Evidence that insulin and androgens may participate in the regulation of serum leptin levels in women

The effect of Plantago major supplementation on leptin and VEGF-A serum levels, endothelial dysfunction and angiogenesis in obese women - a randomised trial

Obesity is associated with increased serum leptin level, endothelial dysfunction and angiogenesis. In vitro studies have shown that vascular endothelial growth factor (VEGF) synthesis is increased by leptin. Animal studies revealed the effectiveness of Plantago supplementation treatment of obesity. The study aim was to evaluate the effect of Plantago major supplementation on serum leptin and VEGF blood concentration, endothelial dysfunction and angiogenesis in obese women. Seventy-two obese women received oral Plantago major supplement (Plantago group, n = 35) or placebo (placebo group, n = 37) for 12 weeks. At baseline and after completion, anthropometric and body composition measurements were performed, and blood samples were collected. Serum concentrations of leptin, VEGF-A, adiponectin, tumour necrosis factor α and soluble intercellular adhesion molecule have been determined. At completion, the leptin level was higher in the Plantago group (39 781.55 ± 20 360.73 pg ml-1) compared to both the baseline (36 138.71 ± 25 401.51 pg ml-1) and placebo group (30 502.81 ± 19 003.18 pg ml-1). Also, leptin concentration in the Plantago group at completion correlated positively with an increase in VEGF-A level (R = 0.45), and baseline VEGF-A level correlated negatively with the increase in leptin concentration (R = -0.47). Plantago major supplementation increases leptin serum level, enhances leptin influence on VEGF-A serum level increase and by this mechanism may intensify endothelial dysfunction and angiogenesis in obese women.

Hyperandrogenism, Insulin Resistance, and Acanthosis Nigricans (HAIR-AN) Syndrome Reflects Adipose Tissue Dysfunction ("Adiposopathy" or "Sick Fat") in Asian Indian Girls

BACKGROUND

Whether HAIR-AN syndrome and polycystic ovarian syndrome (PCOS) are distinct entities or represent a phenotypic spectrum of the same syndrome is still unclear. HAIR-AN syndrome is characterized by high insulin resistance, obesity, and hyperinsulinemia as compared to PCOS and could represent adipose tissue dysfunction as the primary pathophysiologic trigger. This study was undertaken to study the role of adipose tissue dysfunction in HAIR-AN syndrome and PCOS using adipocytokines as surrogate markers of "adiposopathy."

MATERIALS AND METHODS

A cross-sectional observational study was conducted at a tertiary care hospital over a period of 1 year. Serum adiponectin, leptin, IL-6, and TNF-α levels were measured in 30 women with HAIR-AN syndrome and in 30 women with PCOS. Correlations between adipocytokines, inflammatory markers, serum testosterone, and serum insulin were determined. Data analysis was performed using the SPSS version 23.0 (IBM SPSS Statistics Inc., Chicago, IL, USA) software program.

RESULTS

Women with HAIR-AN syndrome had significantly higher hyperandrogenemia, hyperinsulinemia, and insulin resistance as compared to PCOS women. They also had high leptin levels and lower adiponectin levels (p < 0.001). However, the levels of inflammatory markers (TNF-α and IL-6) were similar in both the groups (p > 0.05). Serum adiponectin showed a negative correlation with HOMA-IR and testosterone levels, while leptin showed a positive correlation with both in HAIR-AN patients while no such correlation was found in the PCOS group.

CONCLUSION

The significantly raised adipocytokines in HAIR-AN syndrome patients as compared to PCOS patients indicates the primary role of adipose tissue dysfunction ("adiposopathy") in the pathogenesis of HAIR-AN syndrome while only a minor role, if any, in PCOS. Both these syndromes stand as distinct entities pathogenically with an overlapping phenotype.

Adiponectin and leptin levels in normal weight women with polycystic ovary syndrome

Objectives

Since polycystic ovarian syndrome (PCOS) is prevalent in reproductive women with obesity and insulin resistance, adipocytokines are often accused and investigated for pathophysiology. The aim of this study was to evaluate the adiponectin and leptin levels in normal-weight women with PCOS.

Methods

Forty women with PCOS and 40 age and body mass index (BMI) matched controls were included in the study. Adiponectin and leptin levels in addition to other biochemical parameters were measured.

