Polycystic ovary syndrome and insulin resistance: thrifty genes struggling with over-feeding and sedentary life style?

Polycystic Ovary Syndrome: An Evolutionary Adaptation to Lifestyle and the Environment

Polycystic ovary syndrome (PCOS) is increasingly recognized as a complex metabolic disorder that manifests in genetically susceptible women following a range of negative exposures to nutritional and environmental factors related to contemporary lifestyle. The hypothesis that PCOS phenotypes are derived from a mismatch between ancient genetic survival mechanisms and modern lifestyle practices is supported by a diversity of research findings. The proposed evolutionary model of the pathogenesis of PCOS incorporates evidence related to evolutionary theory, genetic studies, in utero developmental epigenetic programming, transgenerational inheritance, metabolic features including insulin resistance, obesity and the apparent paradox of lean phenotypes, reproductive effects and subfertility, the impact of the microbiome and dysbiosis, endocrine-disrupting chemical exposure, and the influence of lifestyle factors such as poor-quality diet and physical inactivity. Based on these premises, the diverse lines of research are synthesized into a composite evolutionary model of the pathogenesis of PCOS. It is hoped that this model will assist clinicians and patients to understand the importance of lifestyle interventions in the prevention and management of PCOS and provide a conceptual framework for future research. It is appreciated that this theory represents a synthesis of the current evidence and that it is expected to evolve and change over time.

Prior caloric restriction increases survival of prepubertal obese- and PCOS-prone rats exposed to a challenge of time-limited feeding and physical activity

We hypothesized that a polycystic ovary syndrome (PCOS) background associated with obese-prone genotype, coupled with preconditioning by caloric restriction, would confer a survival benefit in genetically prepubertal obese/PCOS (O/PCOS)-prone rats faced with an unpredictable challenge of food shortage. Female, juvenile JCR:LA-cp rats, O/PCOS- and lean-prone, were exposed to 1.5 h of daily meals and 22.5 h of voluntary wheel-running, a procedure that leads to activity anorexia (AA). One week before the AA challenge (AAC), O/PCOS-prone rats were freely fed (O/PCOS-FF) or pair fed (O/PCOS-FR) to lean-prone, free-feeding animals (Lean-FF). O/PCOS-FR and lean-prone, food-restricted (Lean-FR) groups were matched on relative average caloric intake. Animals were removed from protocol at 75% of initial body weight (starvation criterion) or after 14 days (survival criterion). The AAC induced weight loss in all rats, but there were significant effects of both genotype and feeding history on weight loss (lean-prone rats exhibited a higher rate of weight loss than O/PCOS-prone; P < 0.001), and rats with prior caloric restriction retained more weight than those free fed previously (90.68 ± 0.59% vs. 85.47 ± 0.46%; P < 0.001). The daily rate of running was higher in lean-prone rats compared with O/PCOS-prone. This difference in running rate correlated with differences in mean days of survival. All O/PCOS-FR rats survived at day 14. O/PCOS-FF rats survived longer (10.00 ± 0.97 days) than Lean-FR (6.17 ± 1.58 days) and Lean-FF (4.33 ± 0.42 days) rats (P < 0.05). Thus preconditioning by caloric restriction induces a substantial survival advantage, beyond genotype alone, in prepubertal O/PCOS-prone rats.

The 312N variant of the luteinizing hormone/choriogonadotropin receptor gene (LHCGR) confers up to 2·7-fold increased risk of polycystic ovary syndrome in a Sardinian population

OBJECTIVE

Polycystic ovary syndrome (PCOS) is a frequent condition, affecting about 15% of women of reproductive age. Because of its familial occurrence, a multifactorial model of susceptibility, including both genetic and environmental factors, has been proposed. However, the identification of genetic factors has been elusive.

DESIGN

Case-control study aimed at evaluating possible associations between functionally relevant variants of the luteinizing hormone/choriogonadotrophin receptor gene (LHCGR) and PCOS phenotype.

PATIENTS

A total of 198 PCOS and 187 non-PCOS women, aged 14-35 years, of Sardinian origin, were referred to the outpatient clinic of the Department of Obstetrics and Gynaecology of the University of Cagliari (Sardinia). PCOS diagnosis was based on the Rotterdam criteria.

