Circulating and cellular adiponectin in polycystic ovary syndrome: relationship to glucose tolerance and insulin action

Evaluation of serum adiponectin as a marker of insulin resistance in women with polycystic ovarian syndrome: a comparative cross-sectional study

BACKGROUND

Insulin resistance (IR) is known to be prevalent amongst women with polycystic ovarian syndrome (PCOS). Its presence has been linked to chronic anovulation and marked long term complications in women. Hence, identification and treatment of IR in women with PCOS is required to prevent the metabolic and reproductive complications of the disease. The aim of this study is to determine if serum adiponectin could be used as a surrogate marker for insulin resistance among women with PCOS.

MATERIALS AND METHODS

A total number of 148 consenting women with PCOS diagnosed using the Rotterdam criteria were recruited for this study. Fifty-two of these women had insulin resistance were compared with 96 of the women who did not have insulin resistance. The serum Adiponectin levels, fasting blood glucose and fasting insulin levels were assayed in all study participants. Insulin resistance was assessed in all the study participants using the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR). Data were analyzed using relevant inferential statistics at 95% confidence interval and p value of < 0.05.

RESULTS

The prevalence of insulin resistance among the study participants was 35.1%. Majority of the women (83.1%) had a high body mass index (BMI). More than half (68.2%) of the participants were in the age range of 21-30years and 76.4% (113) were nulliparous. There was no statistically significant difference in the median adiponectin level among insulin resistant (3.735 ug/ml) and non-insulin resistant participants vs. (3.705 ug/ml) (p = 0.6762). Both univariate and multivariate regression analysis did not show a statistically significant relationship between adiponectin and insulin resistance in PCOS.

CONCLUSION

The prevalence of insulin resistance in women with PCOS is high and serum adiponectin is not a suitable surrogate marker of insulin resistance in women with PCOS.

Role of leptin, adiponectin, and kisspeptin in polycystic ovarian syndrome pathogenesis

INTRODUCTION

Polycystic ovarian syndrome (PCOS) affects 5-20% of females and is the most common cause of anovulatory infertility. Leptin seems to have an important role in reproduction. Many reproductive pathologies such as preeclampsia, PCOS, and endometriosis are associated to plasma adiponectin levels. Kisspeptin levels are increased in PCOS women.

EVIDENCE ACQUISITION

A review of the literature was completed through the PubMed database aiming to find articles regarding leptin, adiponectin and kisspeptin and if they are related to PCOS pathogenesis.

EVIDENCE SYNTHESIS

Even today it is not clear what is the role of leptin in women with PCOS, although most of the researchers found increased levels of leptin as well as leptin resistance in PCOS (both obese and lean individuals). Many more longitudinal studies should be done to discover the usefulness of measuring adiponectin in prepubertal women who apparently have a possibility to develop PCOS to find out if they finally develop PCOS. Most of the researchers found that PCOS women have decreased levels of adiponectin unrelated to BMI levels. Nevertheless, not all studies had the same result. Moreover, it is necessary more studies to be made to investigate the connection between kisspeptin and other metabolic factors such as LH and insulin resistance.

CONCLUSIONS

In general, it remains inconclusive whether leptin, adiponectin, and kisspeptin can be used as clinical and/or biochemical markers of PCOS. Therefore, it is essential to review the current data with regards to the association between PCOS and circulating leptin, adiponectin, and kisspeptin in women with PCOS.

A Study of Serum Adiponectin Levels in Patients with Polycystic Ovarian Syndrome and its Correlation with Various Cardiometabolic Risk Markers

Background

Polycystic ovarian syndrome (PCOS) is the most common metabolic disorder in the reproductive age group, the pathogenesis of which is constantly evolving with the discovery of novel molecules and the lookout for potential therapeutic targets.

Aims

The aim of the present study was to estimate the circulating levels of serum adiponectin in patients with PCOS compared to controls and to find its correlation with markers of cardiovascular risk, with special emphasis on circulating levels of oxidised low-density lipoprotein (oxLDL).

Settings and Design

In this cross-sectional observational study recently diagnosed, PCOS subjects were compared with age- and body mass index (BMI)-matched controls.

Materials and Methods

All the included subjects underwent detailed clinical, biochemical and hormonal evaluation, including lipid profile, 75 g oral glucose tolerance test, fasting serum insulin, fasting serum adiponectin, oxLDL, total testosterone and anti-Mullerian hormone.

Statistical Analysis Used

Appropriate statistical methods were performed using SPSS (version 21) and Microsoft Excel (2019).

Results

A total of 56 PCOS cases and 32 controls were included in the study. Mean values of serum adiponectin (μg/mL) in our study were found to be significantly lower in PCOS cases (11.53 ± 4.74) versus controls (14.73 ± 5.61) irrespective of BMI. Mean values of serum oxLDL (μg/dL) were found to be higher in PCOS cases (157.96 ± 53.89) versus controls (117.52 ± 45.44), with a significant negative correlation between adiponectin and oxLDL in cases. No difference in levels of adiponectin was found between the different PCOS phenotypes.

Conclusion

Hypoadiponectinaemia was found to be associated with PCOS irrespective of obesity in PCOS subjects. Serum oxLDL can complement adiponectin as early predictor of CV risk in PCOS.

Markers of insulin resistance in Polycystic ovary syndrome women: An update

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders, affecting 5%-10% of women of reproductive age. The importance of this syndrome lies in the magnitude of associated comorbidities: infertility, metabolic dysfunction, cardiovascular disease (CVD), plus psychological and oncological complications. Insulin resistance (IR) is a prominent feature of PCOS with a prevalence of 35%-80%. Without adequate management, IR with compensatory hyperinsulinemia contributes directly to reproductive dysfunction in women with PCOS. Furthermore, epidemiological data shows compelling evidence that PCOS is associated with an increased risk of impaired glucose tolerance, gestational diabetes mellitus and type 2 diabetes. In addition, metabolic dysfunction leads to a risk for CVD that increases with aging in women with PCOS. Indeed, the severity of IR in women with PCOS is associated with the amount of abdominal obesity, even in lean women with PCOS. Given these drastic implications, it is important to diagnose and treat insulin resistance as early as possible. Many markers have been proposed. However, quantitative assessment of IR in clinical practice remains a major challenge. The gold standard method for assessing insulin sensitivity is the hyperinsulinemic euglycemic glucose clamp. However, it is not used routinely because of the complexity of its procedure. Consequently, there has been an urgent need for surrogate markers of IR that are more applicable in large population-based epidemiological investigations. Despite this, many of them are either difficult to apply in routine clinical practice or useless for women with PCOS. Considering this difficulty, there is still a need for an accurate marker for easy, early detection and assessment of IR in women with PCOS. This review highlights markers of IR already used in women with PCOS, including new markers recently reported in literature, and it establishes a new classification for these markers.

