Increased skeletal muscle ceramide level in men at risk of developing type 2 diabetes

AIMS/HYPOTHESIS

Intramyocellular lipids, including ceramide, a second messenger in the sphingomyelin signalling pathway, might contribute to the development of insulin resistance. The aim of our study was to assess parameters of the skeletal muscle sphingomyelin signalling pathway in men at risk of developing type 2 diabetes.

METHODS

We studied 12 lean (BMI < 25 kg/m(2)) men without a family history of diabetes (control group), 12 lean male offspring of type 2 diabetic patients, and 21 men with overweight or obesity comprising 12 with NGT (obese-NGT) and nine with IGT (obese-IGT). A euglycaemic-hyperinsulinaemic clamp and a biopsy of vastus lateralis muscle were performed. Ceramide, sphingomyelin, sphinganine and sphingosine levels and sphingomyelinase and ceramidase activities were measured in muscle. Muscle diacylglycerol and triacylglycerol levels were estimated in a subgroup of 27 men (comprising men from all the above groups).

RESULTS

Compared with the control group, the lean offspring of diabetic patients and the men with overweight or obesity showed lower insulin sensitivity (all p < 0.005) and a greater muscle ceramide level (all p < 0.01). The obese-IGT group had lower insulin sensitivity (p = 0.0018) and higher muscle ceramide (p = 0.0022) than the obese-NGT group. There was lower muscle sphingosine level and alkaline ceramidase activity in offspring of diabetic patients (p = 0.038 and p = 0.031, respectively) and higher sphinganine level in the obese-NGT (p = 0.049) and obese-IGT (p = 0.002) groups than in the control group. Muscle sphingomyelin was lower (p = 0.0028) and neutral sphingomyelinase activity was higher (p = 0.00079) in the obese-IGT than in the obese-NGT group. Muscle ceramide was related to insulin sensitivity independently of other muscle lipid fractions.

CONCLUSIONS/INTERPRETATIONS

Ceramide accumulates in muscle of men at risk of developing type 2 diabetes.

Serum visfatin in relation to insulin resistance and markers of hyperandrogenism in lean and obese women with polycystic ovary syndrome

BACKGROUND

Visfatin, a protein secreted by adipose tissue, is suggested to play a role in pathogenesis of insulin resistance. In polycystic ovary syndrome (PCOS), insulin resistance might be involved in the development of endocrine and metabolic abnormalities. The aim of the study was to asses the relation between serum visfatin concentration and insulin sensitivity and markers of hyperandrogenism in lean and obese PCOS patients.

METHODS

The study group consisted of 70 women with PCOS (23 lean and 47 obese) and 45 healthy women (25 lean and 20 obese). Euglycemic hyperinsulinemic clamp and the measurements of serum visfatin, sex hormones were performed.

RESULTS

The PCOS group had lower insulin sensitivity (P=0.00049) and higher serum visfatin (P=0.047) in comparison to the control group. The decrease in insulin sensitivity was present in both the lean (P=0.019) and obese (P=0.0077) PCOS subjects, whereas increase in serum visfatin was observed only in lean PCOS subjects (P=0.012). In the whole group, serum visfatin was negatively correlated with insulin sensitivity (r=-0.27, P=0.004). This relationship was also observed in the subgroup of lean (r=-0.30, P=0.038), but not obese women. Additionally, in lean women, visfatin was associated with serum testosterone (r=0.47, P=0.002) and free androgen index (r=0.48, P=0.002), independently of other potential confounding factors.

CONCLUSIONS

Visfatin is associated with insulin resistance and markers of hyperandrogenism in lean PCOS patients.

GPR55 signalling promotes proliferation of pancreatic cancer cells and tumour growth in mice, and its inhibition increases effects of gemcitabine

The life expectancy for pancreatic cancer patients has seen no substantial changes in the last 40 years as very few and mostly just palliative treatments are available. As the five years survival rate remains around 5%, the identification of novel pharmacological targets and development of new therapeutic strategies are urgently needed. Here we demonstrate that inhibition of the G protein-coupled receptor GPR55, using genetic and pharmacological approaches, reduces pancreatic cancer cell growth in vitro and in vivo and we propose that this may represent a novel strategy to inhibit pancreatic ductal adenocarcinoma (PDAC) progression. Specifically, we show that genetic ablation of Gpr55 in the KRASWT/G12D/TP53WT/R172H/Pdx1-Cre+/+ (KPC) mouse model of PDAC significantly prolonged survival. Importantly, KPC mice treated with a combination of the GPR55 antagonist Cannabidiol (CBD) and gemcitabine (GEM, one of the most used drugs to treat PDAC), survived nearly three times longer compared to mice treated with vehicle or GEM alone. Mechanistically, knockdown or pharmacologic inhibition of GPR55 reduced anchorage-dependent and independent growth, cell cycle progression, activation of mitogen-activated protein kinase (MAPK) signalling and protein levels of ribonucleotide reductases in PDAC cells. Consistent with this, genetic ablation of Gpr55 reduced proliferation of tumour cells, MAPK signalling and ribonucleotide reductase M1 levels in KPC mice. Combination of CBD and GEM inhibited tumour cell proliferation in KPC mice and it opposed mechanisms involved in development of resistance to GEM in vitro and in vivo. Finally, we demonstrate that the tumour suppressor p53 regulates GPR55 protein expression through modulation of the microRNA miR34b-3p. Our results demonstrate the important role played by GPR55 downstream of p53 in PDAC progression. Moreover our data indicate that combination of CBD and GEM, both currently approved for medical use, might be tested in clinical trials as a novel promising treatment to improve PDAC patients' outcome.

