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

Exploring the physiological factors relating to energy balance in women with polycystic ovary syndrome: a scoping review

Polycystic ovary syndrome (PCOS) occurs in 8%-13% of reproductive-aged women and is associated with reproductive, metabolic, and psychological dysfunction. Overweight and obesity are prevalent and exacerbate the features of PCOS. The aim of this review is to evaluate the extent of evidence examining the physiological factors affecting energy homeostasis, which may impact weight gain, weight loss, and weight maintenance in PCOS, and identify research gaps and recommendations for future research. Literature searches using MEDLINE, EMBASE, PsycInfo, AMED, CINAHL, and Cochrane Central Register of Controlled Trials were conducted up to June 22, 2022. Abstracts, non-English-language articles, and reviews were excluded. A total of n = 78 (n = 55 energy intake and n = 23 energy expenditure) primary research papers were included. Papers with multiple outcomes of interest were counted as separate studies. Energy-intake studies (n = 89) focussed on assessing food, nutrient, or supplements stimuli and were grouped into the outcomes of gastrointestinal appetite hormones (n = 43), adipokines (n = 34), subjective appetite (n = 9), functional brain imaging (n = 3), and neuropeptides (n = 0). Energy-expenditure studies (n = 29) were grouped into total energy expenditure (n = 1), resting energy expenditure (n = 15), meal-induced thermogenesis (n = 3), nutrient oxidation (n = 5), and metabolic flexibility (n = 5). Across both energy-intake and -expenditure papers, 60% of the studies compared outcome responses in women with PCOS with a control group. Results were inconsistent, with 57% reporting no differences and 43% reporting altered responses in PCOS compared with controls, including blunted appetite hormone responses, metabolic inflexibility, and reduced energy expenditure. The authors identified that there is inconsistent, yet preliminary, evidence of possible altered physiological factors, which may impact energy balance and weight management. Further work is needed to act on the identified clinical and research gaps to support women with PCOS and health professionals in informing and achieving realistic weight-management goals for women with PCOS.

SYSTEMATIC REVIEW REGISTRATION

The protocol was prospectively registered on the Open Science Framework on February 16, 2021 (https://osf.io/9jnsm).

Changes in adipokine concentrations in antidepressant-resistant bipolar depression after ketamine infusion and electroconvulsive therapy

OBJECTIVES

This study attempts to assess the concentration of two opposite-acting adipokines (anti-inflammatory adiponectin and pro-inflammatory resistin) in antidepressant-resistant patients undergoing ketamine infusion (KI) and electroconvulsive therapy (ECT).

METHODS

The study group comprised 52 patients hospitalised due to episodes of depression in the course of bipolar disorders. The Hamilton depression scale was used to assess the intensity of the depression symptoms before starting therapy and one day after its completion. The serum concentration of adipokines was determined before and after the therapeutic intervention using an ELISA method.

RESULTS

Baseline adipokine levels differed between patients receiving KI and ECT therapy. Regardless of the procedure used, these levels changed after treatment, with the nature of these changes being different. In the case of KI, the adiponectin levels increased, and resistin levels decreased. In contrast, after ECT, the concentrations of both adipokines decreased. Changes in adipokine concentrations correlated with improvement in mental status, as assessed by the Hamilton Rating Scale, type of bipolar disorder, and gender.

CONCLUSIONS

Adipokines remain interesting candidate biomarkers in assessing the state and course of the disease depending on the therapeutic procedure applied. However, the relatively small study group and limited original research available for discussion justify further investigation.

Assessment of Adiponectin and Resistin Indexes Compared to FBG and Useful as Diagnostic Biomarkers in Insulin Resistance and Type 2 Diabetes

Abstract: Background and aim: The world prevalence of diabetes among adults will be 6.4%, affecting 285 million adults, in year 2010, and will increase to 7.7% and 439 million adults by year 2030. Insulin resistance is a prerequisite root factor for development of type 2 diabetes (T2DM). Adiponectin and resistin are adipokines which modulate insulin action, energy, glucose and lipid homeostasis. Meta-analyses showed that hypoadiponectinemia and hyperresistinemia are strongly associated with increased risk of insulin resistance, type 2 diabetes (T2DM), Methods: In this case control study, A total 204 Sudanese males and females were recruited to participate in this study (102 diabetic and 102 non-diabetic) and venous blood samples were collected. Serum levels of blood glucose were measured using the particle-enhanced immunoturbidimetric assay method Cobas C-311®.While Adiponectin and Resistine estimated by ELISA Kits. Results: In this results shows significant difference between the means fasting blood glucose (FBG), adiponectin, resistine of diabetic patient and non-diabetic patient. FBG (mean + SD) (164.5 ± 16.7) versus (95.7 ± 13.6), P = 0.041, adiponectin (mean + SD) (5.9 ± 1.6) versus (10.1 ± 1.3), P = 0.037, resistine (mean + SD) (18.2 ± 2.7) versus (12.2 ± 1.1), P = 0.023.  In this study, observed from this results strong negative Correlation between the levels of serum Adiponectin and Fasting Blood Glucose, Adiponectin and Resistine. (P.value = 0.013, r = -7.9). (P.value = 0.019, r = -6.6). While showing in the other side moderate positive Correlation between the levels of serum Resistine and Fasting Blood Glucose. (P.value = 0.015, r = 6.0). Conclusion: Iccrease of Resistine and Fasting Blood Glucose and reduced of Adiponectin in diabetic patient compare to non-diabetic patient can be useful as diagnostic biomarkers. Keywords: Adiponectin and Resistin, insulin resistance, type 2 diabetes

Blood Circulating Levels of Adipokines in Polycystic Ovary Syndrome Patients: A Systematic Review and Meta-analysis

A body of studies has examined the circulating concentration of adipokines including apelin, vapin, resistin, and chemerin in polycystic ovary syndrome (PCOS) patients. However, their findings have been inconclusive. Therefore, we systematically reviewed available studies to illuminate the overall circulating concentration of adipokines in PCOS subjects. Cochrane's Library, PubMed, Scopus, and ISI Web of Science databases were searched from the earliest available date up to April 2021 for relevant articles. The quality of each study was assessed by the Newcastle-Ottawa Quality Assessment Scale. The pooled effect size was estimated based on the random effects model, and the standard mean differences (SMD) with a 95% confidence interval (CI) were reported. A total of 88 studies met the inclusion criteria and were included in the current systematic review and meta-analysis. The results of the analysis showed that serum levels of vaspin (SMD 0.69; 95% CI, 0.22 to 1.17; P = 0.004; I² = 90.6%), chemerin (SMD 1.87; 95% CI, 1.35 to 2.40; P < 0.001; I² = 94.4%), and resistin (SMD 0.66; 95% CI, 0.41 to 0.91; P < 0.001; I² = 92.6%) were significantly higher in the PCOS group compared to controls. However, there was no significant difference between the PCOS and control groups in relation to apelin levels (SMD - 0.17; 95% CI, - 1.06 to 0.73; P = 0.714; I² = 97.8%). We found that serum levels of vaspin, chemerin, and resistin were significantly higher in PCOS subjects compared with controls. It seems that these adipokines can be measured as a useful marker to predict the development of PCOS.

