Serum fibroblast growth factor 21 in human obesity: regulation by insulin infusion and relationship with glucose and lipid oxidation.

OBJECTIVE: Fibroblast growth factor 21 (FGF21) reduces plasma glucose and triglycerides, and increases free fatty acid oxidation in animal models of diabetes. The aim of the present study was to assess the relationships of serum FGF21 with glucose oxidation (GOx) and lipid oxidation (LOx) in the baseline and insulin-stimulated conditions in lean and obese subjects. DESIGN: Cross-sectional study. SUBJECTS: Eighty-four subjects with normal glucose tolerance, 42 lean (body mass index (BMI) <25 kg m(-2)) and 42 overweight or obese (BMI between 25 and 40 kg m(-2)). MEASUREMENTS: Euglycemic hyperinsulinemic clamp and indirect calorimetry in the baseline state and during last 30 min of the clamp. The change in respiratory quotient (ΔRQ) in response to insulin was used as a measure of metabolic flexibility. Serum FGF21 was determined in the baseline state and after the clamp. RESULTS: Obese subjects had higher LOx in the baseline and insulin-stimulated conditions, lower insulin-stimulated GOx and ΔRQ (all P<0.05). Fasting serum FGF21 did not differ between the groups. Insulin infusion resulted in an increase in serum FGF21 in the obese (P=0.0001), but not in the lean group (P=0.76). Postclamp serum FGF21 was higher in the obese subjects (P=0.0007). In this group, postclamp FGF21 was related to LOx during the clamp (r=0.32, P=0.044), change in GOx and LOx in response to insulin (r=-0.44, P=0.005; r=0.47, P=0.002; respectively) and ΔRQ (r=-0.50, P=0.001). CONCLUSIONS: An increase in serum FGF21 in response to insulin in obese subjects might represent inappropriate response, possibly associated with metabolic inflexibility in obesity and insulin resistance.

Impact of FTO genotypes on BMI and weight in polycystic ovary syndrome: a systematic review and meta-analysis.

AIMS/HYPOTHESIS: FTO gene single nucleotide polymorphisms (SNPs) have been shown to be associated with obesity-related traits and type 2 diabetes. Several small studies have suggested a greater than expected effect of the FTO rs9939609 SNP on weight in polycystic ovary syndrome (PCOS). We therefore aimed to examine the impact of FTO genotype on BMI and weight in PCOS. METHODS: A systematic search of medical databases (PubMed, EMBASE and Cochrane CENTRAL) was conducted up to the end of April 2011. Seven studies describing eight distinct PCOS cohorts were retrieved; seven were genotyped for SNP rs9939609 and one for SNP rs1421085. The per allele effect on BMI and body weight increase was calculated and subjected to meta-analysis. RESULTS: A total of 2,548 women with PCOS were included in the study; 762 were TT homozygotes, 1,253 had an AT/CT genotype, and 533 were AA/CC homozygotes. Each additional copy of the effect allele (A/C) increased the BMI by a mean of 0.19 z score units (95% CI 0.13, 0.24; p = 2.26 × 10(-11)) and body weight by a mean of 0.20 z score units (95% CI 0.14, 0.26; p = 1.02 × 10(-10)). This translated into an approximately 3.3 kg/m(2) increase in BMI and an approximately 9.6 kg gain in body weight between TT and AA/CC homozygotes. The association between FTO genotypes and BMI was stronger in the cohorts with PCOS than in the general female populations from large genome-wide association studies. Deviation from an additive genetic model was observed in heavier populations. CONCLUSIONS/INTERPRETATION: The effect of FTO SNPs on obesity-related traits in PCOS seems to be more than two times greater than the effect found in large population-based studies. This suggests an interaction between FTO and the metabolic context or polygenic background of PCOS.

Relationships between serum adiponectin and soluble TNF-α receptors and glucose and lipid oxidation in lean and obese subjects.

