Insulin Receptor Protein Expression Research Articles

ß- Caryophyllene Ameliorates Insulin Resistance in Liver of High Fat Diet and Fructose-Induced Type-2 Diabetic Rats

Insulin resistance may impact organs that transmit insulin signals, like skeletal muscle, adipose tissue, and the liver. Hyperglycemia and hypertriglyceridemia in the fasting state of type 2 diabetes mellitus are more significantly impacted by insulin resistance in the liver. Hypertriglyceridemia is the culprit behind beta-cell failure in type 2 diabetes. Treating insulin resistance in liver as a primary mechanism of traditional antidiabetic drugs, but unfortunately traditional drugs has unalterable advisory effect. In the present research, insulin resistance in the liver is addressed with the versatile natural phytonutrient beta-caryophyllene to demonstrate effectiveness in managing diabetes. An effective dose of -Caryophyllene taken by non-parental route (200 mg/kg b.wt) was given for 30 days to experimentally induced (high-fat diet and fructose-fed) type-2 diabetic rats to find out whether β-Caryophyllene regulates the IRS-2/akt pathway of insulin signaling. In the liver of diabetic rats, the data demonstrates that ß-caryophyllene treatment significantly increased the mRNA and protein expression of insulin receptor (IR) and GLUT-2. However, there was a significant variation in the mRNA expression of akt and insulin receptor-substrate-2 (IRS-2) between groups. Taking caryophyllene supplements can be beneficial for the control of type 2 diabetes. Studies conducted with this sesquiterpene could have tremendous potential and benefit for the treatment of type 2 diabetes.

Effect of electroacupuncture at different frequencies on brain insulin signaling transduction pathway in Alzheimer's disease mice

To observe the effect of electroacupuncture (EA) at different frequencies on learning and memory functions, as well as the relevant proteins of brain insulin signal transduction pathway in Alzheimer's disease (AD) mice and explore the effect mechanism of EA in treatment of AD. Seventy-two SPF Kunming male mice were randomized into a blank group, a sham-operation group, a model group, a 2 Hz EA group, a 15 Hz EA group and a 30 Hz EA group, 12 mice in each one. In the model group and each EA group, AD model were established by the injection with streptozotocin (ST2) solution (8 mg/kg) into the left lateral ventricles. In the sham-operation group, 0.9% sodium chloride solution of the same volume was injected into the left lateral ventricles. After successful modeling, in each EA group, EA was applied at "Baihui" (GV 20), "Dazhui" (GV 14) and "Shenshu" (BL 23) with corresponding frequencies, once daily. One course of EA intervention consisted of 7 treatments and 2 courses were given totally at interval of 1 day. After modeling and intervention, Morris water maze test was conducted for the mice of each group. Using immunohistochemistry and Western blot method, the protein expression of insulin receptor (IR), insulin receptor substrate-1 (IRS-1) and phosphatidylinositol 3-kinase (PI3K) was detected in the hippocampal of the mice after intervention. Compared with the blank group, in the model group, the 2 Hz, 15 Hz and 30 Hz EA groups, the escape latency and the first time of crossing the platform were all extended (P<0.01), and the number of crossing the platform was reduced (P<0.01) after modeling. When compared with the blank group, the escape latency and the first time of crossing the platform were all extended (P<0.01), and the number of crossing the platform was reduced (P<0.01) in the model group after intervention. In the 2 Hz, 15 Hz and 30 Hz EA groups, the escape latency and the first time of crossing the platform were all shortened (P<0.01), and the number of crossing the platform was increased (P<0.05, P<0.01) after intervention when compared with the model group. The escape latency and the first time of crossing the platform were all shortened (P<0.01, P<0.05), and the number of crossing the platform was increased (P<0.05) in the 15 Hz and 30 Hz EA groups in comparison with the 2 Hz EA group. The protein expression levels of IR, IRS-1 and PI3K were reduced in the model group when compared with those of the blank group (P<0.01, P<0.05); and these protein expression levels were increased in the 15 Hz and 30 Hz EA groups compared with the model group (P<0.05, P<0.01). Compared with the 2 Hz EA group, the protein expression levels of IR, IRS-1 and PI3K were all elevated in the 15 Hz and 30 Hz EA groups (P<0.05). The learning and memory function of AD mice may be improved through regulating brain insulin signaling transconduction pathway with electroacupuncture, and electroacupuncture at 15 Hz and 30 Hz obtains the overall better effect compared with the intervention at 2 Hz.

Impact of Glyphosate on the Development of Insulin Resistance in Experimental Diabetic Rats: Role of NFκB Signalling Pathways.