MEASUREMENTS

We determined the genotype of ins18LQ, S291N and S312N variants at the LHCGR locus. Genotype was related to the presence or absence of PCOS and to several clinical and biochemical characteristics.

RESULTS

The presence of at least one 312N allele was strongly associated with PCOS risk (OR, 2·04; 95% CI, 1·32-3·14; χ(2) , 10·47; P = 0·001). 312N homozygosity was associated with a further risk increase (OR, 2·73; 95% CI, 1·25-5·95; χ(2) , 6·65; P = 0·01). The number of ins18LQ alleles was associated with LH serum levels in controls (χ(2) , 8·04, P = 0·017).

CONCLUSIONS

For the first time, we have identified a genetic variant that is strongly associated with PCOS in an isolated population. These results, if confirmed in other cohorts, may provide the opportunity to test the S312N genotype at the LHCGR locus in fertile women to assess the risk of PCOS. The avoidance of triggering factors like weight increase may improve the reproductive outcome of potentially at-risk subjects.

Assessment of insulin resistance and impaired glucose tolerance in lean women with polycystic ovary syndrome

OBJECTIVE

To analyze insulin resistance (IR) and determine the need for a 2-hour oral glucose tolerance test (OGTT) for the identification of IR and impaired glucose tolerance (IGT) in lean nondiabetic women with polycystic ovary syndrome (PCOS).

METHODS

This was a cross-sectional analysis of treatment-naive women with PCOS who enrolled in a university-based clinical trial. Nondiabetic women with PCOS based on the Eunice Kennedy Shriven National Institute of Child Health and Human Development (NICHD) definition, aged 18-43 years and weighing ≤113 kg, were evaluated. Glucose and insulin levels were assessed at times 0, 30, 60, 90, and 120 minutes after a 75-g glucose load. Lean was defined as body mass index (BMI) <25 kg/m(2). Multiple linear regression was performed.

RESULTS

A cohort of 78 women was studied. The prevalence of IR was 0% among lean women vs. 21% among nonlean subjects based on fasting insulin I(0) and 40%-68% based on two different homeostatic model assessment (HOMA) cutoff points (p < 0.005). All women with IR had a BMI ≥ 28. Controlling for age and race, BMI explained over 57% of the variation in insulin fasting (I(o)), glucose fasting/Io (G(o)/I(o)), the qualitative insulin sensitivity check index (QUICKI), and HOMA and was a highly significant predictor of these outcomes (p < 0.0001). Only 1 of 31 (3%) of the lean PCOS women had IGT based on a 2-hour OGTT, and no lean subjects had IGT based on their fasting blood glucose.

CONCLUSIONS

Diabetes mellitus, IGT, and IR are far less common in young lean women with PCOS compared with obese women with PCOS. These data imply that it is unnecessary to routinely perform either IR testing or 2-hour OGTT in lean women with PCOS; however, greater subject accumulation is needed to determine if OGTT is necessary in lean women with PCOS. BMI is highly predictive of both insulin and glucose levels in women with PCOS.

Insulin resistance and adolescent girls with polycystic ovary syndrome

STUDY OBJECTIVES

To estimate (1) the prevalence of insulin resistance (IR), by fasting glucose: insulin ratio (G:I<7.0) in adolescent girls with polycystic ovary syndrome (PCOS), (2) to compare the clinical and biochemical parameters between insulin-resistant and non-insulin resistant groups.

DESIGN

Case series.

SETTING

Clinic based.

PARTICIPANTS

49 adolescent girls with complaints of oligomenorrhoea with hirsutism and or acne.

INTERVENTIONS

Forty-nine adolescent girls diagnosed to have PCOS (Rotterdam 2003 criteria) were studied. Body mass index (BMI), abdominal circumference (AC), hirsutism (Ferriman Gallway score > or = 6), presence of acne, acanthosis nigricans (AN) were noted in each case. Serum testosterone, sex hormone binding globulin (SHBG), fasting plasma glucose and insulin levels were measured. Free androgen index (FAI) was calculated.

RESULTS

69.4% of these girls were found to have IR. There were no differences in age, BMI, AC, serum testosterone, FAI and fasting glucose levels between insulin resistant and non-insulin resistant girls. But there were significant differences in frequencies of hirsutism, acne, AN, and serum levels of SHBG and fasting insulin between the two groups.

