OBJECTIVETo explore the association of insulin resistance and β cell function with lipid metabolism in middle-aged and elderly Hui and Han populations.

METHODSA total of 1000 subjects age over 40 years were recruited from five urban communities in Yinchuan and Wuzhong cities of Ningxia. The composition ratio between Hui and Han nationality was 1:2. A questionnaire-based survey was performed. Physical examinations were carried out to measure the height, body mass, waistline, and hipline. The levels of triglyceride (TG), total cholesterol (TC), blood uric acid (BUA), fasting blood glucose and insulin were measured. The boby mass index (BMI), waist-hip ratio (WHR), and secretion related index including insulin resistance index (IR), insulin sensitivity index (IAI), and beta cell function index (HBCI) were calculated.

RESULTSThe BMI, WHR, IAI, HBCI, and the prevalence rate of diabetes in Hui nationality were significantly higher than those in Han nationality (P<0.01). The levels of BUA, fasting blood glucose, TC, and IR in Han nationality were significantly lower than those in Hui nationality (P<0.01). In Hui populations, TG, BMI, WHR, and BUA were positively correlated with IR (r=0.234, r=0.193, r=0.143, and r=0.129, respectively; P<0.01) and were negatively correlated with IAI (r=-0.234, r=-0.193, r=-0.143, r=-0.129, respectively; P<0.01), whereas TC was negatively correlated with HBCI (r=-0.169, P<0.01). In Han populations, TC, TG, BMI, WHR, and BUA were positively correlated with IR (r=0.140, r=0.257, r=0.288, r=0.163, r=0.104, P<0.01) and negatively correlated with IAI (r=-0.140, r=-0.257, r=-0.288, r=-0.163, and r=-0.104, P<0.01), whereas BMI was negatively correlated with HBCI (r=-0.111, P<0.01). After the influential factors such as gender, nationality, and age were adjusted, the TC, TG, BMI, WHR, BUA levels were positively correlated with IR (r=0.109, r=0.256, r=0.253, r=0.139, and r=0.142, P<0.01) and negatively correlated with IAI (r=-0.109, r=-0.256, r=-0.253, r=-0.139, and r=-0.142, P<0.01). TC and BMI were negatively correlated with HBCI (r=-0.113, r=-0.086, P<0.01). TG and BMI were independently associated with IR and IAI (r=0.218, r=0.182, r=-0.218, r=-0.182), while TC and BMI were independently associated with HBCI (r=-0.113, r=-0.086).

CONCLUSIONSThe distributions of TC, TG, BMI, WHR, BUA, IR, IAI, and HBCI differ between Han and Hui populations. The development of insulin resistance is closely related with the increased levels of TC, TG, BMI, WHR, and BUA. However, the HBCI increases with the increased level of TC and BMI. TG and BMI may be related with insulin resistance. Also, TC and BMI may affect the secretion function of β cells.

Aged ; Asian Continental Ancestry Group ; Blood Glucose ; analysis ; Body Mass Index ; Cholesterol ; blood ; Ethnic Groups ; Humans ; Insulin ; blood ; Insulin Resistance ; Insulin-Secreting Cells ; cytology ; Lipid Metabolism ; Middle Aged ; Triglycerides ; blood ; Uric Acid ; blood

Inhibition of CD36, a fatty acid transporter, has been reported to prevent glucotoxicity and ameliorate high glucose induced beta cell dysfunction. Ezetimibe is a selective cholesterol absorption inhibitor that blocks Niemann Pick C1-like 1 protein, but may exert its effect through suppression of CD36. We attempted to clarify the beneficial effect of ezetimibe on insulin secreting cells and to determine whether this effect is related to change of CD36 expression. mRNA expression of insulin and CD36, intracellular peroxide level and glucose stimulated insulin secretion (GSIS) under normal (5.6 mM) or high glucose (30 mM) condition in INS-1 cells and primary rat islet cells were compared. Changes of the aforementioned factors with treatment with ezetimibe (20 μM) under normal or high glucose condition were also assessed. mRNA expression of insulin was decreased with high glucose, which was reversed by ezetimibe in both INS-1 cells and primary rat islets. CD36 mRNA expression was increased with high glucose, but decreased by ezetimibe in INS-1 cells and primary rat islets. Three-day treatment with high glucose resulted in an increase in intracellular peroxide level; however, it was decreased by treatment with ezetimibe. Decrease in GSIS by three-day treatment with high glucose was reversed by ezetimibe. Palmitate uptake following exposure to high glucose conditions for three days was significantly elevated, which was reversed by ezetimibe in INS-1 cells. Ezetimibe may prevent glucotoxicity in pancreatic β-cells through a decrease in fatty acid influx via inhibition of CD36.
Animals ; Anticholesteremic Agents/*pharmacology ; Antigens, CD36/antagonists & inhibitors/genetics/*metabolism ; Cells, Cultured ; Ezetimibe/*pharmacology ; Flow Cytometry ; Glucose/toxicity ; Insulin/genetics/metabolism/secretion ; Insulin-Secreting Cells/cytology/*drug effects/metabolism ; Male ; Palmitic Acid/metabolism ; RNA, Messenger/metabolism ; Rats ; Rats, Sprague-Dawley ; Reactive Oxygen Species/metabolism ; Real-Time Polymerase Chain Reaction