Glyphosate, an endocrine disruptor, has an adverse impact on human health through food and also has the potential to produce reactive oxygen species (ROS), which can lead to metabolic diseases. Glyphosate consumption from food has been shown to have a substantial part in insulin resistance, making it a severe concern to those with type 2 diabetes (T2DM). However, minimal evidence exists on how glyphosate impacts insulin-mediated glucose oxidation in the liver. Hence the current study was performed to explore the potential of glyphosate toxicity on insulin signaling in the liver of experimental animals. For 16 weeks, male albino Wistar rats were given 50 mg, 100 mg and 250 mg/kg b. wt. of glyphosate orally. In the current study, glyphosate exposure group was linked to a rise in fasting sugar and insulin as well as a drop in serum testosterone. At the same time, in a dose dependent fashion, glyphosate exposure showed alternations in glucose metabolic enzymes. Glyphosate exposure resulted in a raise in H2O2 formation, LPO and a reduction in antioxidant levels those results in impact on membrane integrity and insulin receptor efficacy in the liver. It also registered a reduced levels of mRNA and protein expression of insulin receptor (IR), glucose transporter-2 (GLUT2) with concomitant increase in the production of proinflammatory factors such as JNK, IKKβ, NFkB, IL-6, IL-1β, and TNF-α as well as transcriptional factors like SREBP1c and PPAR-γ leading to pro-inflammation and cirrhosis in the liver which results in the development of insulin resistance and type 2 diabetes. Our present findings for the first time providing an evidence that exposure of glyphosate develops insulin resistance and type 2 diabetes by aggravating NFkB signaling pathway in liver.

Correlation Study on the Expression of INSR, IRS-1, and PD-L1 in Nonsmall Cell Lung Cancer.

Objective To study the expression and correlation of insulin receptor (INSR), insulin receptor substrate-1 (IRS-1), and programmed cell death ligand-1 (PD-L1) in nonsmall cell lung cancer (NSCLC). Methods 45 lung cancer tissues and 30 adjacent normal tissues of NSCLC patients diagnosed in the Second Affiliated Hospital of Shandong First Medical University from June 2019 to August 2020 were selected. The expressions of INSR, IRS-1, and PD-L1 proteins in tumor tissues and adjacent tissues of NSCLC were detected by immunohistochemical staining. Results The expression of INSR and IRS-1 in NSCLC was significantly higher than that in adjacent normal lung tissue (P < 0.05). INSR expression had statistical significance with the degree of pathological differentiation of nonsmall cell carcinoma (P = 0.031), but had no significant association with age, gender, pathological type, TNM stage, and lymph node metastasis status (P > 0.05). There was no significant correlation between IRS-1 positive expression and NSCLC patients' age, gender, pathological typing, degree of differentiation, TNM stage, and lymph node metastasis (P > 0.05). PD-L1 positive expression was correlated with lymph node metastasis of NSCLC (P = 0.028), while there was no significant correlation with gender, age, pathological type, TNM stage, and pathological differentiation degree of NSCLC patients (P > 0.05). Spearman correlation analysis showed that PD-L1 protein expression had a significant positive correlation with IRS-1 protein expression (r = 0.373), but was not correlated with the expression of INSR protein. Conclusion IRS-1 may be involved in the regulation of PD-L1 expression and mediate the occurrence of tumor immune escape, which is expected to become a new target for NSCLC immunotherapy and provide new clinical evidence for immunosuppressive therapy.

The crucial role of thioredoxin interacting protein in the liver insulin resistance induced by di (2-ethylhexyl) phthalates

The widespread usage of plastic products in human life has led to extensive exposure to plasticizers and resulted in serious health problems for humans, which has become a focus of toxicology research in the world. We aimed to explore the potential mechanism of liver insulin resistance induced by di(2-ethylhexyl) phthalate (DEHP) and working on a novel treatment to alleviate insulin resistance caused by excessive exposure to DEHP. For this purpose, in vivo and in vitro experiments were conducted, and the pivotal factors in the insulin signaling pathway were analyzed. In vivo study showed DEHP could lead to liver injury and insulin resistance. DEHP could break the balance of oxidative stress and cause accumulation of inflammatory factors. Genomics and proteomics experiment results revealed that DEHP could inhibit the mRNA and protein expression of insulin receptor, insulin receptor substrate, PI3K/Akt/mTOR, and glucose transporter 4. Nevertheless, the liver insulin resistance induced by DEHP could be reversed by Verapamil (thioredoxin interacting protein (TXNIP) inhibitor). Thus, we confirmed that DEHP caused insulin resistance by affecting the TXNIP in liver, further damaging the conduction of insulin signaling pathway. Therefore, adding Verapamil to the treatment of patients with insulin resistance due to plasticizers might be more effective.