Serum visfatin and adiponectin - markers in women with polycystic ovarian syndrome

Aim: Polycystic ovary syndrome (PCOS) is a leading cause of female infertility. Adipose tissue releases various adipokines, including visfatin and adiponectin, which have influence on insulin resistance (IR).Objective: To determine serum insulin levels, IR, serum visfatin and adiponectin levels in PCOS subjects.Materials and methods: Case-control study on 100 diagnosed PCOS patients (50 obese and 50 non-obese) and 100 control subjects (50 obese and 50 non obese). Investigations included serum measurement of insulin, visfatin and adiponectin using an enzyme-linked immunosorbant assay and Sinbe magnum technique.Results: There were higher levels of serum fasting glucose levels, serum insulin levels, IR and visfatin levels and lower levels of adiponectin in women with PCOS irrespective of body mass index, compared to their respective controls with a p value of < 0.001.Conclusion: The study suggests that serum visfatin levels positively correlate and serum adiponectin levels negatively correlate to insulin and IR in women with PCOS irrespective of obesity. Hence they can serve as markers in women with PCOS.

A Systematic Review of the Effects of Exercise on Hormones in Women with Polycystic Ovary Syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that is characterized by menstrual irregularity and elevated serum androgens, and is often accompanied by insulin resistance. The etiology of PCOS is unknown. Lifestyle interventions and weight loss, where appropriate, remain first-line treatments for women with PCOS. Regular physical activity is recommended for women with PCOS to maintain a healthy weight and cardiovascular fitness.

PURPOSE

To review the evidence for the impact of various exercise interventions on hormone levels in women with PCOS.

METHODS

A systematic review of original studies indexed in PubMed that utilized an exercise intervention in women with PCOS and reported hormone values pre- and post-intervention. Studies in which the effects of the exercise intervention could be determined were included.

RESULTS

Vigorous aerobic exercise improves insulin measures in women with PCOS. Resistance or strength training may improve androgen levels, though additional studies are warranted. Studies with yoga are limited but suggest improvements in androgens. Limited information is available on the impact of exercise on adipokines and anti-Müllerian hormone, warranting further investigation.

CONCLUSIONS

Recommended guidelines for women with PCOS include vigorous aerobic exercise and resistance training to improve measures of insulin sensitivity and androgen levels.

New markers of insulin resistance in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine-metabolic disorder in women of reproductive age. The diagnostic criteria include two out of three features: hyperandrogenism, polycystic ovaries on ultrasound and menstrual irregularities (Rotterdam Criteria 2003). PCOS patients are more vulnerable to develop diabetes, cardiovascular diseases and metabolic syndrome. Insulin resistance (IR) is prevalent in women with PCOS independently of obesity and is critically involved in reproductive and metabolic complications of the syndrome. Several tests have been developed to measure IR, some very reliable but complex like the hyperinsulinemic euglycemic glucose clamp and others less precise but easier and less invasive like HOMA-IR. New markers are needed to reach a more reliable assessment of insulin resistance. To date, several surrogate markers have been proposed in the literature to facilitate and improve the determination of IR. Many new proteins are strongly involved with PCOS physiopathology and IR, such as some adipocytokines (adiponectin, visfatin, vaspin and apelin), copeptin, irisin, PAI-1 and zonulin. Many other proteins have been proposed as potential new markers of IR in PCOS, such as resistin, leptin, RBP4, kisspetin and ghrelin, but their role is still controversial. In this review, we provide a short characterization of these new markers, recently studied as indicators of metabolic state.

Influence of Fasting Status and Sample Preparation on Metabolic Biomarker Measurements in Postmenopausal Women

BACKGROUND

Epidemiologic data linking metabolic markers-such as insulin, insulin-like growth factors (IGFs)-and adipose tissue-derived factors with cancer are inconsistent. Between-study differences in blood collection protocols, in particular participant's fasting status, may influence measurements.

METHODS

We investigated the impact of fasting status and blood sample processing time on components of the insulin/IGF axis and in adipokines in a controlled feeding study of 45 healthy postmenopausal-women aged 50-75 years. Fasting blood samples were drawn (T0), after which subjects ate a standardized breakfast; subsequent blood draws were made at 1 hour (T1), 3 hours (T3), and 6 hours (T6) after breakfast. Serum samples were assayed for insulin, C-peptide, total- and free-IGF-I, IGF-binding protein [BP]-1 and -3, total and high molecular weight (HMW)-adiponectin, retinol binding protein-4, plasminogen activator inhibitor (PAI)-1, and resistin.

RESULTS

Insulin and C-peptide levels followed similar postprandial trajectories; intra-class correlation coefficients [ICC] for insulin = 0.75, (95%CI:0.64-0.97) and C-peptide (ICC = 0.66, 95%CI:0.54-0.77) were similarly correlated in fasting (Spearman correlation, r = 0.78, 95%CI:0.64-0.88) and postprandial states (T1, r = 0.77 (95%CI: 0.62-0.87); T3,r = 0.78 (95%CI: 0.63-0.87); T6,r = 0.77 (95%CI: 0.61-0.87)). Free-IGF-I and IGFBP-1 levels were also affected by fasting status, whereas total-IGF-I and IGFBP-3 levels remained unchanged. Levels of adipokines were largely insensitive to fasting status and blood sample processing delays.

CONCLUSION

Several components of the insulin/IGF axis were significantly impacted by fasting state and in particular, C-peptide levels were substantially altered postprandially and in a similar manner to insulin.

In quest for method of insulin resistance assessment in everyday clinical practice-Insulin resistance indices

Insulin resistance (IR) a state of decreased sensitivity of target tissues to insulin is suspected usually in obese so can be overlooked in normal weight subjects thus it is important to find optimal method of IR assessment in clinical practice.

METHODS

HOMA, HOMA2, QUICKI, Matsuda index were calculated using data obtained from medical history of 130 female subjects - patients of the Department of Endocrinology and Metabolic Diseases, in whom oral glucose tolerance test (OGTT) with parallel insulin concentrations assessment was performed.

RESULTS

IR correlated positively with body mass index (BMI) in the entire study group, regardless which of four analyzed IR indices was used. Insulin resistance occurred in the obese as well as in normal weight and underweight subjects. The incidences of IR in the study group varied, depending upon chosen method and adopted cut-off values.