Insulin resistance, serum adiponectin, and proinflammatory markers in young subjects with the metabolic syndrome

Insulin resistance is the underlying metabolic abnormality in the metabolic syndrome. The low-grade chronic inflammation may be associated with metabolic risk factors and atherogenesis. The aim of our study was to establish the link between the metabolic syndrome, as defined by the National Cholesterol Education Program (NCEP) criteria, and insulin sensitivity, serum adiponectin, and parameters of chronic inflammation in young subjects. The group of 223 subjects (mean age, 25.86 +/- 5.49 years; body mass index, 28.04 +/- 6.91 kg/m2) was studied. Oral glucose tolerance test, euglycemic hyperinsulinemic clamp, and estimation of serum adiponectin and proinflammatory factors were performed. The NCEP-defined metabolic syndrome was present in 49 subjects (21.97%). The higher the number of NCEP criteria fulfilled was, the bigger were the decrease in insulin sensitivity (P < .0001) and adiponectin (P < .0001) and the increase in fasting and postload insulin (both Ps < .0001), C-reactive protein (P < .0001), interleukin 18 (P < .0001), interleukin 6 (P < .0001), and soluble tumor necrosis factor-alpha receptors sTNFR1 (P < .0001) and sTNFR2 (P < .0001) observed. Multiple regression analysis revealed that adiponectin and inflammatory factors predicted NCEP score independent of insulin sensitivity (all adjusted beta values between .16 and .32, all Ps < .01). Young subjects with metabolic syndrome demonstrate an increased inflammatory response and lower adiponectin concentration.

Circulating brain-derived neurotrophic factor concentration is downregulated by intralipid/heparin infusion or high-fat meal in young healthy male subjects

OBJECTIVE

Insulin resistance and type 2 diabetes are associated with an increased risk of neurodegenerative diseases. Brain-derived neurotrophic factor (BDNF) regulates neuronal differentiation and synaptic plasticity, and its decreased levels are supposed to play a role in the pathogenesis of Alzheimer's disease and other disorders. The aim of the current study was to estimate the effects of hyperinsulinemia and serum free fatty acids (FFA) elevation on circulating BDNF concentration in humans.

RESEARCH DESIGN AND METHODS

We studied 18 healthy male subjects (mean age 25.6 ± 3.0 years; mean BMI 26.6 ± 4.8 kg/m(2)). Serum and plasma BDNF concentration was measured in the baseline state and in the 120 and 360 min of euglycemic hyperinsulinemic clamp with or without intralipid/heparin infusion. Furthermore, plasma BDNF was measured in 20 male subjects (mean age 22.7 ± 2.3 years; mean BMI 24.9 ± 1.5 kg/m(2)) 360 min after a high-fat meal.

RESULTS

Insulin sensitivity was reduced by ~40% after 6 h of intralipid/heparin infusion (P < 0.001). During both clamps, serum and plasma BDNF followed the same pattern. Hyperinsulinemia had no effect on circulating BDNF. Raising FFA had no effect on circulating BDNF in 120 min; however, it resulted in a significant decrease by 43% in serum and by 35% in plasma BDNF after 360 min (P = 0.005 and 0.006, respectively). High-fat meal also resulted in a decrease by 27.8% in plasma BDNF (P = 0.04).

CONCLUSIONS

Our data show that raising FFA decreases circulating BDNF. This might indicate a potential link between FFA-induced insulin resistance and neurodegenerative disorders.

Hyperinsulinemia acutely increases serum macrophage inhibitory cytokine-1 concentration in anorexia nervosa and obesity

CONTEXT

Macrophage inhibitory cytokine-1 (MIC-1) plays a role in the regulation of cellular responses to stress signals and inflammation. MIC-1 has also been implicated in mediation of tumour-induced anorexia and weight loss. Increased serum concentrations of MIC-1 were found in patients with anorexia nervosa (AN), obesity and type 2 diabetes.