Insulin resistance might be associated with an impaired ability of insulin to stimulate glucose oxidation and inhibit lipid oxidation. Insulin action is also inversely associated with TNF-α system and positively related to adiponectin. The aim of the present study was to analyze the associations between serum adiponectin, soluble TNF-α receptors concentrations and the whole-body insulin sensitivity, lipid and glucose oxidation, non-oxidative glucose metabolism (NOGM) and metabolic flexibility in lean and obese subjects. We examined 53 subjects: 25 lean (BMI < 25 kg × m(-2)) and 28 with overweight or obesity (BMI > 25 kg × m(-2)) 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. Obese subjects had lower insulin sensitivity, adiponectin and higher sTNFR1 (all P < 0.001) and sTNFR2 (P = 0.001). Insulin sensitivity was positively related to adiponectin (r = 0.49, P < 0.001) and negatively related to sTNFR1 (r = -0.40, P = 0.004) and sTNFR2 (r = -0.52, P < 0.001). Adiponectin was related to the rate of glucose (r = 0.47, P < 0.001) and lipid (r = -0.40, P = 0.003) oxidation during the clamp, NOGM (r = 0.41, P = 0.002) and metabolic flexibility (r = 0.36, P = 0.007). Serum sTNFR1 and sTNFR2 were associated with the rate of glucose (r = -0.45, P = 0.001; r = -0.51, P < 0.001, respectively) and lipid (r = 0.52, P < 0.001; r = 0.46, P = 0.001, respectively) oxidation during hyperinsulinemia, NOGM (r = -0.31, P = 0.02; r = -0.43, P = 0.002, respectively) and metabolic flexibility (r = -0.47 and r = -0.51, respectively, both P < 0.001) in an opposite manner than adiponectin. Our data suggest that soluble TNF-α receptors and adiponectin have multiple effects on glucose and lipid metabolism in obesity.

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.

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.

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.

Protection from inflammatory disease in insulin resistance: the role of mannan-binding lectin.

AIMS/HYPOTHESIS: Decreased sensing of the innate immune system may lead to chronic activation of the inflammatory cascade. We hypothesised that mannan-binding lectin (MBL) deficiency may confer risk of obesity and insulin resistance. MATERIALS AND METHODS: We performed a cross-sectional study of MBL protein concentration (n=434) and MBL2 gene mutations (exon 1) (n=759) in association with obesity, markers of inflammation and insulin action (euglycaemic clamp, n=113), and a longitudinal study of MBL protein before and after weight loss in obese patients (n=10). We also studied the effects of MBL in vitro in muscle cells and circulating MBL-A (mouse equivalent of human MBL) in a mouse model. RESULTS: Among 434 consecutive non-diabetic men, the age-adjusted serum MBL concentration was lower in obese subjects than in lean subjects (median: 959 microg/ml [interquartile range: 116.8-2,044 microg/ml] vs 1,365 [467-2,513] microg/ml; p=0.01) and was accompanied by increased serum inflammatory markers. Insulin action correlated significantly with serum MBL (r=0.49, p<0.0001). Serum MBL concentration increased by a median of 110.2% after weight loss. The change in serum concentration of MBL was positively associated with the increase in insulin sensitivity (r=0.713, p=0.021). At least one MBL2 gene mutation was present in 48.2% of obese vs 39.3% of non-obese subjects (p=0.037). The plasma concentration of MBL-A was lower in insulin-resistant obese ob/ob mice, as was the glucose/insulin ratio. Incubation of rat soleus muscle with human MBL markedly increased fatty acid oxidation. CONCLUSIONS/INTERPRETATION: These findings suggest that MBL, previously thought only to be involved in inflammation and immune system function, affects metabolic pathways.

Plasma adiponectin and E-selectin concentrations in patients with coronary heart disease and newly diagnosed disturbances of glucose metabolism.

