OBJECTIVE: To determine the effects of long-term estrogen replacement treatment on blood pressure and expressions of insulin receptor (IR) and insulin receptor substrate-1 ( IRS-1) in myocardium. METHODS: Fifty female SD rats were randomly divided into 3 groups. And then sham ( n = 16), ovariectomy (OVX, n = 17), and estrogen replacement treatment group (OVX + E2, n = 17) were established. Systolic blood pressure of tail artery was determined by tail-cuff technique before the operation and on week 12 after the operation. The expressions of IR and IRS-1 were measured by RT-PCR in myocardium of SD rats. RESULTS: Blood pressure [ (118.75+/-2.77) mmHg] in OVX was significantly higher than that in the sham [ ( 103.86+/-1.84) mmHg, P < 0.05 ] and OVX + E2 [( 107.83+/-3.24) mmHg, P < 0.05 ] rats. Expression of IRS-1 in OVX group was significantly lower ( 1.2588+/-0.1045)than that in the sham(2.2089+/-0.0988, P <0.05) and OVX + E2 groups ( 1.9100+/-0.1230, P <0.05 ). However, there was no difference on blood pressure and expression of IRS-1 between sham and OVX + E2 groups (P > 0.05 ). The difference of IR expression has no statistical significance among the 3 groups. CONCLUSION Long-term estrogen replacement treatment might protect cardiovascular system through decreasing the blood pressure and inducing the expression of IRS-1 in myocardium. However, plasma estrogen level doesn't significantly influence the IR expression.
Animals ; Blood Pressure ; drug effects ; Estradiol ; pharmacology ; Estrogen Replacement Therapy ; Female ; Insulin Receptor Substrate Proteins ; Myocardium ; metabolism ; Ovariectomy ; Phosphoproteins ; biosynthesis ; genetics ; Rats ; Rats, Sprague-Dawley ; Receptor, Insulin ; biosynthesis ; genetics ; Time Factors

OBJECTIVETo investigate the molecular mechanism of the effect of alcohol on insulin sensitivity.

METHODSFour groups of Wistar rats were used, i.e. control (C) group, and low (L), moderate (M) and high (H) alcohol group. Alcohol doses of each group were 0, 0.6, 1.8 and 3.0 ml.(kg.bw)(-1).day(-1). Each group was comprised of 10 male and 10 female rats. Alcohol was given to rats by gastric intubation. Thirteen weeks later, serum was collected for testing of fasting plasma glucose and insulin. HOMA-IR index of each group were calculated. Total muscle RNA was extracted using Trizol Reagent (Promega). The expression level of IRS-1 mRNA in muscle was detected by RT-PCR.

RESULTSIn female rats, the fasting plasma glucose of group (8.36 +/- 0.57) mmol/L was higher and the fasting plasma insulin (15.25 +/- 3.32) was lower than those of group C (7.56 +/- 0.85, 20.80 +/- 3.25). The HOMA-IR of group L (1.775 3 +/- 0.138 1) was lower than that of group C (1.982 6 +/- 0.124 6) (P < 0.05), while IRS-1 mRNA (0.766 1 +/- 0.076 9) was up-regulated (P < 0.05); HOMA-IR of group M (2.202 2 +/- 0.271 0) was higher than that of group C (P < 0.01), while IRS-1 mRNA (0.501 8 +/- 0.049 2) was suppressed (P < 0.01); HOMA-IR of group H (1.850 1 +/- 0.162 8) was not significantly changed as compared with that of group C (1.982 6 +/- 0.124 6) (P > 0.05), while IRS-1 mRNA (0.418 1 +/- 0.049 1) was significantly suppressed (P < 0.01). In male rats, the fasting plasma glucose and insulin had the similar change as those of female rats. The HOMA-IR of group M (1.878 5 +/- 0.250 2) was lower than that of C group (2.147 3 +/- 0.330 8) (P < 0.05), IRS-1 mRNA was up-regulated (0.824 9 +/- 0.064 7) (P < 0.05).