Mammalian pancreatic β-cells play a pivotal role in development and glucose homeostasis through the production and secretion of insulin. Functional failure or decrease in β-cell number leads to type 2 diabetes (T2D). Despite the physiological importance of β-cells, the viability of β-cells is often challenged mainly due to its poor ability to adapt to their changing microenvironment. One of the factors that negatively affect β-cell viability is high concentration of free fatty acids (FFAs) such as palmitate. In this work, we demonstrated that Yes-associated protein (Yap1) is activated when β-cells are treated with palmitate. Our loss- and gain-of-function analyses using rodent insulinoma cell lines revealed that Yap1 suppresses palmitate-induced apoptosis in β-cells without regulating their proliferation. We also found that upon palmitate treatment, re-arrangement of F-actin mediates Yap1 activation. Palmitate treatment increases expression of one of the Yap1 target genes, connective tissue growth factor (CTGF). Our gain-of-function analysis with CTGF suggests CTGF may be the downstream factor of Yap1 in the protective mechanism against FFA-induced apoptosis.
Actins ; metabolism ; Adaptor Proteins, Signal Transducing ; antagonists & inhibitors ; genetics ; metabolism ; Animals ; Apoptosis ; drug effects ; physiology ; Bridged Bicyclo Compounds, Heterocyclic ; pharmacology ; Cell Line, Tumor ; Connective Tissue Growth Factor ; genetics ; metabolism ; pharmacology ; Cytochalasin D ; pharmacology ; Fatty Acids, Nonesterified ; pharmacology ; HEK293 Cells ; Humans ; Immunohistochemistry ; Insulin-Secreting Cells ; cytology ; drug effects ; metabolism ; Mice ; Microscopy, Fluorescence ; Palmitic Acid ; pharmacology ; Phosphoproteins ; antagonists & inhibitors ; genetics ; metabolism ; RNA Interference ; RNA, Small Interfering ; metabolism ; Rats ; Recombinant Proteins ; genetics ; metabolism ; pharmacology ; Thiazolidines ; pharmacology

Insulin resistance and insulin secretion deficiency are main machanisms in inducing type 2 diabetes mellitus (T2DM), and mitochondria damage plays an important role in them. Research shows that autophagy is a self-protective mechanism of cells, which plays an important role in maintaining the normal structure and function of pancreatic β cells and improving insulin resistance. Previous studies show that traditional Chinese medicine can regulate cell autophagy to influence β cells and insulin resistance, type 2 diabetes mellitus and its complications. Thus this review will talk about the process of the relationship between autophagy and T2DM and the intervention effect of traditional Chinese medicine.
Animals ; Autophagy ; drug effects ; Diabetes Mellitus, Type 2 ; drug therapy ; metabolism ; physiopathology ; Drugs, Chinese Herbal ; therapeutic use ; Humans ; Insulin ; metabolism ; Insulin Resistance ; Insulin-Secreting Cells ; cytology ; drug effects ; metabolism