PURPOSE: Adiponectin is a fat derived hormone, which enhances insulin sensitivity. In experimental studies adiponectin was shown to have antiatherogenic properties by suppressing endothelial expression of adhesion molecules. Therefore, the aim of the study was to evaluate plasma adiponectin and E-selectin concentrations in patients with coronary artery disease and impaired glucose metabolism and evaluation of their relationship with selected anthropometric, biochemical and clinical parameters. MATERIAL AND METHODS: The study group consisted of 62 patients with coronary heart disease, without previous diagnosis of diabetes mellitus (mean age 48.6 +/- 6.0 years; mean BMI 28.6 +/- 3.13 kg/m2). In the studied group the OGTT with glucose and insulin estimation was performed and insulin resistance index (HOMA-IR) was calculated. In the fasting state, the plasma adiponectin, soluble form of E-selectin, HbA1c and lipid parameters were estimated. RESULTS: Adiponectin concentration was not different in patients with type 2 diabetes mellitus and impaired glucose tolerance (n = 36) in comparison to the group with normal glucose tolerance (n = 26). There was also no difference in adiponectin concentration in relation to atherosclerosis progression. There was no significant correlation between adiponectin and calculated insulin resistance index, while there was marked inverse correlation between adiponectin and BMI (r = -0.30; p = 0.018), body weight (r = -0.33; p = 0.008), E-selectin (r = -0.263; p = 0.039), TG concentration (r = -0.27; p = 0.036), duration of coronary heart disease (r = -0.33; p = 0.009) and borderline significance with ejection fraction (r = -0.268; p = 0.06). CONCLUSIONS: Our study supports the hypothesis that adiponectin could be recognised as a protective protein for the development of atherosclerosis.

Homocysteine concentrations and vascular complications in patients with type 2 diabetes.

OBJECTIVE: Hyperhomocysteinemia is a well known risk factor for the diseases of the cardiovascular system, which seem to be the main cause of increased mortality in patients with type 2 diabetes. The aim of the study was to evaluate the levels of homocysteine in patients with type 2 diabetes in respect to the regimen of diabetes treatment as well as the presence of diabetic complications. METHODS: The investigation was carried out in the group of 64 patients with type 2 diabetes and in 18 healthy subjects from the control group. Clinical examination and measurements of homocysteine, folic acid, vitamin B12, glycosylated hemoglobin concentration and evaluation of parameters of the lipid metabolism, microalbuminuria and creatinine were done in both groups. RESULTS: Homocysteine concentration was significantly higher in the group of patients with diabetes in comparison to the control group (p = 0.0007). Diabetic patients had significantly lower concentrations of folic acid (p = 0.028) and HDL cholesterol (p = 0.025) together with higher levels of systolic blood pressure (p = 0.007). In the group of patients with diabetes no differences in homocysteine levels were found in respect to diabetes treatment. Diabetic patients with coronary artery disease had significantly higher homocysteine concentration in comparison to the group with diabetes without history of coronary artery disease (p = 0.0097). Homocysteine levels correlated significantly with incidence of ischaemic heart disease (r = 0.44, p = 0.001) and microalbuminuria (r = 0.26, p = 0.019). Negative correlation was noticed in HDL concentrations (r = -0.30, p = 0.013) and the levels of folic acid (r = -0.30, p = 0.008). CONCLUSION: Our results suggest that hyperhomocysteinemia in diabetic patients may contribute to the development of chronic complications. The influence of diabetes treatment on Hcy levels requires further observations.

Post-partum evaluation of amylin in lean patients with gestational diabetes mellitus.

The aim of our study was to compare the secretion of amylin, as well as glucose, insulin and C-peptide at baseline and in response to glucagon stimulation in 26 lean women with gestational diabetes mellitus (GDM) and in 19 age- and BMI-matched pregnant women with normal glucose tolerance (NGT). Intravenous 1-mg glucagon stimulation test was performed 6 weeks after delivery. Fasting and stimulated glucose levels were significantly higher in GDM patients than in subjects with NGT ( p<0.01 at 0 and 6 min; glucose area under the curve (AUC), 604.8+/-41.8 mg/6 min vs. 572.4+/-52.4 mg/6 min, p<0.05). Insulin AUC was also markedly higher in GDM subjects than in healthy controls (373.9+/-144.2 micro IU/6 min vs. 283.7+/-139.1 micro IU/6 min, p<0.05). There was no difference in fasting C-peptide levels between the groups studied, but stimulated concentrations, as well as C-peptide AUC were significantly higher in patients with GDM ( p<0.01 at 1 min and p<0.005 at 6 min; AUC, 27.4+/-11.3 pmol/6 min vs. 18.4+/-6.9 pmol/6 min, p<0.01). Amylin levels were higher in GDM group in comparison to healthy subjects ( p<0.005 at 1 and 6 min; amylin AUC, 113.3+/-51.2 pg/6 min vs. 72.5+/-15.7 pg/6 min; p=0.14), but in contrast to the other hormones, did not rise in response to glucagon injection. In conclusion, our results provide evidence that in patients with GDM in the post-partum period, the levels of amylin, as well as the secretion of insulin and C-peptide remain elevated, when compared to women with NTG. Further investigations are needed to clarify the significance of this elevation as a predictive factor for the development of late maternal type 2 diabetes.

