Allelic variants of insulin receptor substrate-1 gene in Egyptian women with polycystic ovary syndrome

The insulin receptor substrate gene-1 (IRS-1) polymorphisms have been incriminated in insulin resistance; a frequent finding in polycystic ovary syndrome (PCOS). The commonest polymorphism associated with insulin resistance is gly972arg. Another polymorphism is the ala512 pro. This study aimed at elucidating the association of the gly972arg and the ala512pro polymorphisms of the IRS-1 gene with PCOS in Egyptian females. We employed a case–control study. The two polymorphisms were analyzed in 62 PCOS Egyptian female patients and 43 age-matched controls using a PCR-RFLP strategy. Fasting insulin, plasma glucose, and testosterone were analyzed by routine analytical methods and calculation of the homeostasis model assessment (HOMA) and the quantitative sensitivity check index (QUICK I) were done based on the results of the fasting insulin and glucose. It was found that 6.5% of the PCOS cases showed the Gly972Arg genotype. The Gly972Arg in IRS-1 polymorphism was not associated with PCOS (p?=?0.556). A positive association was found between the gly972arg and the HOMA quartiles (p?=?0.01). PCOS patients with the 972gly/arg genotype had higher glucose (p?=?0.040), insulin (0.000), HOMA (0.000), and lower QUICK I (0.023) than PCOS with wild 972arg/arg genotype. Patients of PCOS with the 972gly/arg genotype were more insulin resistant than other patients with the wild genotype. Neither the patients nor the controls showed the mutant ala512pro genotype. Screening for gly972arg genotype can be based on the HOMA quartile ranking. The ala512pro genotype was not found in studied Egyptian women.     

Abnormal glucose tolerance and insulin resistance in polycystic ovary syndrome amongst the Taiwanese population- not correlated with insulin receptor substrate-1 Gly972Arg/Ala513Pro polymorphism

Background  

Insulin resistance and glucose dysmetabolism in polycystic ovary syndrome (PCOS) are related with the polymorphisms in the genes encoding the insulin receptor substrate (IRS) proteins, especially Gly972Arg/Ala513Pro polymorphism being reported to be associated with type-2 diabetes and PCOS. We intended to assess the prevalence of abnormal glucose tolerance (AGT) and insulin resistance in Taiwanese PCOS women. We also tried to assess whether the particular identity of Gly972Arg/Ala513Pro polymorphic alleles of the IRS-1 gene mutation can be used as an appropriate diagnostic indicator for PCOS.     

多囊卵巢综合征胰岛素抵抗患者Gly972Arg多态性与子宫内膜胰岛素受体底物1表达的关系

目的:研究多囊卵巢综合征(Polycystic ovary syndrome,PCOS)胰岛素抵抗(Insulin resistance,IR)患者胰岛素受体底物1(Insulin receptor substrate,IRS-1)基因Gly972Arg多态性与子宫内膜IRS-1表达的关系。方法:PCOS患者51例,用聚合酶链反应(PCR)技术,检测IRS-1Gly972Arg多态性。于月经周期第1天刮取子宫内膜,合并胰岛素抵抗者28例,非胰岛素抵抗者23例,应用免疫组化技术检测子宫内膜IRS-1,计算机图像分析系统分析子宫内膜IRS-1的表达。结果:Gly972Arg多态性:51例PCOS患者中,基因型GG 49例,基因型GA 2例,IR组与无IR组各1例,两组比较无统计学意义。子宫内膜IRS-1的表达:IR组、非IR组IRS-1表达的灰度值分别为131.94±18.39、78.16±6.87,比较有统计学意义(P<0.01)。结论:IRS-1Gly972Arg的突变率较低,其多态性在PCOS IR组与无IR组比较无统计学意义(P>0.05),不影响子宫内膜IRS-1的表达。     

The importance of IRS-1 Gly972Arg polymorphism in evaluating the response to metformin treatment in polycystic ovary syndrome