CONCLUSIONS

The need for quantitative assessment of IR in clinical practice is apparent. Proper selection of the best method of IR assessment remains a problem. HOMA appears the method of first choice for clinical use. There is an urgent need to establish universal or, at least, national standard cut-off values for IR, to introduce IR assessment in clinical practice.

Adiponectin-resistin index and its strong association with acute coronary syndrome in South Indian men

BACKGROUND

India has the highest burden of acute coronary syndromes worldwide. Apart from certain lipid alterations that have been established to be definite risk factors, low level of adiponectin, high levels of resistin, and IL-6 have been shown to be risk factors for cardiovascular events. Insulin resistance is also a significant predictor of poor outcome in patients admitted with ACS.

METHODS

69 male patients with ACS and 70 age-matched healthy males were recruited in the study. Insulin, total adiponectin, resistin, and IL-6 levels were assayed in all study subjects. Indices of insulin resistance and novel adipokine indices were calculated using standard formulae. Multiple logistic regression analysis was done to find out the best predictor of ACS.

RESULTS

Resistin, IL-6, insulin resistance indices, AR index, and IRAR index were found to be significantly higher, while insulin sensitivity indices and total adiponectin were found to be lower in cases, as compared with controls (p < 0.001). Insulin resistance was found to be higher in the admission sample, when compared to the fasting sample in patients with ACS (p = 0.01). On multivariate logistic regression analysis, HOMA-IR and AR index were found to be significantly associated with ACS. AR index was the best independent predictor of ACS, with the highest odds ratio (AR index: adjusted OR 17.528, p < 0.0001 versus HOMA-IR: adjusted OR 1.146, p = 0.001).

CONCLUSIONS

The present results implicate that adipokines are significantly associated with pathogenesis of ACS, warranting adequate and early appropriate treatment to reverse this metabolic dysregulation. In our study, AR index was the best predictor of ACS. Hence, the novel AR index might be useful in routine clinical practice for screening persons with increased risk of future development of ACS.

Insulin resistance and its relationship with high molecular weight adiponectin in adolescents with polycystic ovary syndrome and a maternal history of polycystic ovary syndrome

OBJECTIVE

To assess the rate of insulin resistance (IR) and the relationship between IR and high molecular weight (HMW) adiponectin in normal weight adolescents with polycystic ovary syndrome (PCOS) and a maternal history of PCOS.

DESIGN

Case-controlled study.

SETTING

Adolescent clinic of a teaching and research hospital.

PATIENT(S)

Forty normal weight adolescents with PCOS and a maternal history of PCOS and 40 normo-ovulatory age- and body mass index (BMI)-matched controls.

INTERVENTION(S)

A 75-g oral glucose tolerance test (OGTT) was performed for each participant.

MAIN OUTCOME MEASURE(S)

Homeostasis model assessment of IR and HMW adiponectin.

RESULT(S)

There were no statistically significant differences between the PCOS and control groups in terms of fasting glucose, fasting insulin, and lipid parameters. Although total and free T were significantly higher, HMW adiponectin levels were significantly lower in the PCOS group compared with the control group. When the PCOS group was compared according to the IR, the HMW adiponectin level was significantly lower in the adolescents with PCOS and IR. The adolescents with PCOS and biochemical hyperandrogenemia had significantly lower HMW adiponectin levels and significantly higher homeostasis model assessment of IR score compared with the adolescents with PCOS and normoandrogenemia.

CONCLUSION(S)

The adolescents with PCOS had a significantly increased rate of IR without clinical findings of metabolic disorders or obesity. The HMW adiponectin levels were negatively correlated with IR.

Efficacy of omega-3 in the treatment of polycystic ovary syndrome

The purpose of this study was to evaluate the efficacy and safety of omega-3 in the treatment of polycystic ovary syndrome and to compare the clinical, hormonal, TNF-α and resistin levels in the patients treated with omega-3. A total of 45 non-obese PCOS women were studied. Women were treated with daily oral 1,500 mg of omega-3 for 6 months. Body mass index (BMI), hirsutism score, fasting glucose and insulin levels were noted for each case. Hirsutism was assessed at 6-month intervals using the Ferriman-Gallwey (F-G) scoring system. Hormonal, TNF-α and resistin levels at 6 months of therapy were compared with baseline values. BMI, F-G scoring, insulin and HOMA levels decreased significantly during treatment, but glucose levels did not change. In the hormonal profile, serum LH and testosterone levels decreased and sex hormone-binding globulin levels increased significantly after the 6 months of therapy. On the other hand, TNF-α levels showed a significant increase, whereas resistin levels showed no change. Omega-3 may be also effective in improving hirsutism and insulin resistance in patients with PCOS.

Effect of a combined estrogen and progesterone oral contraceptive on circulating adipocytokines adiponectin, resistin and DLK-1 in normal and obese female rhesus monkeys

BACKGROUND

Hormonal contraception is the most common medication used by reproductive aged women but there is little understanding of the impact of hormonal contraception on obesity and metabolism. Adipokine levels (adiponectin, resistin) and markers of adipocyte development (DLK-1) are altered in obese animals and humans and are associated with increased cardiovascular risk. We sought to determine the effect of combined hormonal oral contraceptive pills (COCs) on circulating adiponectin, resistin and DLK-1 levels in obese and normal-weight rhesus macaque monkeys.

METHODS

Serum adiponectin, resistin and DLK-1 levels in reproductive-age female rhesus macaques of normal (n = 5, mean = 5.76 kg) and inherently obese (n = 5, mean = 8.11 kg) weight were determined before, during and 2 months after cessation of 8 months of continuous treatment with COCs.

RESULTS

The obese group alone showed a significant decrease (p<.01) in weight with COC use, which returned to baseline after COC cessation. Baseline adiponectin levels prior to COC treatment were lower in the obese group (p<.05). Adiponectin levels increased from baseline in both groups, but more so in the obese group (p<.05). Resistin levels were similar at baseline, with an increase in both groups following treatment. Circulating resistin remained elevated above baseline levels after COC cessation, particularly in the obese group (p<.05). While DLK-1 levels did not change significantly in either group, a trend for higher levels in obese animals was observed.

CONCLUSIONS

COC use may alter metabolic processes via direct (resistin) or indirect (adiponectin) means, while unchanging DLK1 levels suggest they do not affect adipocyte development. COCs may directly increase resistin levels, as observed in both groups. As adiponectin is inversely related to adipocyte mass, increased levels in the obese group are likely attributed to weight loss.

Dysregulated adipokines in the pathogenesis of type 2 diabetes and vascular disease

Obesity is commonly associated with type 2 diabetes and vascular disease. Changes in body composition in the obese state lead to a dysregulation of secretion of adipocyte-secreted hormones known as adipokines. Adipokines such as leptin and adiponectin are known to be involved in many physiological and pathological processes. Current knowledge suggests that adipokines provide potential therapeutic targets against type 2 diabetes and vascular disease.