Changes in tumor necrosis factor-alpha system and insulin sensitivity during an exercise training program in obese women with normal and impaired glucose tolerance.

OBJECTIVE: Tumor necrosis factor-alpha (TNFalpha) plays an important role in the pathogenesis of insulin resistance and type 2 diabetes. Plasma levels of the soluble (s) fractions of TNFalpha receptors, especially sTNFR2, are good indicators of TNFalpha system activation in obesity. The aim of the present study was to assess the effect of exercise training on the TNFalpha system and to evaluate the relationship with changes in insulin sensitivity. DESIGN AND METHODS: Sixteen obese women (body mass index (BMI)>27.8 kg/m(2)), 8 with normal (NGT) and 8 with impaired glucose tolerance (IGT), participated in an exercise training program which lasted for 12 weeks and included exercise performed on a bicycle ergometer at an individual intensity of 70% maximal heart rate, for 30 min, 5 days a week. Anthropometrical measurements and blood biochemical analyses were performed, and plasma TNFalpha, sTNFR1 and sTNFR2 levels were assessed. Insulin sensitivity was evaluated using the hyperinsulinemic euglycemic clamp technique (insulin infusion: 50 mU x kg(-1)xh(-1)). RESULTS: At baseline, despite similar anthropometrical parameters, IGT subjects were markedly more insulin resistant and had higher TNFalpha and sTNFR2 concentrations. Exercise training increased insulin sensitivity and decreased TNFalpha and sTNFR2 levels, while sTNFR1 remained unchanged. The decrease in sTNFR2 was significantly related to the increase in insulin sensitivity; that relationship remained significant after adjustment for the concurrent changes in BMI, waist circumference, percentage of body fat, plasma glucose, insulin and free fatty acids. CONCLUSIONS: Regular physical exercise decreases TNFalpha system activity and that decrease may be responsible for the concurrent increase in insulin sensitivity.

Insulin, leptin, IGF-I and insulin-dependent protein concentrations after insulin-sensitizing therapy in obese women with polycystic ovary syndrome.

OBJECTIVE: To determine the clinical, hormonal and biochemical effect of 4-5 months of insulin-sensitizing therapy (hypocaloric diet+metformin) in obese patients with polycystic ovary syndrome (PCOS). DESIGN: Prospective study. METHODS: Twenty-three obese patients with PCOS, 19 obese patients without menstrual disturbances and 11 healthy control women were recruited from the Department of Endocrinology and Endocrine Gynecology, Medical Academy, Bialystok, Poland. Obese patients received 500 mg metformin together with hypocaloric diet three times daily for 4-5 months, after baseline study. The clinical parameters, menstrual pattern and serum concentrations of insulin, leptin, IGF-I, insulin-dependent proteins (sex hormone-binding protein (SHBG), insulin-like growth factor-binding protein-1 (IGFBP-1)), gonadotropins and sex steroids were determined before and after treatment. RESULTS: In the baseline study, obese patients with PCOS had significantly higher insulin, testosterone and LH concentrations in comparison with the other groups. The serum leptin, IGF-I, IGFBP-1 and SHBG were not different between the two groups of obese patients, but there was a significant difference in comparison with the control group. After metformin therapy a significant reduction in BMI, % of body fat and leptin concentration were observed in both groups of obese patients. Fasting insulin, testosterone and LH concentrations decreased significantly only in the PCOS group. Six out of 11 patients in the PCOS group had more regular menstrual cycles; two patients conceived. CONCLUSIONS: Insulin-sensitizing therapy could be considered as an additional therapeutic option in obese women with PCOS.