Adiponectin levels and its relation with insulin secretion and insulin sensitivity in a group of sub-Saharan African women with polycystic ovary syndrome

Objectives

Low levels of adiponectin have been reported in Polycystic Ovary Syndrome (PCOS). In sub-Saharan Africa, little data are available on the topic. We aimed to investigate the levels of adiponectin and its relation with insulin secretion and insulin sensitivity in women with PCOS in Yaoundé, Cameroon. A comparative cross-sectional study was conducted in 32 women presenting PCOS and 32 controls matched for age and Body Mass Index. For each participant, adiponectin levels were measured. We estimated insulin sensitivity using Homeostasis model index (HOMA-IR) and insulin secretion with C-peptide levels.

Results

Women with PCOS had higher insulin secretion levels than controls (C-peptide: 4.98 ± 3.83 vs 3.25 ± 1.62 mUI/l; p = 0.02). Also, the HOMA-IR index was higher compared to that of women without PCOS (1.15 ± 0.90 vs 0.77 ± 0.38; p = 0.03) suggesting greater insulin resistance. The median [25th–75th percentile] values of adiponectin concentrations were similar between the two groups (22.68 [21.72–23.41] μg/ml vs 22.03 [21.40–22.93] μg/ml; p = 0.1). There was no association between insulin sensitivity and adiponectin levels in the PCOS group. PCOS is not associated with changes in adiponectin in a population of sub-Saharan African women. Further studies are needed to shed more light on this condition.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05878-0.

Protective effects of intracerebroventricular adiponectin against olfactory impairments in an amyloid β1-42 rat model

BACKGROUND

Alzheimer's disease (AD) is characterized by cognitive impairment that eventually develops into dementia. Amyloid-beta (Aβ) accumulation is a widely described hallmark in AD, and has been reported to cause olfactory dysfunction, a condition considered an early marker of the disease associated with injuries in the olfactory bulb (OB), the hippocampus (HIPP) and other odor-related cortexes. Adiponectin (APN) is an adipokine with neuroprotective effects. Studies have demonstrated that APN administration decreases Aβ neurotoxicity and Tau hyperphosphorylation in the HIPP, reducing cognitive impairment. However, there are no studies regarding the neuroprotective effects of APN in the olfactory dysfunction observed in the Aβ rat model. The aim of the present study is to determine whether the intracerebroventricular (i.c.v) administration of APN prevents the early olfactory dysfunction in an i.c.v Amyloid-beta1-42 (Aβ1-42) rat model. Hence, we evaluated olfactory function by using a battery of olfactory tests aimed to assess olfactory memory, discrimination and detection in the Aβ rat model treated with APN. In addition, we determined the number of cells expressing the neuronal nuclei (NeuN), as well as the number of microglial cells by using the ionized calcium-binding adapter molecule 1 (Iba-1) marker in the OB and, CA1, CA3, hilus and dentate gyrus (DG) in the HIPP. Finally, we determined Arginase-1 expression in both nuclei through Western blot.

RESULTS

We observed that the i.c.v injection of Aβ decreased olfactory function, which was prevented by the i.c.v administration of APN. In accordance with the olfactory impairment observed in i.c.v Aβ-treated rats, we observed a decrease in NeuN expressing cells in the glomerular layer of the OB, which was also prevented with the i.c.v APN. Furthermore, we observed an increase of Iba-1 cells in CA1, and DG in the HIPP of the Aβ rats, which was prevented by the APN treatment.

CONCLUSION

The present study describes the olfactory impairment of Aβ treated rats and evidences the protective role that APN plays in the brain, by preventing the olfactory impairment induced by Aβ1-42. These results may lead to APN-based pharmacological therapies aimed to ameliorate AD neurotoxic effects.

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.

Relationship between adipocytokines and angiotensin converting enzyme gene insertion/deletion polymorphism in lean women with and without polycystic ovary syndrome

This study was designed to investigate the relationship between the levels of select adipocytokines (adiponectin, visfatin and apelin) and angiotensin in converting enzyme (ACE) gene insertion/deletion (ID) polymorphism in lean women with and without polycystic ovary syndrome (PCOS). The PCOS group (N = 94) was identified according to the Rotterdam criteria. The Control group (N = 68) included age- and body mass index (BMI)-matched healthy volunteers. Serum levels of adipocytokines were measured using enzyme immunoassays (EIA) and ACE genes were evaluated by polymerase chain reaction (PCR). The PCOS group, when compared to the Control group had lower adiponectin (p < .001) but higher visfatin (p < .001) and apelin (p = .003). There was no significant correlation of the levels of these adipocytokines with BMI, fasting glucose, fasting insulin or Homeostasis Model Assessment-Insulin Resistance (HOMA-IR). The PCOS and the Control groups also differed with regard to the ACE ID genotype distribution (p < .001). The ID, DD, and II genotype frequencies were, respectively, 34, 57 and 9% in the PCOS group and 49, 22 and 29% in the Control group. When stratified according to individual ID genotypes, the levels of adipocytokines in the PCOS and the Control groups remained significantly different. There was no statistically significant relationship between the levels of adipocytokines and ACE ID genotypes.

Serum Anti-Müllerian Hormone in Polycystic Ovary Syndrome and its Relationship with Insulin Resistance, Lipid Profile and Adiponectin

OBJECTIVES

This study was done to estimate serum anti-Müllerian hormone (AMH) level in polycystic ovary syndrome (PCOS) patients and to correlate serum AMH level with insulin resistance, lipid profile, and adiponectin levels.