OBJECTIVE

To estimate serum MIC-1 concentration in women with AN and obese women, its regulation by hyperinsulinemia and relationship with insulin sensitivity.

PATIENTS

We examined 20 women with AN, 28 healthy normal-weight female controls and 28 obese women.

MEASUREMENTS

Serum MIC-1 concentration was measured in the fasting state and after 2-h euglycemic hyperinsulinemic clamp.

RESULTS

At baseline, serum MIC-1 was higher in AN in comparison with other groups (normal-weight, P = 0·018; obese, P = 0·01). Hyperinsulinemia resulted in a significant increase in serum MIC-1 concentration in the entire study population (P < 0·001) and in AN (P < 0·001), normal-weight (P = 0·002) and obese (P < 0·001) groups analysed separately. Postclamp serum MIC-1 was still higher in AN women in comparison with other groups (normal-weight, P = 0·012; obese, P = 0·023). When normal-weight and obese women were analysed together, with the exclusion of AN group, an inverse correlation between insulin sensitivity and the change in serum MIC-1 during the clamp was observed (r = -0·27, P = 0·042).

CONCLUSIONS

Hyperinsulinemia resulted in a significant increase in serum MIC-1 in different states of adiposity. Increased serum MIC-1 in AN women might be an additional factor responsible for weight loss in this group.

Serum retinol binding protein 4 is related to insulin resistance and nonoxidative glucose metabolism in lean and obese women with normal glucose tolerance

CONTEXT

Retinol-binding protein (RBP) 4 is secreted by adipose tissue and is postulated to be a determinant of insulin sensitivity. The mechanisms of RBP4 insulin desensitizing action remain unclear.

OBJECTIVE

The aim of the present study was to estimate the relationships between serum RBP4 concentration with insulin sensitivity and oxidative and nonoxidative glucose metabolism in lean and obese women.

DESIGN AND PARTICIPANTS

The study group consisted of 67 women with normal glucose tolerance, 27 lean and 40 overweight or obese. Insulin sensitivity was estimated with the euglycemic hyperinsulinemic clamp. Glucose and lipid oxidation was measured with indirect calorimetry in the basal state and during the last 30 min of the clamp. Nonoxidative glucose metabolism was calculated in insulin-stimulated conditions by subtracting glucose oxidation from total glucose metabolism.

RESULTS

There was no difference in serum RBP4 concentration between lean and obese women. Serum RBP4 was inversely related to insulin sensitivity and nonoxidative glucose metabolism in the entire group (r = -0.36, P =0.003 in both cases) and within the subgroups of lean (r = -0.41, P =0.034 and r = -0.41, P =0.031) and obese women (r = -0.41, P =0.009 and r = -0.40, P =0.01, respectively). These relationships were independent of potential confounding factors. RBP4 levels were not associated with oxidative metabolism of glucose or lipid.

CONCLUSIONS

Our data indicate that serum RBP4 is related to decreased insulin sensitivity, mostly through its association with nonoxidative glucose metabolism.

The FTO gene modifies weight, fat mass and insulin sensitivity in women with polycystic ovary syndrome, where its role may be larger than in other phenotypes

AIM

Genome-wide association studies have shown that variation in the FTO gene predisposes to obesity and related traits that are common features of polycystic ovary syndrome (PCOS). The aim of the present study was to assess the effect of FTO variation on obesity, insulin sensitivity, and metabolic and hormonal profiles in PCOS.

METHODS

We examined 136 PCOS women (mean body mass index [BMI]: 28.28+/-6.95kg/m(2), mean age: 25.36+/-5.48 years). Anthropometric measurement, euglycaemic-hyperinsulinaemic clamp and oral glucose tolerance tests and sex hormone assessments were performed. The study group was genotyped for the FTO rs9939609 polymorphism.

RESULTS

BMI (29.0+/-6.9kg/m(2) vs 26.1+/-6.8kg/m(2); P=0.023), body weight (80.1+/-20.7kg vs 72.6+/-20.2kg; P=0.048), fat mass (29.7+/-1 6.6kg vs 24.6+/-17.7kg; P=0.045) and waist circumference (89.8+/-16.7cm vs 83.2+/-17.1cm; P=0.028) were higher in carriers of at least one copy of the A allele. Differences in these parameters were more significant when comparing AA and TT homozygotes. Women with the AA genotype also had decreased insulin sensitivity (P=0.025) and follicle-stimulating hormone (P=0.036). In logistic-regression analyses, the association of the FTO gene polymorphism with insulin sensitivity was no longer significant when BMI was included in the model.