CONCLUSIONSThe present study showed that low-to-moderate dose of alcohol could increase insulin sensitivity; while alcohol abuse could decrease insulin sensitivity. Sex difference in this effect was found. Changes of IRS-1 mRNA expression may be involved in the molecular mechanism of the effects of alcohol on insulin sensitivity.

Animals ; Dose-Response Relationship, Drug ; Ethanol ; pharmacology ; Female ; Insulin ; blood ; Insulin Receptor Substrate Proteins ; Insulin Resistance ; Male ; Muscle, Skeletal ; metabolism ; Phosphoproteins ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Rats, Wistar ; Up-Regulation

OBJECTIVETo investigate the effect of Yangjing Zhongyu Decoction (YJZYD) on expression of insulin-like growth factor II (IGF-II) and its receptor II (IGF-II R) in endometrium of women with unexplained infertility, and the relationship of which with the receptibility of endometrium to ovum implantation.

METHODSReverse transcription-polymerase chain reaction (RT-PCR) assay was used to detect quantitatively the expression of IGF-II and IGF-II R in 22 women with unexplained infertility before and after YJZYD treatment during mid-luteal phase.

RESULTSThe levels of IGF-II and IGF-II R before treatment were 0.794 +/- 0.453 and 0.725 +/- 0.354 (in grey level, the same below) respectively, which were significantly increased in the same phase after treatment, reaching 1.202 +/- 0.551 and 1.045 +/- 0.581 respectively (P < 0.01 and P < 0.05). Correlation analysis showed the level of IGF-II mRNA was positively correlated with the level of IGF-II mRNA either before or after treatment.

CONCLUSIONYJZYD could enhance the expression of IGF-II and IGF-II R in the endometrium during mid-luteal phase, promote the differentiation of endometrium and increase its reception to ovum implantation.

Adult ; Embryo Implantation ; drug effects ; Endometrium ; metabolism ; Female ; Humans ; Infertility, Female ; drug therapy ; metabolism ; Insulin-Like Growth Factor II ; biosynthesis ; genetics ; Luteal Phase ; RNA, Messenger ; biosynthesis ; genetics ; Receptor, IGF Type 2 ; biosynthesis ; genetics

OBJECTIVETo explore the effect of peroxisome proliferator-activated receptor-alpha ( PPAR-alpha) agonist fenofibrate on adipokines expression in high-fat diet fed SD rats and its relationship to insulin resistance (IR).

METHODSRats were randomized into three groups (n = 10) : HD group, fed with high-fat diet; HDF group, fed with high fat diet and treated with fenofibrate; and control group, fed with normal diet. Animals were sacrificed after 4-week follow-up. Plasma lipids, fasting plasma insulin, free fatty acids (FFA), and insulin sensitivity were detected. Reverse transcription-polymerase chain reaction was used to semi-quantitatively determine the mRNA expression of adipokines including tumor necrosis factor-alpha (TNF-alpha) , interleukin-6 (IL-6), angiotensinogen (AGT), angiotensin 11 type 1 receptor (AT1R), and adiponectin in brown fat.

RESULTSThe plasma level of FFA, TG, and homeostatic model approach-IR index were (2. 37+/-0. 60) vs (1. 59+/-0. 30) vs (1. 33+/-0. 34 ) mmol/L, (0. 48+/-0. 11) vs (0. 30+/-0. 04) vs (0. 36+/-0. 07) mmol/L, and 12. 30+/-3. 97 vs 5. 03 +/-1. 88 vs 4. 17+/-1. 27 in the HD group, HDF group, and control group after 4 weeks of treatment with fenofibrate, respectively. The mRNA expressions of TNF-alpha and adiponectin were 1. 726+/-1. 408 vs 0. 713+/-0. 711 vs 0. 593+/-0. 382 and 0. 660+/-0. 192 vs 0. 949+/-0. 35 vs 0. 936+/-0. 130 in these three groups, which showed significant difference between HD group and HDF group (P < 0. 05 ) , while no significant difference between HDF group and control group (P > 0. 05). The mRNA expressions of AGT, AT1 R, and IL-6 had no significant difference among these three groups (P > 0. 05 ).