Lactoferrin improves hepatic insulin resistance and pancreatic dysfunction in high-fat diet and streptozotocin-induced diabetic mice

Lactoferrin (Lf) is an iron-binding glycoprotein with potentially beneficial biological functions. However, the interaction between Lf and type 2 diabetes mellitus (T2DM) remains unclear. We hypothesized that Lf would improve hepatic insulin resistance and pancreatic dysfunction in diabetic mice. Male C57BL/6J mice were fed a high-fat diet for 15 weeks and injected with streptozotocin (STZ) for 5 consecutive days to establish a T2DM model. One week after STZ injection, mice with ≥11.1 mmol/L fasting blood glucose concentration were considered T2DM mice. These mice received 0.5% or 2% Lf solution for another 12 weeks. Biochemical parameters were measured, and histopathological examination of the pancreas and liver was performed. Hepatic protein expression related to the insulin signalling pathway was also assessed. Diabetic mice showed insulin resistance and abnormal glucolipid metabolism. Lf decreased serum concentrations of glycated serum protein, fasting insulin, cholesterol, and triglyceride and increased liver insulin sensitivity. Hematoxylin-eosin staining showed that Lf reversed the abnormal pancreatic islets of diabetic mice. Lf improved pancreatic dysfunction by reducing oxidative stress and inflammation responses. Furthermore, Lf upregulated the protein expression of insulin receptor, insulin receptor substrate-1, glucose transporter 4, phosphor phosphatidylinositol 3-kinase/phosphatidylinositol 3-kinase (PI3K), and phosphor protein kinase B/protein kinase B (AKT) in the liver. This study indicated that Lf supplementation improved hepatic insulin resistance and pancreatic dysfunction, possibly by regulating the PI3K/AKT signaling pathway in T2DM mice.

Role of 14-3-3β protein on ovarian folliculogenesis, steroidogenesis and its correlation in the pathogenesis of PCOS in mice

This study was designed to assess for the first time the circulating and ovarian level of 14-3-3β protein in the PCOS mice and the possible correlation between 14-3-3β protein with PCOS related increase in testosterone (HA), insulin levels (HI) and reduced insulin sensitivity in the ovary. PCOS was induced in mice using treatment of letrozole (by oral gavage) for 21 days. Immunohistochemical study showed increased expression of 14-3-3β protein in PCOS ovary compared to the control ovary. The circulating testosterone and insulin levels, together with circulating and ovarian levels of 14-3-3β protein also showed significant increase in PCOS mice compared to the control mice. An increase in 14-3-3β protein was observed positively correlated with circulating testosterone and insulin levels but showed a negative correlation with ovarian expression of insulin receptor protein in PCOS mice. The treatment of 14-3-3β protein in vitro to the normal ovary showed a significant increase in testosterone synthesis but a significant decline in insulin receptor protein expression compared to the vehicle-treated ovary of adult mice. The present study showed the direct role of 14-3-3β protein in increasing testosterone synthesis along with decreasing insulin sensitivity. Thus, 14-3-3β protein may be playing possible role in PCOS pathogenesis.

Effect of β-Caryophyllene on insulin resistance in skeletal muscle of high fat diet and fructose-induced type-2 diabetic rats.

High fat diet feeding results in hyperglycemia and insulin resistance, which is a major pathological feature of type-2 diabetes mellitus. The use of oral hypoglycaemic drugs is limited due to its deleterious side effects and there is a need to find more efficacious agents for diabetes management. Hence, it is of interest to show the mechanism of action of β-Caryophyllene on insulin signalling molecules in gastrocnemius muscle of high fat diet - induced type-2 diabetic rats. An oral effective dose of with β-Caryophyllene (200 mg/kg b.wt) was given for 30 days to high fat diet (comprising 2% cholesterol, 1% cholic acid, 30% coconut oil, 67% conventional rat feed) and fructose fed type-2 diabetic rats to find out whether β-Caryophyllene regulates IRS-1/Akt pathway of insulin signalling. The data shows that, β-Caryophyllene treatment significantly increased the mRNA and protein expression of insulin receptor (IR) in diabetic rats whereas there is no significant difference in mRNA expression of insulin receptor-substrate-1 (IRS-1) was observed among groups. The Akt mRNAand GLUT-4mRNA and protein level were also improved in gastrocnemius muscle of type-2 diabetic rats. Thus, we concluded that β-Caryophyllene could be used as potential phyto medicine for type-2 diabetes management.