CONCLUSION

Adolescent girls with PCOS and IR are more hirsute and have more AN and lower SHBG and higher fasting insulin levels compared to non-insulin resistant girls.

Insulin resistance and overweight-obese women with polycystic ovary syndrome

AIM

To estimate (1) the prevalence of insulin resistance (IR) by fasting glucose: insulin ratio (G:I) (G:I <or= 4.5) in overweight-obese polycystic ovary syndrome (PCOS) women, (2) to compare the clinical and biochemical parameters between insulin-resistant and insulin-sensitive groups.

MATERIALS AND METHODS

Eighty-one overweight-obese PCOS women (body mass index (BMI) >or= 23 kg/m(2)) were studied. PCOS was diagnosed as per the Rotterdam 2003 criteria. BMI, abdominal circumference (AC), hirsutism (Ferriman Gallway score >or=6), presence of acne and acanthosis nigricans (AN) were noted in each case. Serum testosterone, sex hormone binding globulin (SHBG), fasting plasma glucose and insulin levels were measured.

RESULTS

23.5% women were found to have IR. There were no differences in age, frequency of hirsutism, acne, serum testosterone and fasting glucose levels between insulin-resistant and insulin-sensitive women. However, there were significant differences in BMI, AC, frequency of AN, SHBG levels, fasting insulin levels and FAI between the two groups.

CONCLUSION

PCOS women with IR are more obese; they have more upper body adiposity and AN. They are more hyperandrogenic. Simple clinical parameters will help to suspect IR in PCOS women.

Women with polycystic ovary syndrome are often depressed or anxious--a case control study

OBJECTIVE

Polycystic ovary syndrome (PCOS) is a common hyperandrogenic endocrine disorder affecting women of fertile age. The aim of this study was to survey whether the rate of clinical psychiatric disorders in PCOS differs from the normal population.

METHOD

Women with PCOS (n=49) meeting the Rotterdam criteria for PCOS, and 49 age-matched controls identified from the population registry, were recruited. Trained clinicians used the MINI International Neuropsychiatric Interview to establish lifetime occurrence of Axis I DSM diagnoses. Serum-testosterone and sex hormone binding globulin were analyzed.

RESULTS

Women with PCOS had higher lifetime incidence of depressive episodes, social phobia, and eating disorders than controls. Suicide attempts were seven times more common in the PCOS group than in the controls. Current as well as lifetime use of antidepressants and anxiolytic drugs were more common in the PCOS group.

CONCLUSIONS

Previous studies have found that PCOS is associated with decreased quality of life and self-rated mental symptoms. This study demonstrates that PCOS is also linked to psychiatric syndromes as verified by structured clinical assessments. The clinical implication of this study is that clinicians treating women with PCOS should be aware that these women are a high risk group for common affective and anxiety disorders as well as suicide attempts.

Prevalence of insulin resistance and determination of risk factors for glucose intolerance in polycystic ovary syndrome: a cross-sectional study of Chinese infertility patients

OBJECTIVE

To determine the prevalence of abnormalities in glucose metabolism in patients with polycystic ovary syndrome (PCOS) and control infertility patients in Taiwan, and to determine the predictive risk factors for PCOS.

DESIGN

Cross-sectional study.

SETTING

Infertility Center, Taiwan Adventist Hospital.

PATIENT(S)

Three hundred fifty-six patients with PCOS and 974 control infertility patients.

INTERVENTION(S)

None.

MAIN OUTCOMES MEASURE(S)

Hormone assay and 75-g oral glucose tolerance test.

RESULT(S)

Patients with PCOS were younger (32.7 vs. 35.3 years) with a higher body mass index (BMI) (22.4 vs. 20.6 kg/m(2)) than controls. Even after BMI adjustment, patients with PCOS still had significantly higher fasting glucose (97.2 vs. 94.4 mg/dL), fasting insulin (5.6 vs. 4.1 microIU/mL), 2-hour glucose (108.1 vs. 96.0 mg/dL), and 2-hour insulin levels (38.0 vs. 27.0 microIU/mL), and higher homeostasis model assessment of insulin resistance (HOMA-IR) values (1.3 vs. 1.0) than control patients. The prevalence of impaired glucose tolerance and diabetes mellitus in patients with PCOS was 7.6% and 3.1%, respectively, compared with 2.9% and 0.2% in the control group, respectively. Only fasting glucose and insulin, 2-hour insulin, HOMA-IR, age, androstenedione, and status (PCOS vs. control) had a significant impact on 2-hour glucose level. However, BMI and waist/hip ratio did not show a significant impact on 2-hour glucose level.