Results

Leptin levels were statistically significantly higher in the study group compared to the control group (6.53 ± 2.670 vs 3.37 ± 2.002 ng/mL, p < 0.001 respectively). Although Adiponectin levels were lower in the study group compared to the control group (28.89 ± 16.124 μg/mL vs 31.05 ± 20.507, p = 0.714 respectively) the difference did not reach statistical significance. Leptin levels were positively correlated with fasting glucose, fasting insulin, free testosterone levels and homeostatic model assessment of insulin resistance (HOMA-IR) values. Adiponectin levels were negatively correlated with BMI.

Conclusions

Adiponectin and leptin have been suggested to play a crucial role in the pathogenesis of PCOS. Different adipocytokine levels in the normal weight PCOS group compared to age and BMI matched controls support the idea that adipose tissue in this group of women has some distinctive features not only in high BMI subgroup but also in normal weight subgroup.

Neuroendocrine Regulation of Food Intake in Polycystic Ovary Syndrome

Several peripheral and central signals are involved in the sophisticated regulation of food intake. Women with polycystic ovary syndrome (PCOS) are prone to consume a diet higher in saturated fat and foods with high glycemic index and show impaired appetite regulation and measures of satiety. As a consequence, obesity, mostly of the central type, is prevalent in the syndrome and worsens the endocrine and metabolic profile of the affected patients. This review article briefly analyzes the current knowledge about the neuroendocrine mechanisms underlying the interplay between feeding behavior, obesity, and reproductive abnormalities in PCOS.

The integrative role of leptin, oestrogen and the insulin family in obesity-associated breast cancer: potential effects of exercise

Obesity is an established risk factor for postmenopausal breast cancer. The mechanisms through which obesity influences the development and progression of breast cancer are not fully elucidated; however, several factors such as increased oestrogen, concentrations of various members of the insulin family and inflammation that are associated with adiposity are purported to be important factors in this relationship. Emerging research has also begun to focus on the role of adipokines, (i.e. adipocyte secreted factors), in breast cancer. Leptin secretion is directly related to adiposity and is believed to promote breast cancer directly and independently, as well as through involvement with the oestrogen and insulin signalling pathways. As leptin is secreted from white adipose tissue, any intervention that reduces adiposity may be favourable. However, it is also important to consider that energy expenditure through exercise, independent of fat loss, may improve leptin regulation. The purpose of this narrative review was to explore the role of leptin in breast cancer development and progression, identify key interactions with oestrogen and the insulin family, and distinguish the potential effects of exercise on these interactions.

Ovarian function in Samoan women shows stronger association with signals of energy metabolism than fat reserves

OBJECTIVES

The relative influence of prominent energetic hormones such as insulin and leptin on ovarian steroid production has yet to be determined and demonstrated consistently in vivo. This study reports preliminary findings on the relationship between insulin, leptin, and estradiol, a major ovarian steroid, in a sample of Samoan women.

METHODS

Participants were 34 regularly cycling, nonlactating, premenopausal women in the follicular phase of their menstrual cycle with indicators of normal glucose tolerance. Fasting serum samples provided one-time, cross-sectional measures of glucose, insulin, leptin, and estradiol. Main statistical analyses consisted of Student's t-tests, used to determine significant differences in mean estradiol level between contrasting groups of insulin and leptin.

RESULTS

Relatively high insulin levels within the normal range of variation showed a positive association with estradiol levels whereas relatively high leptin levels did not. The association between insulin and estradiol appeared to conform to a step-like categorical relationship--with the highest insulin levels exerting the greatest positive effect--rather than a dose-response linear relationship.

CONCLUSIONS

This study adds to the growing evidence that peripheral regulation of ovarian function likely involves permissive signals that emphasize a state of energy surplus, related primarily to energy metabolism rather than energy reserves, and warrant more extensive study.