374-P: Oleate Prevents Palmitate-Induced Abnormalities in Insulin Signaling in Human Cardiac Progenitor Cells

Myocardial ectopic lipid deposition has been associated with insulin resistance and cardiovascular risk. Palmitate, one of the most abundant saturated fatty acids, has been shown to impair insulin signaling in multiple cell types. Human cardiac progenitor cells (CPC) represent a compartment of multipotent stem cells essential for constant tissue repair and renewal in the adult heart. In this study, the ability of palmitate to impair insulin signaling, and the modulatory effects of oleate, a mono-unsaturated fatty acid, on palmitate-induced abnormalities were investigated in human CPC isolated from control subjects undergoing cardiac surgery. Human CPC express insulin receptor (IR), as assessed by quantitative RT-PCR and immunoblotting. Specifically, in human CPC both IR isoforms, A (IR-A) and B (IR-B), were identified, and IR-A was more expressed than IR-B. Exposure of human CPC to 100 nM insulin for 15 minutes resulted in increased Akt and p44/p42 MAPK phosphorylation (p&amp;lt;0.05), evidenced by immunoblotting. Treatment of human CPC with 0.25 mM palmitate for 24 h impaired the ability of insulin, added for the last 15 minutes, to phosphorylate both Akt and p44/p42 MAPK (p&amp;lt;0.05), without no effect on total Akt and p44/p42 MAPK protein levels. Interestingly, palmitate was able to increase both IR-A and IR-B mRNA levels (p&amp;lt;0.05), and to reduce IR protein expression (p&amp;lt;0.05). Co-incubation of palmitate with 0.1 mM oleate prevented the ability of palmitate to reduce insulin-induced Akt phosphorylation (p&amp;lt;0.05), but did not rescue the impaired p44/p42 MAPK phosphorylation. In addition, co-treatment with oleate also prevented both palmitate-induced upregulation of IR-A and IR-B mRNA (p&amp;lt;0.05), and downregulation of IR protein levels (p&amp;lt;0.05). In conclusion, oleate prevents some of the palmitate-induced impairments in insulin signaling in human CPC, thus contributing to cardiac protection from lipotoxicity-induced metabolic alterations. Disclosure R. Doria: None. F. Giorgino: Consultant; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Lilly Diabetes, Novo Nordisk, Roche Diabetes Care, Sanofi, Research Support; Self; Lilly Diabetes, Roche Diabetes Care. C. Caccioppoli: None. R. Schipani: None. V. Genchi: None. A. Leonardini: None. A. Natalicchio: Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Lilly Diabetes, Sanofi. S. Perrini: None. A. Cignarelli: None. L. Laviola: Advisory Panel; Self; A. Menarini Diagnostics, Abbott, AstraZeneca, Lilly Diabetes, Novo Nordisk Inc., Roche Diabetes Care, Sanofi-Aventis, Speaker’s Bureau; Self; Boehringer Ingelheim International GmbH, Medtronic.

Effect of maternal nutrient restriction on expression of glucose transporters (SLC2A4 and SLC2A1) and insulin signaling in skeletal muscle of SGA and Non-SGA sheep fetuses

Maternal nutrient restriction (NR) causes small for gestational age (SGA) offspring, which are at higher risk for accelerated postnatal growth and developing insulin resistance in adulthood. Skeletal muscle is essential for whole-body glucose metabolism, as 80% of insulin-mediated glucose uptake occurs in this tissue. Maternal NR can alter fetal skeletal muscle mass, expression of glucose transporters, insulin signaling, and myofiber type composition. It also leads to accumulation of intramuscular triglycerides (IMTG), which correlates to insulin resistance. Using a 50% NR treatment from gestational day (GD) 35 to GD 135 in sheep, we routinely observe a spectral phenotype of fetal weights within the NR group. Thus, we classified those fetuses into NR(Non-SGA; n = 11) and NR(SGA; n = 11). The control group (n = 12) received 100% of nutrient requirements throughout pregnancy. At GD 135, fetal plasma and gastrocnemius and soleus muscles were collected. In fetal plasma, total insulin was lower in NR(SGA) fetuses compared NR(Non-SGA) and control fetuses (P < 0.01), whereas total IGF-1 was lower in NR(SGA) fetuses compared with control fetuses (P < 0.05). Within gastrocnemius, protein expression of insulin receptor (INSRB; P < 0.05) and the glucose transporters, solute carrier family 2 member 1 and solute carrier family 2 member 4, was higher (P < 0.05) in NR(SGA) fetuses compared with NR(Non-SGA) fetuses; IGF-1 receptor protein was increased (P < 0.01) in NR(SGA) fetuses compared with control fetuses, and a lower (P < 0.01) proportion of type I myofibers (insulin sensitive and oxidative) was observed in SGA fetuses. For gastrocnemius muscle, the expression of lipoprotein lipase (LPL) messenger RNA (mRNA) was upregulated (P < 0.05) in both NR(SGA) and NR(Non-SGA) fetuses compared with control fetuses, whereas carnitine palmitoyltransferase 1B (CPT1B) mRNA was higher (P < 0.05) in NR(Non-SGA) fetuses compared with control fetuses, but there were no differences (P > 0.05) for protein levels of LPL or CPT1B. Within soleus, there were no differences (P > 0.05) for any characteristic except for the proportion of type I myofibers, which was lower (P < 0.05) in NR(SGA) fetuses compared with control fetuses. Accumulation of IMTG did not differ (P > 0.05) in gastrocnemius or soleus muscles. Collectively, the results indicate molecular differences between SGA and Non-SGA fetuses for most characteristics, suggesting that maternal NR induces a spectral phenotype for the metabolic programming of those fetuses.