CONCLUSIONPPAR-alpha agonist fenofibrate may reverse high-fat diet induced lipid abnormalities, improve insulin sensitivity, and regulate the mRNA expressions of TNF-alpha and adiponectin in adipose tissues.

Adiponectin ; biosynthesis ; Adipose Tissue ; drug effects ; metabolism ; Angiotensins ; biosynthesis ; Animals ; Dietary Fats ; adverse effects ; Disease Models, Animal ; Fenofibrate ; pharmacology ; Insulin Resistance ; Interleukin-6 ; biosynthesis ; Lipofuscin ; biosynthesis ; Male ; PPAR alpha ; antagonists & inhibitors ; RNA, Messenger ; biosynthesis ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 2 ; biosynthesis ; Tumor Necrosis Factor-alpha ; biosynthesis

BACKGROUND/AIMS: The insulin-like growth factor (IGF) system has been implicated in tumor growth, invasion, and metastasis. However, reports on the IGF-1 receptor (IGF-1R) based on radioimmunoassays are conflicting, and its prognostic implications in non-small-cell lung cancer (NSCLC) are still controversial. METHODS: Seventy-one paraffin-embedded tissue sections from stage I NSCLC patients were stained using a mouse monoclonal antibody against human IGF-1R. RESULTS: The intensity and frequency of IGF-1R expression on the membrane and cytoplasm of cancer cells was evaluated and scored using a semiquantitative system. IGF-1R expression was detected in nine of 71 (12.7%) cases. No significant relationship was found between clinical/histopathological parameters and IGF-1R expression. None of the patients whose tumor expressed IGF-1R had experienced distant metastasis or cancer-related death, although the difference did not reach statistical significance. CONCLUSIONS: We conclude that IGF-1R expression may not be a major prognostic factor for stage I NSCLC.
Adult ; Aged ; Aged, 80 and over ; Animals ; Carcinoma, Non-Small-Cell Lung/*immunology/mortality/pathology ; Female ; Humans ; Immunohistochemistry ; Insulin-Like Growth Factor I/*biosynthesis ; Male ; Mice ; Middle Aged ; Neoplasm Metastasis ; Neoplasm Staging ; Prognosis ; Receptor, IGF Type 1/*biosynthesis

To study the morphological characteristics of hepatic stem cells and the expression of HGF, IGF-I, TGFbeta1 and their receptors in human embryonic livers at 3-5 weeks of gestation. The SABC immunohistochemical method with HE counterstaining was employed. We found that the hepatic bud formed at the end of the 3rd week. At the 4th week, the cells of hepatic bud migrated into the septum transversum mesenchyme and formed the hepatic cords. The hepatic cells at 3-4 weeks displayed the typical characteristics of immature cells: small size, a round or ovoid nucleus with dark color, scant cytoplasm with slight blue and a high ratio of nuclei/cytoplasm. They were positive for alpha-Fetoprotein (AFP), c-Met and negative for cytokertin 19 (CK19), and proliferating cell nuclear antigen (PCNA). At the 5th week, compared to those at the 4th week, the number of cells within the hepatic cords increased. But the cells at the 5th week were homogeneous and displayed the typical characteristic of immature cells. Those cells began to express PCNA at the 5th week. The hepatic cells at the 5th week were positive for insulin-like growth factor I (IGF-I), transforming growth factor beta1 (TGFbeta1) and their receptors, and were negative for hepatocyte growth factor (HGF), while HGF were positive in the cardiac cells and septum transversum mesenchyme. The results indicated that the cells of hepatic bud and cords were the hepatic stem cells. The difference of morphology and proteins expression at 3-5 weeks of gestation inferred that those stem cells belong to different developmental stage. AFP and c-Met were the markers of hepatic stem cells at the early stage of human embryo. HGF, IGF-I, TGFbeta1 and their receptors may involve in regulating the development of early embryonic human liver.
Embryo, Mammalian ; Gestational Age ; Hepatocyte Growth Factor ; biosynthesis ; genetics ; Humans ; Insulin-Like Growth Factor I ; biosynthesis ; genetics ; Liver ; cytology ; metabolism ; Proto-Oncogene Proteins c-met ; biosynthesis ; genetics ; Receptor, IGF Type 1 ; biosynthesis ; genetics ; Stem Cells ; cytology ; Transforming Growth Factor beta ; biosynthesis ; genetics ; Transforming Growth Factor beta1

