OBJECTIVE: In this study, the combined effect of two stressors, namely, electromagnetic fields (EMFs) from mobile phones and fructose consumption, on hypothalamic and hepatic master metabolic regulators of the AMPK/SIRT1-UCP2/FOXO1 pathway were elucidated to delineate the underlying molecular mechanisms of insulin resistance. METHODS: Weaned Wistar rats (28 days old) were divided into 4 groups: Normal, Exposure Only (ExpO), Fructose Only (FruO), and Exposure and Fructose (EF). Each group was provided standard laboratory chow ad libitum for 8 weeks . Additionally, the control groups, namely, the Normal and FruO groups, had unrestricted access to drinking water and fructose solution (15%), respectively. Furthermore, the respective treatment groups, namely, the ExpO and EF groups, received EMF exposure (1,760 MHz, 2 h/day x 8 weeks). In early adulthood, mitochondrial function, insulin receptor signaling, and oxidative stress signals in hypothalamic and hepatic tissues were assessed using western blotting and biochemical analysis. RESULT: In the hypothalamic tissue of EF, SIRT1, FOXO 1, p-PI3K, p-AKT, Complex III, UCP2, MnSOD, and catalase expressions and OXPHOS and GSH activities were significantly decreased ( P < 0.05) compared to the Normal, ExpO, and FruO groups. In hepatic tissue of EF, the p-AMPKα, SIRT1, FOXO1, IRS1, p-PI3K, Complex I, II, III, IV, V, UCP2, and MnSOD expressions and the activity of OXPHOS, SOD, catalase, and GSH were significantly reduced compared to the Normal group ( P < 0.05). CONCLUSION The findings suggest that the combination of EMF exposure and fructose consumption during childhood and adolescence in Wistar rats disrupts the closely interlinked and multi-regulated crosstalk of insulin receptor signals, mitochondrial OXPHOS, and the antioxidant defense system in the hypothalamus and liver.
Humans ; Rats ; Animals ; Adult ; Rats, Wistar ; Fructose/metabolism* ; Catalase ; Receptor, Insulin/metabolism* ; AMP-Activated Protein Kinases/metabolism* ; Electromagnetic Fields/adverse effects* ; Sirtuin 1/metabolism* ; Cell Phone ; Phosphatidylinositol 3-Kinases/metabolism* ; Forkhead Box Protein O1/metabolism* ; Uncoupling Protein 2

Objective: To investigate the effect and mechanism of miR-96-5p on apoptosis of PC12 cells induced by maltol aluminum. Methods: In January 2021, PC12 cells at logarithmic growth phase were divided into blank control group and low, medium and high dose group. Cells in each group were treated with 0, 100, 200 and 400 μmol/L maltol aluminum for 24 hours respectively. Cells were collected and cell apoptosis rates were detected by flow cytometry, miR-96-5p and insulin receptor substrate 1 (IRS1) mRNA expressions were detected by qRT-PCR, and the protein expression levels of cysteine protease 3 (Caspase3) 、activated cysteine protease 3 (Cleaved-caspase3) 、IRS1、phosphorylated protein kinase B (p-AKT) and phosphorylated glucose synthesis kinase 3β (p-GSK3β) were detected by western blotting. The target binding relationship between miR-96-5p and IRS1 was detected by double luciferase reporter gene experiment. The miR-96-5p inhibitor cells and negative control cells were constructed after transfecting PC12 cells with miR-96-5p inhibitor for 24 hours. The cells were divided into blank control group, negative control group, aluminum exposure group, aluminum exposure+negative control group, aluminum exposure+miR-96-5p inhibition group, and miR-96-5p inhibition group. After transfecting PC12 cells with miR-96-5p inhibition and IRS1 siRNA for 24 h, the cells were divided into aluminum exposure+miR-96-5p inhibition+negative control group and aluminum exposure+miR-96-5p inhibition+IRS1 inhibition group. The control group was cultured in complete culture medium, and cells in the aluminum exposure group were treated with 200 μmol/L maltol aluminum for 24 hours. Cells in each group were collected and the apoptosis rate, miR-96-5p and IRS1 mRNA expression levels, as well as protein expression levels of Caspase3, Cleaved-caspase3, IRS1, p-AKT, and