Effect of short-term standard therapeutic regimens on neuropeptide Y and adipose tissue hormones in overweight insulin-resistant women with polycystic ovary syndrome

AIM

The study was aimed at elucidating the influence of a 3-month treatment with routine therapeutic regimens--oral hormonal contraceptives (OHC) with antiandrogenic activity (a standard combination of ethynil estradiol 35 microg plus cyproterone acetate 2 mg) in combination with insulin sensitizing agents--metformin (Group I) and rosiglitazone (Group II) on adipose tissue hormones and hypothalamic neuropeptide Y (NPY) in women with polycystic ovary syndrome.

PATIENTS AND METHODS

The study included 66 overweight insulin resistant women with PCOS according to the recent ESHRE-ASRM criteria randomized into 2 age-matched therapeutic groups.

RESULTS

Significant decrease of leptin (P < 0.01; P = 0.001, resp.), resistin (P < 0.01; P < 0.01, resp.), tumour necrosis factor alpha (TNF alpha) (P = 0.001; P < 0.001, resp.), and NPY (P < 0.05; P < 0.001, resp.) was observed in both groups after treatment. These findings were in parallel with a significant decrease in the anthropometric parameters of body weight in the metformin group only. No significant changes in hormonal characteristics of the groups were found except for a significant decrease in androstenedione and DHEA-S (P < 0.05) in the metformin group and in 17-OH-progesterone (P < 0.05) in the rosiglitazone group. HDL-cholesterol rose and diastolic blood pressure fell significantly (P < 0.05) in the metformin group.

CONCLUSION

Our data suggest beneficial effects of the treatment on potential cardiovascular risk in insulin resistant PCOS women.

Adipokines (adiponectin and plasminogen activator inhhibitor-1) in metabolic syndrome

BACKGROUND

The clustering of cardiovascular risk factors is termed the metabolic syndrome (MS), which strongly predicts the risk of diabetes and cardiovascular disease (CVD). Adipokines may contribute to the development of obesity and insulin resistance and may be a causal link between MS, diabetes and CVD. Hence, we studied the adipokines - adiponectin and plasminogen activator inhibitor-1 (PAI-1) - in subjects with MS.

MATERIALS AND METHODS

We studied 50 subjects with MS diagnosed by International Diabetes Federation (IDF) criteria and 24 healthy age- and sex-matched controls. Clinical evaluation included anthropometry, body fat analysis by bioimpedance, highly sensitive C-reactive protein, insulin, adiponectin, and PAI-1 measurement.

RESULTS

Subjects with MS had lower adiponectin (4.01 ± 2.24 vs. 8.7 ± 1.77 μg/ml; P < 0.0001) and higher PAI-1 (53.85 ± 16.45 vs. 17.35 ± 4.45 ng/ml; P < 0.0001) levels than controls. Both were related with the number of metabolic abnormalities. Adiponectin was negatively and PAI-1 was positively associated with body mass index, waist hip ratio (WHR), body fat mass, percent body fat, and all the parameters of MS, except HDL where the pattern reversed. WHR and triglycerides were independent predictors of adipokines in multiple regression analysis. Receiver operating characteristic curve analysis showed that adiponectin (6.7 μg/ml) and PAI-1 (25.0 ng/ml) levels predicted the MS with high sensitivity, specificity and accuracy in Indian population.

CONCLUSIONS

Subjects with MS have lower adiponectin and higher PAI-1 levels compared to healthy controls. Lifestyle measures have been shown to improve the various components of MS, and hence there is an urgent need for public health measures to prevent the ongoing epidemic of diabetes and CVD.

The plasma level and gene expression of resistin in polycystic ovary syndrome

OBJECTIVES

To investigate the relationship between plasma resistin, polycystic ovary syndrome (PCOS), and insulin resistance (IR). To compare the mRNA level of resistin in mononuclear cells and monocyte-derived macrophages in women with PCOS and controls.

MATERIALS AND METHODS

Patients with PCOS and controls were enrolled and IR was considered as the stratified factor for subgroups. Fasting blood was collected to determine the levels of sex hormones, insulin, glucose, blood lipid, and resistin. Resistin gene expression was evaluated by quantitative real-time RT-PCR in mononuclear cells and monocyte-derived macrophages cultured with or without rosiglitazone for 96 h.

RESULTS

No significant difference of plasma resistin levels was found among PCOS-IR, PCOS-non-IR, control-IR, and control-non-IR groups. There were no significant differences in resistin mRNA expression between participants with and without PCOS and with and without IR. Resistin mRNA expression in monocyte-derived macrophages was higher than that in mononuclear cells (p = 0.04), and could be reduced by rosiglitazone (p < 0.001).

CONCLUSIONS

Plasma resistin does not correlate with normal weight PCOS or IR. Resistin gene expression in mononuclear cells and monocyte-derived macrophages in PCOS and IR is the same as controls. Further researches on the role of resistin in the pathogenesis of PCOS or IR should concentrate on the tissue level.

Total and high-molecular weight adiponectin in women with the polycystic ovary syndrome

Adiponectin, an adipokine with antidiabetic properties, forms multimers; and the high-molecular weight (HMW) form most closely correlates with insulin sensitivity (S(i)). Therefore, we hypothesize that HMW adiponectin levels are decreased in women with polycystic ovary syndrome (PCOS), a condition characterized by insulin resistance, compared with healthy controls and that HMW adiponectin correlates with testosterone and S(i). A cross-sectional study involving 13 women with PCOS and 13 age- and body mass index-matched healthy controls was performed. Waist-to-hip ratios (WHRs), glucose, insulin, sex hormone-binding globulin, total testosterone, and total and HMW adiponectin levels were measured after an overnight fast. Free testosterone was calculated from sex hormone-binding globulin and total testosterone, and S(i) was determined using a frequently sampled intravenous glucose tolerance test. The study's primary outcomes were differences in total and HMW adiponectin between women with PCOS and healthy control women. Total adiponectin (P < .01), HMW adiponectin (P < .01), and the ratio of HMW to total adiponectin (P = .03) were lower in women with PCOS compared with healthy women. Total and HMW adiponectin levels correlated inversely with WHR (P < .01) and free testosterone (P < .01) and positively with S(i) (P < .001). Using forward stepwise multivariate analysis, HMW adiponectin and WHR, but not PCOS status, were independent predictors of S(i). Women with PCOS have lower total and HMW adiponectin levels compared with healthy women. High-molecular weight adiponectin also comprises a smaller proportion of total circulating adiponectin in women with PCOS. Alterations in HMW adiponectin levels in women with PCOS may contribute to the insulin resistance intrinsic to the syndrome.

