Serum and adipocyte resistin in polycystic ovary syndrome with insulin resistance

BACKGROUND: The aim of this study was to investigate the relationship between resistin and insulin resistance in patients with polycystic ovary syndrome (PCOS). METHODS: We compared serum resistin levels in 17 PCOS women and 10 lean, healthy, age-matched non-PCOS women and also compared levels of insulin receptor (IR), phosphatidylinositol-3 kinase (PI3-kinase), glucose transporter 4 (GLUT4) protein and resistin mRNA in adipocytes isolated from the omental adipose tissue of five of the PCOS patients and five age- and weight-matched, non-PCOS controls, to look for local defects in insulin action in PCOS. RESULTS: The PCOS group was hyperinsulinaemic and displayed an impaired insulin response in a 75 g oral glucose tolerance test and an abnormal homeostasis model insulin resistance index. Serum resistin levels were similar in PCOS patients and controls; however, resistin mRNA levels were 2-fold higher in adipocytes from PCOS patients. No correlation was found between serum resistin levels and either the BMI or testosterone levels. Western blot analysis showed that adipocyte levels of insulin receptor, PI3-kinase, and GLUT4 were respectively decreased by 56, 39.4 and 54% in PCOS patients compared with controls. CONCLUSIONS: These results suggest that overexpression of the resistin gene in adipocytes may be a local determinant factor in the pathogenesis of PCOS.     

Adipocyte resistin mRNA levels are down-regulated by laparoscopic ovarian electrocautery in both obese and lean women with polycystic ovary syndrome

BACKGROUND: The aim of this study was to investigate serum and adipocyte mRNA expression of resistin in lean and obese women with polycystic ovary syndrome (PCOS) before and 3 months after laparoscopic ovarian electrocauterization (LOE). METHODS: Adipose tissue obtained from 12 women with PCOS (six obese and six lean, body mass index > 27 kg m(-1) as threshold point) before and after LOE was analysed. Gene expression of resistin was measured by semi-quantitative RT-PCR. Ten lean, age-matched healthy women served as controls. RESULTS: Both lean and obese women with PCOS had significantly higher fasting and 2 h insulin and homeostasis model insulin resistance index (HOMA(IR)) values and lower fasting glucose-to-insulin ratios (G(0)/I(0)) than did the controls. The serum levels of glucose and insulin and HOMA(IR) were significantly decreased, and the G(0)/I(0) ratio was significantly increased 3 months after LOE. No difference was found in serum resistin levels between controls and either obese or lean women with PCOS before LOE, nor between PCOS patients before and after LOE. However, resistin mRNA expression levels in both lean and obese women with PCOS before LOE were significantly higher than that in controls and were decreased significantly after LOE back to control levels. CONCLUSION: Local resistin activity may be actively involved in the pathogenesis of PCOS. LOE reduces insulin resistance and down-regulates resistin mRNA expression in lean and obese women with PCOS.     

Serum and follicular fluid levels of soluble Fas, soluble Fas ligand and apoptosis of luteinized granulosa cells in PCOS patients undergoing IVF

BACKGROUND: There are limited data about the levels of soluble apoptotic factors and their modulation with therapeutic regimens in IVF cycles. The aim of the current study was to determine follicular fluid, and serum levels of soluble Fas (sFas) and soluble Fas ligand (sFasL) in PCOS patients undergoing IVF/ICSI cycles; also to investigate the effects of metformin on these factors and on apoptosis of luteinized granulosa cells. METHODS: We investigated the serum and follicular fluid levels of sFas and sFasL in patients with PCOS (n = 28) and compared them with those of the patients with infertility due to male factor (n = 12) undergoing IVF cycles. Effects of metformin therapy on these parameters and apoptosis of luteinized granulosa cells were also investigated among the patients with PCOS. RESULTS: Serum levels of sFas were significantly lower in the PCOS group compared to those in women with infertility due to male factor. Metformin therapy in PCOS patients preceding IVF cycles increased serum levels of sFas and decreased follicular fluid levels of sFasL compared to those on placebo. Follicular fluid from PCOS patients demonstrated luteinized granulosa cell DNA fragmentation in agarose gel, whereas a similar pattern was not observed among PCOS patients undergoing metformin therapy. CONCLUSION: Decreased serum levels of sFas and luteinized granulosa cell DNA fragmentation is observed in patients with PCOS undergoing IVF cycles. Metformin therapy preceding IVF demonstrates an antiapoptotic effect with increased serum levels of sFas, decreased follicular fluid levels of sFasL and prevention of luteinized granulosa cell DNA fragmentation.     