BACKGROUND: Recent evidence suggests that one of the modes of action of metformin may be through phosphorylation of the insulin receptor and insulin receptor substrates. With this in mind, we supposed that the G972A variant of insulin receptor substrate-1 (IRS-1) may modulate the response to metformin treatment in women with polycystic ovary syndrome (PCOS). METHODS: This preliminary study involved 60 randomly selected women with PCOS. All patients received dietary instructions and metformin 500 mg three times daily for 6 months. Main outcome measures were androgen levels, parameters of glucose and insulin metabolism and anthropometric variables. After a second evaluation of the patients at 6 months, they were genotyped for the Gly972Arg variant of the IRS-1 gene. RESULTS: Metformin had differential effects on fasting insulin levels, insulin resistance as demonstrated by homeostasis model assessment (HOMA), LH, total testosterone, dehydroepiandrosterone sulphate and free testosterone index on the basis of IRS genotype. The response to metformin therapy in other parameters was not different according to IRS genotype. CONCLUSION: There was a differential effect of metformin therapy in PCOS women on the basis of IRS genotype. This study may call attention to the importance of molecular markers in the management of women with PCOS.     

Interaction effect between common polymorphisms in PPARγ2 (Pro12Ala) and insulin receptor substrate 1 (Gly972Arg) on insulin sensitivity

The Pro12Ala polymorphism in the peroxisome proliferator-activated receptor (PPAR) gamma2 gene is associated with a reduced risk of type 2 diabetes. A beneficial effect on insulin sensitivity is reported in some but not all populations. It is possible that this genetic variant produces a characteristic phenotype only against a certain genetic background. We therefore tested the hypothesis that carriers of the Ala allele of PPARgamma2 exhibit a different phenotype against the background of the Gly972Arg polymorphism in the insulin receptor substrate (IRS) 1. We determined insulin sensitivity in the four combinations defined by the absence or presence of the polymorphic allele (healthy, glucose tolerant subjects), by the oral glucose tolerance test (OGTT; using a validated index, n=318) and hyperinsulinemic clamp ( n=201). Insulin sensitivity was not or was only marginally different between Pro/Pro and X/Ala in the overall population. Interestingly, using the OGTT index, insulin sensitivity was significantly greater in X/Ala (PPARgamma2) + X/Arg (IRS-1) than in Pro/Pro (PPARgamma2) + X/Arg (IRS-1). On the other hand, insulin sensitivity was similar in the X/Ala (PPARgamma2) + Gly/Gly (IRS-1 972) and the Pro/Pro (PPARgamma2) + Gly/Gly (IRS-1). The results were practically identical using insulin sensitivity from the clamp. In conclusion, the Arg972 (IRS-1) background produced a marked difference in insulin sensitivity between X/Ala and Pro/Pro (PPARgamma) which was not present in the whole population or against the Gly972 (IRS-1) background. This suggests that the Ala allele of PPARgamma2 becomes particularly advantageous against the background of an additional, possibly disadvantageous genetic polymorphism. Allowing for gene-gene interaction effects may reveal novel information regarding metabolic effects of genetic variants.     

Amelioration of insulin resistance in women with PCOS via reduced insulin receptor substrate-1 Ser312 phosphorylation following laparoscopic ovarian electrocautery

BACKGROUND: Increased Ser(312) phosphorylation of insulin receptor substrate (IRS)-1 is one possible molecular mechanism of insulin resistance in polycystic ovary syndrome (PCOS). We investigated whether laparoscopic ovarian electrocautery (LOE) improved insulin sensitivity in women with PCOS and examined the underlying molecular mechanism of LOE. METHODS: Adipose tissue and blood samples from 12 women with PCOS before, and 3 months after, LOE were analysed. RESULTS: Before LOE, women with PCOS were found to have significantly higher 2 h glucose, fasting and 2 h insulin levels, homeostasis model insulin resistance index and lower fasting glucose-to-insulin ratio (G(0)/I(0)) than healthy, lean, age-matched controls. Serum levels of glucose and insulin were significantly decreased, and G(0)/I(0) ratio was significantly increased 3 months after LOE. Levels of activated extracellular signal-regulated kinase 1/2 in PCOS women were higher than in controls, but were significantly decreased after LOE. Levels of insulin receptor, glucose transporter-4 and phosphatidylinositol 3-kinase were lower in PCOS patients before LOE than in controls and increased after LOE. Levels of Ser(312)-phosphorylated IRS-1 in PCOS women before LOE were higher than in controls and decreased significantly after LOE, whereas IRS-1 tyrosine phosphorylation in PCOS women before LOE was lower than in controls and increased significantly after LOE. CONCLUSION: Over the short observation period of this study, our results demonstrated that LOE effectively ameliorated insulin resistance in women with PCOS via decreased IRS-1 Ser(312) phosphorylation.     