Novel adiponectin-resistin (AR) and insulin resistance (IRAR) indexes are useful integrated diagnostic biomarkers for insulin resistance, type 2 diabetes and metabolic syndrome: a case control study

Background

Adiponectin and resistin are adipokines which modulate insulin action, energy, glucose and lipid homeostasis. Meta-analyses showed that hypoadiponectinemia and hyperresistinemia are strongly associated with increased risk of insulin resistance, type 2 diabetes (T2DM), metabolic syndrome (MS) and cardiovascular disease. The aim of this study was to propose a novel adiponectin-resistin (AR) index by taking into account both adiponectin and resistin levels to povide a better indicator of the metabolic homeostasis and metabolic disorders. In addition, a novel insulin resistance (IR_AR) index was proposed by integration of the AR index into an existing insulin resistance index to provide an improved diagnostic biomarker of insulin sensitivity.

Methods

In this case control study, anthropometric clinical and metabolic parameters including fasting serum total adiponectin and resistin levels were determined in 809 Malaysian men (208 controls, 174 MS without T2DM, 171 T2DM without MS, 256 T2DM with MS) whose ages ranged between 40-70 years old. Significant differences in continuous variables among subject groups were confirmed by ANCOVA or MANCOVA test using 1,000 stratified bootstrap samples with bias corrected and accelerated (BCa) 95% CI. Spearman's rho rank correlation test was used to test the correlation between two variables.

Results

The AR index was formulated as 1+log₁₀(R₀)-log₁₀(A₀). The AR index was more strongly associated with increased risk of T2DM and MS than hypoadiponectinemia and hyperresistinemia alone. The AR index was more strongly correlated with the insulin resistance indexes and key metabolic endpoints of T2DM and MS than adiponectin and resistin levels alone. The AR index was also correlated with a higher number of MS components than adiponectin and resistin levels alone. The IR_AR index was formulated as log₁₀(I₀G₀)+log₁₀(I₀G₀)log₁₀(R₀/A₀). The normal reference range of the IR_AR index for insulin sensitive individuals was between 3.265 and 3.538. The minimum cut-off values of the IR_AR index for insulin resistance assessment were between 3.538 and 3.955.

Conclusions

The novel AR and IR_AR indexes are cost-effective, precise, reproducible and reliable integrated diagnostic biomarkers of insulin sensitivity for screening subjects with increased risk of future development of T2DM and MS.

Serum resistin level in obese male children

Objectives. Resistin is a member of cysteine-rich molecules. Several studies have been carried out to determine the biological effect of resistin, nevertheless a significant number are animal studies. All the studies performed regarding the relationship between serum resistin and obesity were merely accomplished in women. To the best of our knowledge, there is no survey on the correlation of the serum resistin level and obesity in male children. The aim of the present study is to assess serum concentration of resistin in obese male children. Methods. Between June 2009 and January 2010, we enrolled 42 randomly selected obese male students (body mass index (BMI) >95th percentile, age 15.7 ± 1.5). Thirty-eight healthy age-matched male students with normal BMI (<85th percentile) were selected as a control group for the purpose of comparison of the serum resistin levels. Results. Serum resistin levels were measured in obese and control group. No significant difference was found between resistin levels of the 2 groups (obese: 9.21 ± 5.6 ng/mL versus normal: 9.83 ± 4.3 ng/mL; P = .582). There was no significant correlation between serum resistin level and BMI. Assessing the resistin level in male subjects was the distinct feature of our study. The outstanding finding of this research is that there is no correlation between serum resistin level and obesity. Conclusion. We have demonstrated that there is no correlation between obesity in male children and resistin level. Consequently, metabolic abnormalities of insulin resistance seen in obese male patients are not related to resistin.

Adipocyte factors, high-sensitive C-reactive protein levels and lipoxidative stress products in overweight postmenopausal women with normal and impaired OGTT

OBJECTIVE

In obese postmenopausal women we assessed leptin and adiponectin, high-sensitive C-reactive protein (hsCRP), serum lipids and lipoxidative stress products: oxidized LDL (oxLDL) and malondialdehyde (MDA), in relation to impaired glucose tolerance (IGT).

METHODS

Thirty-eight overweight/obese postmenopausal women were included in the study. Eighteen with normal glucose metabolism (NGT) and twenty with IGT, as it is diagnosed by OGTT. Serum leptin, adiponectin, hsCRP and MDA were measured at time 0 and 120 min of OGTT while total-cholesterol, LDL, HDL, triglycerides, oxLDL and anti-oxLDL autoantibodies at time 0. Insulin resistance (HOMA)/sensitivity (QUICKI) indexes were estimated.

RESULTS

In subjects with NGT, hsCRP was positively correlated with fasting leptin and HOMA, while in subjects with IGT negatively with QUICKI. In both groups, hsCRP was positively correlated with fasting insulin, body mass index and waist circumference. Fasting adiponectin was positively associated with HDL in both groups and negatively with triglycerides in subjects with NGT as well as with serum glucose levels at time 120 min of OGTT in subjects with IGT. No association was observed between oxLDL and adipokines. A significant positive association was found between oxLDL and HOMA in subjects with IGT. During OGTT there was a significant increase of leptin and MDA levels in both groups.

CONCLUSIONS

A relationship exists between obesity, insulin and sub-clinical inflammation. Leptin and lipid peroxidation are linked to hyperglycaemic state while oxLDL might be considered as a predictor of insulin resistance. Adiponectin could exert its antiatherogenic effect through HDL independently of the presence of IGT.

Gender differences in cardiovascular disease: hormonal and biochemical influences

OBJECTIVE

Atherosclerosis is a complex process characterized by an increase in vascular wall thickness owing to the accumulation of cells and extracellular matrix between the endothelium and the smooth muscle cell wall. There is evidence that females are at lower risk of developing cardiovascular disease (CVD) as compared to males. This has led to an interest in examining the contribution of genetic background and sex hormones to the development of CVD. The objective of this review is to provide an overview of factors, including those related to gender, that influence CVD.

METHODS

Evidence analysis from PubMed and individual searches concerning biochemical and endocrine influences and gender differences, which affect the origin and development of CVD.

RESULTS

Although still controversial, evidence suggests that hormones including estradiol and androgens are responsible for subtle cardiovascular changes long before the development of overt atherosclerosis.

CONCLUSION

Exposure to sex hormones throughout an individual's lifespan modulates many endocrine factors involved in atherosclerosis.