MATERIALS AND METHODS

A cross-sectional study was conducted at Hospital Universiti Sains Malaysia (Hospital USM), Health Campus, Kubang Kerian, Kelantan, Malaysia. Thirty newly diagnosed patients with PCOS attending gynecology clinic between July 2016 and April 2017 were recruited. Fasting venous blood samples were collected from the subjects. Serum AMH, insulin, adiponectin, triglycerides, high-density lipoprotein cholesterol (HDL-C), and plasma glucose levels were measured, and insulin resistance was calculated based on homeostasis model of assessment-insulin resistance (HOMA-IR). The serum AMH level was estimated, and the correlation of serum AMH level with the metabolic parameters was analyzed.

RESULTS

The median of serum AMH levels in women with PCOS was 6.8 ng/mL (interquartile range: 7.38 ng/mL). There was a significant negative correlation between serum AMH and HOMA-IR or triglyceride levels (r = -0.49, P = 0.006 and r = -0.55, P = 0.002, respectively). A significant positive correlation was observed between serum AMH and serum HDL-C or serum adiponectin levels (r = 0.56, P = 0.001 and r = 0.44, P = 0.014, respectively) in all study subjects.

CONCLUSION

The serum AMH level is associated with HOMA-IR, triglycerides, HDL-C, and adiponectin levels, and hence it may be used as a potential cardiometabolic risk marker in women with PCOS.

The Role of Adiponectin in the Pathogenesis of Metabolic Disturbances in Patients With Schizophrenia

Antipsychotic-induced metabolic disturbance is a common adverse event occurring in patients treated with antipsychotic drugs. The mechanisms underlying metabolic dysregulation are complex, involving various neurochemical and hormonal systems, the interaction of genetic and lifestyle risk factors, and the antipsychotic drug prescribed. Recently, there has been increasing interest in the relationship between antipsychotic-induced metabolic disturbances and body weight regulatory hormones such as adiponectin. Adiponectin, an adipocyte-derived protein related to insulin sensitivity, weight gain, and anti-inflammation, has attracted great attention because of its potential role of being a biomarker to predict cardiovascular and metabolic diseases. Previous studies regarding the effects of antipsychotics on blood adiponectin levels have shown controversial results. Several factors might contribute to those inconsistent results, including different antipsychotic drugs, duration of antipsychotic exposure, age, sex, and ethnicity. Here we summarize the existing evidence on the link between blood adiponectin levels and metabolic disturbances related to antipsychotic drugs in patients with schizophrenia. We further discuss the effects of individual antipsychotics, patients' gender, ethnicity, age, and treatment duration on those relationships. We propose that olanzapine and clozapine might have a time-dependent biphasic effect on blood adiponectin levels in patients with schizophrenia.

Adiponectin: A New Regulator of Female Reproductive System

Adiponectin is the hormone that belongs to the group of adipokines, chemical agents mainly derived from the white adipose tissue. The hormone plays pleiotropic roles in the organism, but the most important function of adiponectin is the control of energy metabolism. The presence of adiponectin and its receptors in the structures responsible for the regulation of female reproductive functions, such as hypothalamic-pituitary-gonadal (HPG) axis, indicates that adiponectin may be involved in the female fertility regulation. The growing body of evidence suggests also that adiponectin action is dependent on the actual and hormonal status of the animal. Present study presents the current knowledge about the presence and role of adiponectin system (adiponectin and its receptors: AdipoR1 and AdipoR2) in the ovaries, oviduct, and uterus, as well as in the hypothalamus and pituitary, the higher branches of HPG axis, involved in the female fertility regulation.

L:A ratio, Insulin resistance and metabolic risk in women with polycystic ovarian syndrome

BACKGROUND AND AIMS

The plasma leptin-adiponectin ratio (L:A) has been suggested as a one of the potentially independent predictor of metabolic risk and Insulin resistance in women with polycystic ovarian syndrome (PCOS).

METHODS

This is a case-control study, total 439 female subjects, comprises in to two group 223 cases (PCOS) and 216 control (non-PCOS women) according to their clinical characteristics. Further both case and control group were sub-grouped in PCOS and non-PCOS with metabolic syndrome (wMetS) and without metabolic syndrome (woMetS) as per National Cholesterol Education Program Treatment Panel (NCEPATP) guidelines. Anthropometrical measurements and biochemical analysis were done. Leptin and adiponectin level were estimated by enzyme-linked immunosorbent assay.

RESULTS

Results indicated that SAD, WHR, BMI, BP, lipid profile, FPG, fasting plasma insulin, IR (HOMA-IR), leptin and L:A ratio were significantly higher (p=<0.001) in PCOS women compare to non PCOS. Furthermore anthropometrical values and level of FPG, TC, TG, Insulin, IR (HOMA-IR) and L:A ratio were significantly high (p=<0.001) in PCOS wMetS compare woMetS, however HDL (p=<0.001) and adiponectin level (p=<0.001) were significantly low. The same trend was also found in comparison between with and without MetS among non-PCOS women. The correlation between L:A Ratio with different metabolic risk markers, L:A ratio was positively significant with SAD (r=0.97, p <0.001), FPG (r=0.96, p<0.001), TC (r=0.44, p<0.001), insulin (r=0.98, p<0.001), IR (r=0.97, p<0.001), Adiponectin (r=0.21, p<0.01) and negatively significant with HDL(r=-0.42, p<0.001) in PCOS wMetS whereas L:A ratio was also positively correlated with SAD, BMI, TG in PCOS woMetS.

CONCLUSIONS

Study concluded L:A ratio may be one of the potential biomarker for metabolic syndrome and insulin resistance which is independent for presence of PCOS disease.

Characterization of visceral and subcutaneous adipose tissue transcriptome in pregnant women with and without spontaneous labor at term: implication of alternative splicing in the metabolic adaptations of adipose tissue to parturition

OBJECTIVE

The aim of this study was to determine gene expression and splicing changes associated with parturition and regions (visceral vs. subcutaneous) of the adipose tissue of pregnant women.

STUDY DESIGN

The transcriptome of visceral and abdominal subcutaneous adipose tissue from pregnant women at term with (n=15) and without (n=25) spontaneous labor was profiled with the Affymetrix GeneChip Human Exon 1.0 ST array. Overall gene expression changes and the differential exon usage rate were compared between patient groups (unpaired analyses) and adipose tissue regions (paired analyses). Selected genes were tested by quantitative reverse transcription-polymerase chain reaction.