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.     

Adiponectin and resistin in PCOS: a clinical, biochemical and molecular genetic study

BACKGROUND: We conducted a cross-sectional case-control study to evaluate the possible involvement of adiponectin and resistin in the pathogenesis of polycystic ovary syndrome (PCOS). METHODS: Seventy-six PCOS patients and 40 non-hyperandrogenic women matched for BMI and degree of obesity were included. Serum adiponectin and resistin levels, anthropometrical and hormonal variables, the 45 T-->G and 276 G-->T polymorphisms in the adiponectin gene, and the -420 C-->G variant in the resistin gene, were analysed. RESULTS: Serum adiponectin concentrations were reduced in PCOS patients compared with controls (P = 0.038) irrespective of the degree of obesity, whereas serum resistin levels were increased in overweight and obese women compared with lean subjects (P = 0.016), irrespective of their PCOS or controls status. The adiponectin and resistin polymorphisms were not associated with PCOS and did not influence serum levels of adiponectin, resistin and other clinical and hormonal variables. In a multiple regression model, the waist-to-hip ratio, free testosterone levels and age, but not insulin resistance, were the major determinants of hypoadiponectinaemia. CONCLUSIONS: PCOS patients present with hypoadiponectinaemia, in relation with abdominal adiposity and hyperandrogenism. Our present results suggest that hyperandrogenism and abdominal obesity, by reducing the serum levels of the insulin sensitizer adipokine adiponectin, might contribute to the insulin resistance of PCOS.     

Serum adiponectin levels in women with polycystic ovary syndrome

BACKGROUND: Adiponectin is regarded as a possible link between adiposity and insulin resistance. The study aim was to measure serum adiponectin levels in women with polycystic ovary syndrome (PCOS) and to assess possible correlations between adiponectin and the hormonal or metabolic parameters of the syndrome. METHODS: Eighty-five selected women were classified as: Group I (n = 35) with PCOS + body mass index (BMI) >25 kg/m(2); group II (n = 35) with PCOS + BMI <25 kg/m(2); and group III (controls; n = 15) ovulating without hyperandrogenaemia and BMI <25 kg/m(2). Blood samples were collected between the days 3 and 6 of a spontaneous menstrual cycle, at 09:00, after an overnight fast. Serum levels of FSH, LH, prolactin, 17alpha-OH-progesterone, sex hormone-binding globulin (SHBG), androgens, insulin, adiponectin and glucose were measured. RESULTS: Adiponectin levels were significantly decreased in group I compared with groups II and III. No significant difference in adiponectin levels was found between groups II and III, despite significant differences in insulin levels and glucose:insulin ratio. Multiple regression analysis showed that Delta(4)-androstenedione levels and BMI values were the only significant determinants of serum adiponectin levels. CONCLUSIONS: Serum adiponectin levels are reduced in obese women with PCOS. Although adiponectin does not seem to be actively involved in the pathogenesis of PCOS, there seems to be an interaction between adiponectin and steroid synthesis or action.     

Six-month treatment with low-dose dexamethasone further reduces androgen levels in PCOS women treated with diet and lifestyle advice, and metformin

BACKGROUND: The purpose of this study was to investigate the effect of low-dose dexamethasone on androgen levels in women with polycystic ovary syndrome (PCOS) treated with diet and lifestyle counselling, and metformin. METHODS: A prospective, randomized, double blind, placebo-controlled study was carried out. Thirty-eight women with PCOS were randomized to either dexamethasone 0.25 mg daily or placebo for 26 weeks. All received diet and lifestyle counselling at inclusion and metformin 850 mg three times daily during the whole study. Main outcome measures were: androgen levels, body mass index (BMI), insulin c-peptide, fasting glucose and serum lipids. Two-tailed t-tests and Pearson's statistics were used. RESULTS: Compared with the placebo, dexamethasone reduced testosterone by 27%, androstenedione by 21%, dehydroepiandrosterone sulphate by 46% and free testosterone index by 50% in women with PCOS treated with diet and lifestyle advice, and metformin. BMI, fasting glucose, insulin c-peptide and serum lipid levels were unaffected. CONCLUSIONS: Six-month, low-dose dexamethasone treatment further reduces androgen levels in metformin-treated PCOS women.     