p-GSK3β were measured. Results: After 24 hours of exposure, compared with blank control group and low-dose group, the apoptosis rates, relative expressions of Caspase3 and Cleaved-caspase3 proteins, and relative expressions of miR-96-5p in the medium and high-dose groups of PC12 cells were significantly increased, while the relative expression levels of IRS1 mRNA, IRS1, p-AKT and p-GSK3β proteins were significantly decreased (P<0.05). Targetscan prediction and double luciferase report experiment both proved that IRS1 was a direct target gene of miR-96-5p. In the transfection experiment, compared with the aluminum exposure group, the apoptosis rate, the relative expressions of Caspase3 and Cleaved-caspase3 proteins, the relative expression of miR-96-5p in the aluminum exposure+miR-96-5p inhibition group were significantly decreased, while the relative expression levels of IRS1 mRNA and IRS1, p-AKT and p-GSK3β proteins were significantly increased (P<0.05). In the IRS1 low expression experiment, compared with the aluminum exposure+miR-96-5p inhibition+negative control group, the apoptosis rate, the relative expressions of Caspase3 and Cleaved-caspase3 proteins in the aluminum exposure+miR-96-5p inhibition+IRS1 inhibition group were significantly increased, while the relative expression levels of IRS1 mRNA and IRS1, p-AKT and p-GSK3β proteins were significantly decreased (P<0.05) . Conclusion: The increased expression of miR-96-5p and the targeted inhibition of IRS1 may be one of the mechanisms of apoptosis of PC12 cells induced by maltol aluminum exposure.
Animals ; Rats ; Aluminum/toxicity* ; Apoptosis ; Cell Proliferation ; Glycogen Synthase Kinase 3 beta/metabolism* ; Insulin Receptor Substrate Proteins/metabolism* ; MicroRNAs/metabolism* ; PC12 Cells ; Proto-Oncogene Proteins c-akt/metabolism* ; RNA, Messenger

OBJECTIVE: To investigate the effect CD36 deficiency on muscle insulin signaling in mice fed a normal-fat diet and explore the possible mechanism. METHODS: Wild-type (WT) mice and systemic CD36 knockout (CD36^-/-) mice with normal feeding for 14 weeks (n=12) were subjected to insulin tolerance test (ITT) after intraperitoneal injection with insulin (1 U/kg). Real-time PCR was used to detect the mRNA expressions of insulin receptor (IR), insulin receptor substrate 1/2 (IRS1/2) and protein tyrosine phosphatase 1B (PTP1B), and Western blotting was performed to detect the protein expressions of AKT, IR, IRS1/2 and PTP1B in the muscle tissues of the mice. Tyrosine phosphorylation of IR and IRS1 and histone acetylation of PTP1B promoter in muscle tissues were detected using co-immunoprecipitation (Co-IP) and chromatin immunoprecipitation (ChIP), respectively. RESULTS: CD36^-/- mice showed significantly lowered insulin sensitivity with obviously decreased area under the insulin tolerance curve in comparison with the WT mice (P < 0.05). CD36^-/- mice also had significantly higher serum insulin concentration and HOMA-IR than WT mice (P < 0.05). Western blotting showed that the p-AKT/AKT ratio in the muscle tissues was significantly decreased in CD36^-/- mice as compared with the WT mice (P < 0.01). No significant differences were found in mRNA and protein levels of IR, IRS1 and IRS2 in the muscle tissues between WT and CD36^-/- mice (P>0.05). In the muscle tissue of CD36^-/- mice, tyrosine phosphorylation levels of IR and IRS1 were significantly decreased (P < 0.05), and the mRNA and protein levels of PTP1B (P < 0.05) and histone acetylation level of PTP1B promoters (P < 0.01) were significantly increased as compared with those in the WT mice. Intraperitoneal injection of claramine, a PTP1B inhibitor, effectively improved the impairment of insulin sensitivity in CD36^-/- mice. CONCLUSION CD36 is essential for maintaining muscle insulin sensitivity under physiological conditions, and CD36 gene deletion in mice causes impaired insulin sensitivity by up-regulating muscle PTP1B expression, which results in detyrosine phosphorylation of IR and IRS1.