RESULTS

Four hundred and eighty-two genes were differentially expressed between visceral and subcutaneous fat of pregnant women with spontaneous labor at term (q-value <0.1; fold change >1.5). Biological processes enriched in this comparison included tissue and vasculature development as well as inflammatory and metabolic pathways. Differential splicing was found for 42 genes [q-value <0.1; differences in Finding Isoforms using Robust Multichip Analysis scores >2] between adipose tissue regions of women not in labor. Differential exon usage associated with parturition was found for three genes (LIMS1, HSPA5, and GSTK1) in subcutaneous tissues.

CONCLUSION

We show for the first time evidence of implication of mRNA splicing and processing machinery in the subcutaneous adipose tissue of women in labor compared to those without labor.

Downregulation of adiponectin system in granulosa cells and low levels of HMW adiponectin in PCOS

PURPOSE

The purpose of the study was to investigate changes in adiponectin system expression in granulosa cells (GCs) and high molecular weight adiponectin levels in serum and follicular fluid (FF) of 40 women with polycystic ovary syndrome (PCOS) compared to those in 40 women with normal ovary function.

METHODS

Adiponectin (Adipo), adiponectin receptor 1 (AdipoR1), and adiponectin receptor 2 (AdipoR2) messenger RNA (mRNA) expression levels were measured using quantitative real-time polymerase chain reaction (qRT-PCR). High molecular weight (HMW) adiponectin protein concentration was evaluated by ELISA method. Data were analyzed using Student's t test and one-way ANOVA in SPSS 21 software. At oocyte retrieval, FF was aspirated and GCs were obtained from a pooled collection of FF per each patient.

RESULTS

PCR results showed expression of adiponectin, AdipoR1, AdipoR2, follicle-stimulating hormone receptor (FSHR), and luteinizing hormone receptor (LHR) in GCs. After controlling body mass index (BMI) values, qRT-PCR demonstrated a decreased expression of adiponectin system in GCs of PCOS patients compared to those in controls (p = 0.001). There was a strong positive correlation among AdipoR1 and AdipoR2 expression and also among FSH and LH receptor expression. (Both r = 0.8, p = 0.001). There were low levels of high molecular weight adiponectin in the serum of PCOS patients with controlled ovarian hyperstimulation (30.19 ± 4.3 ng/ml) compared to the controls (48.47 ± 5.9 ng/ml) and in the FF of PCOS patients with controlled ovarian hyperstimulation (7.86 ± 1.44 ng/ml) compared to the controls (14.22 ± 2.01 ng/ml; p = 0.02).

CONCLUSIONS

Lower expression of adiponectin and its receptors in GCs might be an important manifestation in gonadotropin-stimulated PCOS patients which could influence the physiologic adiponectin roles such as interaction with insulin and LH in induction of GC gene expression.

Physical exercise-induced hippocampal neurogenesis and antidepressant effects are mediated by the adipocyte hormone adiponectin

Adiponectin (ADN) is an adipocyte-secreted protein with insulin-sensitizing, antidiabetic, antiinflammatory, and antiatherogenic properties. Evidence is also accumulating that ADN has neuroprotective activities, yet the underlying mechanism remains elusive. Here we show that ADN could pass through the blood-brain barrier, and elevating its levels in the brain increased cell proliferation and decreased depression-like behaviors. ADN deficiency did not reduce the basal hippocampal neurogenesis or neuronal differentiation but diminished the effectiveness of exercise in increasing hippocampal neurogenesis. Furthermore, exercise-induced reduction in depression-like behaviors was abrogated in ADN-deficient mice, and this impairment in ADN-deficient mice was accompanied by defective running-induced phosphorylation of AMP-activated protein kinase (AMPK) in the hippocampal tissue. In vitro analyses indicated that ADN itself could increase cell proliferation of both hippocampal progenitor cells and Neuro2a neuroblastoma cells. The neurogenic effects of ADN were mediated by the ADN receptor 1 (ADNR1), because siRNA targeting ADNR1, but not ADNR2, inhibited the capacity of ADN to enhance cell proliferation. These data suggest that adiponectin may play a significant role in mediating the effects of exercise on hippocampal neurogenesis and depression, possibly by activation of the ADNR1/AMPK signaling pathways, and also raise the possibility that adiponectin and its agonists may represent a promising therapeutic treatment for depression.

The thrombospondin-1 receptor CD36 is an important mediator of ovarian angiogenesis and folliculogenesis

BACKGROUND

Ovarian angiogenesis is a complex process that is regulated by a balance between pro- and anti-angiogenic factors. Physiological processes within the ovary, such as folliculogenesis, ovulation, and luteal formation are dependent upon adequate vascularization and anything that disrupts normal angiogenic processes may result in ovarian dysfunction, and possibly infertility. The objective of this study was to evaluate the role of the thrombospondin-1 (TSP-1) receptor CD36 in mediating ovarian angiogenesis and regulating ovarian function.

METHODS

The role of CD36 was evaluated in granulosa cells in vitro and ovarian morphology and protein expression were determined in wild type and CD36 null mice.

RESULTS

In vitro, CD36 inhibition increased granulosa cell proliferation and decreased apoptosis. Granulosa cells in which CD36 was knocked down also exhibited an increase in expression of survival and angiogenic proteins. Ovaries from CD36 null mice were hypervascularized, with increased expression of pro-angiogenic vascular endothelial growth factor (VEGF) and its receptor VEGFR-2. Ovaries from CD36 null mice contained an increase in the numbers of pre-ovulatory follicles and decreased numbers of corpora lutea. CD36 null mice also had fewer number of offspring compared to wild type controls.

CONCLUSIONS

The results from this study demonstrate that CD36 is integral to the regulation of ovarian angiogenesis by TSP-1 and the expression of these family members may be useful in the control of ovarian vascular disorders.

Association between circulating adiponectin levels and polycystic ovarian syndrome

Background

Low adiponectin levels in polycystic ovarian syndrome (PCOS) have been largely attributed to obesity which is common among these patients. In addition, evidence also suggests that low adiponectin in PCOS may be related to insulin resistance (IR) in these women. However, studies on the role of adiponectin in younger and lean patients are limited. Therefore, the aim of the present study was to examine the association of adiponectin levels in young and lean women with PCOS.