CONCLUSION

Variation in the FTO gene modifies weight, adiposity and other measures of obesity and insulin sensitivity in PCOS. The examined FTO gene variant appears to have a greater impact on obesity and related traits in PCOS than in other phenotypes. The effect on insulin sensitivity appears to be secondary to its influence on obesity and body fat.

Body Composition, Serum Concentrations of Androgens and Insulin Resistance in Different Polycystic Ovary Syndrome Phenotypes

Insulin resistance and hyperandrogenemia observed in polycystic ovary syndrome (PCOS) are associated with metabolic disturbances and could be connected with body composition pattern. To date, several studies defining the parameters of body composition using dual energy X-ray absorptiometry (DXA) method in the group of PCOS patients have been published, however, without the analysis in different phenotypes. The aim of the present study was to investigate the relationships between serum androgens concentration, insulin resistance and distribution of fat mass using DXA method in various PCOS phenotypes according to the Rotterdam criteria. We examined 146 women: 34 (38%) had PCOS phenotype A, 20 (23%) phenotype B, 20 (23%) phenotype C and 15 (16%) phenotype D (with mean age of each phenotype 25 years), and 57 control subjects (mean age of 25.5 years). Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Serum concentrations of testosterone, androstenedione and dehydroepiandrosterone sulfate (DHEA-S) were assessed and free androgen index (FAI) was calculated. In phenotypes A, B and C, we observed higher FAI in comparison to the control group (all p < 0.01). Serum concentrations of androstenedione and DHEA-S were higher in phenotypes A and C in comparison to the control group (all p < 0.01). However, only in phenotype A we found higher visceral adipose tissue (VAT) mass and android/gynoid ratio (A/G ratio) in comparison to the control group (all p < 0.01). In phenotype A, we observed connection of VAT with FAI (r = 0.58, p < 0.01). Accordingly, A/G ratio was related with FAI in all phenotypes (all p < 0.05). Additionally, in phenotype C, A/G ratio was related to serum concentrations of DHEA-S and androstenedione (r = 0.46, p = 0.03; r = 0.53, p = 0.01, respectively). We also found connections of HOMA-IR with VAT and A/G ratio in all phenotypes (all p < 0.05). Women with phenotype A had higher amount of VAT and A/G ratio in comparison to the control group. Serum concentration of androgens and insulin resistance are connected with VAT and A/G ratio in normoandrogenic and hyperandrogenic PCOS phenotypes.

Increased serum interleukin-18 concentration is associated with hypoadiponectinemia in obesity, independently of insulin resistance

OBJECTIVE

Interleukin-18 (IL-18) is a cytokine with proinflammatory and proatherogenic properties, which might be associated with the development of insulin resistance. In contrast, adiponectin, a protein secreted by adipose tissue, might exert insulin-sensitizing and antiatherogenic effects. The aim of the present study was to analyze the association between serum IL-18 and adiponectin in lean and obese subjects, in relation to insulin resistance.

DESIGN

Cross-sectional study.

SUBJECTS

One hundred and thirty individuals, 62 lean (body mass index (BMI)<25 kg/m(2), 30 men and 32 women) and 68 with overweight or obesity (BMI>25 kg/m(2), 24 men and 44 women), with normal glucose tolerance and without concomitant diseases.

MEASUREMENTS

Oral glucose tolerance test, euglycemic hyperinsulinemic clamp, serum concentrations of IL-18, IL-6, soluble tumor necrosis factor-alpha receptors and adiponectin.

RESULTS

Obese subjects had lower insulin sensitivity (M value, P=0.00029) and serum adiponectin (P=0.01) and higher levels of serum IL-18 (P=0.00055). Circulating IL-18 was negatively related to adiponectin (r=-0.31, P=0.00027) and insulin sensitivity (r=-0.33, P=0.00012). Subgroup analysis revealed that these associations were present in the obese (adiponectin, r=-0.38, P=0.0014; M, r=-0.29, P=0.016), but not in lean individuals (r=-0.17, P=0.18 and r=-0.20, P=0.12, respectively). Association of IL-18 with adiponectin remained significant after adjustment for other estimated parameters, including insulin sensitivity. Also, relationship between IL-18 and insulin sensitivity was independent of other estimated parameters.

CONCLUSION

Serum IL-18 is inversely related to serum adiponectin, independently of insulin resistance. The relationships of IL-18 with adiponectin and insulin sensitivity are influenced by the presence of overweight/obesity.

Increased suppression of serum ghrelin concentration by hyperinsulinemia in women with anorexia nervosa

CONTEXT

Ghrelin is a peptide secreted mainly by the stomach, which has the ability to stimulate appetite and food intake. Serum ghrelin concentration decreases rapidly after a meal, probably because of the concurrent increase in serum insulin. Anorexia nervosa (AN) is an eating disorder, which is characterized by high serum ghrelin concentration; however, the regulation of circulating ghrelin by insulin in this disorder remains unclear.