Animals ; Gene Deletion ; Histones/genetics* ; Insulin ; Insulin Receptor Substrate Proteins/metabolism* ; Insulin Resistance/genetics* ; Membrane Cofactor Protein/genetics* ; Mice ; Mice, Knockout ; Muscles/metabolism* ; Phosphoric Monoester Hydrolases/metabolism* ; Protein Tyrosine Phosphatase, Non-Receptor Type 1/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; RNA, Messenger/metabolism* ; Receptor, Insulin/metabolism* ; Tyrosine/genetics* ; Up-Regulation

OBJECTIVE: To observe the effect of electroacupuncture (EA) on protein expressions of suppressor of cytokine signaling 3 (SOCS3) and insulin receptor substrate-1 (IRS-1) in hypothalamus and morphology of pancreas islet in Zucker diabetic fatty (ZDF) rats, and to explore its possible mechanism on improving plasma glucose and insulin resistance of type 2 diabetes mellitus (T2DM). METHODS: Twelve SPF male ZDF rats were selected and fed with high-fat diet for 4 weeks to establish the T2DM model, after modeling, the rats were randomly divided into a model group and an EA group, 6 rats in each one. Besides, 6 SPF male Zucker lean rats were selected as a blank group. In the EA group, EA was applied at "Pishu" (BL 20), "Weiwanxiashu" (EX-B 3), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), with continuous wave, 15 Hz in frequency, 2 mA in intensity, once a day, 20 min each time, 6 times a week for 4 weeks. The fasting plasma glucose (FPG) was measured before and after intervention. The serum level of fasting insulin (FINS) was measured by radioimmunoassay, and the homeostasis model assessment of insulin resistance index (HOMA-IR) was calculated; the morphological change of pancreas islets was observed by HE staining; the protein expressions of SOCS3 and IRS-1 in hypothalamus were detected by Western blot. RESULTS: Before intervention, compared with the blank group, FPG in the model group and the EA group was increased (P<0.01). After intervention, compared with the blank group, FPG, serum level of FINS and HOMA-IR were increased (P<0.01), the protein expression of SOCS3 was increased while IRS-1 was decreased in the hypothalamus in the model group (P<0.01). Compared with the model group, FPG, serum level of FINS and HOMA-IR were decreased (P<0.01), the protein expression of SOCS3 was decreased while IRS-1 was increased in the hypothalamus in the EA group (P<0.01). In the model group, the shape of pancreas islets was irregular, the area of pancreas islets and the number of islet β cell nuclei were decreased, the nuclei of islet β cell was compensatory enlargement. In the EA group, the shape and the area of pancreas islets and the number of islet β cell nuclei were improved, the compensatory increase of islet β cell nuclei was alleviated compared with the model group. CONCLUSION Electroacupuncture can reduce the fasting plasma glucose, improve the morphology of pancreas islets, and alleviate the insulin resistance in ZDF rats. The mechanism may relate to the down-regulation of SOCS3 and up-regulation of IRS-1 in the hypothalamus, and improving the function of hypothalamus in regulating peripheral glucose metabolism.