Adiponectin and polycystic ovary syndrome

INTRODUCTION

Polycystic ovary syndrome (PCOS) has a prevalence of 5-8% in women of reproductive age. Women with PCOS have an increased risk of metabolic syndrome and associated comorbidities. Adiponectin is a circulating protein produced by adipocytes. Circulating levels of adiponectin are inversely related to adipocyte mass. Low levels occur with insulin resistance, type 2 diabetes, metabolic syndrome, and obesity-related cardiovascular disease. This article reviews the literature on the link between adiponectin and PCOS and the potential use of adiponectin as a biomarker for PCOS.

METHOD

Data-based studies on adiponectin and PCOS and adiponectin measurement were identified through the Medline (1950-2009) and ISI Web of Knowledge (1973-2009) databases.

RESULTS

Fifteen studies related to adiponectin and PCOS met inclusion criteria and were included in this review. These studies present evidence that adiponectin is linked to insulin resistance, insulin sensitivity, body mass index (BMI), and adiposity. In women with PCOS, lower levels, as opposed to higher levels, of adiponectin occur in the absence of adiposity.

CONCLUSION

The relationships between adiponectin and insulin resistance and sensitivity, metabolic syndrome, and BMI in women with PCOS suggest that adiponectin potentially could serve as a marker for disease risk and provide opportunity for earlier intervention if knowledge is successfully translated from laboratory to clinical practice. However, further study of the relationship between adiponectin and PCOS is required before there can be direct application to clinical practice.

Adiponectin action from head to toe

Adiponectin, the most abundant protein secreted by white adipose tissue, is known for its involvement in obesity-related disorders such as insulin resistance, type 2 diabetes mellitus and atherosclerosis. Moreover, modulation of the circulating adiponectin concentration is observed in pathologies that are more or less obesity-related, such as cancer and rheumatoid arthritis. The wide distribution of adiponectin receptors in various organs and tissues suggests that adiponectin has pleiotropic effects on numerous physiological processes. Besides its well-known insulin-sensitizing, anti-inflammatory and antiatherosclerotic properties, accumulating evidence suggests that adiponectin may also have anticancer properties and be cardioprotective. A beneficial effect of adiponectin on female reproductive function was also suggested. Since adiponectin has numerous beneficial biological functions, its use as a therapeutic agent has been suggested. However, the use of adiponectin or its receptors as therapeutic targets is complicated by the presence of different adiponectin oligomeric isoforms and production sites, by multiple receptors with differing affinities for adiponectin isoforms, and by cell-type-specific effects in different tissues. In this review, we discuss the known and potential roles of adiponectin in various tissues and pathologies. The therapeutic promise of administration of adiponectin and the use of its circulating levels as a diagnostic biomarker are further discussed based on the latest experimental studies.

Adiponectin and resistin concentrations after glucose load in adolescents with polycystic ovary syndrome

Our aims were to evaluate the serum adiponectin and resistin levels at fasting and after glucose load and their interaction with risk of cardiovascular disease (CVD) in adolescents with polycystic ovary syndrome (PCOS). Twenty-two adolescents with PCOS and 16 healthy controls were included in the study. Oral glucose tolerance test (OGTT) was performed in all adolescents. Fasting lipids was measured. Insulin, glucose, adiponectin, and resistin levels were measured at 0 and 120 min of OGTT. Homeostasis model assessment of insulin resistance (HOMA-IR), quantitative insulin-sensitivity check index (QUICKI), fasting glucose-to-insulin ratio (FGIR), and the whole -body insulin sensitivity index (ISI) were calculated. Fasting adiponectin was correlated with ISI (r = 0.729, p < 0.0001), FGIR (r = 0.696, p < 0.0001), QUICKI (r = 0.592, p = 0.004) and HDL-C (r = 0.516, p = 0.028), systolic blood pressure (r = -0.732, p < 0.0001), body mass index (r = -0.738, p < 0.0001), waist circumference (r = -0.706, p < 0.0001), and HOMA-IR (r = -0.595, p = 0.003). No correlation was found between resistin and insulin resistance indexes. Obese adolescents with PCOS have increased CVD risk such as dyslipidemia, hypertension, and insulin resistance than normo-weight PCOS. Hypoadiponectinaemia could be increase risks levels in obese girls with PCOS.

Serum resistin and adiponectin levels in women with polycystic ovary syndrome

AIM

This study was performed to compare the serum levels of resistin and adiponectin in women with polycystic ovary syndrome (PCOS) and normal controls.

MATERIALS AND METHODS

Seventy-six patients (36 obese, 40 non-obese) with PCOS and 42 healthy subjects were included in the study. Serum levels of resistin, adiponectin, follicle-stimulating hormone, luteinising hormone, dehydroepiandrosterone sulfate (DHEA-S), 17-hydroxy progesterone, free testosterone, androstenedione, glucose, insulin and lipid parameters were measured. Insulin resistance and carbohydrate metabolism were evaluated by using the homeostasis model (HOMA) and the area under the insulin curve (AUCI).

RESULTS

Plasma resistin levels, HOMA-IR and AUCI were significantly higher and adiponectin level was lower in women with PCOS than those in healthy women. Plasma resistin levels were similar among obese and non-obese women with PCOS. No correlation was observed between resistin, body mass index (BMI), HOMA-IR, AUCI, insulin, lipid parameters and serum androgen levels. In obese PCOS patients, adiponectin levels were lower than in the lean PCOS patients. A negative correlation was observed among adiponectin, HOMA-IR, AUCI, BMI, testosterone, DHEAS, total-cholesterol, LDL-cholesterol and lipoprotein (a) levels.

CONCLUSION

These results suggest that the serum adiponectin level may be involved in the pathogenesis of PCOS. But resistin levels were independently associated with insulin resistance and BMI in PCOS patients. Nevertheless, wider-scale trials are required to be performed on this subject.

Serum resistin correlates with central obesity but weakly with insulin resistance in Chinese children and adolescents

OBJECTIVE

Resistin has been linked with obesity and hypothesized as a potential marker of insulin resistance in addition to being linked with acute inflammation. However, these links are still highly controversial in humans. Our goal was to examine resistin levels in relation to obesity, insulin resistance and inflammation markers in a large population of Asian children and adolescents.

METHODS

Children and adolescents (n=3472) aged 6-18 years, boys (n=1765) and girls (n=1707), were assessed for body size parameters, pubertal development, blood lipids, glucose, insulin, resistin, C-reactive protein (CRP), adiponectin and complement C3 (C3) levels.

RESULTS

Resistin increased with central obesity in both genders but not with simple adiposity in boys. Several markers associated with central obesity correlated in a gender-specific fashion with plasma resistin. Waist circumference, fat-mass percentage, waist-to-height ratio and body mass index (BMI) positively correlated with resistin in both genders. Blood lipids such as triglycerides, nonesterified fatty acids (NEFA) and low-density lipoprotein cholesterol, diastolic and systolic blood pressure correlated positively with resistin in boys. NEFA, high-density lipoprotein cholesterol (negatively) and inflammation markers, such as CRP and C3, positively correlated with resistin in girls. There was no correlation between resistin and adiponectin, and no association of adiponectin with resistin quintiles in either boys or girls. In both boys and girls, resistin tended to decrease with age, with girls having higher levels than boys. Few indices of insulin resistance were linked with plasma resistin in either gender.

