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ObjectiveThis study aims to investigate the therapeutic effect of Tangbikang granules（TBK） on type 2 diabetes mellitus （T2DM） complicated with non-alcoholic fatty liver disease （NAFLD） and to elucidate the underlying mechanism. MethodT2DM and NAFLD were induced in ZDF rats， which were then respectively treated （ig） with low-dose （0.625 g·kg-1）， medium-dose （1.25 g·kg-1）， and high-dose （2.5 g·kg-1） TBK for 12 weeks. Fasting blood glucose （FBG） and body mass were recorded every 4 weeks during the treatment. One week before sampling， the feed intake of rats was detected， and after 12 h night fasting， oral glucose tolerance test （OGTT） was performed. The area under the curve （AUC） was used to evaluate glucose tolerance， and the homeostatic model assessment for insulin resistance （HOMA-IR） was calculated. Blood in abdominal aorta and liver were collected for determination of blood glucose and lipid metabolism indexes： Fasting serum insulin （FINS）， serum total cholesterol （TC）， triglyceride （TG）， low density lipoprotein cholesterol （LDL-C）， high density lipoprotein cholesterol （HDL-C）， and nonesterified fatty acids （NEFA）. The liver was weighed to calculate the liver index， and the liver tissue morphology was observed and analyzed based on hematoxylin-eosin （HE） staining and periodic acid-Schiff （PAS） staining. The protein levels of insulin receptor substrate （IRS）， phosphatidylinositol 3-kinase （PI3K）， protein kinase B （Akt） and phosphorylated IRS and Akt were detected by Western blotting. All data were analyzed by SPSS 20.0. ResultThe feed intake of the model group was higher than that in the normal group （P<0.01）， and the feed intake the administration groups was lower than that in the model group （P<0.05， P<0.01）. At the 8th and 12th week， the body mass in the model group was lower than that in the normal group （P<0.01）. Compared with the model group， TBK reduced FBG in a concentration-dependent manner. The blood glucose level in OGTT and AUC in the model group were higher/larger than those in the normal group （P<0.01）. The blood glucose value in OGTT was decreased in TBK groups and the metformin group compared with that in the model group， and AUC in the administration groups was significantly different from that in the model group （P<0.01）. The serum level of FINS and HOMA-IR in the model group were higher than those in the normal group （P<0.01）， and they were lower in the TBK groups than in the model group （P<0.01）. Serum levels of TG， TC， HDL-C， NEFA （P<0.05， P<0.01）， and LDL-C were higher in the model group than in the normal group. Serum levels of TG， TC， LDL-C， and NEFA in the TBK groups were lower than those in the model group， and the levels of TG， LDL-C， and NEFA in TBK groups were concentration-dependent （lowest levels in high-dose TBK group）. Compared with the model group， high-dose TBK significantly increased the level of HDL-C （P<0.05）. Liver index of the model group was higher than that in the normal group （P<0.01）. The liver index of the administration groups showed a decreasing trend with no significant difference from that in the model group. As for the HE staining result of liver， the model group had unclear structure of liver lobule， enlarged cells of different sizes， and obvious steatosis of hepatocytes. TBK of all doses alleviated liver injury， particularly the high dose. For the PAS staining， compared with the normal group， the model group demonstrated significant fat vacuoles and significant reduction in purplish red glycogen granules in the cytoplasm. The staining results of high- and medium-dose groups of TBK were more similar to the normal group. Western blot was used to detect the protein expression of liver tissue. The expression of PI3K protein， p-IRS1/IRS1， and p-Akt/Akt in the model group were lower than those in the normal group （P<0.01）， and they were higher in the high-dose TBK group than in the model group （P<0.01）. ConclusionTBK exerts therapeutic effect on T2DM combined with NAFLD in ZDF rats by activating the typical PI3K signaling pathway.