Methods

A case–control study was conducted at the Dow University of Health Sciences, Karachi, Pakistan. Cases were 75 patients of PCOS with Body Mass Index (BMI) &23 aged 16–35 years and 75 healthy age and BMI matched controls were selected from family and friends of the cases. Demographic details, family history and past medical history were obtained through interview by a physician. Anthropometric measurements included weight and height of the participants. Fasting glucose, total cholesterol, high-density lipoprotein (HDL), insulin, adiponectin, and androgen levels were determined. IR was calculated using homeostasis model assessment for insulin resistance (HOMA-IR). Logistic regression models were used to assess the association between adiponectin and PCOS after adjusting for co-variates.

Results

On multivariable analysis, PCOS cases were 3.2 times more likely to have low adiponectin level (OR = 3.2, 95% CI 1.49-6.90, p-value 0.003) compared to the controls after adjustment for age, BMI, family history, marital status, total cholesterol, HDL level and IR. Females with a family history of PCOS were significantly more likely to have lower adiponectin (OR = 3.32, 95% CI 1.27-8.67, p-value 0.014) compared to those who did not have a family history of PCOS. The associations of IR and family history with low adiponectin level also remained statistically significant after adjustments for covariates.

Conclusion

Serum adiponectin levels are independently associated with PCOS and are only partly explained by IR. Adiponectin level may serve as a potential independent biomarker for diagnosis of PCOS in young and lean women with fewer symptoms, or women with a family history of PCOS.

Expression of adiponectin and its receptors in avian species

Adipose tissue is a dynamic endocrine organ secreting a variety of hormones that affect physiological functions within the central nervous system, cardiovascular system, reproductive, and immune systems. The endocrine role of avian adipose tissue remains enigmatic as many of the classical hormones found in mammalian adipose tissue have not been found in avians. This mini-review summarizes our current knowledge on avian adiponectin, one of the most abundant adipose tissue hormones, and its receptors. We cloned the genes encoding chicken adiponectin and its receptors, AdipoR1 and AdipoR2. Using anti-chicken adiponectin antibody, we found that chicken adipose tissue and plasma predominantly contain a unique polymer of adiponectin with a mass greater than 669kDa, unlike mammalian adiponectin which is found as three distinct oligomers. Mass spectrometric analyses of chicken adiponectin revealed certain post-translational modifications that are likely to favor the unique multimerization of adiponectin in chickens. Unlike adiponectin, the nucleotide sequences of chicken AdipoR1- and AdipoR2 cDNA are highly similar to that of mammalian adiponectin receptors. Both adiponectin and adiponectin receptors are widely expressed in several tissues in the chicken. Herein, we review the unique biochemistry of adiponectin as well as expression of adiponectin and its receptors in the chicken. Future studies should focus on elucidating the role of adiponectin, AdipoR1, and AdipoR2 on metabolism, steroidogenesis, and adipose tissue remodeling during growth and reproduction in birds.

Effects of adiponectin on ovarian folliculogenesis and steroidogenesis in the vespertilionid bat, Scotophilus heathi

The bat Scotophilus heathi undergo anovulation, known as delayed ovulation, coinciding with the period of seasonal adiposity due to fat accumulation. Because adiponectin is a well known fat cell product, it might be responsible for adiposity related anovulation in S. heathi. The aim of this study was thus to evaluate the effects of adiponectin treatment on ovarian activity in S. heathi. The bat during the period of delayed ovulation was treated with adiponectin (25 μg/day) for 12 days. Changes taken place in the ovarian activity of the treated bat was compared with the control bat and results obtained are presented here. Adiponectin treatment significantly decreased body mass by depleting adipose tissue. It acts directly upon the ovary and promotes antral follicular development by stimulating cell proliferation and modulating ovarian steroidogenesis. The bat treated with adiponectin showed significant decrease in circulating androstenedione (A4) and estradiol (E2) levels, but increase in circulating progesterone (P4) level. The inhibitory effect of adiponectin on androgen synthesis may be due to decreased thecal-interstitial cells differentiation in stroma by suppressing adiponectin receptor type 1 (AdipoR1), luteinizing hormone (LH) and insulin receptors in the ovary of S. heathi. The study provides evidences suggesting that the adiponectin treatment suppresses adiposity and restores normal ovarian activity.

Prediction of metabolic syndrome in women with polycystic ovary syndrome

OBJECTIVE

To identify biochemical factors that serve as predictors for the metabolic syndrome (MetS) in patients with polycystic ovary syndrome (PCOS) and to investigate the value of adipocytokines in the prediction of metabolic syndrome.

MATERIAL AND METHODS

A total of 91 pre-menopausal women with PCOS diagnosed according to the Rotterdam consensus criteria were recruited as study subjects. Waist circumference, blood pressure, body mass index (BMI), fasting glucose, serum lipids, insulin, FSH, LH, E2, total testosteron, homeostatic model assessment-insulin resistance (HOMA-IR), serum leptin and adiponectin levels were evaluated for all patients.

RESULTS

Of the 91 women with PCOS, 15 patients met the criteria for MetS. Body weight, BMI, waist circumference, systolic blood pressure, diastolic blood pressure, fasting glucose, total cholesterol, triglyceride, and VLDL concentrations were significantly higher and HDL was significantly lower in women with PCOS+MetS compared with those with PCOS only. However, the level of LDL, FSH, LH, E2 and total testesterone was not significantly different between these two groups. Women with PCOS+MetS had significantly higher levels of leptin and HOMA-IR, and significantly lower levels of adiponectin compared to the women with PCOS only. In the multiple logistic regression model, the association between HOMA-IR and leptin, and MetS remained statistically significant (p=0.001 and 0.018), while the association between adiponectin and MetS was no longer statistically significant.

CONCLUSION

Aside from the biochemical markers such as glucose, cholesterol and triglyceride, adipose tissue factors and insulin resistance are valuable parameters in the prediction of MetS in patients with PCOS.

Adiponectin receptor signalling in the brain

Adiponectin is an important adipocyte-derived hormone that regulates metabolism of lipids and glucose, and its receptors (AdipoR1, AdipoR2, T-cadherin) appear to exert actions in peripheral tissues by activating the AMP-activated protein kinase, p38-MAPK, PPARα and NF-kappa B. Adiponectin has been shown to exert a wide range of biological functions that could elicit different effects, depending on the target organ and the biological milieu. There is substantial evidence to suggest that adiponectin receptors are expressed widely in the brain. Their expression has been detected in regions of the mouse hypothalamus, brainstem, cortical neurons and endothelial cells, as well as in whole brain and pituitary extracts. While there is now considerable evidence for the presence of adiponectin and its receptors in the brain, their precise roles in brain diseases still remain unclear. Only a few research studies have looked at this facet of adiponectins in brain disorders. This brief review will describe the evidence for important functions by adiponectin, its structure and known actions, evidence for expression of AdipoRs in the brain, their involvement in brain disorders and the therapeutic potential of agents that could modify AdipoR signalling.