CONCLUSION

In this population, plasma resistin levels are a weak biochemical marker of metabolic dysfunction defined by central obesity, adiposity and inflammation and does not predict insulin resistance. Only a small proportion of resistin variation can be explained by factors related to metabolic syndrome, suggesting that resistin is not strongly implicated in a concentration-dependent fashion in any of the examined pathologies.

Role of adiponectin in regulating ovarian theca and granulosa cell function

Adiponectin is an adipokine that has been implicated in insulin resistance, a condition associated with polycystic ovarian syndrome in humans, but whether adiponectin can directly affect ovarian theca or granulosa cell function is unknown. Therefore, to determine the effects of adiponectin on proliferation, steroidogenesis and gene expression of large-follicle theca and granulosa cells, experiments were conducted using bovine ovarian cell cultures. RT-PCR was used to elucidate the effects of adiponectin on gene expression of CYP11A1 and LH receptor (LHR) in large-follicle theca and granulosa cells, as well as expression of CYP17A1 in theca cells and CYP19A1 in granulosa cells. Adiponectin decreased (P<0.05) insulin-induced progesterone and androstenedione production as well as attenuated IGF-I-induced LHR, CYP11A1, and CYP17A1 gene expression in theca cells. In contrast, adiponectin decreased (P<0.05) LHR mRNA abundance in granulosa cells but did not affect steroidogenic enzyme gene expression in granulosa cells. Adiponectin had no effect (P>0.10) on proliferation of large-follicle theca cells. RT-PCR also revealed that abundance of mRNA for the adiponectin receptor (ADIPOR2) was greater (P<0.05) in large-follicle than in small-follicle theca cells and did not significantly differ between small- and large-follicle granulosa cells. In cultured theca cells, LH increased (P<0.05) and IGF-I decreased (P<0.05) ADIPOR2 mRNA abundance. These results indicate that the inhibitory effects of adiponectin on steroidogenesis are primarily localized to theca cells and that the response of theca cells to adiponectin (i.e., ADIPOR2) may be regulated by LH and IGF-I.

Serum resistin is reduced by glucose and meal loading in healthy human subjects

Resistin is an adipokine that induces insulin resistance in mice; serum concentrations are decreased by fasting and increased by feeding. Adiponectin, another adipokine, improves insulin sensitivity. The aims of this study were to determine the effects of glucose and meal loading on serum resistin and total and high-molecular weight (HMW) adiponectin in humans and to explore potential determinants of fasting serum resistin and of changes in resistin. Serum resistin and total and HMW adiponectin were measured by enzyme-linked immunosorbent assay in young, lean, nondiabetic subjects during 75-g oral glucose tolerance test (OGTT) and meal tolerance test (MTT). Resistin single nucleotide polymorphism (SNP) -420 was typed. Serum resistin was decreased at 60 and 120 minutes during OGTT compared with baseline (n = 36, 1-way repeated-measures analysis of variance, P < .0001; Scheffe, P = .0457 and P < .0001, respectively). Serum resistin was also reduced at 240 minutes during MTT (n = 33, 1-way repeated measures analysis of variance, P < .0001; Scheffe, P = .0002). Multiple regression analysis adjusted for age, sex, and body mass index revealed that the reductions in serum resistin were dependent on baseline resistin levels. Subjects with greater baseline concentrations of resistin experienced more pronounced declines in resistin (OGTT, unstandardized regression coefficient (beta) = -0.19, P = .0005; MTT, beta = -0.63, P < .0001). Serum total and HMW adiponectin was unchanged. Fasting serum resistin was positively correlated with the G allele number of SNP -420 (beta = 7.70, P = .01) and white blood cell count (beta = 0.007, P = .0001) adjusted for age, sex, and body mass index. Therefore, in young, lean, nondiabetic humans, serum resistin was reduced by glucose and meal loading; the reduction in resistin was greater in subjects with higher fasting resistin. Fasting resistin was correlated with SNP -420 and white blood cell count.

Prevalence of the metabolic syndrome in Asian women with polycystic ovary syndrome: using the International Diabetes Federation criteria

BACKGROUND

Since insulin resistance and compensatory hyperinsulinemia are the major causes of the metabolic syndrome (MS) and are also the main pathophysiology of polycystic ovary syndrome (PCOS), PCOS women are at risk of MS. The aim of the present cross-sectional study was to determine the prevalence of MS in Asian women with PCOS using the International Diabetes Federation (IDF) criteria and to define the risk factors.

METHODS

One hundred and seventy women with PCOS were enrolled in the study from September 3, 2002 to June 14, 2005. A 75-g oral glucose tolerance test with plasma glucose and serum insulin levels was performed. Also, blood samples were examined for fasting triglycerides, high-density lipoprotein cholesterol and adiponectin levels.

RESULTS

The mean (+/-standard deviation) age, body mass index (BMI) and waist-to-hip ratio were 28.8+/-5.9 years, 27.1 +/- 7.0 kg/m(2) and 0.85+/-0.06, respectively. The prevalence of MS was 35.3%. Age, BMI, waist circumference and all metabolic parameters were higher in PCOS women with MS than in those without MS. MS prevalence increased with age, BMI and insulin resistance as determined by homeostasis model assessment (HOMA-IR), but not with adiponectin after BMI adjustment.

CONCLUSIONS

According to the IDF criteria, one-third of the PCOS women had MS. This study also showed that age, BMI and HOMA-IR are important risk factors for MS.

Plasma levels of leptin, omentin, collagenous repeat-containing sequence of 26-kDa protein (CORS-26) and adiponectin before and after oral glucose uptake in slim adults

BACKGROUND

Adipose tissue secreted proteins are collectively named adipocytokines and include leptin, adiponectin, resistin, collagenous repeat-containing sequence of 26-kDa protein (CORS-26) and omentin. Several of these adipocytokines influence insulin sensitivity and glucose metabolism and therefore systemic levels may be affected by oral glucose uptake. Whereas contradictory results have been published for leptin and adiponectin, resistin has not been extensively investigated and no reports on omentin and CORS-26 do exist.

METHODS

Therefore the plasma levels of these proteins before and 120 min after an oral glucose load were analyzed in 20 highly-insulin sensitive, young adults by ELISA or immunoblot.