OBJECTIVE: To explore the eff ect of silibinin on β cells in C57BL/6J mice fed a high-fat diet and the possible mechanisms. METHODS: A total of 18 male C57BL/6J mice at 3 weeks old were divided into a normal chow group (n=6), a high-fat diet group (n=6) and a high-fat diet plus silibinin group (n=6). Aft er intervention for 10 weeks, fasting blood glucose (FBG), fasting insulin (FINS), triglycerides (TG), alanine aminotransferase (ALT), creatinine (Cr) and blood urea nitrogen (BUN), lipid metabolism, antioxidant enzyme activities and apoptosis were evaluated. Pancreatic tissues were isolated to examine insulin-induced gene-1 (Insig-1), sterol regulatory element binding protein-1c (SREBP-1c) and fatty acid synthetase (FAS) mRNA and protein expression. RESULTS: Compared with the high-fat diet group, the function of insulin secretion was improved, and the level of blood glucose was decreased in the high-fat diet plus silibinin group (P<0.05). The levels of lipid content and oxidative stress and the rates of β cell apoptosis were lower in high-fat diet plus silibinin group than those in the high-fat diet group (both P<0.05). Simultaneously, the silibinin could promote the expression of Insig-1 and depress the expression of SREBP-1c and FAS (all P<0.05). Moreover, there was no significant difference in the levels of serum ALT, Cr and BUN among the 3 groups (all P>0.05). CONCLUSION Silibinin can protect β cells of mice fed a high-fat diet, and this effect might be related to, at least partially, increase in its antioxidative ability through regulation of insig-1/SREBP-1c pathway. Moreover, silibinin is safe for long-term treatment.
Alanine Transaminase ; blood ; Animals ; Apoptosis ; Blood Glucose ; analysis ; Blood Urea Nitrogen ; Creatinine ; blood ; Diet, High-Fat ; Fatty Acid Synthases ; metabolism ; Insulin ; blood ; Insulin-Secreting Cells ; cytology ; drug effects ; Lipid Metabolism ; Lipids ; Male ; Membrane Proteins ; metabolism ; Mice ; Mice, Inbred C57BL ; Oxidative Stress ; Silybin ; Silymarin ; pharmacology ; Sterol Regulatory Element Binding Protein 1 ; metabolism ; Triglycerides ; blood

OBJECTIVETo study the effect of Mudan Granule (MD) on the glucose metabolism and beta cell function in monosodium glutamate (MSG) induced obese mice with insulin resistance (IR).

METHODSMSG obese mice were induced by subcutaneous injecting MSG (4 g/kg for 7 successive days in neonatal ICR mice). Forty MSG mice with IR features were recruited and divided into four groups according to body weight, fasting blood glucose, triglyceride (TG), total cholesterol (TC), and the percentage of blood glucose decreased within 40 min in the IR test, i.e., the model group (Con), the low dose MD group, the high dose MD group, and the Metformin group (Met). Besides, another 10 ICR mice were recruited as the normal control group (Nor). The water solvent of 2.5 g/kg MD or 5 g/kg MD was respectively administered to mice in the low dose MD group and the high dose MD group. Metformin hydrochloride was given to mice in the Met group at 0.2 g/kg body weight. Equal dose solvent distilled water was administered to mice in the Nor group and the Con group by gastrogavage, once per day. All medication was lasted for 15 weeks. Insulin tolerance test (ITT) and oral glucose tolerance test (OGTT) were performed after 6 weeks of treatment. Beta cell function was assessed by hyperglycemic clamp technique. The morphological changes in the pancreas were evaluated by hematoxylin-eosin (HE) staining. Changes of iNOS, NF-kappaB p65, and p-NF-kappaB p65 in the pancreas were tested.

RESULTSCompared with the Nor group, the blood glucose level, AUC, and fasting blood insulin, ONOO-contents, iNOS activities, and the expression of iNOS, NF-kappaB p65 subunit, pNF-kappaB p65 subunit obviously increased; decreased percentage of blood glucose within 40 min in ITT, glucose infusion rate (GIR), Clamp 1 min insulin, and Max-Insulin obviously decreased in the Con group (P < 0.05, P < 0.01). Compared with the Con group, the aforesaid indices could be improved in the Met group (P < 0.05, P < 0.01). In the low dose MD group, AUC, iNOS activities, and the expression of iNOS and p-NF-kappaB p65 subunit obviously decreased; percentage of blood glucose within 40 min in ITT and GIR obviously increased (P < 0.05, P < 0.01). In the high dose MD group, AUC, ONOO-contents, iNOS activities, and the expression of iNOS, NF-kappaB p65 subunit, and p-NF-KB p65 subunit obviously decreased; percentage of blood glucose within 40 min in ITT, Max-Insulin, and GIR obviously increased (P < 0.05, P < 0.01).