CONCLUSION(S)

Chinese women with PCOS are at increased risk for insulin resistance and glucose intolerance compared with controls. Body mass index failed to show significant impact on 2-hour glucose levels in our infertility patients.

Treatment of PCOS in adolescence

Polycystic ovary syndrome (PCOS) is increasingly being recognized in adolescent girls seeking treatment for signs and symptoms of hyperandrogenism. It is difficult to diagnose PCOS in adolescents, therefore a high index of suspicion is necessary. Timely screening and treatment are crucial because another important component of the syndrome is insulin resistance/hyperinsulinemia increasing the risk for type 2 diabetes, dyslipidemia, and cardiovascular sequelae. Diagnosis of PCOS in adolescents should include a thorough family history, exclusion of other causes of hyperandrogenism, and appropriate laboratory evaluation. The scarcity of controlled clinical trials makes treatment controversial. Therapeutic options include lifestyle intervention, oral contraceptive pills, and insulin sensitizers. Long-term follow-up is needed to determine the effectiveness of these approaches in changing the natural history of the reproductive and metabolic outcomes without causing undue harm.

Clustering of cardiovascular risk factors associated with the insulin resistance syndrome: assessment by principal component analysis in young hyperandrogenic women

OBJECTIVE

Hyperinsulinemia is often associated with several metabolic abnormalities and increased blood pressure, which are risk factors for cardiovascular disease. It has been hypothesized that insulin resistance may underlie all these features. However, recent data suggest that some links between insulin resistance and these alterations may be indirect. The aim of our study was to further investigate this issue in a sample of young hyperandrogenic women, who often show insulin resistance and other metabolic abnormalities typical of the insulin resistance syndrome.

RESEARCH DESIGN AND METHODS

We tested the hypothesis of a single factor underlying these features by principal component analysis, which should recognize one component if a single mechanism explains this association. The analysis was carried out in a sample of 255 young nondiabetic hyperandrogenic women. Variables selected for this analysis included the basic features of the insulin resistance syndrome and some endocrine parameters related to hyperandrogenism.

RESULTS

Principal component analysis identified four separate factors, explaining 64.5% of the total variance in the data: the first included fasting and postchallenge insulin levels, BMI, triglycerides, HDL cholesterol, and uric acid; the second, BMI, blood pressure, and serum free testosterone; the third, fasting plasma glucose, postchallenge glucose and insulin levels, serum triglycerides, and free testosterone; and the fourth, postchallenge plasma insulin, serum free testosterone, and gonadotropin-releasing hormone agonist-stimulated 17-hydroxyprogesterone.

CONCLUSIONS

These results support the hypothesis of multiple determinants in the clustering of abnormalities in the so-called insulin resistance syndrome.

Androgen receptor null male mice develop late-onset obesity caused by decreased energy expenditure and lipolytic activity but show normal insulin sensitivity with high adiponectin secretion

Androgen receptor (AR) null male mice (AR(L-/Y)) revealed late-onset obesity, which was confirmed by computed tomography-based body composition analysis. AR(L-/Y) mice were euphagic compared with the wild-type male (AR(X/Y)) controls, but they were also less dynamic and consumed less oxygen. Transcript profiling indicated that AR(L-/Y) mice had lower transcripts for the thermogenetic uncoupling protein 1, which was subsequently found to be ligand-dependently activated by AR. We also found enhanced secretion of adiponectin, which is insulin sensitizing, from adipose tissue and a relatively lower expression of peroxisome proliferator-activated receptor-gamma in white adipose tissue in comparison to AR(X/Y) mice. Both factors might explain why the overall insulin sensitivity of AR(L-/Y) mice remained intact, despite their apparent obesity. The results revealed that AR plays important roles in male metabolism by affecting the energy balance, and it is negative to both adiposity and insulin sensitivity.