Serum leptin level in women with polycystic ovary syndrome: correlation with adiposity, insulin, and circulating testosterone

BACKGROUND

Leptin, an adipocyte-derived hormone encoded by 'ob' gene, serves as a link relaying metabolic signals to the neuronal networks in the brain to modulate hypothalamo-pituitary-ovarian axis. Circulating leptin correlates strongly with obesity, which is frequently associated with polycystic ovarian syndrome (PCOS), a major form of dysovulatory infertility in women, characterized by endocrine abnormalities such as hyperandrogenism and inappropriate LH secretion. PCOS is also often associated with insulin resistance and hyperinsulinemia, features that are linked to leptin and its receptors. However, the relationship between leptin and gonadotropins, androgens, and insulin in PCOS is still controversial.

AIM

Present investigation attempts to evaluate the interrelationship between serum leptin level with body mass index, insulin and with circulating testosterone in PCOS women.

SUBJECTS AND METHODS

Women diagnosed with either tubal block/male factor infertility (Control; n = 18) and with PCOS (n = 16), enrolled for in vitro fertilization and embryo transfer (IVF-ET), were recruited for this study. All were reviewed for body mass index (BMI), endocrine milieu (including pituitary gonadotropins, TSH, prolactin, gonadal steroids, and insulin) and for circulating serum leptin. Interpretation of data was done using PRISM Statistical Software Package (PRISM Version 4.03@1992-2005; GraphPad Software Inc).

RESULTS

Positive correlation was observed between serum leptin, BMI, and insulin in both the groups. Mean BMI, LH, and LH: FSH ratios were found elevated in the PCOS population. PCOS women also had significantly elevated androgens and fasting levels of insulin.

CONCLUSION

Hyperleptinemia in PCOS women appears to be due to the positive correlation between serum leptin, BMI, and insulin.

An update on the pathogenesis, inflammation, and metabolism in hirsutism and polycystic ovary syndrome

Hirsutism is a common endocrine disorder, defined as increased growth of terminal hairs in a male pattern. Hirsutism is most often caused by polycystic ovary syndrome (PCOS), whereas only 5% patients are diagnosed with rare endocrine diseases. PCOS may be considered a multiorgan disease causing not only increased adrenal and ovarian sex hormone secretion but also changed secretion of gonadotrophins, growth hormone, and adrenocorticotrophic hormone (ACTH) from the pituitary. The majority of patients with PCOS are insulin resistant and PCOS is characterized by an increased inflammatory state with abdominal obesity and increased secretion of interleukins, chemokines, and adipokines. PCOS is therefore associated with an increased risk of the metabolic syndrome and type 2 diabetes (T2D). Patients with hirsutism present with increased bone mineral density despite decreased D-vitamin levels. The etiology to hirsutism and PCOS is most likely multifactorial including both genetic and environmental factors such as increased fetal stress and intrauterine growth retardation. In the present review, we give a comprehensive overview of the pathophysiology and multiple endocrine disturbances of hirsutism and PCOS.

Leptin levels in relation to marital status and neuroendocrine function in Iraqi females with polycystic ovary syndrome

The present study was designed to evaluate the relationship between serum leptin levels and the hormones related to fertility in Iraqi females with polycystic ovary syndrome (PCOS) and marital status. This study was conducted during the period from July to December 2007. Twenty-four women (12 married and 12 unmarried) with PCOS and not maintained on any type of therapy were included in the study. Twelve healthy and normal ovulatory women with an age range matched with that of PCOS women were included. After an overnight fasting, blood samples were drawn from all women at random days. While in those with regular menstrual cycles, blood samples were obtained during the follicular phase of the cycle, except for samples utilized for the assay of progesterone that performed in the day 21 of the cycle (luteal phase). After preparation of serum, the levels of leptin, luteinizing hormone (LH), follicle-stimulation hormone (FSH), progesterone, testosterone and prolactin were analyzed. Both groups of PCOS patients showed significantly lower levels of serum leptin, while prolactin, LH and FSH and testosterone were significantly elevated compared to controls. No significant differences were reported among PCOS patients with different marital status. In conclusion, impaired plasma leptin levels in PCOS women were associated with impaired endocrinological parameters related to fertility.