Glucose intolerance, insulin resistance and cardiovascular risk factors in first degree relatives of women with polycystic ovary syndrome

BACKGROUND: The aim of the present study was to evaluate insulin resistance (IR), glucose tolerance status and cardiovascular risk factors in first degree relatives of patients with polycystic ovary syndrome (PCOS). METHODS: A total of 120 family members [Mothers(PCOS) (n = 40), Fathers(PCOS) (n = 38), Sisters(PCOS) (n = 25) and Brothers(PCOS) (n = 17)] of 55 patients with PCOS and 75 unrelated healthy control subjects without a family history of diabetes or PCOS (four age- and weight-matched subgroups, i.e. Control(Mothers), Control(Fathers), Control(Sisters) and Control(Brothers)) were studied. IR was assessed by homeostatic model assessment (HOMA IR), log HOMA, insulin sensivity index (ISI), the quantitative insulin sensitivity check index (QUICKI) and area under the curve for insulin during the oral glucose tolerance test (AUCI, AUCG) in with normal glucose tolerance (NGT) subjects and controls. Serum adiponectin, resistin, homocysteine and lipid levels were measured. RESULTS: The prevalence of any degree of glucose intolerance was 40% in Mothers(PCOS) and 52% in Fathers(PCOS). In total, six (15%) glucose tolerance disorders were identified in the Control(Mothers) and Control(Fathers) in first degree relatives of control subjects. The first degree relatives of PCOS patients had significantly higher serum fasting insulin, HOMA-IR, Log HOMA and AUCI levels in all subgroups than the control subjects. The control subjects had significantly elevated QUCKI, ISI levels and serum adiponectin levels compared to the first degree relatives of PCOS subjects in all subgroups. The serum Hcy and resistin levels increased significantly in both Fathers(PCOS) and Mothers(PCOS) groups but not Brothers(PCOS) and Sister(PCOS). CONCLUSION: The results of the present study support the finding that the first degree relatives of PCOS patients carry an increased risk of cardiovascular disease, as do PCOS patients.     

Clinical,endocrine and metabolic effects of metformin added to ethinyl estradiol-cyproterone acetate in non-obese women with polycystic ovarian syndrome: a randomized controlled study

BACKGROUND: Oral contraceptive pills (OC) are usually the first choice of treatment for polycystic ovarian syndrome (PCOS), when fertility is not desired. However, they do not improve, or may even further induce impairment of insulin sensitivity, which is already impaired in women with PCOS. In this prospective, randomized study, we analysed the additional benefits of adding metformin to the OC treatment in non-obese women with PCOS. METHODS: After a baseline work-up including body mass index (BMI), waist:hip ratio (WHR), Ferriman-Gallwey score, ovarian volume, serum gonadotrophin, androgen and sex hormone-binding globulin (SHBG) levels, and fasting lipid, glucose and insulin levels, 40 non-obese women with PCOS were assigned either to the OC or to the OC + metformin treatment by computer-assisted randomization. At the end of the 4 month follow-up period, subjects were re-evaluated. RESULTS: The two groups were similar at baseline. After treatment, women in the OC + metformin group had significant decreases in BMI and WHR, and a significant increase in insulin sensitivity, in contrast to those in the OC group, who had insignificant changes in these parameters. Adding metformin also caused significant improvements in serum androstenedione and SHBG levels compared with the OC treatment alone. CONCLUSIONS: Adding metformin to the OC treatment may improve the insulin sensitivity, and may further suppress the hyperandrogenaemia in non-obese women with PCOS.     

Antiphospholipid antibodies in serum and follicular fluid--is there a correlation with IVF implantation failure?

BACKGROUND: Antiphospholipid antibodies (aPLs) are associated with infertility, but the mechanism underlying this statistical association is currently obscure. We aimed to investigate the finding that aPLs are concentrated in follicular fluid and to establish if this is associated with a poorer outcome from IVF. METHODS AND RESULTS: In 19.2% of 99 women undergoing IVF, at least one aPL was detected in their serum and/or follicular fluids, but the antibody levels in follicular fluid were not higher than in serum. Women with aPLs had a lower implantation rate (14%) than women without these antibodies (24.1%), but this difference was not significant (P=0.127). There was also a non-significant reduction in the live birth rate for women with aPLs. In a parallel investigation, 10 sheep immunized with beta2 glycoprotein I (beta2GPI) or irrelevant control antigens showed strong immune responses, but there were no significant differences between the levels of antibodies in the follicular fluid or serum from beta2GPI or control immunized sheep. CONCLUSION: aPLs do not appear to be selectively concentrated in follicular fluids and, when present, do not adversely affect the reproductive outcome of women undergoing IVF.     