The molecular-genetic basis of functional hyperandrogenism and the polycystic ovary syndrome

The genetic mechanisms underlying functional hyperandrogenism and the polycystic ovary syndrome (PCOS) remain largely unknown. Given the large number of genetic variants found in association with these disorders, the emerging picture is that of a complex multigenic trait in which environmental influences play an important role in the expression of the hyperandrogenic phenotype. Among others, genomic variants in genes related to the regulation of androgen biosynthesis and function, insulin resistance, and the metabolic syndrome, and proinflammatory genotypes may be involved in the genetic predisposition to functional hyperandrogenism and PCOS. The elucidation of the molecular genetic basis of these disorders has been burdened by the heterogeneity in the diagnostic criteria used to define PCOS, the limited sample size of the studies conducted to date, and the lack of precision in the identification of ethnic and environmental factors that trigger the development of hyperandrogenic disorders. Progress in this area requires adequately sized multicenter collaborative studies after standardization of the diagnostic criteria used to classify hyperandrogenic patients, in whom modifying environmental factors such as ethnicity, diet, and lifestyle are identified with precision. In addition to classic molecular genetic techniques such as linkage analysis in the form of a whole-genome scan and large case-control studies, promising genomic and proteomic approaches will be paramount to our understanding of the pathogenesis of functional hyperandrogenism and PCOS, allowing a more precise prevention, diagnosis, and treatment of these prevalent disorders.

Impaired cholecystokinin secretion and disturbed appetite regulation in women with polycystic ovary syndrome

Increased amount of abdominal fat and obesity are common in polycystic ovary syndrome (PCOS). A higher prevalence of bulimia nervosa and greater cravings for sweets have also been reported in these patients. The present study aimed to compare meal-related appetite and secretion of the 'satiety peptide' cholecystokinin (CCK) and glucose regulatory hormones in PCOS women and controls. Sixteen pairs of women with PCOS and controls matched for age and body mass index participated in the study. After an overnight fast, blood samples were collected during ingestion of a standardized meal. We determined basal and postprandial blood levels of CCK, insulin, C-peptide, glucagon, cortisol, growth hormone and glucose. Self-ratings of appetite were assessed by a visual analog scale. PCOS women had a significantly lower meal-related CCK response (p < 0.05) with no association with satiety, as in the controls (r = 0.64). There was a tendency to higher ratings of craving for sweets in PCOS women (p = 0.07) but no correlation with insulin, as in the controls (r = 0.50). Within the PCOS group, ratings of craving for sweets were inversely related to testosterone (r = - 0.60) and the CCK response was positively correlated with levels of free testosterone (r = 0.50). We conclude that women with PCOS have reduced postprandial CCK secretion and deranged appetite regulation associated with increased levels of testosterone. Impaired CCK secretion may play a role in the greater frequency of binge eating and overweight in women with PCOS.

Screening for and treatment of polycystic ovary syndrome in teenagers

Polycystic ovary syndrome (PCOS) usually arises during puberty and is marked by hyperinsulinemia and hyperandrogenism. Adolescents with PCOS are at an increased risk of developing health problems later on in life such as type 2 diabetes, cardiovascular disease, and infertility. Furthermore, the physical signs of PCOS can be detrimental to a teenage girl's self-image. Early diagnosis and treatment of PCOS in adolescents are essential in ensuring adulthood health and restoring self-esteem. Treatments for an adolescent with PCOS include diet and exercise, metformin, and oral contraceptive pills. Each of these options has been shown to be effective in improving certain aspects of PCOS, and probably the best treatment plan involves some combination of them.

Effect of electro-acupuncture stimulation of different frequencies and intensities on ovarian blood flow in anaesthetized rats with steroid-induced polycystic ovaries

BACKGROUND

Maintenance of ovarian blood flow (OBF) is suggested to be important for regular ovulation in women with polycystic ovaries (PCO). The purpose of the present study was to investigate whether electro-acupuncture (EA) of different frequencies and intensities can improve the OBF of anaesthetized rat in the animal model of PCO.