Free and total leptin serum levels and soluble leptin receptors levels in two models of genetic obesity: the Prader-Willi and the Down syndromes

Alterations in energy balance and feeding behavior and the subsequent high frequency of obesity are hallmarks of 2 chromosomal diseases: the Prader-Willi syndrome (PWS) and the Down syndrome (DS). Leptin, an important regulator of food intake and energy homeostasis, circulates in 2 forms: a free, therefore active, fraction and a fraction bound to the soluble leptin receptor, whose bioavailability consequently participates in the regulation of leptin action. To investigate the possible role of the free-bound leptin balance in the pathogenesis of obesity in PWS and DS, we enrolled 7 obese women with DS, 5 obese women with PWS, 7 obese women, and 7 normal-weight healthy control women. Basal hormonal concentrations, total and free leptin levels, and leptin receptors levels were measured in plasma samples obtained from the 4 groups. No significant differences were observed in the hormonal milieu. Women with DS exhibited lower total leptin concentrations (P<.01), comparable leptin receptor level and, therefore, lower free leptin values (P<.01) when compared with obese controls, then resembling the profile peculiar to normal-weight control women. At variance, subjects with PWS did not differ from obese controls regarding both leptin and leptin receptor levels. Our data suggest that, whereas subjects with PWS have a leptin assessment corresponding to their degree of obesity, subjects with DS may have a defect in the secretion of leptin that could at least partially account for this form of syndromal obesity.

Inverse relationship between luteinizing hormone and body mass index in polycystic ovarian syndrome: investigation of hypothalamic and pituitary contributions

CONTEXT

Patients with polycystic ovarian syndrome (PCOS) have increased LH relative to FSH, but LH is modified by body mass index (BMI).

OBJECTIVE

The objective of the study was to determine whether the impact of BMI on neuroendocrine dysregulation in PCOS is mediated at the hypothalamic or pituitary level. PARTICIPANTS/INTERVENTIONS/SETTING: Twenty-four women with PCOS across a spectrum of BMIs underwent frequent blood sampling, iv administration of GnRH (75 ng/kg), and sc administration of the NAL-GLU GnRH antagonist (5 microg/kg) in the General Clinical Research Center at an academic hospital.

MAIN OUTCOME MEASURES

LH pulse frequency and LH response to submaximal GnRH receptor blockade were used as measures of hypothalamic function; LH response to GnRH was used as a measure of pituitary responsiveness.

RESULTS

BMI was negatively correlated with mean LH, LH/FSH, and LH pulse amplitude. There was no effect of BMI on LH pulse frequency. Percent inhibition of LH was decreased in PCOS, compared with normal women (53.9 +/- 1.5 vs. 63.1 +/- 4.1, respectively; P < 0.01), suggesting an increase in the amount of endogenous GnRH, but was not influenced by BMI. Pituitary responsiveness to GnRH was inversely correlated with BMI (peak LH, R = -0.475, P < 0.02; and LH area under the curve R = -0.412, P < 0.02).

CONCLUSIONS

LH pulse frequency and quantity of GnRH are increased in PCOS, but there is no influence of BMI on either marker of hypothalamic function. The pituitary response to a weight-based dose of GnRH is inversely related to BMI in PCOS. These studies suggest that the effect of BMI on LH is mediated at a pituitary and not a hypothalamic level in PCOS.

Impact of the selective serotonin reuptake inhibitor citalopram on insulin sensitivity, leptin and basal cortisol secretion in depressed and non-depressed euglycemic women of reproductive age

INTRODUCTION

Major depression in women of reproductive age may be accompanied by multiple endocrine and metabolic disturbances, which, in turn, may affect reproductive functioning. Enhanced cortisol synthesis, impaired leptin production and diminished insulin sensitivity have been reported in some depressed populations. We sought to determine whether an 8-week administration of citalopram would have an effect on these endocrine factors in a group of euglycemic depressed and non-depressed women of reproductive age.

MATERIALS AND METHODS

Fourteen depressed and 18 non-depressed women (diagnosed by structured clinical interview) aged between 18 and 45 years completed an 8-week study. All depressed women were treated with citalopram and non-depressed subjects randomized to citalopram or no treatment in an open label cohort study. An oral glucose tolerance test with insulin levels was performed at baseline and at the end of the 8-week trial. Weight, blood pressure, fasting serum cortisol, fasting serum leptin and Beck Depression Inventory were assessed at baseline, 2, 4 and 8 weeks.