Association of rs10830963 and rs10830962 SNPs in the melatonin receptor (MTNR1B) gene among Han Chinese women with polycystic ovary syndrome

The aim of the present study was to determine whether or not the 'melatonin receptor (MTNR1B)' gene polymorphisms are associated with a predisposition for polycystic ovary syndrome (PCOS). The single-nucleotide polymorphisms (SNPs), rs10830963 and rs10830962, in the MTNR1B gene were detected in 526 patients with PCOS and 547 healthy Chinese Han women. The association between MTNR1B gene variants and plasma glucose and insulin levels during the oral glucose tolerance test (OGTT) and hormone levels was investigated. The frequencies of three genotypes and two allelotypes of the SNP, rs10830963, differed significantly between women with PCOS and healthy controls (P < 0.001 and P < 0.001, respectively). The SNP, rs10830963, was significantly associated with higher fasting plasma glucose concentrations (P < 0.001) and increased the area under the curve of plasma glucose levels during the OGTT (P < 0.001), as well as increased homeostasis model assessment of insulin resistance (HOMA-IR; P = 0.027). No significant differences were observed in the genotypes and allele distributions of rs10830962 polymorphisms between the PCOS and the control groups (P = 0.311 and P = 0.178, respectively). There was no significant difference in the clinical and the metabolic characteristics in women with PCOS with different genotypes in the SNP, rs10830962 (all P > 0.005). The present study suggest that the SNP, rs10830963, in the MTNR1B gene is not only associated with susceptibility to PCOS, but also contributes to the PCOS phenotype.     

Common polymorphisms in the PPARgamma2 and IRS-1 genes and their interaction influence serum adiponectin concentration in young Finnish men

The Gly972Arg substitution of the insulin receptor substrate-1 (IRS-1) gene and the Pro12Pro genotype of the peroxisome proliferator-activated receptor gamma 2 (PPARgamma2) gene have been suggested to be associated with type 2 diabetes mellitus. In this study, the influence of these two polymorphisms on serum adiponectin concentrations was investigated. The Pro12Ala polymorphism of the PPARgamma2 gene and the Gly972Arg polymorphism of the IRS-1 gene were genotyped in 252 young Finnish servicemen. The Ala12Ala genotype of PPARgamma2 was associated with a higher adiponectin level compared to the Pro12Ala genotype (p=0.02) and the Pro12Pro genotype (p=0.02). Total (p=0.02) and low-density lipoprotein (LDL) cholesterol (p=0.03) levels were higher in subjects with the Pro12Pro genotype compared to the Pro12Ala genotype. No difference was observed in serum adiponectin level between the IRS-1 genotype groups. The subjects with X972Arg of this gene had high total and LDL cholesterol levels (p<0.05). The interaction between the PPARgamma2 and IRS-1 genes with respect to their effects on adiponectin levels was statistically significant (p=0.02). Adiponectin was significantly higher (p<0.05) in subjects who simultaneously had the Ala/Ala (PPARgamma2)+Gly/Gly (IRS-1) genotype combination compared to subjects with the Pro/Pro+Gly/Gly and Pro/Ala+Gly/Gly genotype combinations. Total and LDL cholesterol was higher (p<0.05) in subjects with Pro/Pro+X/Arg compared to subjects with the two before mentioned genotype combinations. We conclude that the Ala12Ala genotype of PPARgamma2 is associated with elevated adiponectin level, and that the PPARgamma2 and IRS-1 genes have a possible interaction in their effects on adiponectin concentration.     