Adipokines: new emerging roles in fertility and reproduction

Adipose tissue is a specialized endocrine and paracrine organ producing specific factors called adipokines. It is well known that adipokines balance is fundamental to prevent obesity, metabolic syndrome, and cardiovascular diseases. During the last years, new roles of adipokines have been emerging in the field of fertility and reproduction. Although the literature is still quite controversial, this review serves to resume current knowledge on this topic. Alterations in adipokine levels or in their mechanism of action are associated with fertility impairment and pregnancy diseases, as well as with obesity, metabolic syndrome, and cardiovascular diseases. Normal levels of adipokines are fundamental to maintain integrity of hypothalamus-pituitary-gonadal axis, regular ovulatory processes, successful embryo implantation, and physiologic pregnancy. More efforts are needed to understand the mechanisms and to the extent to which adipokine changes are involved in the impairment of fertility and pregnancy outcome, to find possible medical treatments.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this educational activity, the obstetrician/gynecologist should be better able to demonstrate current knowledge in the research field of adipokines in fertility and reproduction; evaluate the central role of metabolism balance in good pregnancy outcome; and apply new perspectives of studies.

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.

Distribution of adiponectin multimeric forms in Chinese women with polycystic ovary syndrome and their relation to insulin resistance

OBJECTIVE

Adiponectin, an abundant adipokine with insulin-sensitizing properties, exists in different multimeric forms, including low-molecular weight, medium-molecular weight, and high-molecular weight (HMW) species. Alterations in the distribution of adiponectin multimers and the relationship between adiponectin multimers and insulin resistance (IR) in women with polycystic ovary syndrome (PCOS) remain unclear. The objective of this study was to compare adiponectin multimerization status and estimate insulin sensitivity in Chinese women with PCOS compared with age- and body mass index (BMI)-matched controls.

METHODS

Cross-sectional study involving 64 Chinese women with PCOS and 59 normal women. Circulating total adiponectin and its multimeric forms were determined by ELISA, and IR was estimated using the homeostasis model assessment IR index (HOMA-IR).

RESULTS

After controlling for BMI status, levels of both total and HMW adiponectin were significantly lower in women with PCOS compared with normal women (P<0.05). Furthermore, HMW adiponectin provided a stronger contribution to models predicting IR than total adiponectin. Lastly, decreased HMW adiponectin was associated with increased HOMA-IR in both normal and PCOS women, and this association was independent of both overall adiposity and visceral adiposity.

CONCLUSION

Levels of both total and HMW adiponectin were decreased in Chinese women with PCOS compared with normal control women, and the differences in HMW adiponectin persisted after controlling for BMI. Furthermore, HMW adiponectin is a stronger predictor of IR than total adiponectin in both women with PCOS and normal women.

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.

High-molecular-weight adiponectin is selectively reduced in women with polycystic ovary syndrome independent of body mass index and severity of insulin resistance

CONTEXT

High-molecular-weight (HMW) adiponectin contributes to insulin resistance (IR), which is closely associated with the pathophysiology of polycystic ovary syndrome (PCOS). Abnormalities in adipocyte function have been identified in PCOS and potentially contribute to lower adiponectin concentrations.

OBJECTIVE

Our objective was to determine which variables in plasma and adipose tissue influence HMW adiponectin in a well characterized cohort of women with PCOS.

DESIGN

This was a cross-sectional study.

SETTINGS AND PARTICIPANTS

A teaching hospital. Women with PCOS (n = 98) and body mass index (BMI)-matched controls (n = 103) (including 68 age-, BMI-, and IR-matched pairs).

INTERVENTIONS

A standard 75-g oral glucose tolerance test was performed for each participant. Subcutaneous adipose tissue samples were taken by needle biopsy for a subset of PCOS women (n = 9) and controls (n = 8).

MAIN OUTCOME MEASURES

Serum levels of HMW adiponectin and their relation to indices of insulin sensitivity, body composition, and circulating androgens as well as adipose tissue expression levels of ADIPOQ, TNFalpha, PPARgamma, and AR were assessed.

RESULTS

HMW adiponectin was significantly lower in women with PCOS compared with both BMI- and BMI- and IR-matched controls (P = 0.009 and P = 0.027, respectively). Although BMI and IR were the main predictors of HMW adiponectin, an interaction between waist to hip ratio and plasma testosterone contributed to its variance (P = 0.026). Adipose tissue gene expression analysis demonstrated that AR and TNFalpha (P = 0.008 and P = 0.035, respectively) but not ADIPOQ mRNA levels were increased in PCOS compared with controls.

CONCLUSIONS

HMW adiponectin is selectively reduced in women with PCOS, independent of BMI and IR. Gene expression analysis suggests that posttranscriptional/translational modification contributes to reduced HMW adiponectin in PCOS.

Developmental programming: effect of prenatal steroid excess on intraovarian components of insulin signaling pathway and related proteins in sheep

Prenatal testosterone (T) excess increases ovarian follicular recruitment, follicular persistence, insulin resistance, and compensatory hyperinsulinemia. Considering the importance of insulin in ovarian physiology, in this study, using prenatal T- and dihydrotestosterone (DHT, a nonaromatizable androgen)-treated female sheep, we tested the hypothesis that prenatal androgen excess alters the intraovarian insulin signaling cascade and metabolic mediators that have an impact on insulin signaling. Changes in ovarian insulin receptor (INSRB), insulin receptor substrate 1 (IRS1), mammalian target of rapamycin (MTOR), phosphatidylinositol 3-kinase (PIK3), peroxisome proliferator-activated receptor-gamma (PPARG), and adiponectin proteins were determined at fetal (Days 90 and 140), postpubertal (10 mo), and adult (21 mo) ages by immunohistochemistry. Results indicated that these proteins were expressed in granulosa, theca, and stromal compartments, with INSRB, IRS1, PPARG, and adiponectin increasing in parallel with advanced follicular differentiation. Importantly, prenatal T excess induced age-specific changes in PPARG and adiponectin expression, with increased PPARG expression evident during fetal life and decreased antral follicular adiponectin expression during adult life. Comparison of developmental changes in prenatal T and DHT-treated females found that the effects on PPARG were programmed by androgenic actions of T, whereas the effects on adiponectin were likely by its estrogenic action. These results suggest a role for PPARG in the programming of ovarian disruptions by prenatal T excess, including a decrease in antral follicular adiponectin expression and a contributory role for adiponectin in follicular persistence and ovulatory failure.