Melatonin and insulin modulates the cellular biochemistry, histoarchitecture and receptor expression during hepatic injury in diabetic rats

Aims; The present study was designed to ameliorate the integrated efficacy of exogenous melatonin and insulin on tissue biochemical, serological, histopathological architecture and receptor expression of melatonin (MT1, MT2) and insulin receptor (IR) expression against the hepatic injury in diabetic rats. Materials and Method; the rats were randomly allocated into nine different experimental groups. Diabetes was induced by streptozotocin (15 mg/kg) for 6 days. Rats having blood glucose level above 250 mg/dl were considered as diabetic. Animals euthanized after 4 weeks, blood and liver samples were collected to perform various biochemical, serological, histopathological and receptor expression of melatonin (MT1, MT2) and insulin receptor (IR). Key findings; Diabetic rats revealed significant increase in lipid peroxidation (LPO) of liver tissue, liver function tests (ALT, AST and ALP), increase in serum cholesterol, LDL, VLD, but decrease in HDL level. Further, diabetic rats exhibited significant decrement in antioxidative enzymatic system (GSH, SOD, CAT, GR, GPX, G6PDH and GST), total tissue protein and glycogen content. Histomicrograph of liver of diabetic rats resulted in vacuolization indicating cellular damages as well as upregulation in liver MT1, MT2 and IR protein expression. However, the combined therapy (Melatonin and insulin treatment) revealed significant recovery and restoration in biochemical, cellular architecture of liver cells and receptor expression pattern of MT1, MT2 and IR. Significance; It may establish a synergistic action of melatonin and insulin, which might be a novel evidence for clinicians to combat the hepatic complication along with controlling diabetes.

Effect of 1-Deoxynojirimycin Isolated from Mulberry Leaves on Glucose Metabolism and Gut Microbiota in a Streptozotocin-Induced Diabetic Mouse Model.

1-Deoxynojirimycin (DNJ) exerts hypoglycemic effects. However, the traditional method for DNJ extraction is inefficient, and the hypoglycemic mechanism of DNJ remains unclear. In this study, the mixed fermentation by Lactobacillus fermentum and Saccharomyces cerevisiae was used to enhance DNJ extraction efficiency. It was found that this strategy was more efficient than the traditional method as the yield improved from the original 3.24 mg/g to 5.97 mg/g. The purified DNJ significantly decreased serum glucose (P < 0.01) and insulin levels (P < 0.05), improved serum lipid levels (P < 0.05), and reversed insulin resistance (P < 0.05) in diabetic mice. These changes were caused by up-regulating the protein expression of insulin receptor and glycolysis enzymes (GK, PK, and PFK) (P < 0.05) and down-regulating the protein expression of insulin receptor substrate-1 and gluconeogenesis enzymes (PCB, PEPCK, FBPase, and G-6-Pase) (P < 0.05), thus alleviating glucose tolerance. Additionally, DNJ treatment relieved gut dysbiosis in diabetic mice by promoting the growth of Lactobacillus, Lachnospiraceae NK4A136 group, Oscillibacter, norank Lachnospiraceae, Alistipes, and Bifidobacterium (P < 0.05) and suppressing the growth of Ruminococcaceae UCG-014, Weissella, Ruminococcus, Prevotellaceae Ga6A1 group, Anaerostipes, Klebsiella, Prevotellaceae UCG-001, and Bacteroidales S24-7 group (P < 0.05).