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Diabetic nephropathy (DN) is one of the most common complications of diabetes. It is an important cause of diabetes disability and death. DN is a systemic metabolic syndrome. In its pathogenesis, the interaction of various cell activities and a large number of cytokine biological activities, the activation of signal pathways and so on are involved in the development of DN. At present, the clinical treatment of DN is mainly Western medicine, but it has limitations such as strong toxicity, high side effects and poor compliance. Therefore, the discovery of natural anti-DN substances has also become an important means to treat DN. Mulberry leaves are the dry leaves of Morus alba L. It is not only a tradi?tional Chinese medicine, but also a dual-purpose medicinal material for medicine and food. It has the effects of dispelling wind and clearing heat, cooling blood and brightening eyes, tonifying and so on. Mulberry leaf polysaccharide (MLP) is a kind of high molecular compound in mulberry leaves. It has many pharmacological effects, such as hypoglycemic, antiox?idant, anti-stress, anti-virus and so on. Therefore, the pharmacological effects of mulberry leaf polysaccharides on dia?betic nephropathy are reviewed in this paper, so as to provide references for further research and application. The patho?genesis of DN is complex, and the mechanism of renal injury has not been completely clarified. The current studies believe that DN is closely related to heredity, abnormal glucose metabolism, abnormal lipid metabolism, microcirculation disorder, cytokine action, oxidative stress and so on. Relevant studies show that the pharmacological effects of mulberry leaf polysaccharide in the prevention and treatment of DN mainly include: ① Effect on transforming factor-β1 (TGF-β1):TGF-β1 has become an important cytokine involved in the formation of renal fibrosis by regulating cell proliferation and differentiation and the production of extracellular matrix (ECM). MLP can significantly inhibit TGF-β1 protein, and then inhibit the synthesis of extracellular matrix by renal interstitial fibroblasts and inhibit the realization of fibrosis.②Effect on insulin receptor substrate (IRS-1): IRS-1 is an important signal molecule at the beginning of IR signal transduction. The decrease of IRS-1 gene expression or the decrease of expression can affect the effective transmission of IR signal and lead to the development and deterioration of diabetes. MPL can significantly increase the expression of IRS-1 mRNA in liver tissue of DN rats, so as to prevent and treat DN. ③ Effect on the expression of resistin protein in adipose tis?sue. Resistin is a secretory polypeptide derived from adipose tissue and is specifically expressed in white adipose tissue and is closely related to type 2 diabetes mellitus (T2DM). Experimental studies show that MLP can effectively reduce the expression of resistin protein in white adipose tissue of T2DM rats, indicating that MLP may reduce the level of IR by inhibiting the expression of resistin in adipose tissue, thereby reducing the insulin resistance state of T2DM rats, so as to achieve the goal of treating diabetes.④Effect on adiponectin receptor 1 (AdipoR1):adiponectin can improve insulin resistance, reduce blood glucose and lipid. AdipoR1 is mainly expressed in skeletal muscle and kidney. Studies have shown that AdipoR1 is closely related to the occurrence and development of DN. The results showed that MLP could reduce the blood glucose and blood lipid level and up regulate the expression of AdipoR1 mRNA in DN rats, suggesting that MLP may delay the occurrence and development of DN. This article reviewed the pharmacological effects of mulberry leaf polysaccharides on diabetic nephropathy, and provided a useful basis for further development and utilization of mul?berry leaf polysaccharides in the treatment of DN.
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Objective:To study the effect of Baihutang on blood glucose， blood lipid metabolism and vascular remodeling in type 2 diabetic rats and its regulation on insulin receptor substrate-1（IRS-1）/ phosphatidylinositol-3 kinase（PI3K）/ protein kinase B（Akt） signal pathway. Method:The 90 rats were randomly divided into normal group， model group， Baihutang low， middle and high dose groups and metformin group， with 15 rats in each group. Except for normal group， the other rats were injected intraperitoneally with streptozotocin to establish the model of type 2 diabetes. The rats in the low， middle and high dose groups were given Baihutang formula granules of 5， 10， 20 g·kg-1 respectively according to their body weight. The positive control group was given metformin （100 mg·kg-1） by intragastric administration， while those in the control group and model group were given the same amount of normal saline once a day for 12 weeks. The levels of fasting blood glucose， glycosylated hemoglobin， serum tumor necrosis factor-α（TNF-α）， interleukin-6（IL-6）， interleukin-1 β（IL-1β）， total cholesterol（TC）， triglyceride（TG） and low-density lipoprotein cholesterol（LDL-C） were measured after administration. The levels of sterol regulatory element binding protein 1C （SREBP1C）， acetyl CoA carboxylase （ACC）， fatty acid synthase gene （FASN） and carnitine palmitoyl transferase 1A （CPT1A）， acylcoa oxidase 1（ACOX1）， recombinant human acylcoa dehydrogenase （ACADM） mRNA in liver of rats were detected by Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR）， Western blot was used to detect the protein levels of IRS-1， PI3K and Akt in liver of rats. Hematoxylin-eosin（HE） staining was used for histopathological examination of rat thoracic aortic vessels. The migration ability of vascular smooth muscle cells in rat thoracic aorta was detected by scratch test. Result:Compared with the normal group， the fasting blood glucose， glycosylated hemoglobin， serum TNF-α， IL-6，IL-1β， TC，TG and LDL-C levels， liver lipid synthesis gene mRNA level and vascular smooth muscle cell migration ability of thoracic aorta in model group were significantly higher than those in normal group （P<0.05）， while fatty acid oxidation gene mRNA level and IRS-1，PI3K，Akt protein level in liver were significantly decreased in model group （P<0.05）. The vascular wall thickness of thoracic aorta increased significantly in rats （P<0.05）. Compared with model group， the levels of fasting blood glucose， glycosylated hemoglobin， serum TNF-α，IL-6， IL-1β， TC， TG and LDL-C， the level of lipid synthesis gene mRNA in liver and the migration ability of vascular smooth muscle cells in thoracic aorta of rats in all Baihutang groups were significantly lower than those in model group （P<0.05）. The mRNA level of fatty acid oxidation gene and the protein levels of IRS-1， PI3K and Akt in liver were significantly increased（P<0.05）， and the histopathology of thoracic aorta was significantly improved and the vascular wall thickness decreased significantly（P<0.05）. Conclusion:Baihutang can reduce the levels of blood glucose， blood lipid and serum inflammatory factors in type 2 diabetic rats， regulate the expression of genes related to lipid metabolism in liver， and improve the histopathology and vascular remodeling of thoracic aorta. The mechanism may be related to the regulation of IRS-1/PI3K/Akt signal pathway.