RESULTS

Citalopram significantly improved depressive symptoms and Beck Depression Inventory scores in the depressed cohort. Cortisol production was higher in depressed women but did not diminish with citalopram therapy over 8 weeks. Indices of insulin sensitivity and leptin production were similar between depressed and non-depressed women and did not change despite citalopram therapy.

CONCLUSION

. Insulin sensitivity in moderately depressed women of reproductive age does not differ from that in a similar group of non-depressed women. Insulin sensitivity, cortisol secretion and leptin production do not change significantly in depressed women following an 8-week course of citalopram despite substantial improvement in depression scores.

Are growth factors and leptin involved in the pathogenesis of premature adrenarche in girls?

A transient increase in height and bone age as well as hyperinsulinism is seen in patients with premature adrenarche (PA). In addition, the weights of these patients are more than those of healthy peers. The aim of this study was to evaluate the role of leptin, IGF-I and IGFBPs in hyperandrogenemia and increased body weight observed in girls with PA. In this study, IGF-I, IGFBP-3, IGFBP-1 and leptin levels were investigated in 27 children with PA aged 5.4-8.6 years and 13 healthy children aged 5.7-8.58 years. Twenty patients were lean. The bone ages and BMIs of the children with PA were significantly higher than those of the healthy controls (p < 0.05). IGF-I (p < 0.005), IGFBP-3 (p < 0.05) and leptin (p < 0.0001) levels of lean PA girls were higher than controls. The leptin level of the obese PA girls was higher than that of the lean PA girls (p < 0.05) and controls (p < 0.0001). The IGFBP-1 level of the PA girls with and without obesity was lower than controls (p < 0.05). A negative correlation was observed between IGFBP-1 and leptin levels of the girls with PA (r = -0.64, p < 0.05). Serum leptin levels were influenced by BMI (p = 0.001), basal 17-OHP (p = 0.002) and stimulated 17-OHP (p = 0.019) in patients with PA. In conclusion, we suggest that elevated IGF-I and insulin give rise to increased adrenal androgens and leptin levels. On the other hand, both insulin and leptin cause decreased levels of IGFBP-1 in girls with PA, even if they are lean.

Leptin and its association with polycystic ovary syndrome: a twin study

Polycystic ovary syndrome (PCOS) is a common endocrinopathy with symptoms such as obesity, insulin resistance and hyperandrogenemia. PCOS might be the result of a genetic disorder. Genetic discrepancy in the production of leptin, a product of the obesity gene, may lead to various endocrinopathies such as PCOS. The objective of this study was first, to ascertain the incidence of PCOS, using the gold standard; second, to ascertain the genetic property of leptin; and third, to evaluate the association between leptin concentration and PCOS. A total of 154 Tehran-resident female-female twins were studied. They included 48 pairs of monozygotic (MZ) and 29 pairs of dyzygotic (DZ) twins, aged 15-45 years. Clinical, ultrasound and biochemical findings were used to diagnose PCOS. The incidence of PCOS using biochemical and clinical features was 16.2%. The correlation coefficient between serum leptin levels of MZ twins was higher than that of the DZ twins. The serum level of leptin was similar between subjects with or without PCOS, irrespective of their zygosity. It was concluded that the incidence of PCOS is high among twins, and that leptin is likely to be genetically determined, although the effect of environmental factors cannot be denied. This study did not find any association between the diagnosis of PCOS and leptin level. However, the link between the two may lie with other entities such as eating disorders and/or obesity.

A randomized trial of the effects of two types of short-term hypocaloric diets on weight loss in women with polycystic ovary syndrome

OBJECTIVE

We performed this study as a pilot experiment to investigate the short term effects of two diets of varying composition on weight loss as the primary outcome in obese women with polycystic ovary syndrome (PCOS) seeking fertility.

DESIGN

Randomized clinical trial.

SETTING

Academic medical center.

PATIENT(S)

Thirty-five obese women with PCOS.

INTERVENTION(S)

We examined the effects of a 1-month dietary intervention on the PCOS phenotype. Participants were randomized to one of two energy-restricted diets; high protein (HP: 30% protein, 40% carbohydrate, and 30% fat) or high carbohydrate (HC: 15% protein, 55% carbohydrate, and 30% fat). The fat content was held constant in both diets.