Endocrine and metabolic effects of rosiglitazone in overweight women with PCOS: a randomized placebo-controlled study

BACKGROUND: The objective of the study was to assess the therapeutic effects of rosiglitazone in overweight women with polycystic ovary syndrome (PCOS). METHODS: A double-blind, placebo-controlled study was conducted on 30 (BMI > 25 kg/m2, mean age 29.1 +/- 1.2 years) overweight women with PCOS treated with rosiglitazone or placebo for 4 months. Waist-to-hip ratios (WHRs), serum concentrations of sex hormones and binding proteins, blood glucose, serum insulin and serum C-peptide during a 75-g oral glucose tolerance test (OGTT), first-phase insulin secretion as determined by an intravenous glucose tolerance test (IVGTT), M values (expressing insulin sensitivity using a euglycaemic clamp) and calorimetric data were assessed at 0 and 4 months of treatment. RESULTS: Rosiglitazone improved menstrual cyclicity, increased serum sex hormone-binding globulin (SHBG) levels and decreased serum levels of androstenedione, 17-hydroxyprogesterone (17-OHP), dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEA-S). Glucose tolerance [expressed as AUC(glucose) during the OGTT] improved (P = 0.002) and peripheral insulin response (expressed as AUC(insulin)) decreased (P = 0.004) in the rosiglitazone group (ROSI group). M value improved in the ROSI group from 33.4 +/- 3.27 to 40.0 +/- 5.51 micromol/kg min (P = 0.04). CONCLUSION: Rosiglitazone, by improving menstrual cyclicity, hyperandrogenism, insulin resistance and hyperinsulinaemia, represents an alternative treatment for overweight anovulatory women with PCOS and no pregnancy desire.     

Interleukin-6 as an early chronic inflammatory marker in polycystic ovary syndrome with insulin receptor substrate-2 polymorphism

Citation Lin Y‐S, Tsai S‐J, Lin M‐W, Yang C‐T, Huang M‐F, Wu M‐H. Interleukin‐6 as an early chronic inflammatory marker in polycystic ovary syndrome with insulin receptor substrate‐2 polymorphism. Am J Reprod Immunol 2011; 66: 527–533 Problem Polycystic ovary syndrome (PCOS) is a common gynecological endocrine disorder. This study was to evaluate whether insulin receptor substrate (IRS)‐2 Gly1057Asp polymorphism influences chronic inflammatory parameters in Taiwanese patients with PCOS. Method of study DNA was extracted from whole blood samples for genotyping and detection of IRS‐2 Gly1057Asp polymorphism in 129 PCOS women and 109 control women. Ninety‐seven PCOS women accepted metformin treatment for 3 months, and low‐grade chronic inflammatory markers were assessed. Results The levels of IL‐6 were significantly elevated in PCOS women compared with normal women. Among allelic variant of IRS‐2, concentrations of IL‐6 were greater in IRS‐2 homozygous Asp population. Treatment with metformin significantly reduced IL‐6, especially in PCOS patients with IRS‐2 homozygous Asp variant. Conclusion The results showed that IL‐6 may be an early low‐grade chronic inflammatory marker among PCOS patients with IRS‐2 polymorphism in Taiwanese population. This pharmacologic study in IRS‐2 polymorphism may provide more information for preventing long‐term complications in PCOS.     

The role of insulin-like growth factor-1 (IGF-1) and IGF binding protein-1 (IGFBP-1) in the pathogenesis of polycystic ovary syndrome.

The objective of this study was to elucidate the relationship and role of insulin-like growth factor-1 (IGF-1), IGF binding protein-1 (IGFBP-1), insulin and luteinizing hormone (LH) in the pathogenesis of polycystic ovary syndrome (PCOS). In a pilot study, serum concentrations of IGF-1 were determined in women with PCOS (n = 10), hypopituitarism (n = 12) and normal controls (n = 10). In the main study, serum concentrations of IGF-1, IGFBP-1, insulin and LH in women with anovulation associated (n = 23) and not associated (n = 47) with PCOS were determined. Serum concentrations of IGF-1 were not different in women with PCOS, anovulatory non-PCOS and healthy women but were low in those with hypopituitarism. Mean serum IGFBP-1 in PCOS (33.8 +/- 21.2 micrograms/l) was decreased compared with anovulatory non-PCOS (60.0 +/- 22 micrograms/l) (P = 0.0001), and correlated negatively with insulin concentrations (r = -0.67, P = 0.0006). Patients with PCOS could be separated into those with high LH and those with high insulin levels. It was concluded that women with PCOS have normal serum IGF-1 concentrations but IGFBP-1 levels, regulated by insulin, are low. Hyperinsulinaemia and raised LH are independently capable of stimulating ovarian androgen production. Growth factors may have an important role in the pathogenesis of PCOS.     