OBJECTIVE

To estimate serum ghrelin concentration in the fasting state and after hyperinsulinemia in women with AN.

DESIGN AND PARTICIPANTS

We examined 19 women with AN, 26 lean healthy women, and 25 women who were overweight or obese. Serum ghrelin concentration was measured in the fasting state and after euglycemic hyperinsulinemic clamp.

RESULTS

Insulin sensitivity was similar in AN and normal-weight women, and was markedly decreased in the obese subjects. In the fasting state, serum ghrelin was higher in AN group than in other groups (normal-weight, P=0.017; obese, P=0.0001) and in normal-weight women than in obese women (P=0.044). Hyperinsulinemia resulted in a marked decrease in serum ghrelin in AN (P<0.0001) and normal-weight women (P=0.002). The fall in serum ghrelin was higher in AN group than in other groups (normal-weight, P=0.0008; obese, P=0.0001), and was related to insulin sensitivity (r=0.24, P<0.05). In multiple regression analysis, only fasting serum ghrelin and the presence of AN were independent predictors of this fall.

CONCLUSIONS

Women with AN have an increased suppression of serum ghrelin by hyperinsulinemia. This phenomenon might lead to an increased and more rapid feeling of satiety in AN.

Insulin sensitivity, metabolic flexibility, and serum adiponectin concentration in women with anorexia nervosa

Anorexia nervosa (AN) is an eating disorder resulting in sustained low weight and marked decrease in fat mass. The lack of adipose tissue observed in lipodystrophies is accompanied by insulin resistance. It remains unclear if the same phenomenon would be present in AN. The objective of the study was to estimate insulin sensitivity, oxidative and nonoxidative glucose metabolism in insulin-stimulated conditions, metabolic flexibility, and serum adiponectin concentration in women with AN. We examined 21 women with AN and 24 healthy normal-weight female controls. Euglycemic hyperinsulinemic clamp, indirect calorimetry, and the measurement of serum adiponectin concentration were performed in all the subjects. We did not observe differences in insulin sensitivity, oxidative and nonoxidative glucose metabolism in insulin-stimulated conditions, and metabolic flexibility between AN and control subjects. Serum adiponectin was higher in AN women in comparison with control group (P = .002). Women with AN have normal insulin sensitivity because of the preserved response of glucose oxidation, nonoxidative glucose metabolism in response to insulin, and normal metabolic flexibility. High adiponectin concentration and normal insulin sensitivity in anorectic women suggest that in AN the adipocytes are still capable of functioning at the level that is sufficient to prevent the metabolic consequences.

Serum irisin and its regulation by hyperinsulinemia in women with polycystic ovary syndrome

Irisin is an adipokine/myokine which could be connected with insulin sensitivity. Polycystic ovary syndrome (PCOS) is characterized by oligo- or anovulation, polycystic ovary, hyperandrogenism and insulin resistance. The aim of the present study was to determine the relationship between serum irisin concentration and insulin sensitivity (M_ffm) as well as the effect of insulin infusion on circulating irisin levels in PCOS women as compared with healthy controls. Seventy seven women were enrolled in the study - 57 with PCOS and 20 healthy controls matched for BMI and age. Hyperinsulinemic euglycemic clamps were performed in all of the study participants. The serum concentrations of irisin at baseline and after the clamp, as well as changes of serum irisin concentration in response to insulin supplied during the clamp (Δ irisin), were estimated. The mean serum concentrations of irisin at baseline and after hyperinsulinemia were higher in PCOS women in comparison to the control group (p=0.01; p=0.006, respectively). Insulin infusion resulted in a decrease of serum irisin concentration only in the PCOS group (p=0.007). In the control group, Δ irisin positively correlated with M_ffm (r=0.56, p=0.009). In the entire group, multiple regression analysis showed that Δ irisin (β=0.70, p=0.0002), FFAs 60' during the clamp study (β=-0.22, p=0.01), SHBG (β=0.54, p<0.0001) and the interaction between Δ irisin and PCOS (β=-0.67, p=0.0004) were significantly associated with M_ffm. The higher serum irisin concentrations at baseline and in response to insulin infusion might be secondary to insulin resistant conditions in PCOS women.

Decreased serum brain-derived neurotrophic factor concentration in young nonobese subjects with low insulin sensitivity

OBJECTIVE

Insulin resistance and type 2 diabetes are associated with an increased risk of neurodegenerative diseases. Decreased brain-derived neurotrophic factor (BDNF) levels might play a role in the pathogenesis of neuropsychiatric disorders. The aim of our study was to estimate serum BDNF concentration in nonobese women divided into subgroups according to their insulin sensitivity.