MAIN OUTCOME MEASURE(S)

Primary - change in body weight; Secondary - biometric, hormonal, lipid and lipoprotein, and markers of glucose homeostasis and energy metabolism.

RESULT(S)

Twenty-six women completed the study. Both the HP (-3.7 +/- 1.9 kg) and HC (-4.4 +/- 1.5 kg) diets resulted in significant weight loss, but there was no significant difference in mean weight loss between the two groups. There were also no differences between diets on a variety of measures including circulating androgens, measures of glucose metabolism, and leptin. However, the effects of a hypocaloric diet per se on improving metabolic and reproductive abnormalities in a group of PCOS women were marked by a decline in circulating androgens (P=.03), fasting and area under the curve (AUC) insulins (P<.05) on a 3-hour oral glucose tolerance test (OGTT), and fasting and AUC leptin levels (P<.0001). There was a high prevalence of menstrual bleeding during the trial (14 out of 26 patients).

CONCLUSION(S)

Those who completed the short-term hypocaloric diet had a significant weight loss and a significant improvement in their reproductive and metabolic abnormalities. There was no increased benefit to a high-protein diet. Future diet studies evaluating the ideal composition of a hypocaloric diet in women with PCOS will require a large study population, and will most likely require a multicenter trial.

Pathogenesis of polycystic ovary syndrome: what is the role of obesity?

Both obesity and the polycystic ovary syndrome (PCOS) are commonly seen in women of reproductive age. Fifty percent of all patients with PCOS are obese, and the presence of obesity affects the clinical manifestations of PCOS. The underlying pathogenetic mechanisms appear to involve insulin resistance and hyperinsulinemia, the magnitude of which is greater in obese than in non-obese women with PCOS. Specific effects of obesity on the manifestations of PCOS, underlying mechanisms of the interactions between obesity and PCOS, and therapeutic implications of these interactions are discussed in this article.

Determinants of serum leptin levels in healthy postmenopausal women

The aim of this study was to evaluate factors that influence leptin levels in postmenopausal women. One hundred and forty-four postmenopausal women were evaluated cross-sectionally. In every woman a complete medical history was obtained, body mass index (BMI) was recorded and morning fasting blood was obtained for the determination of serum leptin, follicle stimulating hormone (FSH), estradiol, testosterone, delta4androstendione, dehydroepiandrosterone sulphate (DHEAS) and insulin. In univariate analysis, age, BMI and insulin were positively correlated with serum leptin, while DHEAS showed a negative association with leptin concentrations (age r=0.21, p=0.005, BMI r=0.41, p=0.0001, insulin r=0.20, p=0.008, DHEAS r=-0.28, p=0.0001). In stepwise multivariate regression analysis serum leptin could be best predicted from BMI, serum insulin and serum DHEAS [leptin= (1.41 * BMI) - (0.01 * DHEAS) + (3.26 * insulin) - 26.3; model r2=0.24, p=0.001]. In conclusion, BMI and serum insulin have a positive while serum DHEAS has a negative impact on serum leptin. Neither endogenous estradiol, nor endogenous testosterone are associated with leptin levels. Further studies are needed to elucidate the role of leptin in determining body weight and composition in postmenopausal women.

Is serum leptin level regulated by thyroid functions, lipid metabolism and insulin resistance in polycystic ovary syndrome?

Our aim was to determine whether serum leptin level is regulated by thyroid hormones, lipid metabolic products and insulin resistance status in women with polycystic ovary syndrome (PCOS). A prospective case-controlled study was carried out in Istanbul University, Cerrahpasa School of Medicine in 25 lean PCOS (L-PCOS) women, 19 obese PCOS (O-PCOS) women and 28 normal women. The diagnosis of PCOS was established according to the clinical, hormonal (elevated luteinizing hormone and serum androgens) and ultrasonographic findings. Fasting serum levels of thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), fasting glucose, insulin, total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), very low-density lipoprotein-cholesterol (VLDL-C) and leptin were measured and compared in the three groups and the correlations between serum levels of leptin and other parameters were evaluated. Serum leptin levels were higher in the O-PCOS group, while its level was comparable between the L-PCOS and control groups. Serum levels of FT4 were significantly lower in both L-PCOS and O-PCOS groups than the control group. Women in both L-PCOS and O-PCOS groups were found to be significantly hyperinsulinemic and insulin resistant. Serum levels of TC, VLDL-C and TG were significantly higher in the O-PCOS group, while serum HDL-C level was lower. There was a poor correlation between serum leptin, and FT4, TC, TG, HDL-C and VLDL-C levels. A significant correlation was observed between serum leptin levels and both BMI and insulin resistance status in PCOS. We believe that, although thyroid hormones and lipid metabolic products do not seem to participate in the regulation of serum leptin levels, BMI and insulin resistance status may have a key role in women with PCOS.