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BACKGROUND@#MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression, influence cellular processes, and promote disease development. Variations in miRNA expression have been observed in many diseases, including hepatitis, cardiovascular disease, and cancer. The aim of this study is to investigate the effect of miR-144-3p on the invasion and metastasis of lung adenocarcinoma by targeting recombinant insulin receptor substrate 1 (IRS1).@*METHODS@#The expression of miR-144-3p in patients with lung adenocarcinoma was queried through bioinformatics database. MirTarPathway was used to analyze the KEGG enrichment pathway of miRNA. The expression and plasmid transfection efficiency of miR-144-3p in lung adenocarcinoma cell lines were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Transwell assay was used to detect the changes of cell invasion and migration ability in different groups. Bioinformatics determined the key genes (Hub genes) of miR-144-3p; Double luciferase target assay was used to detect the mutual binding of miR-144 and IRS1. Western blot assay was used to detect the expression of IRS1 in different cell lines and the expression of after overexpression of miR-144.@*RESULTS@#The expression of miR-144-3p in lung adenocarcinoma tissues was decreased, qRT-PCR results indicated that the expression of miR-144-3p in lung adenocarcinoma cell A549 was significantly decreased (P<0.05), and the overexpressed plasmid was successfully transfected (P<0.05). Overexpression of miR-144 decreased the ability of cell migration and invasion (P<0.05). The expression of IRS1 was up-regulated in lung adenocarcinoma tissues. Survival analysis showed that patients with lung adenocarcinoma with high IRS1 expression had a poor prognosis (P<0.05). Double luciferase assay results showed that miR-144 could specifically identify 3'-UTR of IRS1 and inhibit reporter enzyme expression (P<0.05). Western blot indicated that the expression of IRS1 was increased in A549 cells (P<0.05). After overexpression of miR-144, the expression level of IRS1 protein was decreased (P<0.05). Transwell experiment proved that miR-144-3p could inhibit invasion and metastasis of lung adenocarcinoma cells by targeting IRS1 (P<0.05).@*CONCLUSIONS@#MiR-144-3p inhibits the invasion and migration of A549 cells through targeted regulation of IRS1, thus playing an anticancer role in tumors.
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Objective: The present study was designed to investigate the modulating effect of Zhenxin Xingshui Yizhi Fang and its essential oil extract on cognitive deficits in mice.Method: For the purpose of this study 5 months old APP/PS1 double transgenic mice and wild-type C57BL/6JNju were selected as experimental animals.Then APP/PS1 double transgenic mice were randomly divided into model group,essential oil low and high-dose groups (12.13,48.50 mg·L-1),Zhenxin Xingshui Yizhi Fang group (0.46 g·kg-1).Meanwhile,wild-type C57BL/6JNju mice were used as a normal group.APP/PS1 double transgenic mice were treated with Zhenxin Xingshui Yizhi Fang and its essential oil extract for 22 consecutive days.Mice were subjected to a Morris water maze test and a platform test in order to determine their cognitive effect.Nissl's staining was used to observe pathological changes in brain tissue.Meanwhile,senile plaques (SP) were observed by employing Thioflavin-S staining.The expression of glucose transporter 1(GLUT1) and insulin receptor substrate-1(IRS-1) were analyzed using immunohistochemistry techniques.The levels of neurotransmitters such as acetylcholine (ACH),glutamate (GLU) and γ-aminobutyric acid (GABA) in the hippocampus were quantified by enzyme-linked immunosorbent assay (ELISA).Result: The memory function was significantly reduced in model group,and severe brain injury and neuronal apoptosis were also observed in comparison to normal group (PPPPPPPConclusion: These results indicate that Zhenxin Xingshui Yizhi Fang and its essential oil extract could ameliorate cognitive deficits and GLUT1 and IRS-1 could be a possible therapeutic target for AD.It may be an interesting approach to the treatment of Alzheimer's disease.