DESIGN AND METHODS

We studied 46 young, healthy, nonobese women. Insulin sensitivity was estimated with the euglycemic-hyperinsulinemic clamp technique. Then, participants were divided into subgroups of high (mean, 12.79±2.01mg/kg fat-free mass/min) and low insulin sensitivity (mean, 7.33±1.66mg/kg fat-free mass/min).

RESULTS

We observed decreased serum BDNF concentration in women with low insulin sensitivity in comparison to high insulin sensitivity group (3306.11±603.10 vs 4141.91±755.37pg/mL, p=0.001). Serum BDNF was positively related to insulin sensitivity (r=0.43, p=0.003). This correlation remained significant after adjustment for other estimated parameters.

CONCLUSIONS

Serum BDNF is decreased in young nonobese women with low insulin sensitivity. Early detection and prevention of insulin resistance might be useful in the prevention of neurodegenerative disorders.

Metformin Intervention—A Panacea for Cancer Treatment?

The molecular mechanism of action and the individual influence of various metabolic pathways related to metformin intervention are under current investigation. The available data suggest that metformin provides many advantages, exhibiting anti-inflammatory, anti-cancer, hepatoprotective, cardioprotective, otoprotective, radioprotective, and radio-sensitizing properties depending on cellular context. This literature review was undertaken to provide novel evidence concerning metformin intervention, with a particular emphasis on cancer treatment and prevention. Undoubtedly, the pleiotropic actions associated with metformin include inhibiting inflammatory processes, increasing antioxidant capacity, and improving glycemic and lipid metabolism. Consequently, these characteristics make metformin an attractive medicament to translate to human trials, the promising results of which were also summarized in this review.

Serum soluble glycoprotein 130 concentration is inversely related to insulin sensitivity in women with polycystic ovary syndrome

OBJECTIVE

Insulin resistance might play a role in the pathogenesis of polycystic ovarian syndrome (PCOS). The family of glycoprotein 130 (gp130) cytokines could influence insulin action. One of these cytokines is interleukin (IL)-6, which exerts a short-term insulin-sensitizing effect, whereas in a long-term period, it might induce insulin resistance. Some other gp130 activators are supposed to have beneficial metabolic effects. Gp130 is present in the circulation in the soluble form (sgp130), which inhibits intracellular gp130 signaling. The aim of the present study was to estimate the relation between sgp130 and insulin sensitivity in women with PCOS.

RESEARCH DESIGN AND METHODS

We studied 78 women with PCOS (35 lean and 43 obese) and 34 healthy women (18 lean and 16 obese). The euglycemic-hyperinsulinemic clamp and the measurements of serum sgp130, IL-6, soluble IL-6 receptor (sIL-6R), and sex hormones were performed.

RESULTS

Both obesity and PCOS were characterized by an increased sgp130 (P < 0.0001 and P = 0.0002, respectively). sIL-6R concentration was lower (P = 0.0036) in women with PCOS independently of obesity. Serum sgp130 was negatively correlated with insulin sensitivity when control and PCOS women were analyzed together (r = -0.36, P < 0.0001) and in the PCOS subjects separately (r = -0.34, P = 0.002). In multiple regression analysis, this correlation was significant after adjustment for BMI, waist, percent of body fat, postload glucose and insulin, triglycerides, and high-sensitive C-reactive protein.

CONCLUSIONS

Serum sgp130 is inversely and independently associated with insulin sensitivity in women with PCOS. An increased serum sgp130 in obesity and PCOS suggests an inhibition of intracellular gp130 signaling in insulin-resistant conditions.

Metabolic syndrome and the risk of cardiovascular complications in young patients with different phenotypes of polycystic ovary syndrome

PURPOSE

Insulin resistance is an important factor in the pathogenesis of polycystic ovary syndrome (PCOS), which is associated with higher risk of metabolic syndrome (MetS) and cardiovascular complications. Early atherosclerotic lesions may be diagnosed by ultrasonographic parameters: brachial artery flow-mediated dilation after reactive hyperaemia (FMD) and intima-media thickness of common carotid artery (IMT). The aim of the study was to assess the relation of IMT and FMD with clinical and laboratory parameters reflecting metabolic status in young women with different PCOS phenotypes.

METHODS

The study included 154 PCOS patients diagnosed with the Rotterdam criteria, divided into four phenotypes, and 113 healthy women. Laboratory analyses, transvaginal ultrasound, and IMT and FMD measurements were conducted. MetS was diagnosed with International Diabetes Federation/American Heart Association (IDF/AHA) consensus criteria.