Predictive value of serum and follicular fluid leptin concentrations during assisted reproductive cycles in normal women and in women with the polycystic ovarian syndrome

Leptin is an adipocyte-derived hormone which plays a central role in the regulation of body weight and energy homeostasis and in signalling to the brain that adequate energy stores are available for reproduction. Although leptin may affect reproduction by regulating the hypothalamic-pituitary-gonadal axis, recent in-vitro observations indicate that leptin may also have direct intra-ovarian actions. Leptin concentrations were measured in women who succeeded in becoming pregnant within three cycles of in-vitro fertilization (IVF) or gamete intra-fallopian transfer (n = 53), in women who failed to become pregnant within three cycles (n = 50), and in women with polycystic ovarian syndrome (PCOS) (n = 22). It was found that lower follicular fluid leptin concentrations were a marker of assisted reproduction treatment success in normal women. Women with PCOS had higher leptin concentrations than women without such a diagnosis, but this was due to their higher body mass index (BMI). After adjustment for age and BMI, women with PCOS who became pregnant tended to have lower mean follicular fluid leptin concentrations than women with PCOS who did not succeed at becoming pregnant. Further studies exploiting the strengths of the IVF model are needed to assess whether the prognostic role for follicular fluid leptin in human reproduction is independent of other factors, and to elucidate the underlying mechanisms.     

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.     

The effects of rosiglitazone and metformin on oxidative stress and homocysteine levels in lean patients with polycystic ovary syndrome

BACKGROUND: Oxidative stress and hyperhomocysteinaemia are risk factors for cardiovascular diseases. The aim of this study was to assess the effects of rosiglitazone and metformin on cardiovascular disease risk factors such as insulin resistance, oxidative stress and homocysteine levels in lean patients with polycystic ovary syndrome (PCOS). METHODS: Fifty lean patients (BMI <25 kg/m2) with PCOS and 35 healthy subjects were included this study. Serum homocysteine, sex steroids, fasting insulin, fasting glucose and lipid levels were measured. Total antioxidant status (TAS; combines concentrations of individual antioxidants) and malonyldialdehyde concentration (MDA) were determined. Insulin resistance was evaluated by using the homeostasis model insulin resistance index (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), Area under the curve insulin (AUCI) and the insulin sensitivity index (ISI). Patients were divided into two groups. One group was treated with metformin (n = 25) and the other received rosiglitazone (n = 25) for 12 weeks. All measurements were repeated at the end of 12 weeks. RESULTS: Compared with healthy women, those with PCOS had significantly elevated serum MDA, homocysteine, HOMA-IR, AUCI and lipoprotein a levels, and significantly decreased serum TAS, QUICKI and ISI. Serum free testosterone levels showed a significant positive correlation with MDA, AUCI and HOMA-IR, and a negative correlation with TAS, ISI and QUICKI in PCOS patients. HOMA-IR and AUCI significantly decreased, while QUICKI and ISI significantly increased after treatment in both groups. Serum TAS level increased and serum MDA level decreased after the rosiglitazone treatment, but these parameters did not change after the metformin treatment. Serum homocysteine and lipid levels did not change in either group, while serum androgen levels and LH/FSH ratio significantly decreased after the treatment period in only the rosiglitazone-treated group. CONCLUSION: Elevated insulin resistance, oxidative stress and plasma homocysteine levels and changes in serum lipid profile (risk factors for cardiovascular disease) were observed in lean PCOS patients. Rosiglitazone seemed to decrease elevated oxidative stress when compared with metformin treatment in lean PCOS patients.     