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OBJECTIVE: To observe the effect of electroacupuncture (EA) on insulin signaling pathway in liver tissues of central neuronal specific signal transduction and activator of transcription 5 conditional-knockout (Stat 5 NKO) mice, so as to explore its mechanism underlying improvement of insulin resistance (IR)．. METHODS: Twenty-four male Stat 5 NKO mice were randomly divided into model and EA groups (n＝12 mice/group), and 12 Stat 5 fl/fl mice were used as the normal control group. EA (2 Hz/15 Hz, 0.8－1.0 mA) was alternatively applied to ipsilateral "Zusanli" (ST 36) and "Neiting" (ST 44) for 20 min, once a day, 6 times a week for 4 weeks. The glucose tolerance test (GTT) and insulin tolerance test (ITT) were performed, and the values of fasting plasma glucose (FPG) and fasting insulin (FINS) were measured by glucometer and ELISA, separately. The insulin sensitivity index (ISI) was calculated. The phosphorylation protein expressions of insulin receptor substrate 1 (IRS 1), insulin receptor β (IRβ) and protein kinases B (Akt) in the liver tissues were detected by Western blot. RESULTS: In Stat 5 NKO mice (model group), FPG level and glucose area under the curve (GAUC) of ITT and GTT were significantly increased (P0.05). Compared with the normal group, the protein expression levels of liver p-IRS 1 and p-IRβ were significantly up-regulated (P<0.001), and the p-Akt expression was significantly down-regulated (P<0.01) in the model group. Following EA treatment, the increased p-IRS 1 and p-IRβ protein expression and the decreased p-Akt expression were apparently reversed in the EA group relevant to the model group (P<0.001, P<0.01)．. CONCLUSION: EA can improve the IR induced by central neuronal Stat 5-knockout in mice, which may contribute to its effectiveness in regulating hepatic IRβ/IRS 1/Akt signaling pathway.
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The insulin receptor substrate (IRS) proteins are a family of cytoplasmic proteins that integrate and coordinate the transmission of signals from the extracellular to the intracellular environment via transmembrane receptors, thus regulating cell growth, metabolism, survival and proliferation. The PI3K/AKT/mTOR and MAPK signaling pathways are the best-characterized downstream signaling pathways activated by IRS signaling (canonical pathways). However, novel signaling axes involving IRS proteins (noncanonical pathways) have recently been identified in solid tumor and hematologic neoplasm models. Insulin receptor substrate-1 (IRS1) and insulin receptor substrate-2 (IRS2) are the best-characterized IRS proteins in hematologic-related processes. IRS2 binds to important cellular receptors involved in normal hematopoiesis (EPOR, MPL and IGF1R). Moreover, the identification of IRS1/ABL1 and IRS2/JAK2V617F interactions and their functional consequences has opened a new frontier for investigating the roles of the IRS protein family in malignant hematopoiesis. Insulin receptor substrate-4 (IRS4) is absent in normal hematopoietic tissues but may be expressed under abnormal conditions. Moreover, insulin receptor substrate-5 (DOK4) and insulin receptor substrate-6 (DOK5) are linked to lymphocyte regulation. An improved understanding of the signaling pathways mediated by IRS proteins in hematopoiesis-related processes, along with the increased development of agonists and antagonists of these signaling axes, may generate new therapeutic approaches for hematological diseases. The scope of this review is to recapitulate and review the evidence for the functions of IRS proteins in normal and malignant hematopoiesis.
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Humans , Signal Transduction/physiology , Leukemia, Lymphoid/metabolism , Leukemia, Myeloid/metabolism , Insulin Receptor Substrate Proteins/metabolism , Hematopoiesis/physiology , Leukemia, Lymphoid/physiopathology , Leukemia, Myeloid/physiopathology , Insulin Receptor Substrate Proteins/physiologyABSTRACT
Objective To investigate the effects of chronic intermittent hypoxia on the adipose factor and the expressions of insulin receptor substrate 2 (IRS-2),glucose transporter 2 (GLUT-2) and leptin in rat liver.Methods Twenty-four mature SD rats were randomly divided into 3 groups:control group (UC),chronic intermittent hypoxia group (CIH) and reoxygenation group (RH).The arterial blood gas analysis was performed after the establishment of rat model.The serum fasting blood glucose (FBG) and fasting insulin (FINS) in each group were detected by peroxidase method;the concentrations of free fatty acids (FFA) and leptin were detected by ELISA.The expressions ofmRNA and protein of GLUT-2,IRS-2 and leptin were detected by qRT-PCR and Western blotting.Results The serous concentrations of FBG,FINS,FFA and leptin were significantly higher in CIH group than in UC group (P＜0.05),and were dramatically higher in RH group than in both CIH group (P=0.003) and UC group (P=0.000).Western blotting and qRT-PCR detection showed that the protein and mRNA expressions of GLUT-2 and IRS-2 were significantly lower in CIH group than in RH group of rat liver (P＜0.05),while were markedly lower in RH group than in UC group (P＜0.05);the expressions of leptin protein and mRNA were significantly higher in CIH group than in RH group (P＜0.05),while were obviously higher in RH group than in UC group of rat liver (P＜0.05).Conclusion Insulin resistance induced by chronic intermittent hypoxia may be associated with the elevation of serum FFA and leptin,and be related to the decreased expression of GLUT-2 and IRS-2 and increased expression of leptin in liver.