Decreased serum paraoxonase 1 (PON1) activity: an additional risk factor for atherosclerotic heart disease in patients with PCOS?

BACKGROUND: Patients with polycystic ovary syndrome (PCOS) may have an increased risk for the development of hypertension and atherosclerotic heart disease (AHD), the pathophysiological mechanisms of which are not clear. Paraoxonase1 (PON1) is a high-density lipoprotein-associated enzyme that prevents oxidative modification of low-density lipoprotein. The aim of this study was to measure the serum levels of PON1 activity in patients with PCOS and to compare with those of regularly cycling controls. METHODS: Serum lipid parameters, malondialdehyde (MDA) levels and PON1 activity, were measured in PCOS patients (n = 23) and regularly cycling, age-, body mass index- and smoking status-matched controls (n = 23). All patients had normal glucose tolerance test as assessed by a 75 g oral glucose tolerance test. None of the patients had clinically evident hypertension or AHD. RESULTS: Apart from the mean serum PON1 activity, all parameters in the lipid profile including serum MDA levels were comparable between the two groups. There were no significant differences in respect to fasting glucose (4.64 +/- 0.5 versus 4.43 +/- 0.83 mmol/l) and fasting glucose insulin ratio (11.06 +/- 8.26 versus 11.49 +/- 4.90) among the two groups (P > 0.05). However, HOMA insulin resistance index was significantly higher in patients with PCOS compared with the controls (2.06 +/- 0.86 versus 1.51 +/- 0.49; P = 0.01). Also, mean serum PON1 activity was significantly lower in the PCOS group compared with the controls (151.2 +/- 90.8 versus 217.7 +/- 101.6, respectively; P = 0.027). CONCLUSIONS: Reduced serum PON1 activity might contribute to the increased susceptibility for the development of AHD in women with PCOS.     

Adiponectin and resistin serum levels in women with polycystic ovary syndrome during oral glucose tolerance test: a significant reciprocal correlation between adiponectin and resistin independent of insulin resistance indices

Polycystic ovary syndrome (PCOS) is associated with an increased incidence of insulin resistance (IR), obesity, and type 2 diabetes. Resistin, an adipocytokine, may represent a link between obesity, and these metabolic disorders. There is also evidence that inflammation is a hyperresistinemic state in humans, and cytokine induction of resistin may contribute to insulin resistance in endotoxemia, obesity, and other inflammatory states. In contrast, adiponectin, increases insulin sensitivity, improves glucose tolerance, inhibits inflammatory pathways, while adenovirus-expressed adiponectin reduces atherosclerotic lesions in a mouse model of atherosclerosis. We aimed to assess, in women with PCOS, whether there is a relationship between adiponectin and resistin and the indices of IR, and whether serum levels of these adipocytokines are altered by glucose-induced hyperinsulinaemia. Serum levels of resistin and adiponectin were measured at 0, 60, and 120 min during 75 g oral glucose tolerance test (OGTT), in 19 women with PCOS, age 36.3+/-11.4 years (mean+/-SD), body mass index (BMI) 29.3+/-7.7 kg/m2, and correlated with the indices of IR, such as HOMA-IR, QUICKI, and the insulin resistance index calculated from glucose and insulin levels obtained during OGTT. There was no change in resistin concentrations (7.31+/-4.58, 7.47+/-5.40, 7.22+/-5.12 pg/ml, at 0, 60, and 120 min of OGTT, respectively, P = 0.77), but there was an increase in adiponectin from 11.32+/-4.64 microg/ml at baseline to 14.78+/-7.41 microg/ml, at 120 min of OGTT (P < 0.01). The magnitude of the overall rise in adiponectin was greater from 60 to 120 min (from 12.31+/-5.72 to 14.78+/-7.41 microg/ml, P < 0.006). Neither resistin, nor adiponectin correlated with the indices of IR, lipids, or other hormonal parameters of the PCOS. There was, however, a significant negative correlation between serum resistin and adiponectin (P = 0.001). In conclusion, we observed a strong negative correlation between serum adiponectin and resistin, despite the lack of direct correlation with the indices of IR. Given the opposite effects of resistin and adiponectin on the inflammatory process, we speculate that relative proportion of adiponectin-to-resistin might potentially influence cardiometabolic risk in women with the PCOS independently of IR parameters. The observed increase in adiponectin during OGTT requires further study.     