Dietary chokeberry and dried jujube fruit attenuates high-fat and high-fructose diet-induced dyslipidemia and insulin resistance via activation of the IRS-1/PI3K/Akt pathway in C57BL/6\u2009J mice

BackgroundThe incidence of metabolic syndrome linked to dyslipidemia and insulin resistance has increased; thus, studies must be conducted to elucidate this phenomenon. The present study aimed to investigate the protective effects of chokeberry and dried jujube diet on high-fat and high-fructose diet-induced dyslipidemia in mice.MethodsMale C57BL/6 J mice were divided into five groups: ND, mice fed normal diet and tap water; HFFD, mice fed 60% high-fat and 10% fructose diet (HFFD) in tap water; HFFD+C, mice fed HFFD with 1% chokeberry powder; HFFD+J, mice fed HFFD with 1% jujube fruit powder; and HFFD+M, mice fed HFFD with 0.5% chokeberry + 0.5% jujube fruit powder mixture.ResultsAfter 10 weeks of dietary treatment, chokeberry and dried jujube fruits reduced HFFD-induced weight gain and central obesity and decreased liver weight and abdominal and epididymal fat mass. Furthermore, such fruits attenuated HFFD-induced dyslipidemia; decreased triglyceride, total cholesterol, non-high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, and very-low-density lipoprotein-cholesterol levels. Insulin resistance was improved via the consumption of dietary chokeberry and dried jujube fruits according to various indicators (serum insulin level, fasting blood glucose level, homeostatic model assessment-insulin resistance score, and oral glucose tolerance test value). These treatments were found to lower serum triglyceride levels. Moreover, the consumption of chokeberry and dried jujube changed the hepatic protein expression of insulin receptor, insulin receptor substrate 1, phosphoinositide 3-kinase, Akt, and catalase, which are associated with insulin resistance.ConclusionsChokeberry and dried jujube could be used in the management of dyslipidemia and insulin resistance associated with metabolic syndrome by reducing risk parameters in mice with HFFD.

1874-P: A Novel Role for SerpinB1 in the Regulation of Insulin Signaling in Hepatocytes

Compensatory expansion of β cell mass has been pursued as a potential therapeutic strategy to cure diabetes. We previously identified SerpinB1 as a hepatocyte-derived circulating factor that contributes to adaptive beta cell expansion in the liver-specific insulin receptor knockout (LIRKO) mouse. To understand how SerpinB1 is regulated and secreted, we began by first investigating the mechanism(s) and signaling pathways that modulate the gene and protein expression of SerpinB1 in hepatocytes. Hepatic SerpinB1 expression was elevated in insulin resistant mouse models such as db/db and ob/ob, and circulating interleukin-6 (IL-6) levels were higher in these mice. Indeed, IL-6 induced SerpinB1 expression in HepG2 cells and human primary hepatocytes via the JAK/STAT3 pathway, indicating an important role for this cytokine in inducing the expression of the protease inhibitor in insulin resistant states. Conversely, silencing of SERPINB1 gene in hepatocytes decreased INSR gene and protein expression with a consequent alteration of expression of several downstream signaling genes related to gluconeogenesis and cell proliferation in hepatocytes. Ribosomal protein S3 (RPS3), identified as a binding partner of SerpinB1 in HepG2 cells, exhibited reduced expression in db/db and ob/ob mice liver along with reduced insulin receptor (IR) expression. Silencing of RPS3 gene in HepG2 cells, phenocopied the effects of SerpinB1 gene silencing, and decreased IR protein expression with consequent alterations in downstream signaling proteins. Additional studies are required to examine the precise regulation of IR expression by SerpinB1 and how the latter is secreted from insulin resistant hepatocytes. These results indicate that SerpinB1 expression is upregulated in insulin resistance by IL-6 and the SerpinB1/RPS3 complex plays a role in regulating insulin signaling in hepatocytes. Disclosure K. Orime: None. D.F. De Jesus: None. U. Jhala: None. R. Kulkarni: None.

Aberrant insulin receptor expression is associated with insulin resistance and skeletal muscle atrophy in myotonic dystrophies.

Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are autosomal dominant multisystemic disorders linked to two different genetic loci and characterized by several features including myotonia, muscle atrophy and insulin resistance. The aberrant alternative splicing of insulin receptor (IR) gene and post-receptor signalling abnormalities have been associated with insulin resistance, however the precise molecular defects that cause metabolic dysfunctions are still unknown. Thus, the aims of this study were to investigate in DM skeletal muscle biopsies if beyond INSR missplicing, altered IR protein expression could play a role in insulin resistance and to verify if the lack of insulin pathway activation could contribute to skeletal muscle wasting. Our analysis showed that DM skeletal muscle exhibits a lower expression of the insulin receptor in type 1 fibers which can contribute to the defective activation of the insulin pathway. Moreover, the aberrant insulin signalling activation leads to a lower activation of mTOR and to an increase in MuRF1 and Atrogin-1/MAFbx expression, possible explaining DM skeletal muscle fiber atrophy. Taken together our data indicate that the defective insulin signalling activation can contribute to skeletal muscle features in DM patients and are probably linked to an aberrant specific-fiber type expression of the insulin receptor.