METHODS

PCO was experimentally induced by a single intramuscular (i.m.) injection of estradiol valerate (EV) in rats. Control rats were given i.m. injection of oil. The involvement of the two ovarian sympathetic nerves; superior ovarian nerve (SON) and plexus ovarian nerve (OPN), in OBF responses was elucidated by severance of SON and OPN in both control and PCO rats. How systemic circulatory changes affect OBF was evaluated by continuous recording of the blood pressure. OBF was measured on the surface of the ovary-using laser Doppler flowmetry. Acupuncture needles were inserted bilaterally into the abdominal and hind limb muscles and connected to an electrical stimulator. Two frequencies--2 Hz (low) and 80 Hz (high)--with three different intensities--1.5, 3, and 6 mA--were applied for 35 s.

RESULTS

Low-frequency EA at intensities of 3 and 6 mA elicited significant increases in OBF in the Control group compared to baseline. In the PCO group the increases in OBF were significant only when stimulating with low-frequency EA at 6 mA. After severance of the ovarian sympathetic nerves, the increased response of OBF that had been induced by low-frequency EA in both the Control and PCO group was abolished, indicating that the OBF response is mediated via the ovarian sympathetic nerves. High-frequency EA at 6 mA significantly decreased OBF and mean arterial blood pressure (MAP) in the Control group compared to baseline. In the PCO group, the same stimulation produced similar decreases in MAP, but not in OBF.

CONCLUSION

Low-frequency EA stimulation with a strong intensity (6 mA) increases OBF in rats with steroid-induced PCO whereas less strong intensity (3 mA) induces similar changes in control rats. Severance of the ovarian sympathetic nerves, abolish this OBF increase in both study groups, which suggests that the responses of OBF to EA are mediated via the ovarian sympathetic nerves.

Body size from birth to adulthood as a predictor of self-reported polycystic ovary syndrome symptoms

OBJECTIVE

To study the association between body size from birth to adulthood and self-reported symptoms of polycystic ovary syndrome (PCOS), particularly hirsutism and menstrual disturbances.

DESIGN

Longitudinal, population-based study of a cohort of women born in 1966 in northern Finland. The study population included 2007 women who were not pregnant and did not use hormonal contraception. Of these 528 (26%) had self-reported symptoms of PCOS.

RESULTS

Weight at birth, gestational age, being small for gestational age or growth retardation at birth were not associated with PCOS symptoms at 31 y. An increased risk of PCOS symptoms was observed among women with abdominal obesity (waist/hip ratio >85th percentile) at 31 y who had normal weight in adolescence and were overweight (body mass index (BMI) 25.0-29.9 kg/m(2)) or obese (BMI>30.0 kg/m(2)) at 31 y (relative risk (RR) (95% CI) 1.44(1.10-1.89)), and among women with abdominal obesity who were overweight or obese at both 14 and 31 y (1.71 (1.30-2.24)). A total of 30% and 41% of the women with PCOS symptoms in these groups could be attributed, respectively, to overweight, obesity and abdominal obesity at 31 y.

CONCLUSIONS

These results suggest that obesity in adolescence and in adulthood, and also weight gain after adolescence, particularly in the presence of abdominal obesity, are associated with self-reported PCOS symptoms in adulthood. Thus, based on the results from intervention studies treating PCOS and the results of this study, the prevention of obesity and abdominal obesity is important among young women.

Reproductive adaptations to a large-brained fetus open a vulnerability to anovulation similar to polycystic ovary syndrome

During the ovarian or menstrual cycle, prior to ovulation, many female primates exhibit a relatively prolonged follicular phase and terminate the postovulatory luteal phase with menstrual bleeding. The prolonged follicular phase is a trait that distinguishes primate from nonprimate species. It enables extended estrogen-induced proliferation and growth of the uterine endometrium prior to progesterone-induced maturation during the luteal phase to accommodate a potential pregnancy with a rapidly invading placenta. Progressive development of both an extended duration of estrogen-induced, preimplantation endometrial proliferation and a rapidly invading placenta across the Primate order may well have been necessary to accommodate differentiation and growth of an increasingly large fetal brain. Prolongation of the follicular phase in primates has also led to the isolation of the final stages of follicle selection (growth deviation of the dominant follicle from its contemporaries) solely within the follicular phase and thus outside the protection of luteal phase progesterone inhibition of pituitary luteinizing hormone (LH) secretion. Such primate reproductive characteristics put the latter stages of ovarian follicle selection at risk of exposure to excessive pituitary secretion of LH. Excessive secretion of LH during follicle selection could result not only in impaired follicle development, excessive ovarian androgen secretion, and ovulation failure, but also in excessive estrogenic stimulation of the uterine endometrium without intervening menstrual periods. Such reproductive abnormalities are all found in a single, prevalent infertility syndrome afflicting women in their reproductive years: polycystic ovary syndrome (PCOS). We propose that successful female reproductive adaptations to accommodate the growth demands of large-brained primate fetuses have facilitated a particular vulnerability of higher primates to hypergonadotropic disruption of ovulatory function, as found in PCOS.