Insulin resistance in patients with polycystic ovary syndrome is associated with elevated plasma homocysteine

BACKGROUND: Elevated levels of plasma homocysteine have recently been implicated as a significant risk factor for cardiovascular disease, pre-eclampsia, and recurrent pregnancy loss, and have been found to be associated with insulin resistance in a number of clinical situations. We examined the relationship between plasma homocysteine and insulin resistance in patients with polycystic ovary syndrome (PCOS). METHODS: A total of 155 infertile patients with PCOS as defined by clinical, biochemical and ultrasound criteria were screened for insulin resistance utilizing single-sample fasting insulin and glucose measurement, calculated by glucose:insulin ratio or homeostasis model assessment (HOMA) index. Total plasma homocysteine was measured by fluorescence polarization immunoassay. One hundred normo-ovulatory women with normal ovaries being treated for other infertility diagnoses served as a control group. RESULTS: Insulin resistance was found in the majority of PCOS patients: -53.5% (83/155), 60.6% (94/155) and 65.8% (102/155), when defined by fasting insulin, glucose:insulin ratio, or logHOMA respectively. Mean plasma homocysteine in the PCOS group was significantly higher than in the normal ovary group (11.5 +/- 7.4 versus 7.4 +/- 2.1 micromol/l, P < 0.001). Insulin-resistant PCOS patients had significantly higher plasma homocysteine (12.4 +/- 8.4 micromol/l) than non-insulin-resistant PCOS patients (9.6 +/- 4.4 micromol/l) regardless of body mass index (P = 0.003 by groups, P = 0.005 by correlation of single samples). Thirty-four per cent (53/155) of the PCO patients had homocysteine values >95th percentile of the controls (11.0 micromol/l, P < 0.0001). Statistically significant correlations were found between all insulin resistance indices and homocysteine levels. Multiple logistic regression defined insulin resistance as the major factor examined that influenced homocysteine levels. CONCLUSIONS: Insulin resistance and hyperinsulinaemia in patients with PCOS is associated with elevated plasma homocysteine, regardless of body weight. This finding may have important implications in the short term regarding reproductive performance, and in the long term regarding cardiovascular complications associated with insulin-resistant PCOS.     

Interaction between the G1057D variant of IRS-2 and overweight in the pathogenesis of type 2 diabetes

The insulin receptor substrate-2 (IRS-2) is a major insulin signalling molecule. IRS-2 inactivation in mice induces a form of diabetes characterized by peripheral insulin resistance and reduced beta cell mass. We tested the hypothesis that a common non-conservative amino acid substitution of IRS-2 (G1057D) might interact with overweight in the pathogenesis of type 2 diabetes. The variant was genotyped in 193 Italian patients with type 2 diabetes and 206 control subjects. In the absence of overweight, the risk of type 2 diabetes decreased according to the dosage of the D1057 allele (odds ratio for GD genotype 0.46 [95% CI 0.25-0.86]; DD genotype 0.18 [0.04-0.68]; P for trend = 0.0012). Conversely, the interaction between overweight and genotype increased the risk of type 2 diabetes according to the dosage of the D1057 allele (odds ratio for GD genotype 2.50 [1.11-5.65]; DD genotype 5.74 [1.11-29. 78]; P for trend = 0.0047). Among controls, fasting C-peptide levels, after adjustment for plasma glucose, were inversely related to the dosage of the D1057 allele (P = 0.020). This finding suggested that carriers of the D1057 allele may have higher insulin sensitivity and supported the protective effect of this allele. Conversely, among overweight patients there was a parallel increase in fasting plasma glucose (P for trend = 0.037) and fasting C-peptide according to the dosage of the D1057 allele, suggesting that higher insulin resistance and relative beta cell failure contributed to the increased risk of type 2 diabetes in overweight carriers of this allele. These data provide evidence for a strong association between type 2 diabetes and the G1057D common genetic variant of IRS-2, which appears to be protective against type 2 diabetes in a codominant fashion. Overweight appears to modify the effect of this polymorphism toward a higher risk of type 2 diabetes. Carriers of this polymorphism may represent an elective target for prevention of type 2 diabetes through preventing or treating excessive weight.     