Cognitive, behavioral and metabolic effects of oral galactose treatment in the transgenic Tg2576 mice

Alzheimer's disease (AD) is the most common neurodegenerative disorder associated with insulin resistance and glucose hypometabolism in the brain. Oral administration of galactose, a nutrient that provides an alternative source of energy, prevents and ameliorates early cognitive impairment in a streptozotocin-induced model (STZ-icv) of the sporadic AD (sAD). Here we explored the influence of 2-month oral galactose treatment (200 mg/kg/day) in the familial AD (fAD) by using 5- (5M) and 10- (10M) month-old transgenic Tg2576 mice mimicking the presymptomatic and the mild stage of fAD, and compared it to that observed in 7-month old STZ-icv rats mimicking mild-to-moderate sAD. Cognitive and behavioral performance was tested by Morris Water Maze, Open Field and Elevated Plus Maze tests, and metabolic status by intraperitoneal glucose tolerance test and fluorodeoxyglucose Positron-Emission Tomography scan. The level of insulin, glucagon-like peptide-1 (GLP-1) and soluble amyloid β1-42 (sAβ1-42) was measured by ELISA and the protein expression of insulin receptor (IR), glycogen synthase kinase-3β (GSK-3β), and pre-/post-synaptic markers by Western blot analysis. Although galactose normalized alterations in cerebral glucose metabolism in all Tg2576 mice (5M+2M; 10M+2M) and STZ-icv rats, it did not improve cognitive impairment in either model. Improvement of reduced grooming behavior and normalization in reduced plasma insulin levels were seen only in 5M+2M Tg2576 mice while in 10M+2M Tg2576 mice oral galactose induced metabolic exacerbation at the level of plasma insulin, GLP-1 homeostasis and glucose intolerance, and additionally increased hippocampal sAβ1-42 level, decreased IR expression and increased GSK-3β activity. The results indicate that therapeutic potential of oral galactose seems to depend on the stage and the type/model of AD and to differ in the absence and the presence of AD-like pathology.

Eugenosedin-A improves glucose metabolism and inhibits MAPKs expression in streptozotocin/nicotinamide-induced diabetic rats

This study examined the effects of eugenosedin-A (Eu-A) in a streptozotocin (STZ)/nicotinamide-induced rat model of type II diabetes mellitus (T2DM). Six-week-old Sprague–Dawley rats were randomly divided into three groups: (1) RD group, normal rats fed a regular diet (RD), (2) DM group, T2DM rats fed a high-fat diet, and (3) Eu-A group, T2DM rats fed a high fat diet plus oral Eu-A (5 mg/kg/day). After 30 days, the DM group had higher body weight, higher blood glucose and lower insulin levels than the RD group. The DM group also had increased protein expression of glycogen synthase kinase (GSK) in liver and skeletal muscle and decreased protein expression of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), IRS-2, AMP-activated protein kinase (AMPK), glucose transporter-4 (GLUT-4), glucokinase (GCK), and peroxisome proliferator-activated receptor γ (PPAR-γ). STZ/nicotinamide-induced T2DM increased the expression of mitogen-activated protein kinases (MAPKs: p38, ERK, JNK) and inflammatory p65 protein. In the Eu-A treated T2DM rats, however, blood glucose was attenuated and the insulin concentration stimulated. Changes in IR, IRS-1 and IRS-2 proteins as well as AMPK, GLUT-4, GCK, GSK, PPAR-γ, MAPKs, and inflammatory p65 proteins were ameliorated. These results suggested that Eu-A alleviates STZ/nicotinamide-induced hyperglycemia by improving insulin levels and glucose metabolism, and inhibiting the MAPKs- and p65-mediated inflammatory pathway.

Gene expression of insulin receptor, insulin-like growth factor increases and insulin-like growth factor-binding protein-3 reduces with increase in prostate size in benign prostatic hyperplasia

Introduction: Although the role of insulin in the development of benign prostatic hyperplasia (BPH) is well established, there are no studies regarding alteration in the gene expression of components of insulin-signaling pathway and their association with prostate size in BPH. Hence, the study was designed to analyze the gene and protein expression of insulin receptor and its related components in patients with BPH.Materials and methods: Twenty-seven BPH patients aged between 55 and 75 years were recruited in the study and prostatic tissues were obtained after transurethral resection of the prostate. Gene expression levels of Insulin receptor (IR), insulin receptor substrate (IRS), insulin-like growth factor (IGF) and insulin-like growth factor-binding protein-3 (IGFBP-3) were assessed by q-PCR.Results: Insulin receptor (IR-A and B) and insulin-like growth factors (IGF-1 and IGF-2) gene expression were significantly increased and IGFBP-3 gene expression was reduced in BPH patients with larger prostate size. Also, serum insulin was significantly increased and IGFBP-3 was significantly reduced in patients with larger prostate size.Conclusion: Increased expression of IR-A, B and IGF-1, 2 genes and reduced IGFBP-3 gene expression was associated with larger prostate size in BPH.