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Objective To investigate the regulation of insulin VGLUT2 gene expression in pancreatic β cells and its exactly mechanism.Methods The rat pancreatic β cell line RIN-5F was treated by different insulin concentrations and different siRNA.The changes of VGLUT2 mRNA and protein expression levels were detected by adopting real-time qPCR and Western blot.Results In-sulin with a concentration of 100,200 nmol/L significantly inhibited the expressions of VGLUT2 mRNA and protein in RIN-5RF cells(P<0.05),moreover the inhibiting effect was most significant at 100 nmol/L.After 100 nmol/L insulin treatment,the expres-sions of VGLUT2 mRNA and protein at 12,18,24 h were significantly inhibited compared with that at 0 h(P<0.05).Compared with the Blank group,Lip2000 group and Control-siRNA group,after interfering RIN-5F by using IR-siRNA,IRS1-siRNA and IRS2-siRNA,the inhibition situation of VGLUT2 mRNA and protein expressions by 100 nmol/L insulin in each group was signifi-cantly recovered(P<0.05).Conclusion Insulin at low concentration could inhibit VGLUT 2 gene expression in rat pancreatic β cell line RIN-5F.
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OBJECTIVE: To investigate the relationship of the function and gene polymorphism of insulin receptor substrate (IRS) with type 2 diabetes mellitus (T2DM), and to provide a new perspective for T2DM drug development. METHODS: Relevant literatures included in CNKI, Wanfang, VIP, PubMed, SpringerLink and other databases from Jan. 1991 to Nov. 2017 were retrieved by using "Insulin receptor substrate" "Type 2 diabetes" "Insulin resistance" "Polymorphism" as Chinese keywords, and "Insulin receptor substrate" "IRS" "Type 2 diabetes" "Insulin resistance" "Polymorphism" as English keywords. The relationship of the function and gene polymorphism of IRS family with T2DM was reviewed. RESULTS & CONCLUSIONS: A total of 328 literatures were retrieved, of which there were 38 valid literatures. At present, IRS family has six members (IRS-1 to IRS-6). The dysfunction of IRS-1 and IRS-2 will lead to insulin resistance and induce T2DM. The relationship of IRS-3 and IRS-4 with T2DM remains controversial. IRS-5 and IRS-6 were newly found and their functions are not clear. The Gly972Arg mutation of IRS-1 is positively correlated with the pathogenesis of T2DM. Gly1057Asp mutation of IRS-2 combined with obesity can induce insulin resistance, but there is controversy. The mutation types of IRS family other members include Ala94Thr, Ala512Pro and Ser892Gly mutation of IRS-1, ACC, Ala157Thr and Leu647Val mutation of IRS-2. The relationship between these types of mutation and T2DM has not yet been fully supported. Multiracial and large-scale studies are required. Some achievements have been made in the present study, but the study is not yet comprehensive. Relationship of IRS family members and their mutation sites with T2DM still needs to be further tested in the expanded population.
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Objective To investigate the effect of electroacupuncture on hypothalamic insulin receptor substrate 1 (IRS-1) in a rat model of type 2 diabetes mellitus (T2DM). Methods Sixty Wistar rats were randomized to a normal group (15 rats) and an observation group (45 rats). In the observation group, a rat model of T2DM was made by high-energy diet induction. After the model was successfully made 8 weeks later, the observation group was randomized to model making, treatment and blocker groups, 15 rats each. The treatment group received electroacupuncture and the blocker group, electroacupuncture plus intraventricular perfusion of phosphatidylinositol 3-hydroxyl kinase (PI3K) blocker. After 8 weeks of treatment, fasting plasma glucose (FPG) was measured using a glucometer, fasting insulin (Fins) was determined by ELISA, insulin resistance index (IRI) was calculated and IRS-1 expression was examined by SABC immunohistochemistry assay in every group of rats. Results FPG and Fins increased significantly (both P<0.01) and IRI and IRS-1 expression decreased significantly (P<0.01) in the model making group compared with the normal group. FPG and Fins decreased significantly (both P<0.01) and IRI and IRS-1 expression increased significantly (P<0.01) in the treatment group compared with the model making group. FPG and Fins decreased significantly (P<0.05, P<0.01) and IRI and IRS-1 expression increased significantly (P<0.01) in the treatment group compared with the blocker group. Conclusion Electroacupuncture can improve FPG, Fins and insulin sensitivity by regulating hypothalamic IRS-1 expression in T2DM rats.