卵巢局部IGF-I系统与多囊卵巢综合征胰岛素抵抗的相关性研究

目的：研究卵巢局部胰岛素样生长因子-I系统（IGF-I系统）在伴有胰岛素抵抗多囊卵巢综合征中的作用机制。方法选择30例合并胰岛素抵抗的PCOS（polycystic ovary syndrome）患者为试验组,30例患有卵巢良性肿瘤需手术探查的患者为对照组。检测并对比血清、小卵泡液中IGF-I、胰岛素样生长因子结合球蛋白-1（IGFBP-1）与各项性激素,FI,2hI,ISI,QUICK I,卵巢超声指标,研究其与各种指标间的相关性。结果试验组小卵泡液IGF-I高于对照组（P〈0.01）,小卵泡液及血清IGFBP-1低于对照组（P〈0.05,P〈0.01）。试验组小卵泡液IGF-I水平高于血清（P〈0.01）,小卵泡液IGFBP-1水平低于血清（P〈0.05）。试验组小卵泡液IGF-I与T0、E2及卵巢体积（OV）,卵巢总面积（TA）,卵泡数（FN）,空腹胰岛素（FI）,服糖后2h胰岛素（2hI）呈正相关（P〈0.05）;血清IGF-I与胰岛素敏感指数（ISI）,体重指数（BMI）,腰臀比（WHR）呈正相关（P〈0.05）,与定量胰岛素敏感指数（QUICK I）呈负相关（P〈0.05）;试验组小卵泡液及血清IGFBP-1与FI,2hI呈负相关（P〈0.05）。结论 IR可能通过影响卵巢局部IGF-I系统,刺激卵巢分泌雄激素,引发排卵障碍,在PCOS的发病机制中起到重要作用。     

Follicular hyperandrogenism and insulin resistance in polycystic ovary syndrome patients with normal circulating testosterone levels

Polycystic ovary syndrome (PCOS) is a common reproductive disease with high heterogeneity. The role of excess androgen in PCOS etiology remains disputed, since around 20%–50% of PCOS women do not display hyperandrogenemia. The microenvironment of the ovary critically influences follicular development. In the present study, we assessed the role of androgen in PCOS by investigating whether excessive follicular fluid androgen was present in PCOS patients with normal serum androgen levels and influenced by follicular fluid insulin resistance (IR). Follicular fluid samples of 105 women with PCOS and 105 controls were collected. Levels of steroid hormones, glucose and insulin in the follicular fluid were examined and compared with data from serum biochemistry tests. We found that 64.9% (63/97) of PCOS patients with normal serum androgen levels displayed abnormally high follicular fluid androgen level. The follicular fluid androgen level was positively correlated with follicular fluid IR within a certain range and follicular fluid estrogen-to-testosterone (E2/T) ratio was significantly reduced in these patients. These results indicated that there existed a subgroup of PCOS patients who displayed excessive follicular fluid androgen and IR despite their normal circulating testosterone (T) levels. Our study highlights the importance of ovary hyperandrogenism and IR in the etiology of PCOS.     

The relationship between anti-Mullerian hormone, androgen and insulin resistance on the number of antral follicles in women with polycystic ovary syndrome

BACKGROUND: Anti-Müllerian hormone (AMH) is a biomarker that predicts the number of antral follicles and is involved in follicle arrest for women with polycystic ovary syndrome (PCOS). We investigated the association between the characteristic hyperandrogenemia, insulin resistance (IR), AMH, and the morphology and size of ovaries for women with PCOS. METHODS: A total of 99 Taiwanese women with PCOS who were willing to undergo vaginal ultrasonography were enrolled in this cross-sectional study. RESULTS: The number of antral follicles and the ovarian volume showed a significant correlation with AMH, total testosterone and the free androgen index, but not with age, body mass index (BMI) or the homeostasis model assessment of insulin resistance (HOMA-IR). AMH had a significant negative association with both BMI and HOMA-IR. Multiple stepwise regression analysis demonstrated that AMH, BMI and total testosterone were independently related to the number of antral follicles. AMH and total testosterone were the main determinants for ovarian volume in a stepwise regression model. CONCLUSIONS: Our results suggest that not only the AMH level, but also obesity, IR and elevated androgen levels may relate to the development of the large size of antral follicle pool and ovarian volume in women with PCOS. Obesity and IR may enhance the follicular excess through the dysregulation of AMH or through the pathway of hyperandrogenemia. These findings might partly explain why adequate body weight management and improvement in IR can improve the ovulatory function for women with PCOS.     

Association of the T45G polymorphism in exon 2 of the adiponectin gene with polycystic ovary syndrome: role of Delta4-androstenedione