Selective alterations in insulin receptor substrates-1, -2 and -4 in theca but not granulosa cells from polycystic ovaries

The elevated insulin concentrations that occur in many women with polycystic ovary syndrome (PCOS) can contribute significantly to ovarian hyperandrogenism. The objective of the present study was to compare the content of proximal insulin signalling molecules in theca and granulosa cells between polycystic ovaries and regular cycling controls. Individual follicles (3-7 mm) were obtained from 11 women with PCOS and 10 regularly cycling control women. The theca and granulosa cells were microdissected from each follicle. Total protein was extracted and signalling proteins were measured by western blot analysis. There was no difference in insulin receptor content between PCOS and controls in either theca or granulosa cells. Insulin receptor substrate (IRS)-1 and -2 were increased (P<0.05), but IRS-4 was decreased (P<0.03) in PCOS theca cells. There were no changes in IRS-1, -2 or -4 in granulosa cells. IRS-3 was undetectable in all samples. There were no changes in phosphatidyl inositol-3 kinase catalytic subunits p110alpha or p110beta in either theca or granulosa cells. These data demonstrate cell-specific alterations in IRS protein concentrations in theca cells from polycystic ovaries that are consistent with an exaggerated amplification of the insulin signal and which may play an important role in ovarian hyperandrogenism and thecal hyperplasia.     

Acute insulin response to intravenous glucagon in polycystic ovary syndrome

In order to evaluate the acute insulin response after i.v. injection of glucagon in polycystic ovary syndrome (PCOS), 35 women affected by PCOS and 11 normo-ovulatory controls underwent a 75 g oral glucose tolerance test (OGTT) and, 2 days later, a glucagon test (1 mg i.v.). Patients were analysed according to their degree of obesity; the insulin release after glucagon injection for lean PCOS subjects and control women was not statistically significantly different. Conversely obese PCOS patients had higher insulin secretion after both i.v. glucagon and OGTT when compared to the other groups. Moreover the insulin secretory patterns were heterogeneously represented in lean and obese PCOS women. When the patients were analysed according to their insulinaemic response to OGTT, normoinsulinaemic PCOS women and control subjects had a similar insulin response to i.v. glucagon whereas the hyperinsulinaemic PCOS group had a higher insulin response (P < 0.0001). Moreover, a highly significant relationship was found between the insulin response to OGTT and to glucagon administration in the PCOS population (P < 0.0001; r = 0.73), which was maintained also after controlling for obesity. Our results are consistent with the hypothesis that PCOS patients could have an insulin hyper-response to glucagon administration, that is partially independent from obesity and related to their insulinaemic status. Moreover, the glucagon test could represent an effective alternative to OGTT in screening insulin disorders of PCOS patients (at least in the absence of other risk factors), due to its reliability, simplicity, and speed of performance.      

Toll-like receptor (TLR) 2 and 4 mutations in periodontal disease

Toll-like receptors (TLR) are signal molecules essential for the cellular response to bacterial cell wall components. Different functional effective polymorphisms for the TLR 4 gene (Asp299Gly; Thr399Ile) and for the TLR 2 gene (Arg677Trp, Arg753Gln) have recently been described that are associated with impaired lipopolysaccharide signal transduction. A total of 122 patients with chronic periodontal disease and 122 healthy unrelated controls were genotyped for the Asp299Gly and Thr399Ile polymorphism of the TLR 4 gene and the Arg677Trp and Arg753Gln mutation of the TLR 2 gene. The mutations were identified with polymerase chain reaction followed by restriction fragment length polymorphism (RFLP) analysis. The prevalence of the Asp299Gly and the Thr399Ile mutant allele was 4.1% (10/244) and 4.5% (11/244) among periodontitis patients. For the healthy controls the prevalence was 3.3% (8/244) for the Asp299Gly (P = 0.810) and 3.7% (9/244) for the Thr399Ile mutant allele (P = 0.819). The Arg753Gln mutant allele was found in 2.9% (7/244) of the periodontitis subjects as compared to 4.1% (10/244) in the control group (P = 0.622). The Arg677Trp mutant allele was not found in any of the study subjects. Unlike in ulcerative colitis there was not observed an association between chronic periodontitis and the various mutations of the TLR 2 and 4 gene.     