The association of serum androsterone glucuronide with inflammatory lesions in women with adult acne

Serum androsterone glucuronide (AoG) is a metabolite of circulating androgens under the influence of 5alpha-reductase activity and has been shown to be particularly elevated in women with acne. In this study, we wanted to evaluate changes in AoG before and after treatment with an oral contraceptive or placebo, and to assess whether changes correlated with the number and type of acne lesions. In order to accomplish these aims, we obtained sera from a completed prospective randomized trial, which was designed to assess the effectiveness of an oral contraceptive compared to placebo. Assessments were carried out in 56 women with moderate acne who were treated with Ortho Tri-Cyclen (norgestimate and ethinylestradiol) (30 patients) or placebo (26 patients) for 6 months. Before and after treatment, the number and type of skin lesions, serum levels of total T, free-T, DHEAS and AoG were determined. Serum AoG increased significantly in women with moderate acne, although T, free-T and DHEAS were normal. 75% of acne patients had elevated levels of serum AoG. Ratios of serum AoG to androgen precursors were also elevated. Oral contraceptive (OC) treatment significantly reduced levels of free-T and AoG, both of which were unaffected by placebo. While both OC and placebo treatment resulted in improvement of comedones and inflammatory lesions, OC treatment decreased inflammatory lesions to a greater extent (p<0.05). After treatment, serum AoG correlated with the number of inflammatory lesions. Results showed that serum AoG is a sensitive marker of acne in women, even in those with normal circulating precursor androgens; and is lowered by OC treatment, correlating with the reduction of inflammatory lesions. We hypothesize that the increase of serum AoG in normoandrogenic acne may be related to inflammation, and serum AoG may serve as a marker of this process.

Evidence for competing effects of body mass, hyperinsulinemia, insulin resistance, and androgens on leptin levels among lean, overweight, and obese women with polycystic ovary syndrome

OBJECTIVE

To evaluate the relationships between leptin, body composition, insulin resistance, androgens, and reproductive indices among women with polycystic ovary syndrome (PCOS).

DESIGN

Matched case-control study.

SETTING

Academic reproductive endocrine practice; school of public health.

PATIENT(S)

Forty-six Caucasian women with PCOS and 46 population-based controls matched by age and body mass index (BMI).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Leptin, insulin, androgenic hormones, body composition parameters; reproductive parameters.

RESULT(S)

Overall, leptin levels among women with PCOS did not differ significantly from those of control women (20.4 +/- 14.9 vs. 21.9 +/- 14.3 ng/mL). However, within the lowest BMI tertile, women with PCOS had significantly lower leptin levels (9.6 vs. 18.3 ng/mL), comparable insulin, and higher testosterone concentrations than controls of similar body mass. Within the overweight and obese subgroups, both insulin and testosterone levels were increased among women with PCOS; leptin levels, although higher among obese cases, were not statistically different than those in controls.

CONCLUSION(S)

Below a certain BMI, hyperandrogenic women with PCOS have lower leptin levels than controls. Conversely, overweight and obese PCOS subjects appear to produce insufficient leptin for a given fat mass, relative to the degree of hyperinsulinemia, potentially because of the competing effects of adipocyte insulin resistance and androgens on leptin.

Baseline non-fasting serum leptin concentration to body mass index ratio is predictive of IVF outcomes

BACKGROUND

The present study was designed to determine whether circulating leptin concentrations and/or body mass index (BMI) in women undergoing IVF are predictive of outcomes.

METHODS

IVF cycle outcomes, e.g. fertilization, embryo development, implantation, pregnancy, were analysed relative to baseline (i.e. day gonadotrophin stimulation was initiated) non-fasting serum leptin concentrations and BMI.