Adipose tissue insulin receptor and glucose transporter 4 expression, and blood glucose and insulin responses during glucose tolerance tests in transition Holstein cows with different body condition

Glucose uptake in tissues is mediated by insulin receptor (INSR) and glucose transporter 4 (GLUT4). The aim of this study was to examine the effect of body condition during the dry period on adipose tissue mRNA and protein expression of INSR and GLUT4, and on the dynamics of glucose and insulin following the i.v. glucose tolerance test in Holstein cows 21 d before (d -21) and after (d 21) calving. Cows were grouped as body condition score (BCS) ≤3.0 (thin, T; n = 14), BCS = 3.25 to 3.5 (optimal, O; n = 14), and BCS ≥3.75 (overconditioned, OC; n = 14). Blood was analyzed for glucose, insulin, fatty acids, and β-hydroxybutyrate concentrations. Adipose tissue was analyzed for INSR and GLUT4 mRNA and protein concentrations. During the glucose tolerance test 0.15 g/kg of body weight glucose was infused; blood was collected at -5, 5, 10, 20, 30, 40, 50, and 60 min, and analyzed for glucose and insulin. On d -21 the area under the curve (AUC) of glucose was smallest in group T (1,512 ± 33.9 mg/dL × min) and largest in group OC (1,783 ± 33.9 mg/dL × min), and different between all groups. Basal insulin on d -21 was lowest in group T (13.9 ± 2.32 µU/mL), which was different from group OC (24.9 ± 2.32 µU/mL. On d -21 the smallest AUC 5-60 of insulin in group T (5,308 ± 1,214 µU/mL × min) differed from the largest AUC in group OC (10,867 ± 1,215 µU/mL × min). Time to reach basal concentration of insulin in group OC (113 ± 14.1 min) was longer compared with group T (45 ± 14.1). The INSR mRNA abundance on d 21 was higher compared with d -21 in groups T (d -21: 3.3 ± 0.44; d 21: 5.9 ± 0.44) and O (d -21: 3.7 ± 0.45; d 21: 4.7 ± 0.45). The extent of INSR protein expression on d -21 was highest in group T (7.3 ± 0.74 ng/mL), differing from group O (4.6 ± 0.73 ng/mL), which had the lowest expression. The amount of GLUT4 protein on d -21 was lowest in group OC (1.2 ± 0.14 ng/mL), different from group O (1.8 ± 0.14 ng/mL), which had the highest amount, and from group T (1.5 ± 0.14 ng/mL). From d -21 to 21, a decrease occurred in the GLUT4 protein levels in both groups T (d -21: 1.5 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL) and O (d -21: 1.8 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL). These results demonstrate that in obese cows adipose tissue insulin resistance develops prepartum and is related to reduced GLUT4 protein synthesis. Regarding glucose metabolism, body condition did not affect adipose tissue insulin resistance postpartum.

Possible Role of GnIH as a Mediator between Adiposity and Impaired Testicular Function

The aim of the present study was to evaluate the roles of gonadotropin-inhibitory hormone (GnIH) as an endocrine link between increasing adiposity and impaired testicular function in mice. To achieve this, the effect of GnIH on changes in nutrients uptake and hormonal synthesis/action in the adipose tissue and testis was investigated simultaneously by in vivo study and separately by in vitro study. Mice were treated in vivo with different doses of GnIH for 8 days. In the in vitro study, adipose tissue and testes of mice were cultured with different doses of GnIH with or without insulin or LH for 24 h at 37°C. The GnIH treatment in vivo showed increased food intake, upregulation of glucose transporter 4 (GLUT4), and increased uptake of triglycerides (TGs) in the adipose tissue. These changes may be responsible for increased accumulation of fat in white adipose tissue, resulting in increase in the body mass. Contrary to the adipose tissue, treatment with GnIH both in vivo and in vitro showed decreased uptake of glucose by downregulation of glucose transporter 8 (GLUT8) expressions in the testis, which in turn resulted in the decreased synthesis of testosterone. The GnIH treatment in vivo also showed the decreased expression of insulin receptor protein in the testis, which may also be responsible for the decreased testicular activity in the mice. These findings thus suggest that GnIH increases the uptake of glucose and TGs in the adipose tissue, resulting in increased accumulation of fat, whereas simultaneously in the testis, GnIH suppressed the GLUT8-mediated glucose uptake, which in turn may be responsible for decreased testosterone synthesis. This study thus demonstrates GnIH as mediator of increasing adiposity and impaired testicular function in mice.