Insulin sensitivity and beta-cell function in women with polycystic ovary syndrome

OBJECTIVE

To evaluate insulin sensitivity (IS) and beta-cell function (beta F) in lean and obese women with polycystic ovary syndrome (PCOS), either separately or by using a disposition index (DI).

RESEARCH DESIGN AND METHODS

A total of 64 women with PCOS and 20 healthy women were examined by anthropometry, oral glucose tolerance tests (OGTTs), and insulin tolerance tests. Statistical analysis used one-way ANOVA, Kruskal-Wallis, and Mann-Whitney U tests, as appropriate.

RESULTS

A significantly higher waist-to-hip ratio (P < 0.0001) was found in both lean and obese women with PCOS. Higher basal blood glucose (P < 0.004) and blood glucose values at 3 h of OGTT (P < 0.008) were found in lean and obese PCOS subjects in comparison with control subjects. Insulin resistance by homeostasis model assessment (P < 0.007) was significantly higher in obese PCOS than in control or lean PCOS subjects. Early-phase insulin secretion (insulinogenic index [Delta I/Delta G(30-0), where I is insulin and G is glucose]; P < 0.0007) was significantly higher in both lean and obese PCOS subjects than in healthy women. All tested combinations of parameters of IS and beta F (DIs) followed a physiological hyperbolic relationship. Significantly lower values of the fasting state-derived DIs were found (all P < 0.05) in obese PCOS subjects. Significantly higher values of all of these indexes derived from nonfasting values were found in lean PCOS as compared with control and obese PCOS subjects (all P < 10(-3)).

CONCLUSIONS

Increased beta F was found even in lean individuals with PCOS. Insulin hypersecretion is thus probably connected to the pathogenesis of PCOS.

A unique defect in the regulation of visceral fat cell lipolysis in the polycystic ovary syndrome as an early link to insulin resistance

The etiology of polycystic ovary syndrome (PCOS) is unknown. However, PCOS has a strong resemblance to the insulin resistance (metabolic) syndrome, where an increased rate of visceral fat cell lipolysis is believed to play a pathophysiological role. We hypothesized that primary defects in visceral lipolysis might also exist in PCOS. Ten young, nonobese, and otherwise healthy PCOS women were compared with 13 matched control women. In vitro lipolysis regulation and stoichiometric properties of the final step in lipolysis activation, namely the protein kinase A (PKA)-hormone sensitive lipase (HSL) complex, were investigated in isolated visceral (i.e., omental) fat cells. Body fat distribution and circulating levels of insulin, glucose, and lipids were normal in PCOS women. However, in vivo insulin sensitivity was slightly decreased (P = 0.03). Catecholamine-induced adipocyte lipolysis was markedly (i.e., about twofold) increased in PCOS women due to changes at the postreceptor level, although there was no change in the antilipolytic properties of visceral fat cells. Western blot analyses of visceral adipose tissue showed twofold increased levels of the catalytic and the regulatory Ialpha components of PKA. In contrast, the regulatory RIIbeta component of PKA was almost 50% decreased in visceral adipose tissue in PCOS women. Recent studies on genetically modified mice have shown that a similar transition in the regulatory PKA units induces an increased lipolytic response to catecholamines. Further analysis showed that the level of HSL-short, an enzymatically inactive splice form of HSL, was decreased in PCOS (P < 0.01). The altered lipolysis in PCOS is different from that observed in visceral fat cells in the insulin resistance syndrome that occurs at the level of adrenergic receptors. We concluded that increased catecholamine-induced lipolysis in visceral fat cells may be due to unique alterations in the stoichiometric properties of the adipose PKA-HSL holoenzymes. This could be an early and possibly primary lipolysis defect in PCOS.