Acupuncture Points ; Animals ; Blood Glucose/metabolism* ; Diabetes Mellitus, Type 2/therapy* ; Electroacupuncture ; Hypothalamus/metabolism* ; Insulin Receptor Substrate Proteins/metabolism* ; Insulin Resistance ; Male ; Pancreas/metabolism* ; Rats ; Rats, Zucker ; Suppressor of Cytokine Signaling 3 Protein/metabolism*

OBJECTIVE: To explore the effect of curcumin on the insulin receptor substrate 1 (IRS1)/phosphatidylinositol-3-kinase (PI3K)/endometrial expression of glucose 4 (GLUT4) signalling pathway and its regulator, phosphatase and tensin homolog (PTEN), in a rat model of polycystic ovarian syndrome (PCOS). METHODS: PCOS model was induced by letrozole intragastric administration. Sprague-Dawley rats were randomized into 4 groups according to a random number table: (1) control group; (2) PCOS group, which was subjected to PCOS and received vehicle; (3) curcumin group, which was subjected to PCOS and treated with curcumin (200 mg/kg for 2 weeks); and (4) curcumin+LY294002 group, which was subjected to PCOS, and treated with curcumin and LY294002 (a specific PI3K inhibitor). Serum hormone levels (17 β-estradiol, follicle stimulating hormone, luteinizing hormone, progesterone, and testosterone) were measured by enzyme linked immunosorbent assay, and insulin resistance (IR) was assessed using the homeostasis model assessment of IR. Ovarian tissues were stained with haematoxylin and eosin for pathological and apoptosis examination. Expression levels of key transcriptional regulators and downstream targets, including IRS1, PI3K, protein kinase B (AKT), GLUT4, and PTEN, were measured via reverse transcription polymerase chain reaction and Western blot, respectively. RESULTS: The PCOS group showed impaired ovarian morphology and function. Compared with the PCOS group, curcumin treatment exerted ovarioprotective effects, down-regulated serum testosterone, restored IR, inhibited inflammatory cell infiltration in ovarian tissues, decreased IRS1, PI3K, and AKT expressions, and up-regulated GLUT4 and PTEN expressions in PCOS rats (P<0.05 or P<0.01). In contrast, IRS1, PI3K, AKT, and PTEN expression levels were not significantly different between PCOS and curcumin+LY294002 groups (P>0.05). CONCLUSION The beneficial effects of curcumin on PCOS rats included the alteration of serum hormone levels and recovery of morphological ovarian lesions, in which, PTEN, a new target, may play a role in regulating the IRS1/PI3K/GLUT4 pathway.
Animals ; Female ; Humans ; Rats ; Cell Proliferation ; Curcumin/therapeutic use* ; Follicle Stimulating Hormone ; Glucose ; Hyperandrogenism ; Insulin Receptor Substrate Proteins/metabolism* ; Insulin Resistance ; Ovarian Cysts ; Ovarian Neoplasms ; Phosphatidylinositol 3-Kinase/metabolism* ; Phosphatidylinositol 3-Kinases/metabolism* ; Polycystic Ovary Syndrome/drug therapy* ; Proto-Oncogene Proteins c-akt/metabolism* ; Rats, Sprague-Dawley ; Testosterone

OBJECTIVE: To study the expression of tumor associated vascular insulin receptor (TVIR) in colorectal cancer with or without metabolic syndrome (MS) and its relationship with the pathological features of colorectal cancer. METHODS: The expression of TVIR in 220 colorectal cancer specimens was detected by tissue microarray and immunohistochemistry. The relationships between the expression of TVIR and the pathological features (pathological subtypes, histological grade, invasion depth, lymph node metastasis and TNM stage) of colorectal cancer with/without MS were analyzed. RESULTS: The insulin receptor expression was observed in colorectal cancer tissue or border area between cancer and normal tissue, but not in normal intestinal tissue. The high-expression rates of TVIR in MS group was remarkably lower than that of non-MS group (21.6%vs. 41.0%, CONCLUSIONS s: High-expression of TVIR is associated with aggressive pathological features such as invasion, lymph node metastasis and high TNM stage of colorectal cancer, especially for those patients without MS. TVIR could be a useful biological marker for prognosis of colorectal cancer.