RESULTS

MetS was more prevalent in PCOS patients than healthy women (14.29 vs. 5.31%; p = 0.019), with highest prevalence in phenotypes I and II (p = 0.039). IMT and FMD did not differ between PCOS patients and the controls, nor between the PCOS phenotypes. PCOS patients with MetS presented lower FMD than other PCOS patients (p = 0.018). In women with PCOS, FMD correlated with glucose and insulin concentrations in the fasting state (R = -0.33, p = 0.002; R = -0.23, p = 0.026) and at 2 h of OGTT (R = -0.29, p = 0.006; R = -0.26, p = 0.014). In patients with phenotype I, correlations were found between IMT and BMI (R = 0.45, p = 0.006) and between FMD and fasting glucose concentrations (R = -0.46, p = 0.011).

CONCLUSIONS

Metabolic disturbances and the diagnosis of MetS in patients with PCOS, especially in hyperandrogenic phenotypes, might be associated with alterations in IMT and FMD.

Impact of the FTO gene variation on fat oxidation and its potential influence on body weight in women with polycystic ovary syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is a heterogeneous disorder where insulin resistance might be involved in the development of endocrine and metabolic abnormalities. It has recently been shown that the FTO gene modifies weight, fat mass and insulin sensitivity in women with PCOS, where its role might be larger than in other phenotypes.

OBJECTIVE

The aim of this study was to estimate the effect of a variation of the FTO gene on carbohydrate and lipid oxidation in PCOS women.

PATIENTS

The study group consisted of 65 women with PCOS and 28 healthy, normally menstruating women.

MEASUREMENTS

Clinical examination, anthropometric measurements, euglycaemic hyperinsulinaemic clamp and measurements of serum sex hormones were performed. Carbohydrate and lipid oxidation were evaluated with indirect calorimetry in the baseline state and during last 30 min of the clamp. The FTO rs9939609 polymorphism was genotyped using the restriction fragment length polymorphism method.

RESULTS

There were no differences in carbohydrate and lipid oxidation between PCOS and control women. In the PCOS group, TT homozygotes had higher baseline fat oxidation in comparison with carriers of the A allele (P = 0·018), which was not found in the control group. We did not observe the effect of the FTO gene variation on insulin-stimulated lipid oxidation and neither on the baseline nor on the insulin-stimulated carbohydrate oxidation.

CONCLUSION

Our data show that this FTO gene variation might influence the baseline lipid oxidation in PCOS patients. This might potentially be one of the mechanisms explaining the impact of the FTO gene on body weight in PCOS.

Oxidative stress and radioiodine treatment of differentiated thyroid cancer

It is hypothesized that the oxidative stress level in thyroid cancer patients is additionally upregulated by radioactive iodine (RAI) treatment, that may exert an important impact on future health concerns. In our study, we evaluated the oxidative stress level changes using the measurement of malondialdehyde (MDA) concentration in patients with differentiated thyroid cancer (DTC) undergoing RAI treatment. Considering the results obtained in the study group, the serum levels of MDA in DTC patients were significantly higher compared to the healthy subjects (p < 0.05). The MDA concentration was significantly higher on the third day after RAI (p < 0.001) and significantly lower one year after RAI (p < 0.05) in DTC patients compared to the baseline concentration. Moreover, the redox stabilization after RAI treatment in patients with DTC during a year-long observation was demonstrated. Accordingly, an increased oxidative stress impact on the related biochemical parameters reflecting the health conditions of the DTC patients was determined. Our study showed that increased oxidative stress reflected by MDA measurements in DTC patients is further enhanced by RAI, but this effect is no longer observed one year after the therapy.

Ovarian Reserve and Serum Concentration of Thyroid Peroxidase Antibodies in Euthyroid Women With Different Polycystic Ovary Syndrome Phenotypes

Objective: It has been shown that women with polycystic ovary syndrome (PCOS), as well as Hashimoto's thyroiditis (HT), are characterized by increased incidence of infertility. Serum anti-Müllerian hormone (AMH), which reflects ovarian reserve, is elevated in PCOS women and is decreased in women with HT. The Rotterdam criteria recognize four clinical PCOS phenotypes, i.e., phenotypes A, B, C, and D. The aim of the present study was to investigate the relation between serum concentrations of thyroid peroxidase antibodies (TPOAbs) and ovarian reserve in different PCOS phenotypes. Patients and methods: We examined 141 women with PCOS [phenotype A was diagnosed in 67 (47.5%) women, phenotype B in 30 (21.3%), phenotype C in 28 (19.9%), and phenotype D in 16 (11.3%)] and 88 control subjects of similar age; all women were euthyroid. Serum concentrations of AMH, thyroid-stimulating hormone (TSH), thyroid hormones, and TPOAbs were assessed. Results: We observed positive serum TPOAbs in 21.9% women with PCOS and in 23.9% controls (p = 0.07). We did not find differences in the frequency of detection of positive serum TPOAbs between phenotypes A, B, and C and the control group (p > 0.05). We did not observe a difference in AMH levels between TPOAbs-positive and TPOAbs-negative women, both in the control group and the PCOS women (all p > 0.05). However, serum AMH concentration was markedly higher in the whole PCOS group (p < 0.01) and in phenotype A (p < 0.01) vs. controls when the serum concentration of TPOAbs was negative. In the groups with positive serum levels of TPOAbs, serum concentration of AMH did not differ between PCOS phenotypes and controls (p = 0.23). Additionally, we observed that serum AMH concentration was related to the level of TPOAbs in the PCOS group (r = -0.4, p = 0.02). Conclusions: The frequency of serum detection of positive TPOAbs did not differ between PCOS phenotypes with clinical/biochemical hyperandrogenism and the control group. The observation of the difference in serum AMH between the PCOS and control groups only in TPOAbs negative women together with the inverse relation of TPOAbs with serum AMH only in the PCOS group might suggest that ovarian reserve is influenced by TPOAbs in PCOS.