CONCLUSIONMD could significantly improve IR and functional disorder of 3 cells in MSG obese mice, which might be associated with lowering inflammatory reaction in the pancreas.

Animals ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Female ; Insulin Resistance ; Insulin-Secreting Cells ; drug effects ; metabolism ; Male ; Metformin ; pharmacology ; Mice ; Mice, Inbred ICR ; Mice, Obese ; Obesity ; chemically induced ; metabolism ; Pancreas ; cytology ; drug effects ; Sodium Glutamate

AIM: To observe the effect of modified Si-Miao-San (mSMS) on advanced glycation end products (AGEs)-induced pancreatic B cell dysfunction, as well as examining the underlying mechanisms. METHOD: Pancreatic B cells (INS-1) were stimulated with advanced glycation end products (AGEs, 200 μg·mL(-1)) for 24 h to produce dysfunction in pancreatic B cells and the effects of mSMS observed on insulin secretion, NF-κB (p65) phosphorylation, reactive oxygen species (ROS) production, mitochondria membrane potential (Δψm), cell apoptosis, phosphorylation of AMP-kinase (AMPK), and caspase 3 activity. RESULTS: The AGEs challenge resulted in increased basal insulin secretion, but decreased insulin secretion in response to high glucose, whereas this situation was reversed by mSMS treatment. AGEs stimulation induced NF-κB (p65) phosphorylation and reactive oxygen species (ROS) production, as well as Δψm collapse and cell apoptosis. mSMS inhibited ROS production and inhibited NF-κB activation by attenuating p65 phosphorylation. Meanwhile, AGEs-induced Δψm collapse and cell apoptosis were also reversed by mSMS treatment. Compound C, an inhibitor of AMP-Kinase (AMPK), abolished the beneficial effects of mSMS on the regulation of B cell function, indicating the involvement of AMPK. CONCLUSION mSMS ameliorated AGEs-induced B cell dysfunction by suppressing ROS-associated inflammation, and this action was related to its beneficial regulation of AMPK activity.
AMP-Activated Protein Kinases ; genetics ; metabolism ; Animals ; Apoptosis ; drug effects ; Cell Line, Tumor ; Drugs, Chinese Herbal ; pharmacology ; Glucose ; metabolism ; Glycation End Products, Advanced ; metabolism ; Humans ; Inflammation ; drug therapy ; enzymology ; genetics ; metabolism ; Insulin-Secreting Cells ; cytology ; drug effects ; enzymology ; metabolism ; Phosphorylation ; Rats ; Reactive Oxygen Species ; metabolism

Upon glucose elevation, pancreatic beta-cells secrete insulin in a Ca(2+)-dependent manner. In diabetic animal models, different aspects of the calcium signaling pathway in beta-cells are altered, but there is no consensus regarding their relative contributions to the development of beta-cell dysfunction. In this study, we compared the increase in cytosolic Ca(2+) ([Ca(2+)]i) via Ca(2+) influx, Ca(2+) mobilization from endoplasmic reticulum (ER) calcium stores, and the removal of Ca(2+) via multiple mechanisms in beta-cells from both diabetic db/db mice and non-diabetic C57BL/6J mice. We refined our previous quantitative model to describe the slow [Ca(2+)]i recovery after depolarization in beta-cells from db/db mice. According to the model, the activity levels of the two subtypes of the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) pump, SERCA2 and SERCA3, were severely down-regulated in diabetic cells to 65% and 0% of the levels in normal cells. This down-regulation may lead to a reduction in the Ca(2+) concentration in the ER, a compensatory up-regulation of the plasma membrane Na(+)/Ca(2+) exchanger (NCX) and a reduction in depolarization-evoked Ca(2+) influx. As a result, the patterns of glucose-stimulated calcium oscillations were significantly different in db/db diabetic beta-cells compared with normal cells. Overall, quantifying the changes in the calcium signaling pathway in db/db diabetic beta-cells will aid in the development of a disease model that could provide insight into the adaptive transformations of beta-cell function during diabetes development.
Animals ; Calcium ; metabolism ; Calcium Signaling ; drug effects ; Cell Membrane Permeability ; drug effects ; Cells, Cultured ; Down-Regulation ; drug effects ; Endoplasmic Reticulum ; metabolism ; Glucose ; pharmacology ; Insulin-Secreting Cells ; cytology ; drug effects ; metabolism ; Mice ; Mice, Inbred C57BL ; Mice, Obese ; Potassium Chloride ; pharmacology ; Sarcoplasmic Reticulum Calcium-Transporting ATPases ; metabolism ; Sodium-Calcium Exchanger ; metabolism ; Thapsigargin ; pharmacology ; Up-Regulation ; drug effects

