The Glycemic Control Potential of Some Amaranthaceae Plants, with Particular Reference to In Vivo Antidiabetic Potential of Agathophora alopecuroides.

Natural products continue to provide inspiring moieties for the treatment of various diseases. In this regard, investigation of wild plants, which have not been previously explored, is a promising strategy for reaching medicinally useful drugs. The present study aims to investigate the antidiabetic potential of nine Amaranthaceae plants: Agathophora alopecuroides, Anabasis lachnantha, Atriplex leucoclada, Cornulaca aucheri, Halothamnus bottae, Halothamnus iraqensis, Salicornia persia, Salsola arabica, and Salsola villosa, growing in the Qassim area, the Kingdom of Saudi Arabia. The antidiabetic activity of the hydroalcoholic extracts was assessed using in vitro testing of α-glucosidase and α-amylase inhibitory effects. Among the nine tested extracts, A. alopecuroides extract (AAE) displayed potent inhibitory activity against α-glucosidase enzyme with IC50 117.9 µg/mL noting better activity than Acarbose (IC50 191.4 µg/mL). Furthermore, AAE displayed the highest α- amylase inhibitory activity among the nine tested extracts, with IC50 90.9 µg/mL. Based upon in vitro testing results, the antidiabetic activity of the two doses (100 and 200 mg/kg) of AAE was studied in normoglycemic and streptozotocin (STZ)-induced diabetic mice. The effects of the extract on body weight, food and water intakes, random blood glucose level (RBGL), fasting blood glucose level (FBGL), insulin, total cholesterol, and triglycerides levels were investigated. Results indicated that oral administration of the two doses of AAE showed a significant dose-dependent increase (p < 0.05) in the body weight and serum insulin level, as well as a significant decrease in food and water intake, RBGL, FBGL, total cholesterol, and triglyceride levels, in STZ-induced diabetic mice, compared with the diabetic control group. Meanwhile, no significant differences of both extract doses were observed in normoglycemic mice when compared with normal control animals. This study revealed a promising antidiabetic activity of the wild plant A. alopecuroides.

Chronic Exposure to SCO-267, an Allosteric GPR40 Full Agonist, Is Effective in Improving Glycemic Control in Rats.

Full agonist-mediated activation of free fatty acid receptor 1 (FFAR1/GPR40) alleviates diabetes in rodents. Considering that diabetes is a chronic disease, assessment of treatment durability of chronic exposure to a GPR40 full agonist is pivotal for treating patients with diabetes. However, the physiologic significance of chronic in vitro and in vivo exposure to GPR40 full agonists is largely unclear. Here, we evaluated the in vitro and in vivo effects of chronic treatment with SCO-267, a GPR40 full agonist, on signal transduction and glucose control. In vitro experiments showed that SCO-267 is an allosteric full agonist for GPR40, which activates the Gα q, Gα s, and Gα 12/13 pathways and ß-arrestin recruitment. The calcium signal response was largely sustained in GPR40-overexpressing CHO cells even after prolonged incubation with SCO-267. To evaluate the in vivo relevance of chronic exposure to GPR40 full agonists, SCO-267 (1 and 10 mg/kg) was administered once daily to neonatally streptozotocin-induced diabetic rats for 15-33 days, and glucose control was evaluated. After 15 days of dosing followed by the drug washout period, SCO-267 improved glucose tolerance, most likely by increasing insulin sensitivity in rats. After 33 days, repeated exposure to SCO-267 was highly effective in improving glucose tolerance in rats. Furthermore, chronic exposure to SCO-267 increased pancreatic insulin content. These results demonstrated that even after chronic exposure, SCO-267 effectively activates GPR40 in cells and rats, suggesting the clinical application of SCO-267 in treating chronic diseases including diabetes. SIGNIFICANCE STATEMENT: GPR40 is a validated therapeutic target for diabetes. This study showed that even after chronic exposure, SCO-267, an allosteric GPR40 full agonist, effectively activates GPR40 in cells and rats; these results suggest a durable efficacy of SCO-267 in patients.

Distinct alterations of gut morphology and microbiota characterize accelerated diabetes onset in nonobese diabetic mice.