It is well known that exercise can have beneficial effects on insulin resistance by activation of glucose transporter. Following up our previous report that caveolin-1 plays an important role in glucose uptake in L6 skeletal muscle cells, we examined whether exercise alters the expression of caveolin-1, and whether exercise-caused changes are muscle fiber and exercise type specific. Fifity week-old Sprague Dawley (SD) rats were trained to climb a ladder and treadmill for 8 weeks and their soleus muscles (SOL) and extensor digitorum longus muscles (EDL) were removed after the last bout of exercise and compared with those from non-exercised animals. We found that the expression of insulin related proteins and caveolins did not change in SOL muscles after exercise. However, in EDL muscles, the expression of insulin receptor beta (IRbeta) and glucose transporter-4 (GLUT-4) as well as phosphorylation of AKT and AMPK increased with resistance exercise but not with aerobic exercise. Also, caveolin-1 and caveolin-3 increased along with insulin related proteins only in EDL muscles by resistance exercise. These results suggest that upregulation of caveolin-1 in the skeletal muscle is fiber specific and exercise type specific, implicating the requirement of the specific mode of exercise to improve insulin sensitivity.
AMP-Activated Protein Kinases ; Animals ; Caveolin 1/*biosynthesis ; Caveolin 3/metabolism ; Female ; Glucose Transporter Type 4/biosynthesis ; Insulin/*physiology ; Multienzyme Complexes/metabolism ; Muscle Fibers, Skeletal/*metabolism ; Muscle, Skeletal/metabolism/*physiology ; Phosphorylation ; *Physical Conditioning, Animal ; Protein-Serine-Threonine Kinases/metabolism ; Proto-Oncogene Proteins c-akt/metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor, Insulin/biosynthesis ; Up-Regulation

The specific inhibition of angiotensin II action at AT(1) receptors by losartan has been shown to decrease peripheral insulin resistance in type 2 diabetic patients and animal models. We examined the effect of losartan on the expression of insulin receptor substrate 1 (IRS-1), protein kinase B (PKB) and glucose transporter 4 (GLUT4), as well as the phosphorylation status of IRS-1 and the association between IRS-1 and phosphatidylinositol (PI) 3-kinase in skeletal muscle from fat-fed and-streptozotocin (STZ)-treated rats, an animal model of type 2 diabetes mellitus. In addition, the effects of losartan on GLUT4 translocation in muscle cells and on insulin sensitivity were also evaluated. Muscle tissues were isolated from male losartan-treated and untreated normal or non-insulin-dependent diabetes mellitus (NIDDM) rats with a dose of 4 mg/kg per day for 6 weeks. Oral administration of losartan improved insulin sensitivity, which was determined by an oral glucose tolerance test (OGTT). In skeletal muscles, the protein levels of IRS-1, PKB and GLUT4 in NIDDM rats were not significantly different from those of the control rats, and they were not affected by losartan. The levels of IRS-1 tyrosine phosphorylation, PI 3-kinase activity associated with IRS-1 and PKB activation after stimulation with insulin in muscle tissue of NIDDM rats were significantly decreased (P<0.01) compared with those in the control rats, while they were not increased by losartan. Losartan had a major effect on GLUT4 translocation in myocytes, as it significantly increased (P<0.05) the insulin-induced amounts of GLUT4 in plasma membrane (PM) and T-tubules (TT) in myocytes from NIDDM rats. Consistent with these results, the plasma glucose level in losartan-treated NIDDM rats was decreased (P<0.05) compared with that in untreated NIDDM rats. Our results suggest that losartan may exert beneficial effects on insulin resistance by increasing the translocation of GLUT4 in muscle tissue, which is probably associated with a non-PI 3-kinase-dependent mechanism.
Animals ; Diabetes Mellitus, Experimental ; blood ; drug therapy ; Diabetes Mellitus, Type 2 ; blood ; drug therapy ; physiopathology ; Glucose Transporter Type 4 ; Insulin Receptor Substrate Proteins ; Insulin Resistance ; Losartan ; pharmacology ; therapeutic use ; Male ; Monosaccharide Transport Proteins ; biosynthesis ; genetics ; Muscle Proteins ; biosynthesis ; genetics ; Muscle, Skeletal ; metabolism ; Phosphoproteins ; biosynthesis ; genetics ; Protein-Serine-Threonine Kinases ; biosynthesis ; genetics ; Proto-Oncogene Proteins ; biosynthesis ; genetics ; Proto-Oncogene Proteins c-akt ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo detect the effect of resistin on the transcription of insulin receptor promoter.