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 levels in adolescent girls with polycystic ovary syndrome (PCOS)

OBJECTIVE

To determine serum adiponectin concentrations in adolescent girls with and without polycystic ovary syndrome (PCOS) and to assess possible correlations of adiponectin levels with insulin and androgen levels.

DESIGN

Prospective case-control study.

SETTING

Endocrine clinics in the community.

PATIENTS

Forty-four adolescent girls were grouped as follows: 14 were overweight [body mass index (BMI) standard deviation score >1.645] with PCOS; 16 were lean (BMI SDS <1.036) with PCOS; and 14 were lean (BMI SDS <1.036) without PCOS. Intervention Blood samples were collected from all girls between 8 and 11 am, after an overnight fast.

MAIN OUTCOME MEASURES

Serum levels of adiponectin, leptin, insulin, Müllerian-inhibiting substance, luteinizing hormone, follicle-stimulating hormone, testosterone, 17-alpha-hydroxyprogesterone, androstendione, dehydroepiandrosterone sulphate (DHEAS) and 17beta-oestradiol.

RESULTS

Adiponectin concentrations were significantly decreased in obese adolescents with PCOS (10.5 +/- 5.5 mug/ml) compared with that in lean girls with or without PCOS (16.9 +/- 8.64 and 18.0 +/- 7.4 mug/ml respectively). Leptin levels were significantly elevated in obese adolescents with PCOS compared with the levels in normal weight adolescents with PCOS, and compared with that in normal weight controls. Insulin levels were markedly higher in obese adolescents with PCOS compared with that in normal weight adolescents (12.3 +/- 12.2 vs. 4.5 +/- 2.9, P < 0.05), and compared with that in normal weight PCOS adolescents (7.4 +/- 4.9); however, this difference was not statistically significant. Insulin levels did not differ between normal weight adolescents with PCOS and normal controls. Adiponectin concentrations correlated inversely with BMI, leptin and insulin.

CONCLUSIONS

Hypoadiponectinaemia is evident only in obese adolescents with PCOS and therefore does not seem to be involved in the pathogenesis of PCOS in this age group.

Selective regulation of cellular and secreted multimeric adiponectin by antidiabetic therapies in humans

Adiponectin, an insulin-sensitizing factor secreted from adipose tissue, is decreased in individuals with type 2 diabetes (T2D) and increased in response to thiazolidinedione (TZD) therapy. Changes in its secretion and assembly into higher-order forms affect insulin sensitivity. To determine the relative potency of TZDs on intra-adipocyte multimerization and secretion of adiponectin, we assessed the impact of in vivo low- or high-dose rosiglitazone treatment alone or combined with metformin in subjects with T2D. T2D subjects received high-dose rosiglitazone (8 mg/day), high-dose metformin (2,000 mg/day), or low-dose combination rosiglitazone-metformin therapy (4 mg + 1,000 mg/day) for 4 mo. All subjects were then switched to high-dose rosiglitazone-metformin combination therapy (8 mg + 2,000 mg/day) for another 4 mo. Low-dose rosiglitazone increased serum adiponectin, whereas the high dose increased both adipocyte content and serum adiponectin levels. TZDs selectively increased the percentage of circulating adiponectin in the potent, high-molecular-weight (HMW) form. No TZD effects were evident on multimer distribution in the cell. Expression of the chaperone protein ERp44, which retains adiponectin within the cell, was decreased by TZD treatment. No changes occurred in Ero1-Lalpha expression. Metformin had no effect on any of these measures. Increases in adiponectin correlated with improvements in insulin sensitivity. In vivo, TZDs have apparent dose-dependent effects on cellular and secreted adiponectin. TZD-mediated improvements in whole body insulin sensitivity are associated with increases in circulating but not cellular levels of the HMW adiponectin multimer. Finally, TZDs promote the selective secretion of HMW adiponectin, potentially, in part, through decreasing the expression of the adiponectin-retaining protein ERp44.

Adiponectin levels reflect the different phenotypes of polycystic ovary syndrome: study in normal weight, normoinsulinemic patients

Diagnosis of polycystic ovary syndrome (PCOS), at present very common in women of reproductive age, is implicated with potential long-term metabolic consequences that are difficult to be investigated due to the heterogeneity in the manifestation of the syndrome. The present study constitutes an effort to explore the graduated metabolic impact of the different PCOS phenotypic groups through the levels of adiponectin, an adipose-derived hormone, in 100 normal weight, normoinsulinemic patients with PCOS.

Coronary heart disease risk factors in adult premenopausal white women with polycystic ovary syndrome compared with a healthy female population

Our specific aim was to determine whether coronary heart disease (CHD) risk factors in polycystic ovary syndrome (PCOS) patients were independent of their higher body mass index (BMI) and centripetal obesity. In adult, premenopausal, white women, CHD risk factors were compared between 488 patients with well-defined PCOS and 351 healthy free-living population controls from the Princeton Follow-up Study (PFS). After excluding women with irregular menses (putative PCOS phenotypes), comparisons were also made between the 261 PFS women with a history of regular menses and the 488 women with PCOS. Fasting lipids, insulin, glucose, homeostasis model assessment of insulin resistance (HOMA-IR), HOMA insulin secretion, blood pressure, BMI, and waist circumference were measured. Compared with both the full cohort of 351 PFS women and the subgroup of 261 PFS women with regular menses, women with PCOS had higher BMI, waist circumference, total and low-density lipoprotein cholesterol, triglyceride, systolic blood pressure, diastolic blood pressure, insulin, glucose, and HOMA-IR (all Ps < or = .005). After adjusting for age and BMI, women with PCOS, compared with the 351 and 261 PFS women, had lower high-density lipoprotein cholesterol (P < .0001, .0008) and higher systolic blood pressure (P = .0002, < .0001), insulin (P = .017, .039), HOMA-IR (P = .013, .032), and HOMA insulin secretion (P = .022, .037). The small subgroup of PCOS women with normal BMI (<25 kg/m(2)) (36/488, 7%) also had higher age-adjusted insulin, glucose, and HOMA-IR (all Ps < .005) than the subgroup of PFS women with BMI less than 25 kg/m(2) (123/261, 47%). Increased CHD risk factors and high HOMA-IR in PCOS cannot be exclusively attributed to their preponderant centripetal obesity. Identification of women with clinical features of PCOS should alert the clinician to potentially increased risk for CHD and prompt CHD risk factor testing.