The aim of this study was to assess the prevalence of diabetes and to study the effects of excess growth hormone (GH) on insulin sensitivity and beta-cell function in Korean acromegalic patients. One hundred and eighty-four acromegalic patients were analyzed to assess the prevalence of diabetes, and 52 naive acromegalic patients were enrolled in order to analyze insulin sensitivity and insulin secretion. Patients underwent a 75 g oral glucose tolerance test with measurements of GH, glucose, insulin, and C-peptide levels. The insulin sensitivity index and beta-cell function index were calculated and compared according to glucose status. Changes in the insulin sensitivity index and beta-cell function index were evaluated one to two months after surgery. Of the 184 patients, 17.4% were in the normal glucose tolerance (NGT) group, 45.1% were in the pre-diabetic group and 37.5% were in the diabetic group. The insulin sensitivity index (ISI0,120) was significantly higher and the HOMA-IR was lower in the NGT compared to the diabetic group (P = 0.001 and P = 0.037, respectively). The ISI0,120 and disposition index were significantly improved after tumor resection. Our findings suggest that both insulin sensitivity and beta-cell function are improved by tumor resection in acromegalic patients.
Acromegaly/*diagnosis/etiology/metabolism ; Adult ; Asian Continental Ancestry Group ; Blood Glucose/analysis ; C-Peptide/analysis ; Diabetes Mellitus/epidemiology ; Female ; Glucose Tolerance Test ; Human Growth Hormone/secretion ; Humans ; Insulin/blood/secretion ; *Insulin Resistance ; Insulin-Secreting Cells/cytology/*physiology ; Male ; Middle Aged ; Prediabetic State/epidemiology ; Republic of Korea

OBJECTIVETo investigate the differentiation of human amniotic epithelial cells (hAECs) into insulin secreting cells (ISCs) in vitro.

METHODSThe hAECs were isolated from human amnion by trypsin digestion, and the phenotype of the isolated cells were identified by flow cytometry and immunocytochemical staining. The hAECs at passage 3 were treated with nicotinamide and N2 supplement to investigate their differentiation into ISCs. At different times after differentiation, the expression of insulin and beta2 microglobulin (beta2-MG) was determined by immunocytochemical staining, while the content of insulin in supernatant from cultured hAECs was detected by radioimmunoassay and the expressions of insulin, pancreatic and duodenal homeobox factor-1 (PDX-1) mRNA were detected by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS(1) hAECs expressed high percent of CD29, CD73, CD166 and CK19. (2) At 7, 14 and 21 days, the percentages of insulin-positive cells in induced groups were 74.00% +/- 1.73%, 75.33% +/- 1.15% (see symbol) 75.67% +/- 0.58% respectively, which were negative in control groups. (3) At 7, 14 and 21 days, contents of insulin in supernatant from induced groups were (328.47 +/- 3.22) microIU/ml, (332.26 +/- 1.22) microIU/ml and (329.68 +/- 2.57) microIU/ml respectively, they were significantly higher than those in control groups (All P < 0.01). (4) PDX-1 mRNA and beta2-MG were expressed before and after the induction of hAECs, but insulin mRNA was expressed only in the induced groups.

CONCLUSIONhAECs can differentiate into ISCs, having the potential application for therapy of type I diabetes.

Amnion ; cytology ; Cell Culture Techniques ; Cell Differentiation ; physiology ; Cells, Cultured ; Epithelial Cells ; cytology ; Flow Cytometry ; Homeodomain Proteins ; metabolism ; Humans ; Insulin ; metabolism ; Insulin-Secreting Cells ; cytology ; RNA, Messenger ; genetics ; Trans-Activators ; metabolism ; beta 2-Microglobulin ; metabolism