The effect of exercise training on glucose tolerance and skeletal muscle triacylglycerol content in rats fed with a high-fat diet.

The aim of the present study was to evaluate the effect of exercise training on glucose tolerance and glycogen and triacylglycerol (TG) content in different types of skeletal muscles and in the liver of rats fed with a high-fat diet. From 8 to 11 weeks of age male Wistar rats were fed with isocaloric standard (control) or high-fat diet (HFD--59% calories as fat) and were additionally assigned to a sedentary or trained group (4 weeks of training on a treadmill). An intravenous glucose tolerance test (IVGTT) with the determination of basal and post load insulin was performed before the final tissue sampling. HFD rats developed marked hyperinsulinemia. Exercise training improved glucose tolerance and insulin response in the control group only (AUC for glucose in control sedentary vs control trained, p<0.05; AUC for insulin: control sedentary vs control trained, p<0.005). Liver glycogen was significantly lower in the HFD group (p<0.05 vs control sedentary) and did not increase after exercise training. Muscle and liver TG content was markedly higher in the HFD group in comparison to control (p<0.0001 in all cases). Exercise training increased TG content in the control group in all examined tissues except white gastrocnemius (p<0.001 in all cases compared to sedentary controls), and did not affect tissue TG in the HFD group. After exercise training there was still markedly higher tissue TG content in the HFD group vs control (p<0.0001 in all cases). We conclude that beneficial metabolic effects of training are impaired in high-fat fed rats and that training does not completely reverse metabolic disturbances in this group of animals.

The effect of a single bout of exhaustive exercise on muscle carbohydrate and lipid metabolism in a rat model of type 2 diabetes mellitus.

The aim of the present study was to estimate whether a single bout of exhaustive exercise influences the glycogen and triglyceride (TG) content in red and white gastrocnemius muscle and in the liver of rats with experimental type 2 diabetes. Experiments were carried out on male Wistar rats fed from 8 to 11 weeks of age with isocaloric standard or high-fat diet (HFD) with a previous injection of low-dose of streptozotocin (STZ) or vehicle at 2 days of age (I, control group; II, HFD; III, STZ; IV, STZ + HFD). Group IV (STZ + HFD) represents a model of type 2 diabetes. Basal liver glycogen was markedly lower in all the studied groups compared to controls. Glycogen concentration after exercise fell significantly in the examined tissues in all groups in comparison to basal conditions. A significant TG accumulation in examined tissues was observed in all the studied groups in comparison to controls. Exercise decreased tissue TG content in all the groups, but it remained significantly higher in the experimental groups vs. control. We conclude that in this model of type 2 diabetes, a single bout of exercise reveals defective utilization of tissue carbohydrates and lipids.

The effect of fasting and physical exercise on plasma leptin concentrations in high-fat fed rats.

The aim of our study was to estimate the effect of fasting and physical exercise on a treadmill on plasma leptin concentrations in high-fat fed rats. Male Wistar rats were injected a low dose of streptozotocin (STZ) or buffer at 2 days of age and later fed a standard or high-fat diet (HFD). Plasma leptin was measured by RIA method in all the groups studied in basal conditions, after 48h fasting, a single bout of exhaustive exercise, and 4 weeks of exercise training. Plasma leptin concentrations were markedly elevated in the HFD and STZ/HFD groups compared to the control group. The significant correlation between plasma leptin and body weight was noted. Fasting and exercise training decreased plasma leptin in similar percentage in all the groups studied. The observed decrease was greater than expected from changes in body weight. We conclude that high-fat feeding results in an increase in plasma leptin levels in rats independently of plasma insulin or daily calorie intake. High-fat fed rats have maintained leptin response to fasting and exercise training. The reduction in plasma leptin after exercise training is partly independent on changes in body weight or plasma insulin.