Biomarkers, Tumor/genetics* ; Colorectal Neoplasms/physiopathology* ; Gene Expression Regulation, Neoplastic ; Humans ; Neoplasm Staging ; Prognosis ; Receptor, Insulin/genetics*

OBJECTIVE: To observe the effects of AdipoRon orally on the functions of spleen and pancreas in type 2 diabetic mice, in order to present data for clinical application. METHODS: Forty C57/BL6 male mice were randomly divided into 2 groups: normal control group (n=10) and model group (n=30), the former group was fed normally, while the later group was fed with high fat and sugar for 4 weeks.After that, type 2 diabetes model was established in DM group induced by intraperitoneal injection of streptozotocin (STZ, 40 mg/kg).As type 2 diabetes model established successfully, the model mice were randomly divided into three groups (n=10): diabetes mellitus (DM) group, high dose of AdipoRon group (DM + H) and low dose of adiponRon group (DM + L).All the four groups were treated with saline, saline, AdipoRon at the doses of 20 mg/kg and 50 mg/kg by gavages respectively, once a day for 10 days.And then put them to death for collecting blood, pancreas and spleen.Pathological changes of pancreas were observed with a light microscope after HE staining.Protein contents of insulin receptor (INSR), insulin receptor substrate 1( IRS-1) and tumor necrosis factor-α(TNF-α) in pancreatic and spleen tissues were detected by ELISA.The protein level of phosphorylation insulin receptor substrate 1(p-IRS-1) in pancreas was determined by Western blot, and the expression of insulin mRNA in pancreas was tested by RT-PCR. RESULTS: Under the light microscope, it was visible that the pancreatic tissue in NC group was full and closely packed, and the islet was big.Pancreatic tissue of DM mice was incompact and the islet of DM mice was smaller than that of normal mice.As for the mice treated with AdipoRon orally, the pancreatic tissue was full and closely arranged, and the islet was slightly smaller.Compared with NC group, the levels of TNF-α in pancreas and spleen of DM group were increased markedly, the levels of INSR and IRS-1 were decreased, the spleen coefficient, p-IR-1 protein level and insulin mRNA expression in pancreas were decreased, all were significant statistically (P＜0.05).Compared with DM group, the levels of TNF-α in pancreas and spleen of AdipoRon groups were decreased, the levels of INSR and IRS-1 in pancreas and spleen of AdipoRon groups were increased, while the spleen coefficient was increased (P＜0.05).The p-IRS-1 protein level and insulin mRNA expression in pancreas in DM+H group were increased (P＜0.05).Compared with DM + L group, the level of TNF-α was decreased, and the levels of INSR and IRS-1 were significantly increased (P＜0.05) in DM + H group (P＜0.05). CONCLUSION Oral administration of AdipoRon can protect the spleen and pancreas of diabetic mice by decreasing the inflammatory response, up-regulating the expression of INSR, and increasing p-IRS-1 level in diabetic mice.
Animals ; Diabetes Mellitus, Experimental ; Diabetes Mellitus, Type 2 ; complications ; drug therapy ; Inflammation ; Insulin ; Insulin Receptor Substrate Proteins ; drug effects ; Male ; Mice ; Pancreas ; Piperidines ; pharmacology ; Random Allocation ; Receptor, Insulin ; drug effects ; Spleen ; drug effects

More and more evidence suggests that microRNA is widely involved in the regulation of cardiovascular function. Our preliminary experiment showed that miR-494-3p was increased in heart of diabetic rats, and miR-494-3p was reported to be related to metabolism such as obesity and exercise. Therefore, this study was aimed to explore the role of miR-494-3p in diabetic myocardial insulin sensitivity and the related mechanism. The diabetic rat model was induced by high fat diet (45 kcal% fat, 12 weeks) combined with streptozotocin (STZ, 30 mg/kg), and cardiac tissue RNA was extracted for qPCR. The results showed that the level of miR-494-3p was significantly up-regulated in the myocardium of diabetic rats compared with the control (P < 0.05). The level of miR-494-3p in H9c2 cells cultured in high glucose and high fat medium (HGHF) was significantly increased (P < 0.01) with the increase of sodium palmitate concentration, whereas down-regulation of miR-494-3p in HGHF treated cells led to an increase in insulin-stimulated glucose uptake (P < 0.01) and the ratio of p-Akt/Akt (P < 0.05). Over-expression of miR-494-3p in H9c2 cell line significantly inhibited insulin-stimulated glucose uptake and phosphorylation of Akt (P < 0.01). Bioinformatics combined with Western blotting experiments confirmed insulin receptor substrate 1 (IRS1) as a target molecule of miR-494-3p. These results suggest that miR-494-3p reduces insulin sensitivity in diabetic cardiomyocytes by down-regulating IRS1.