The Association of Serum Levels of Leptin and Ghrelin with the Dietary Fat Content in Non-Obese Women with Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) are at an increased risk of developing insulin resistance and abdominal obesity in the state of an improper diet balance. Leptin is a peptide considered to be a satiety hormone that plays an important role in the long-term energy balance, whereas ghrelin is a hormone that controls short-term appetite regulation and is considered a hunger hormone. The aim of the present study was to assess the relationship between serum leptin and ghrelin concentrations and the dietary macronutrient content in PCOS women. We examined 73 subjects: 39 women diagnosed with PCOS by the Rotterdam criteria and 34 healthy controls, matched by the body mass index. The subjects completed a consecutive three-day dietary diary to identify the macronutrient and micronutrient intake. Serum concentrations of leptin and total ghrelin were measured and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. The studied groups did not differ significantly in terms of the intake of macronutrients (proteins, fats, and carbohydrates) and serum concentrations of ghrelin and leptin (all p > 0.05). In the PCOS group, the serum leptin concentration positively correlated with the intake of total fat (r = 0.36, p = 0.02), total cholesterol (r = −0.36, p = 0.02), saturated fatty acids (r = 0.43, p < 0.01), and monounsaturated fatty acids (MUFA) (r = 0.37, p = 0.02), whereas the serum ghrelin concentration correlated in an inverse manner with the intake of total fat (r = −0.37, p = 0.02), MUFA (r = −0.37, p = 0.02), polyunsaturated fatty acids (r = −0.34, p = 0.03), and long chain polyunsaturated fatty acids (r = −0.38, p = 0.02). In this group, we also found a negative association of HOMA-IR with serum ghrelin levels (r = −0.4, p = 0.03) and a positive relationship with the serum leptin concentration (r = 0.5, p < 0.01) and relationships between HOMA-IR and total dietary fat (r = 0.38, p = 0.03) and MUFA (r = 0.35, p = 0.04) intake. In PCOS women, dietary components such as the total fat and type of dietary fat and HOMA-IR are positively connected to serum leptin concentrations and negatively connected to serum ghrelin concentrations, which may influence the energy balance.

Normal metabolic flexibility despite insulin resistance women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common heterogeneous disorder, where insulin resistance might be involved in the development of endocrine and metabolic abnormalities. Insulin resistance (IR) is connected with disturbances in switching between lipid and carbohydrate oxidation in response to insulin, called "metabolic inflexibility". The aim of the present study was to estimate the whole-body insulin sensitivity, lipid and carbohydrate oxidation, metabolic flexibility in lean and obese PCOS women. The study group consisted of 92 women with PCOS, 40 lean (BMI<25 kg/m²) and 52 overweight or obesity (BMI>25 kg/m²), and 30 healthy normally menstruating women (14 lean and 16 overweight/obese) with normal glucose tolerance. Hyperinsulinemic euglycemic clamp and indirect calorimetry were performed. An increase in respiratory exchange ratio in response to insulin was used as a measure of metabolic flexibility. Both the presence of PCOS (P<0.001) and obesity (P=0.005) were independently characterized by lower insulin sensitivity. PCOS (P=0.002) and obesity (P=0.001) independently predisposed to the lower non-oxidative glucose metabolism. Obese women had lower glucose oxidation (P=0.005) and higher lipid oxidation (P<0.001) in insulin-stimulated conditions in comparison to lean subject whereas PCOS had no effect on these parameters (P=0.29 and P=0.43; respectively). Metabolic flexibility was impaired in the obese (P=0.001) but it was not influenced by the presence of PCOS (P=0.78). Our data indicate that PCOS women have normal metabolic flexibility, which could suggest a distinct pathophysiological mechanism for insulin resistance in this group.