RESULTS

Serum leptin concentrations correlated with BMI (r = 0.739, P < 0.0001) as expected. Multiple logistic regression analyses showed correlation between serum leptin and pregnancy success (likelihood ratio = 5.198, P < 0.05), but there was no association between pregnancy and BMI. However, the serum leptin to BMI ratio was more strongly correlated (likelihood ratio = 7.258, P < 0.01) with pregnancy success than was leptin alone. Moreover, women with a low leptin:BMI ratio (< or =0.3) had significantly more superior quality embryos on day 3 post-retrieval (2.5 versus 1.4, P < 0.05, Kruskal-Wallis) and a greater implantation rate (26.7 versus 13.2%, P < 0.025, chi(2)) than women with a high leptin:BMI ratio (> or =0.7).

CONCLUSIONS

The leptin:BMI ratio appears to be highly predictive of IVF success. Elevated leptin concentrations, particularly relative to BMI, may negatively impact fertility by assisted reproduction, possibly through direct ovarian actions resulting in impaired oocyte quality and/or early embryo development.

Leptin, reproduction and sex steroids

Leptin is a hormone secreted mainly by the adipose cells with a primary role in the regulation of body weight by establishing a feedback loop between the energy reserves and the hypothalamic centers that control food intake. Recent data suggest that, in addition, leptin interacts with other endocrine systems to provide critical information about the size of the fat stores, acting as a permissive factor that allows the triggering of energy-demanding situations, as the onset of puberty and the reproduction, only when the size of the fuel reserve is large enough to guarantee its success. In addition, leptin appears to play a role during pregnancy and lactation, as it is produced by the placenta and is present in maternal milk. The fact that leptin levels are always higher in females, even after correcting for body fat content, suggests that the interaction between the adipose tissue and the reproductive system is modulated in a different way in males and females by androgenic and estrogenic hormones. In fact, adipose tissue samples taken from male donors are completely refractory in vitro to the action of both estrogens and androgens. On the contrary, dihydrotestosterone, androstenedione and dehydroepiandrosterone-S are potent inhibitors of leptin secretion, while estradiol induces a strong stimulation in adipose tissue taken from women. Testosterone is devoid of activity in either gender.

Interactions between sex steroid hormones and leptin in women. Studies in vivo and in vitro

OBJECTIVE

To investigate the associations between sex hormones and leptin. In addition, to investigate the direct effect of sex hormones by incubations of human subcutaneous adipose tissue explants, in vitro.

DESIGN

Cross-sectional study and an experimental in vitro study.

SUBJECTS

36 women (age, 23-65 y; body mass index, BMI, 19-65 kg/m2) participated in the cross-sectional study. Subcutaneous abdominal biopsies were taken from nine women (age, 28 - 46 y; BMI, 25.5-36.0 kg/m2) for the in vitro study.

MEASUREMENTS

Fat distribution parameters (by dual-energy X-ray absorptiometry and anthropometry), sex hormones, leptin and insulin.

RESULTS

Leptin correlated significantly with most estimates of adipose tissue mass (r= 0.5 - 0.9, P< 0.05). However, when the study group was divided in three equal groups (non-obese, obese, and very-obese) it revealed that the correlation predominantly was found in non-obese. In simple correlation analysis leptin was significantly associated with estimates of adipose tissue, insulin and several sex hormones. However, in multiple regression analysis only insulin (partial correlation coefficient = 0.55, P < 0.004) and percentage fat mass (partial correlation coefficient = 0.72, P<0.001) were significantly and independently correlated with leptin without any independent effect of sex hormones. These findings were in agreement with the in vitro studies where neither estrogen nor androgens (testosterone or DHT) affected subcutaneous adipose tissue leptin production. Dexamethasone (10nM) stimulated adipose tissue leptin production 3-fold (P < 0.001).

CONCLUSION

In regression analysis, where both insulin and measurements of fat mass were taken into account, androgens or estrogens did not independently contribute to the variation in leptin levels. Estrogens and androgens had no direct effects on adipose tissue leptin production in vitro. Thus, the sexual dimorphism evident in serum leptin is not likely to be due to a direct influence of sex hormones on leptin production in females.