Animals ; Diabetes Mellitus, Experimental ; physiopathology ; Down-Regulation ; Insulin ; Insulin Receptor Substrate Proteins ; physiology ; Insulin Resistance ; MicroRNAs ; genetics ; Myocytes, Cardiac ; physiology ; Rats

A stable hepatoma cell line(Hep G2 cell) insulin resistance model was established and used to analyze the effect of effective components of Mori Folium in alleviating insulin resistance,and preliminary explore the mechanism for alleviating insulin resistance. The Hep G2 insulin action concentration and the duration of action were investigated using the glucose oxidase method(GOD-POD method) to establish a stable Hep G2 insulin resistance model. Normal control group,model group,Mori Folium polysaccharide group,Mori Folium flavonoid group and rosiglitazone group were divided to determine the glucose consumption. The effect of Mori Folium effective components on Hep G2 insulin resistance was analyzed. The mRNA expressions of JNK,IRS-1 and PDX-1 in each group were detected by Real-time quantitative PCR(qRT-PCR). The protein expressions of p-JNK,IRS-1 and PDX-1 were detected by Western blot. And the mechanism of effective components of Mori Folium in alleviating insulin resistance was investigated. The results showed that the glucose consumption was significantly decreased in the insulin resistance cells after incubation with 25. 0 mg·L-1 insulin for 36 h(P<0. 01),and the model was relatively stable within 36 h. Mori Folium polysaccharides and flavonoids all alleviated insulin resistance,among which Mori Folium flavonoids had better effect in alleviating Hep G2 insulin resistance(P<0. 05). The qRT-PCR analysis showed that Mori Folium polysaccharides and flavonoids could inhibit JNK and IRS-1 mRNA expressions,while enhancing PDX-1 mRNA expression. Western blot analysis displayed that Mori Folium polysaccharides and flavonoids could inhibit p-JNK and IRS-1 protein expressions,while enhancing PDX-1 protein expression. Mori Folium polysaccharides and flavonoids can alleviate insulin resistance in Hep G2 cells,and its mechanism may be the alleviation of insulin resistance by inhibiting JNK signaling pathway.
Drugs, Chinese Herbal ; pharmacology ; Glucose ; Hep G2 Cells ; Homeodomain Proteins ; metabolism ; Humans ; Insulin ; Insulin Receptor Substrate Proteins ; metabolism ; Insulin Resistance ; MAP Kinase Kinase 4 ; metabolism ; MAP Kinase Signaling System ; Morus ; chemistry ; Plant Leaves ; chemistry ; Trans-Activators ; metabolism

In 2018, the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) published a consensus recommendation on management of hyperglycemia. This consensus report emphasized the need for patient-centered management considering multimorbidity and individual patient preferences and barriers. Patients with type 2 diabetes with established atherosclerotic cardiovascular disease who fail to control blood glucose with the initial glucose-lowering medication are recommended a sodium-glucose cotransporter 2 (SGLT2) inhibitor or a glucagon-like peptide 1 (GLP-1) receptor agonist. For patients with chronic kidney disease and heart failure, SGLT2 inhibitors are recommended. In patients who need an injectable medication, GLP-1 receptor agonists are the preferred choice over insulin. In this section, we summarize “Management of Hyperglycemia in Type 2 Diabetes, 2018. A Consensus Report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD).”
Atherosclerosis ; Blood Glucose ; Cardiovascular Diseases ; Comorbidity ; Consensus ; Diabetes Mellitus ; Glucagon-Like Peptide 1 ; Glucagon-Like Peptide-1 Receptor ; Heart Failure ; Humans ; Hyperglycemia ; Insulin ; Patient Preference ; Patient-Centered Care ; Renal Insufficiency, Chronic