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Objective To explore the effects of high fat diet on insulin resistance ( IR) and the expression of liver insulin receptor substrate ( IRS) 1 and 2 in Tibet minipigs. Methods Ten Tibet minipigs were randomly divided into 2 groups, normal control (Ctr, n=5) group was fed with normal diet, and IR model (n=5) group fed with high fat/choles-terol diet for 12 weeks. After the establishment of pig models for 12 weeks, the body weight and body length were measured and body mass index ( BMI) was calculated, and the changes of total cholesterol ( TC) , low density lipoprotein ( LDL?C) , high density lipoprotein ( HDL?C) , triglyceride ( TG) , free fatty acids ( FFA) , fasting blood glucose ( FBG) , fasting insu?lin ( insulin) and homeostasis model assessment?insulin resistance ( HOMA?IR) were detected. Glucose tolerance test was performed, the area under the curve of glucose tolerance ( AUC) was also calculated, and the expressions of IRS?1 and IRS?2 gene and protein in liver tissue were detected. The lipid deposition, liver glycogen and pathological changes were ex?amined by pathology using oil?red O, PAS and HE staining, respectively. Results Compared with the control group, the body weight, BMI index, TC, LDL?C, HDL?C, FFA, FBG, insulin and HOMA?IR were significantly increased ( P <0. 05, P<0. 01). Intravenous glucose tolerance test showed that the curve of blood glucose and insulin levels were slowed down, while AUCglucose and AUCinsulin were significantly increased (P<0. 05, P<0. 01). Lipid deposition and liver glyco?gen were increased, and partial hepatocyte swelling, part of the nuclei disappeared or were pushed to one end, occasionally scattered infiltration of lymphocytes in the liver tissue. Furthermore, the expressions of IRS?1 and IRS?2 mRNA and protein were significantly decreased (P<0. 05, P<0. 01). Conclusions High fat diet can induce insulin resistance in Tibet minipigs. The decreased IRS?1 and IRS?2 expression in the liver may be one of the molecular mechanisms involved in the effects of high fat diet on insulin sensitivity in Tibet minipigs.
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Objective To explore the effects of water extract from Jiangtang Decoction (WEJTD) on PI3K/Akt signal pathway of skeletal muscle metabolism in KK-Ay diabetic mice.Methods Totally 50 KK-Ay mice were randomly divided into five groups:model group,metformin (positive drug,250 mg/kg) group,WEJTD low,medium,and high dose (2,4,and 8 g/kg) group,with 10 C57BL/6J mice as normal group.The relative drugs were ig administered once a day for 12 weeks,and mice in control group and model group were perfused with distilled water of equal volume.After 12 weeks' oral administration,mice were executed to separate serum,serum insulin level was detected by ELISA kit method;RNA was extracted from muscle tissue by Trizol,and real-time PCR were used to detect the level of PI3K,Akt,GLUT-4,GSK-3β,GS and IRS-1 mRNA.Results WEJTD can down-regulate concentration of insulin in serum and GSK-3β mRNA in skeletal muscle (P ＜ 0.05 and 0.001),and down-regulate mRNA of PI3K,Akt,IRS-1,GLUT-4,and GS in skeletal muscle (P ＜ 0.05,0.01,and 0.001).Conclusion WEJTD decreased glycogen deposition and stimulated glucose transport in skeletal muscle through upregulation of PI3K/Akt signaling pathway.
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Objective:To investigate the relationship between visfatin and insulin resistance (IR)of type 2 diabetes mellitus(T2DM) through the classic insulin signaling pathway phosphatidy inositol-3 kinase (PI3K).Methods:The human T2DM preadipocyte cells were recoveried, extended and differentiated.The visfatin overexpression vectors were built, transformated, cultivated and extracted.The fat cells were transfected with different overexpression levels (0.0, 1.0, 2.5 and 5.0 μg);0.0 μg group was used as control group,and the remaining three groups as observation groups.The mRNA expression levels of visfatin, insulin receptor substrate-1(IRS-1), insulin receptor substrate-2(IRS-2) and PI3K (P85α) were detected by Q-PCR.The protein expression levels of visfatin, IRS-1, IRS-2, PI3K (P85α), IRS-1 and IRS-2 phosphorylation levels were measured by Western blotting method.The glucose uptake rates of fat cells were determined by [3H]-2-deoxidation-D-glucose uptake assay.Results:The expression levels of visfatin mRNA and protein in various groups were increased with the increase of transfection concentration gradient (P0.05).The glucose uptake rates of fat cells were elevated with the increasing of visfatin expression (P<0.05).Conclusion:The visfatin overexpression of fat cells in vitro can increase the expression levels of IRS-1 and PI3K.