The rising prevalence of type 1 diabetes (T1D) over the past decades has been linked to lifestyle changes, but the underlying mechanisms are largely unknown. Recent findings point to gut-associated mechanisms in the control of T1D pathogenesis. In nonobese diabetic (NOD) mice, a model of T1D, diabetes development accelerates after deletion of the Toll-like receptor 4 (TLR4). We hypothesized that altered intestinal functions contribute to metabolic alterations, which favor accelerated diabetes development in TLR4-deficient (TLR4-/-) NOD mice. In 70-90-day-old normoglycemic (prediabetic) female NOD TLR4+/+ and NOD TLR4-/- mice, gut morphology and microbiome composition were analyzed. Parameters of lipid metabolism, glucose homeostasis, and mitochondrial respiratory activity were measured in vivo and ex vivo Compared with NOD TLR4+/+ mice, NOD TLR4-/- animals showed lower muscle mass of the small intestine, higher abundance of Bacteroidetes, and lower Firmicutes in the large intestine, along with lower levels of circulating short-chain fatty acids (SCFA). These changes are associated with higher body weight, hyperlipidemia, and severe insulin and glucose intolerance, all occurring before the onset of diabetes. These mice also exhibited insulin resistance-related abnormalities of energy metabolism, such as lower total respiratory exchange rates and higher hepatic oxidative capacity. Distinct alterations of gut morphology and microbiota composition associated with reduction of circulating SCFA may contribute to metabolic disorders promoting the progression of insulin-deficient diabetes/T1D development.

Metformin impairs homing ability and efficacy of mesenchymal stem cells for cardiac repair in streptozotocin-induced diabetic cardiomyopathy in rats.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have demonstrated potential in treating diabetic cardiomyopathy. However, patients with diabetes are on multiple drugs and there is a lack of understanding of how transplanted stem cells would respond in presence of such drugs. Metformin is an AMP kinase (AMPK) activator, the widest used antidiabetic drug. In this study, we investigated the effect of metformin on the efficacy of stem cell therapy in a diabetic cardiomyopathy animal model using streptozotocin (STZ) in male Wistar rats. To comprehend the effect of metformin on the efficacy of BM-MSCs, we transplanted BM-MSCs (1 million cells/rat) with or without metformin. Our data demonstrate that transplantation of BM-MSCs prevented cardiac fibrosis and promoted angiogenesis in diabetic hearts. However, metformin supplementation downregulated BM-MSC-mediated cardioprotection. Interestingly, both BM-MSCs and metformin treatment individually improved cardiac function with no synergistic effect of metformin supplementation along with BM-MSCs. Investigating the mechanisms of loss of efficacy of BM-MSCs in the presence of metformin, we found that metformin treatment impairs homing of implanted BM-MSCs in the heart and leads to poor survival of transplanted cells. Furthermore, our data demonstrate that metformin-mediated activation of AMPK is responsible for poor homing and survival of BM-MSCs in the diabetic heart. Hence, the current study confirms that a conflict arises between metformin and BM-MSCs for treating diabetic cardiomyopathy. Approximately 10% of the world population is diabetic to which metformin is prescribed very commonly. Hence, future cell replacement therapies in combination with AMPK inhibitors may be more effective for patients with diabetes.NEW & NOTEWORTHY Metformin treatment reduces the efficacy of mesenchymal stem cell therapy for cardiac repair during diabetic cardiomyopathy. Stem cell therapy in diabetics may be more effective in combination with AMPK inhibitors.

Liraglutide regulates lipid metabolism via FGF21- LKB1- AMPK- ACC1 pathway in white adipose tissues and macrophage of type 2 diabetic mice.

Liraglutide (LRG), a glucagon-like peptide 1 analogue (GLP1A), could decrease body mass of type 2 diabetes (T2DM), but the exact molecular mechanism of LRG has not been elucidated. This study was performed to explore whether LRG regulated TG synthesis via secretion of FGF21 and modulating AMP-dependent protein kinase (AMPK) pathway in an autocrine mode. Two-month-old male C57BL/6 mice were fed high-fat diet (HFD) for 4 months followed by injection of 30 mg/kg streptozotocin (STZ) to induce state of T2DM. Then DM mice were given LRG (0.4 mg/kg/d) for 4 months. Body mass, serum lipids and FGF21 levels, related gene expression were analyzed. Lipopolysaccharide (LPS)-induced RAW264.7 cells were treated with palmitic acid and different concentrations of LRG. Then Exendin (9-39), siRNA targeted to liver kinase B1 (LKB1) and Compound C were used to confirm the signaling pathway. LRG decreased adipocyte size, increased secretion of FGF21, and promoted phosphorylation of LKB1, AMPK and Acetyl coenzyme A carboxylase 1 (ACC1) in white adipose tissue (WAT) of DM mice. LRG also increased phosphorylation of fibroblast growth factor receptor 3 (FGFR3), LKB1, AMPK and ACC1 via FGF21 secretion, which ultimately inhibited synthesis of TG in macrophage. In conclusion, FGF21 is induced to be expressed in macrophage by LRG, which then activates LKB1-AMPK-ACC1 pathway in an autocrine manner.