Adiponectin multimers in maternal plasma

OBJECTIVE

Adiponectin is an anti-diabetic, anti-atherogenic, anti-inflammatory, and angiogenic adipokine that circulates in oligomeric complexes including: low molecular weight (LMW) trimers, medium molecular weight (MMW) hexamers, and high molecular weight (HMW) isoforms. The aim of this study was to determine whether there are changes in adiponectin multimers in pregnancy and as a function of maternal weight.

STUDY DESIGN

In this cross-sectional study, plasma concentrations of total, HMW, MMW, and LMW adiponectin were determined in women included in three groups: (1) normal pregnant women of normal body mass index (BMI) (n = 466), (2) overweight pregnant women (BMI >or=25; n = 257), and (3) non-pregnant women of normal weight (n = 40). Blood samples were collected once from each woman between 11 and 42 weeks of gestation. Plasma adiponectin multimer concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Non-parametric statistics were used for analysis.

RESULTS

(1) The median HMW adiponectin concentration and the median HMW/total adiponectin ratio were significantly higher, and the median LMW adiponectin concentration was significantly lower in pregnant women than in non-pregnant women. (2) Among pregnant women, the median plasma concentration of total, HMW, and MMW adiponectin was significantly higher in normal weight women than in overweight patients. (3) Maternal HMW was the most prevalent adiponectin multimer regardless of gestational age or BMI status. (4) There were no significant differences in the median concentration of total, MMW, and LMW adiponectin and their relative distribution with advancing gestation.

CONCLUSION

Human pregnancy is characterized by quantitative and qualitative changes in adiponectin multimers, especially the most active isoform, HMW adiponectin.

Metabolic and hormonal changes induced by pioglitazone in polycystic ovary syndrome: a randomized, placebo-controlled clinical trial

CONTEXT

Polycystic ovary syndrome (PCOS) is characterized by insulin resistance, compensatory hyperinsulinemia, increased prevalence of impaired glucose tolerance, and increased ovarian androgen biosynthesis.

OBJECTIVE

The aim of the study was to evaluate effects of pioglitazone on whole body insulin action and ovarian androgen biosynthesis in PCOS.

DESIGN

We performed a randomized placebo-controlled trial.

SETTING

The study was conducted at the Special Diagnostic and Treatment Unit of the Veterans Affairs Medical Center, San Diego, and the University of California, San Diego, General Clinical Research Center.

PATIENTS OR OTHER PARTICIPANTS

A total of 23 subjects with PCOS were evaluated at baseline and end of treatment. Six age- and body mass index-matched women without PCOS were normal controls for baseline evaluation.

INTERVENTION

Subjects with PCOS were randomized to oral placebo or pioglitazone 45 mg daily for 6 months.

MAIN OUTCOME MEASURE(S)

The primary outcome measures were whole body insulin action as measured by hyperinsulinemic euglycemic clamp and ovarian androgen biosynthesis as measured by leuprolide-stimulated production of 17-hydroxyprogesterone (17-OHP).

RESULTS

Compared with placebo, pioglitazone treatment significantly improved multiple measures of insulin action, including glucose disposal rate (P < 0.01), 2-h glucose during 75-g oral glucose tolerance test (P < 0.01), area under the curve glucose during oral glucose tolerance test (P < 0.01), serum adiponectin (P < 0.01), and fasting hyperinsulinemia (P < 0.01). Compared to placebo, pioglitazone treatment reduced the increment of leuprolide-stimulated 17-OHP (P < 0.02). Improvements in glucose disposal rate correlated with reductions in 17-OHP stimulation (P < 0.02).

CONCLUSIONS

Compared to placebo, pioglitazone treatment in PCOS was associated with improvements in insulin action and glucose homeostasis and ameliorated the hyperandrogenic ovarian response.

Polycystic ovary syndrome is associated with tissue-specific differences in insulin resistance

OBJECTIVE

The potential differential contributions of skeletal muscle and adipose tissue to whole body insulin resistance were evaluated in subjects with polycystic ovary syndrome (PCOS).

RESEARCH DESIGN AND METHODS

Forty-two PCOS subjects and 15 body mass index-matched control subjects were studied. Insulin action was evaluated by the hyperinsulinemic/euglycemic clamp procedure. Isolated adipocytes and cultured muscle cells were analyzed for glucose transport activity; adipocytes, muscle tissue, and myotubes were analyzed for the expression and phosphorylation of insulin-signaling proteins.

RESULTS

Fifty-seven per cent of the PCOS subjects had impaired glucose tolerance and the lowest rate of maximal insulin-stimulated whole body glucose disposal compared to controls (P < 0.01). PCOS subjects with normal glucose tolerance had intermediate reduction in glucose disposal rate (P < 0.05 vs. both control and impaired glucose tolerance subjects). However, rates of maximal insulin-stimulated glucose transport (insulin responsiveness) into isolated adipocytes were comparable between all three groups, whereas PCOS subjects displayed impaired insulin sensitivity. In contrast, myotubes from PCOS subjects displayed reduced insulin responsiveness for glucose uptake and normal sensitivity. There were no differences between groups in the expression of glucose transporter 4 or insulin-signaling proteins or maximal insulin stimulation of phosphorylation of Akt in skeletal muscle, myotubes, or adipocytes.

CONCLUSIONS

Individuals with PCOS display impaired insulin responsiveness in skeletal muscle and myotubes, whereas isolated adipocytes display impaired insulin sensitivity but normal responsiveness. Skeletal muscle and adipose tissue contribute differently to insulin resistance in PCOS. Insulin resistance in PCOS cannot be accounted for by differences in the expression of selected signaling molecules or maximal phosphorylation of Akt.