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Objective To study the expression of sex hormone-binding globulin(SHBG),insulin signaling pathway and glucose transporter in placenta of pregnant women with gestational diabetes mellitus(GDM),and to explore its role in the pathogenesis of GDM. Methods A total of 10 full-term and non-obese(BMI0.05). Results of linear correlation analysis showed that there were positive correlations between SHBG mRNA and IRS-2 mRNA(P<0.05),SHBG mRNA and PI3K p85α mRNA(P<0.05),and SHBG mRNA and GLUT-4 mRNA(P<0.05). There was also a remarkable positive correlation between IRS-2 mRNA and GLUT-4 mRNA(P<0.01). There existed negative correlations between IRS-1 mRNA and PI3K p85α mRNA(P<0.05),and IRS-1 mRNA and GLUT-3 mRNA(P<0.05). There existed a remarkable positive correlation between IRS-2 mRNA and GLUT-1 mRNA(P<0.01). Conclusion The defective receptors of insulin signaling pathway are present in GDM placental tissue. Decreased expression of SHBG may be involved in the regulation insulin signaling ,leading to a concomitant decrease expression of relevant insulin signaling components in placental tissue ,implying insulin resistance and developing GDM finally.
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Objective To investigate the effects of chronic intermittent hypoxia and on GLUT-2, IRS-2 expression in the rat kidney .Methods Rats were randomly divided into control group ( control) , chronic intermittent hypoxia group (CIH), chronic intermittent hypoxia reoxygenation group (RH).The chronic intermittent hypoxia animal models were developed , arterial blood gas analysis was immediately carried out .Serum glucose was measured by peroxidase and serum insulin was detected by radioimmunoassay .After Removing the kidney tissue of rats ,protein expression of GLUT-2, IRS-2 were detected with Western blot and immunohistochemical , mRNA expression of GLUT-2,IRS-2 were observed by qPCR .Results Oximetry in the control group was ≥95%, oxygen saturation in the CIH group was ≤85%, oxygen saturation in the RH group was ≥86%; fasting blood glucose , serum insulin and insulin resistance index in the CIH group were significantly higher those of control group and RH group ( P<0.05);RH group was higher than control group (P<0.05).Protein and mRNA expression of GLUT-2, IRS-2 in the CIH group were higher than the control group and RH group ( P<0.05 ); RH group was higher than control group (P<0.05).Conclusions Chronic intermittent hypoxia can increase blood glucose ,upregulate the expres-sion of GLUT-2 , IRS2 in the rat kidney and enhance insulin resistance and decrease insulin sensitivity .
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Objective To evaluate the effect of Ji Tang Zhi on glucose metabolism in insulin resistance (IR) HepG 2 cell line,and to explore the related mechanism.Methods The HepG2 cells were incubated in culture medium addition of 10-7 mol/L insulin for 24 h to establish the IR cell model.Effect of Ji Tang Zhi on rate of glucose absorption in HepG2 cell was detected by the method of glucose oxidase-peroxidase (GOD-POD).We performed an MTT assay to determine cytotoxicity effects of Ji Tang Zhi on HepG2 cell line.The expression of p-IRS-1 Ser307,PI3K and GLUT-4 were detected by Western blotting.Results Incubated with 10-7 mol/L insulin for 24 h,the insulin resistance cell model had been built.Compared with model group,the rate of glucose absorption of cell treated with JTZ (30 ～ 120 μg/mL) was significantly improved.According to model cells,the expression of GLUT-4 and PI3K decreased significantly compared to control cells.While the expression of p-IRS-1 Ser 307 was inhibited and GLUT-4 and PI3K expression were increased in IR cells after treated with JTZ (30 ～ 120 μtg/mL).Conclusion JTZ exert beneficial effects on hyperglycosemia in IR cell line possibly through regulating the levels of GLUT-4,p-IRS-1 Ser307 and PI3K in HepG2 cell.
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Objective To investigate the effect of high uric acid(HUA) on insulin sensitivity (IS) in 3T3-L1 adipocytes and its mechanism. Methods 3T3-L1 adipocytes were pretreated with HUA with or without NAC,and then stimulated by insulin. The cell viability of 3T3-L1 adipocytes was detected by CCK-8 assay. The glucose consumption was measured by glucose oxidase method. The levels of phospho-IRS-1,phospho-Akt and GluT4 protein were tested by western blot. Results HUA could inhibit insulin-induced glucose consumption,phosphorylation of Akt (Thr308),dephosphorylation of IRS-1 (Ser307) and the GluT4 protein expression (P<0.05). All the above could be blocked by NAC(P<0.05). Conclusion HUA can inhibit inulin stimulated IRS-1/Akt signaling and GluT4 expression,and thus induced insulin resistance in 3T3-L1 adipocytes.