METHODSLuciferase reporter gene was fused downstream of human insulin receptor promoter and the enzymatic activity of luciferase was determined in the presence or absence of resistin. The resistin expressed with plasmid was stained with antibody against Myc tag which was in frame fused with resistin coding sequence, and then imaged with confocal microscopy.

RESULTSThe treatment of pIRP-LUC transfected cells with recombinant resistin did not result in significant difference in the enzymatic activity of luciferase compared to the untreated cells. Cell staining showed that green fluorescence could be observed in the cytoplasm, but not in the nucleus.

CONCLUSIONThe results suggest that the endogenous resistin may functionally locate in the cytoplasm, but does not enter the nucleus and not down-regulate the transcription of insulin receptor promoter.

Cell Line ; Cell Nucleus ; metabolism ; Cytoplasm ; metabolism ; Down-Regulation ; Gene Expression Regulation ; Humans ; Luciferases ; metabolism ; Microscopy, Confocal ; Models, Biological ; Plasmids ; metabolism ; Promoter Regions, Genetic ; Receptor, Insulin ; biosynthesis ; genetics ; Resistin ; pharmacology ; Transcription, Genetic ; Transfection

OBJECTIVE: To investigate the effect of xiaokeling concentration fluid on insulin-like growth factor-1 (IGF-1) mRNA expression in sciatic nerve of Streptozotocin-induced diabetic rats. METHODS: Thirty diabetic rats were randomly divided into model group, mecobalamin tablets group, and xiaokeling concentration fluid group. The IGF-1 mRNA level in sciatic nerve of each group was determined after 8 weeks by relative quantity RT-PCR. RESULTS: The IGF-1 mRNA level in sciatic nerve of diabetic rats between xiaokeling concentration fluid group, mecobalamin tablets group and normal group showed no significant difference ( P = 0.213, P = 0.822, P = 0.304 ), while was significantly higher than that of the model group ( P < 0.05 ). IGF-1 mRNA level was negatively correlated with the level of blood sugar (P < 0.05). CONCLUSION IGF-1 mRNA level decreased in sciatic nerve of diabetic rats. Xiaokeling concentration fluid can increase the IGF-1 mRNA level in sciatic nerve of diabetic rats. Xiaokeling concentration fluid is involved in the regulation of IGF-1 expression, and probably prevents diabetic peripheral neuropathy from deteriorating.
Animals ; Diabetes Mellitus, Experimental ; drug therapy ; metabolism ; Diabetic Neuropathies ; prevention & control ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Hypoglycemic Agents ; pharmacology ; therapeutic use ; Insulin-Like Growth Factor I ; biosynthesis ; genetics ; Male ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Rats ; Receptor, IGF Type 1 ; Reverse Transcriptase Polymerase Chain Reaction ; Sciatic Nerve ; metabolism