RESULTS

Circulating leptin was reduced 2 h after glucose uptake whereas adiponectin and resistin levels are not changed. Distribution of adiponectin and CORS-26 isoforms were similar before and after glucose ingestion. Omentin is highly abundant in plasma and immunoblot analysis revealed no alterations when plasma levels before and 2 h after glucose intake were compared.

CONCLUSION

Taken together our data indicate that only leptin is reduced by glucose uptake in insulin-sensitive probands whereas adiponectin and resistin are not altered. CORS-26 was demonstrated for the first time to circulate as high molecular weight form in plasma and like omentin was not influenced by oral glucose load. Omentin was shown to enhance insulin-stimulated glucose uptake but systemic levels are not correlated to postprandial blood glucose.

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.

Adipose tissue resistin levels in patients with anorexia nervosa

OBJECTIVE

Resistin is a specific fat-derived hormone that affects fuel homeostasis and insulin action in rodents. However, its role in human physiology and pathophysiologic conditions, such as malnutrition, remains uncertain.

METHODS

To enhance understanding of the role of resistin in the pathophysiology of anorexia nervosa (AN), we measured plasma resistin levels in 13 women with a restrictive type of AN and in 16 healthy age-matched women (control). Further, we measured resistin levels in the subcutaneous adipose tissue of eight women from the AN group and eight women from the control group with an in vivo microdialysis technique (CMA/107 pump, CMA/60 catheters, CMA Microdialysis AB, Solna, Sweden).

RESULTS

Body mass index, percentage of body fat, fasting plasma leptin and insulin, and homeostasis model assessment index for insulin resistance were severely decreased in patients with AN compared with the control group. Plasma resistin levels were significantly decreased in patients with AN (P < 0.05), whereas subcutaneous adipose tissue resistin levels were significantly increased in patients with AN compared with the control group (P < 0.05). In both groups, plasma resistin levels showed no significant relation to resistin in dialysate, percentage of body fat, body mass index, homeostasis model assessment index for insulin resistance, and fasting plasma leptin levels.

CONCLUSION

We demonstrated that AN is associated with decreased plasma resistin levels and increased resistin levels in extracellular space of the abdominal adipose tissue. Plasma resistin levels in patients with AN or in healthy normal-weight women were not directly related to body mass index, percentage of body fat, plasma leptin levels, and insulin sensitivity.

Plasma adipokines and body composition in response to modest dietary manipulations in the mouse

OBJECTIVE

The relationship between adipokine levels and body composition has not been carefully examined. Most studies in humans are cross-sectional, and the few studies in mice have been restricted to a comparison of control animals with markedly obese, insulin-resistant mice. Our objective was to study changes in adipokine levels and body composition in response to modest dietary intervention.

RESEARCH METHODS AND PROCEDURES

Plasma resistin, adiponectin, and leptin levels were examined in mice fed ad libitum, a 75% restricted diet, or a diet supplemented with 10% sucrose. Body composition was determined by whole-body DXA.

RESULTS

The percentage body fat was reduced in mice subjected to the restricted diet and increased in mice supplemented with 10% dextrose. Adipokine levels were not different in either of these groups compared with the control mice. A significant inverse correlation was observed between resistin levels and total body fat, whereas there was no significant correlation between body fat and adiponectin levels. Positive correlations were observed between leptin levels and percentage body fat, total body fat, and abdominal fat. Leptin levels correlated with plasma glucose, but multivariate analysis revealed that this correlation was the result of a strong positive correlation between leptin and insulin levels. There were no correlations between glycemia and resistin or glycemia and adiponectin levels, and no correlation was observed between any of the adipokine levels and bone mineral content or density.

DISCUSSION

These data suggest that in the mouse, modest dietary perturbations have little effect on resistin and adiponectin levels despite significant effects on glycemia, insulin levels, and bone parameters.

Resistin

PURPOSE OF REVIEW

Resistin, a cysteine-rich 12.5 kDa polypeptide, is a recently discovered adipocytokine with a controversial history regarding its role in the pathogenesis of obesity-mediated insulin resistance and type 2 diabetes mellitus. Whilst current studies appear to re-affirm the role of resistin on glucose homeostasis in rodent systems, we are still unravelling the functionality of resistin in human biology in respect to glucose metabolism and insulin signalling. This review will summarize the current knowledge, put into context the developments to date and discuss the controversial points.

RECENT FINDINGS

Current evidence appears to suggest that resistin is a pro-inflammatory cytokine. Thus, like many other adipocytokines, resistin may possess a dual role in contributing to metabolic disease: first through its direct effects on substrate metabolism and second, through regulating inflammation within its target tissues. The chemistry of resistin has also been the subject of investigation and like adiponectin, the homo-oligomerization of this protein has a bearing on its function.

SUMMARY

The most recent advances include the identification of circulating higher molecular weight structures of resistin in both rodent and human serum. This has been complemented by work casting light on the function and purpose of multimeric resistin in mice. Resistin appears to have effects on substrate metabolism through impairment of insulin action, particularly in the liver, but in addition, also has effects on insulin independent pathways.

Gender differences in the metabolic syndrome and their role for cardiovascular disease

Women live longer than men and develop cardiovascular disease (CVD) at an older age. The metabolic syndrome represents a major risk factor for the development of CVD, and gender differences in this syndrome may contribute to gender differences in CVD. In recent years, the metabolic syndrome has been more prevalent in men than in women. Prevalence is increasing and this increase has been steeper in women, particularly in young women, during the last decade. The contributions of the different components of the metabolic syndrome differ between genders and in different countries. In a recent survey in Germany, 40% of the adult population had been diagnosed with disturbed glucose tolerance or type 2 diabetes. Undiagnosed diabetes was more frequent in men than in women, and risk factors for undiagnosed diabetes differed between the sexes. Worldwide, in individuals with impaired glucose tolerance, impaired fasting glucose was observed more frequently in men, whereas impaired glucose tolerance occurred relatively more often in women. Lipid accumulation patterns differ between women and men. Premenopausal women more frequently develop peripheral obesity with subcutaneous fat accumulation, whereas men and postmenopausal women are more prone to central or android obesity. In particular, android obesity is associated with increased cardiovascular mortality and the development of type 2 diabetes. Visceral adipocytes differ from peripheral adipocytes in their lipolytic activity and their response to insulin, adrenergic and angiotensin stimulation and sex hormones. Visceral fat is a major source of circulating free fatty acids and cytokines, which are directly delivered via the portal vein to the liver inducing insulin resistance and an atherogenic lipid profile. Inflammation increases cardiovascular risk particularly in women. A relatively greater increase in cardiovascular risk by the appearance of diabetes in women has been reported in many studies.Thus, the presently available data suggest that the pathophysiology of the metabolic syndrome and its contribution to the relative risk of cardiovascular events and heart failure show gender differences, which might be of potential relevance for prevention, diagnostics, and therapy of the syndrome.