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Objective To observe the effects of pioglitazone on secretion of E2 and expressions of P450 aromatase (P450arom), insulin-receptor substrate-1 (IRS-1), and insulin-receptor substrate-2 (IRS-2) mRNA in polycystic ovary syndrome (PCOS) ovarian granulosa cells.Methods In this study, granulosa cells that were fertilization-embryo transferred from 27 PCOS patients were primary cultured in vitro with different concentrations of pioglitazone (0, 10, 102, 103 and 104nmol/L) (Group A), different concentrations of pioglitazone+FSH (50ng/L, Group B) and different concentrations of pioglitazone+insulin-like growth factor I (IGF-I, 50ng/L, Group C).Estradiol concentrations in the culture supernatant were detected by radioimmunoassay;P450arom, IRS-1 and IRS-2 mRNA expressions on granulosa cells were detected by Real-time PCR.Results The levels of E2 secreted by granulosa cells and the expression of P450arom mRNA on granulosa cells of PCOS for 48 hours were different among Groups A, B and C (P<0.05).With increase in pioglitazone concentration, the level of E2 and the expression of P450arom mRNA declined, some of which correlated negatively with the concentration of pioglitazone.Among these groups, the level of E2 secretion and the expression of P450arom mRNA were higher in Group C than in Group B (P<0.01) and Group A (P<0.01) at the same concentration of pioglitazone.The level of E2 secretion and the expression of P450arom mRNA were higher in Group B than in Group A (P<0.05) at the same concentration of pioglitazone.The expressions of IRS-1 and IRS-2 mRNA on granulosa cells of PCOS under pioglitazone stimulation for 48 hour were different among the groups of different pioglitazone concentrations (P<0.05).With increase inpioglitazone concentration, the expression of IRS-1 mRNA on granulosa cells of PCOS was decreased, but the expression of IRS-2 mRNA on granulosa cells of PCOS was increased.Conclusion Pioglitazone may decrease estrogen production by inhibiting p450 aromatase and adjusting the expressions of IRS-1 and IRS-2 on granulosa cells of PCOS to play a role in ovulation induction and ameliorate insulin resistance in ovary of PCOS.Pioglitazone can inhibit IGF-I and FSH in inducing E2 secretion by ovarian granulosa cells.
ABSTRACT
Objective To observe the effects of high-fat feeding on growth and the expression of insulin-like growth factor 1 (IGF-1),insulin receptor substrate 1 (IRS-1) in adolescent rats'liver with non-alcoholic fatty liver disease,and to elucidate the relationship between growth failure in adolescent rats with non-alcoholic fatty liver disease and IGF-1,IRS-1 turbulence.Methods Thirty-six Sprague-Dawley (SD) young rats of 21 days were randomly divided into normal control group(NC group,n =18) and high-fat feeding group(HF group,n =18).Non-alcoholic fatty liver disease(NAFLD) model was induced by feeding the SD rats with high-fat food.Immunohistochemistry was applied to detect the expression levels of IGF-1 and IRS-1 in liver tissue.The expressions of mRNA of IGF-1 and IRS-1 were measured by RT-PCR.Results Compared with NC group,the serum alanine amino transferase (ALT),total cholesterol (TC),triglyceride (TG) of HF group in the 6th,8 th,12th week were gradually increased.The serum ALT [(194.67 ± 11.15) U/L],TC [(1.81 ± 0.09) mmol/L],TG [(0.34 ± 0.05) mmol/L] contents of HF group at 8th week were higher than those at 6th week [(166.00 ± 22.01) U/L,(1.52 ± 0.22) mmol/L,(0.41 ±0.12) mmol/L,respectively],and the serum ALT[(213.0 ±27.67) U/L],TC[(2.15 ±0.37) mmol/L],TG[(0.38 ±0.15)mmol/L] contents of the 12th week were significantly increased compared with 6th week and 8th week.The constitution and body length of the HF group were lower than those of the normal control group.With time extended,the liver tissue steatosis,inflammation,the balloon like change of the liver tissue pathology of HF group in 6,8,12th week gradually increased.Immunohistochemistry results showed that HF group IRS-1 [(1.46 ± 0.23),(0.74 ± 0.17),(0.85 ± 0.31)],IGF-1 [(0.92 ± 0.02),(0.83 ± 0.02),(0.77 ± 0.03)] expression gradually decreased,the difference was statistically significant(F =36.024,P ＜ 0.05).IGF-1 and IRS-1 mRNA expressions in HF group were consistent.Conclusion The liver tissue IGF-1 and IRS-1 are correlated with the weight and body length.The growth failure of young rats induced by high-fat feeding may be related to the decreased expression of IGF-1 and IRS-1.