[The effect of obesity on ovarian function. I. Serum insulin and insulin dependent protein concentrations in obese patients with polycystic ovary syndrome]. / Wplyw otylosci na funkcje jajnika. I. Insulina i bialka insulinozalezne w surowicy krwi otylych kobiet z zespolem policystycznych jajników.

OBJECTIVES: The aim of the present study was to estimate the role of insulin in the pathogenesis of polycystic ovary syndrome. DESIGN: The study was carried out in 21 obese women with PCO, 18 obese women without menstrual disturbances and 9 normal-weight healthy women. MATERIALS AND METHODS: In all patients antropomethric parameters: weight, height, % of body fat, waist and hip girths were measured and than BMI and WHR were calculated. Oral glucose tolerance test after 75 g glucose was done after overnight fast. Plasma glucose and insulin were measured in 0 min, 60 min and 120 min of the test. The concentrations of IGF-I, IGFBP-1, SHBG, LH, FSH, testosterone, cortisol, PRL, estradiol, were estimated. RESULTS: There was statistical significant difference between plasma insulin concentrations in obese patients with PCO in comparison to obese women with normal menstrual cycle (p < 0.05) and control group (p < 0.001). The concentrations of IGFBP-1 and SHBG were similar in both groups of obese patients and differ markedly in comparison to the control group. There were significant correlation between plasma insulin and % body fat, BMI and waist girth in all studied groups. CONCLUSIONS: We conclude that in obese women with PCO insulin influence ovarian androgen production and decreases the serum SHBG and IGFBP-1 which could contribute in the augmentation of the symptoms of PCO.

[The influence of obesity on ovarian function. II. Plasma leptin concentration in women with polycystic ovary syndrome]. / Wplyw otylosci na funkcje jajnika. II. Leptyna w surowicy krwi pacjentek z zespolem policystycznych jajników.

OBJECTIVES: The aim of the present study was to estimate the leptin role in the pathogenesis of polycystic ovary syndrome. DESIGN: The study was carried out in 21 obese women with PCO, 18 obese women without menstrual disturbances and 9 normal-weight healthy women. MATERIALS AND METHODS: In all patients antropomethric parameters: weight, height, % of body fat, waist and hip girths were measured and than BMI and WHR were calculated. Plasma concentrations of leptin, insulin, LH, FSH, testosterone, cortisol, PRL, estradiol were estimated. RESULTS: There were no statistical significant difference between plasma leptin concentrations in obese patients with PCO in comparison to obese women with normal menstrual cycle. In both groups of obese patients plasma leptin concentrations was significantly higher than in control group (p < 0.001, p < 0.001). There were significant correlation between plasma leptin and % body fat, BMI and waist girth in all studied groups. CONCLUSIONS: We conclude that leptin is not directly involved in observed hormonal disturbances in polycystic ovary syndrome. The main predictor of plasma leptin concentrations in patients with PCO is amount of body fat.

[Levels of leptin in plasma of patients with type 2 diabetes]. / Stezenie leptyny w surowicy krwi pacjentów z cukrzyca typu 2.

Leptin, the product of ob gene is secreted by adipose tissue. It is believed that leptin plays an important role in energy balance. The secretion of leptin by adipose tissue is influenced by insulin. The aim of the present study was the estimation of plasma leptin concentrations in patients with type 2 diabetes mellitus. The study was carried out in 21 diabetic obese patients (BMI > 27.5), 8 diabetic patients with BMI < 27.5, 24 obese patients with normal glucose tolerance (BMI > 27.5) and 10 patients from the control group (BMI < 27.5). The mean leptin concentration in obese diabetic patients was 22.5 + 6.5 ng/ml and was not significantly different from that in obese patients without diabetes (24.1 + 10.3 ng/ml) but differed markedly in comparison to the normal weight diabetic patients (7.9 + 4.3 ng/ml, p < 0.01). Plasma leptin concentration correlated significantly and positively with BMI and fasting insulin in all studied groups. There was no significant correlation between leptin and glycated hemoglobin, total cholesterol and triglycerides. We conclude that serum leptin concentrations in patients with type 2 diabetes depends mainly on the amount of body fat.