BACKGROUND: Insulin resistance is a prominent feature of polycystic ovary syndrome (PCOS), independent of obesity. It is possible that insulin resistance in PCOS is genetically determined. Adiponectin is a protein that modulates insulin action and is regarded as a possible link between adiposity and insulin resistance. The objective of this study was to examine the role of the adiponectin gene T45G polymorphism, located in exon 2, in PCOS, since this polymorphism has been shown to be associated with obesity and insulin resistance. SUBJECTS AND METHODS: Two hundred and thirty-two women were studied, and were classified as follows: 132 women with PCOS [62 with body mass index (BMI) > 25 kg/m2 and 70 with BMI < 25 kg/m2] and 100 ovulating women without hyperandrogenemia (controls: 19 with BMI > 25 kg/m2 and 81 with BMI < 25 kg/m2). From all subjects a whole-blood sample was taken and was used for isolation of peripheral blood leukocytes. The adiponectin T45G polymorphism, located in exon 2, was genotyped by amplification of genomic DNA. In all subjects, serum gonadotropin, androgen, 17-OH-progesterone, fasting glucose, insulin and adiponectin levels were measured between the third and sixth day of the menstrual cycle. RESULTS: A statistically significant difference was observed in the frequency of GG and TG genotypes between women with PCOS (40/132; 30.3%) and controls (19/100; 19.0%). In a subgroup of PCOS women with high Delta4-androstenedione levels (Delta4A > 3.11 ng/ml), a statistically significant difference between the frequencies of the genotypes was also noticed compared with the control group, in contrast to the subgroup with relatively low Delta4-androstenedione levels (Delta4A < 3.11 ng/ml). No significant associations were found between this adiponectin polymorphism and BMI, testosterone level, adiponectin levels and glucose-to-insulin ratio. CONCLUSIONS: Our study suggests that adiponectin polymorphisms are not causatively involved in the metabolic disturbances of PCOS, but that an interaction between adiponectin and steroid synthesis or action might exist.     

Advanced oxidation protein products in obese women: its relation to insulin resistance and resistin

Obesity is a major risk factor for insulin resistance and type 2 diabetes mellitus (T2DM). Resistin, an adipocyte-secreted hormone, is thought to take a part in the development of insulin resistance and T2DM. The aim of this study was to characterise the changes in circulating levels of resistin and proinflammatory cytokines tumour necrosis factor-alpha (TNF-α) and interleukin (IL)-6 in diabetic and prediabetic obese patients and to explore their relationship to insulin resistance. Attempts were also made to see whether resistin levels are related to the degree of oxidative stress, as determined by the measurement of advanced oxidation protein products (AOPPs). The study groups consisted of obese diabetic (BMI: 30–42 kg/m², n=28) and prediabetic (BMI: 29–41 kg/m², n=23) women. Fourteen healthy women, with BMI in the range 21.5–25.5 kg/m², were taken as controls. Serum levels of TNF-a, IL-6, resistin, glucose, insulin and AOPPs were measured. Insulin resistance was calculated by the homeostasis model assessment (HOMA-IR). Diabetic and prediabetic obese patients had increases in serum resistin and TNF-α levels (P<0.01 and P<0.001, respectively). IL-6 levels in diabetic patients were significantly higher than in prediabetics (P<0.05). AOPP levels were also significantly higher in diabetics than prediabetics and controls (P<0.05 and P<0.001, respectively); and positively correlated with blood glucose. Insulin was significantly associated with circulating resistin and TNF-α. The development of insulin resistance may contribute to the elevation of circulating resistin or vice versa. Determination of AOPPs may be helpful for monitoring the impaired glucose metabolism in obesity.     

Insulin sensitivity in non-obese women with polycystic ovary syndrome during treatment with oral contraceptives containing low-androgenic progestin.

BACKGROUND: Combined oral contraceptives (COC) effectively suppress hyperandrogenism in women with polycystic ovary syndrome (PCOS), though deterioration of insulin sensitivity during treatment is assumed. The study aim was to investigate insulin action and androgen production during treatment with COC containing low-androgenic progestin. METHODS: A total of 13 PCOS women and nine controls was enrolled into the study. Only non-obese women with a body mass index (BMI) 相似文献   

瘦素、抵抗素、2型糖尿病间的相关性研究

目的：研究血浆瘦素与抵抗素、体重指数、腰围、腰臀比、血脂、胰岛素敏感性指数等的关系。方法：对43例新诊断2型糖尿病患者及37例糖耐量正常者，测定空腹血浆瘦素、胰岛素、血糖、血脂及抵抗素浓度。结果：相关分析显示性别、体重指数（BMI）、腰围、腰臀比、胰岛素与瘦素呈显著正相关（r分别为0.623,0.534，0.516，0.302，0.354，均P<0.01），IAI与瘦素呈显著负相关(r=-0.373,P<0.01),甘油三酯、胆固醇空腹血糖与瘦素无明显相关。瘦素与抵抗素无相关性（r=0.101,P>0.05）结论：空腹血浆瘦素水平与肥胖程度、胰岛素抵抗呈显著正相关，与抵抗素无关。瘦素可能与2型糖尿病的发病有关。