Indices of low-grade chronic inflammation in polycystic ovary syndrome and the beneficial effect of metformin

BACKGROUND: Women with polycystic ovary syndrome (PCOS) have an increased prevalence of insulin resistance (IR) and related disorders. Elevated serum levels of cellular adhesion molecules (CAMs) reflect low-grade chronic inflammation and have been associated with several insulin-resistant states. The objective of this study is to investigate whether soluble inflammatory markers [soluble intercellular adhesion molecule-1 (sICAM-1), soluble endothelial leukocyte adhesion molecule-1 (sE-selectin), soluble vascular cell adhesion molecule-1 (sVCAM-1) and C-reactive protein (CRP)] are altered in PCOS and to further elucidate the effect of metformin treatment on their levels. METHODS: Two young populations were studied [62 women with PCOS and 45 normal women of similar age, BMI and waist-to-hip ratio (WHR)]. Plasma levels of sICAM-1, sVCAM-1, sE-selectin and high-sensitivity CRP (hsCRP) were measured in both groups. Additionally, the effect of metformin on these molecules was investigated in 22 women with PCOS who accepted to metformin protocol (1700 mg daily for a 6-month period). RESULTS: In the total population studied, plasma levels of hsCRP (mg/l), sICAM-1 (ng/ml) and sE-selectin (ng/ml) were higher in the PCOS group compared with those in controls (hsCRP 1.31 +/- 0.22 versus 0.92 +/- 0.27, P = 0.014, sICAM-1 301.21 +/- 24.80 versus 209.86 +/- 17.05, P = 0.025, sE-selectin 57.37 +/- 4.08 versus 45.67 +/- 4.62, P = 0.045, respectively). sVCAM-1 (ng/ml) did not differ statistically among the two groups (P = 0.896). A significant reduction in hsCRP and sVCAM-1 was achieved after 6 months of metformin administration: PCOS pretreatment hsCRP 1.92 +/- 0.60 versus PCOS post-treatment hsCRP 0.52 +/- 0.26, P = 0.005; PCOS pretreatment sVCAM-1 668.09 +/- 98.38 versus PCOS post-treatment sVCAM-1 365.82 +/- 99.77, P = 0.039. CONCLUSION: These findings imply the presence of chronic inflammation in women with PCOS. Metformin decreases the levels of plasma inflammatory indices. Further investigation is required to determine whether these findings may prove to be of clinical significance for PCOS patients.     

Insulin sensitivity, insulin secretion, and metabolic and hormonal parameters in healthy women and women with polycystic ovarian syndrome

To study the contributions of body mass, body fat distribution and family history of type 2 diabetes mellitus to hyperinsulinaemia, insulin secretion and resistance in polycystic ovarian syndrome (PCOS), 17 lean (LC) and 17 obese (OC) healthy control subjects, and 15 lean (LPCOS) and 28 obese (OPCOS) women with PCOS were investigated. Waist:hip ratio (WHR), serum concentrations of sex steroids, glucose and insulin during a 75 g oral glucose tolerance test (OGTT), and insulin and C-peptide early phase secretion, and insulin sensitivity index using a euglycaemic hyperinsulinaemic clamp were assessed. The PCOS subjects had a higher mean WHR than the controls. A trend towards hyperinsulinaemia and impairment of insulin sensitivity (including the rates of both glucose oxidation and non-oxidation) was observed in LPCOS subjects, but only in OPCOS subjects were these changes significant. Early phase insulin secretion but not the early phase C-peptide secretion was increased in PCOS subjects compared to controls, suggesting that peripheral hyperinsulinaemia in PCOS women was mainly due to the observed lowered hepatic insulin extraction and insulin resistance in skeletal muscle. Moreover, the presence of a family history of type 2 diabetes did not affect early phase insulin or C-peptide secretion in the PCOS group. These results confirm and strengthen earlier contentions, that insulin resistance is a characteristic defect in PCOS and is worsened particularly by abdominal obesity.