Cell and molecular mechanisms behind diet-induced hypothalamic inflammation and obesity.

Diet-induced obesity (DIO) is associated with chronic, low-grade inflammation in the hypothalamus, a key regulator of energy homeostasis. Current studies have revealed the involvement of different cell types, as well as cell and molecular mechanisms, that contribute to diet-induced hypothalamic inflammation (DIHI) and DIO. Subsequent to the discovery that high-fat diet and saturated fatty acids increase the expression of hypothalamic cytokines prior to weight gain, research has focused on understanding the cellular and molecular mechanisms underlying these changes, in addition to the role of inflammation in the pathogenesis of obesity. Recent studies have proposed that the inhibition of pro-inflammatory pathways in microglia and astrocytes is sufficient to protect against DIHI and prevent obesity. In addition, impairment of intracellular and epigenetic mechanisms, such as hypothalamic autophagy and changes in the methylation pattern of certain genes, have been implicated in susceptibility to DIHI and DIO. Interestingly, a sexual dimorphism has been found during DIO in hypothalamic inflammation, glial activation and metabolic diseases, and recent data support an important role of sex steroids in DIHI. These new exciting findings uncover novel obesity pathogenic mechanisms and provide targets to develop therapeutic approaches.

Metformin increases norepinephrine transporter expression in placenta of patients with polycystic ovary syndrome.

OBJECTIVE: To evaluate the norepinephrine (NE) and placental NE transporter (NET) in women with polycystic ovary syndrome (PCOS) non-treated and treated with metformin during pregnancy. PATIENTS AND METHODS: We studied sixteen pregnant women with PCOS: 8 without metformin treatment during pregnancy (PCOS-M) and 8 treated with metformin during pregnancy (PCOS+M). Sixteen pregnant women of similar age without PCOS were included as controls (Control). At 24th and 35th weeks of pregnancy, blood samples were obtained. Placentas from full-term pregnancies were collected immediately after delivery. They were divided into two samples representative from the region near the chorionic plate (fetal side) and from the region near the basal plate (maternal side). NE plasma concentrations were measured by HPLC with electrochemical detection, and placental NET protein levels were determined by Western blot. RESULTS: At week 24 of gestation, PCOS-M had higher NE plasma levels compared to control women (p < 0.001). Moreover, NET expression was lower in the maternal side of the placenta of PCOS-M compared to controls (p < 0.05). Metformin treatment normalized NE plasma levels at week 24 of gestation and NET expression in the maternal side of the placenta. In the fetal side of the placenta, NET expression was lower in PCOS-M and PCOS+M compared to control women (p < 0.001 and < 0.01, respectively). CONCLUSIONS: Our results strongly suggest that norepinephrine homeostasis is altered in pregnant women with PCOS. Remarkably, metformin administration during pregnancy decreases circulating norepinephrine levels and increases NET expression in the maternal side of placentas from PCOS women.

Obesity during pregnancy affects sex steroid concentrations depending on fetal gender.

BACKGROUND/OBJECTIVE: It is not clear whether maternal obesity along with fetal gender affect sex steroid metabolism during pregnancy. Therefore, we compared sex steroid concentrations and placental expression of steroidogenic enzymes between non-obese and obese pregnant women with non-pathological pregnancies, and investigated the influence of fetal gender on these parameters. METHODS: In 35 normal weight (body mass index (BMI) 20-24.9 kg m-2) (controls) and 36 obese women (BMI 30-36 kg m-2) (obese), a fasting blood sample was obtained at first and at third trimester of gestation to measure progesterone, dehydroepiandrosterone (DHEA), DHEA sulfate, androstenedione, testosterone and estradiol by liquid chromatography-tandem mass spectrometry and estrone by radioimmunoassay. In a subset of women, placental mRNA and protein expression of steroidogenic enzymes was measured by quantitative PCR and western blot, respectively. The comparisons were primarily made between controls and obese, and then separately according to fetal gender. RESULTS: At first and third trimesters of gestation serum progesterone was lower whereas testosterone was higher in obese women (P<0.05, respectively). Upon analyzing according to fetal gender, lower progesterone levels were present in obese pregnant women with male fetuses at first trimester and with female fetuses at third trimester (P<0.05, respectively). Testosterone was higher in obese women with male fetuses compared to control women with male fetuses (P<0.05). The placental protein expression of P450scc was higher in obese women compared to controls (P<0.05). P450 aromatase was higher in obese women with female fetuses (P=0.009), whereas in obese women with male fetuses P450 aromatase was lower compared to control women (P=0.026). CONCLUSIONS: Obesity in non-pathological pregnancies alters the maternal serum progesterone and testosterone concentrations depending on fetal gender. These changes can be attributed to gender-related placental adaptations, as the expression of P450 aromatase is different in placentas from females compared to males.

Neuroendocrine Regulation of Metabolism.

Given the current environment in most developed countries, it is a challenge to maintain a good balance between calories consumed and calories burned, although maintenance of metabolic balance is key to good health. Therefore, understanding how metabolic regulation is achieved and how the dysregulation of metabolism affects health is an area of intense research. Most studies focus on the hypothalamus, which is a brain area that acts as a key regulator of metabolism. Among the nuclei that comprise the hypothalamus, the arcuate nucleus is one of the major mediators in the regulation of food intake. The regulation of energy balance is also a key factor ensuring the maintenance of any species as a result of the dependence of reproduction on energy stores. Adequate levels of energy reserves are necessary for the proper functioning of the hypothalamic-pituitary-gonadal axis. This review discusses valuable data presented in the 2015 edition of the International Workshop of Neuroendocrinology concerning the fundamental nature of the hormonal regulation of the hypothalamus and the impact on energy balance and reproduction.

Changes in HbA1c and circulating and adipose tissue androgen levels in overweight-obese women with polycystic ovary syndrome in response to electroacupuncture.

AIM: Insulin sensitivity is ~40% lower in women with polycystic ovary syndrome (PCOS) than in controls. We tested the hypothesis that 5 weeks of electroacupuncture treatment improves glucose regulation and androgen levels in overweight/obese women with PCOS. MATERIAL AND METHODS: Seventeen women with PCOS, aged 18 to 38 years, with a body mass index (BMI) ≥25 kg/m2 and diagnosed with PCOS were included in this experimental and feasibility study and subjected to five weeks of electroacupuncture treatments three times/week. The primary outcome was changes in whole-body glucose homeostasis measured by euglycemic hyperinsulinemic clamp before and after the intervention. Secondary outcome were changes in HbA1c, circulating catecholamines, adipocyte size and adipose tissue expression of sex steroids and nerve growth factor (NGF). RESULTS: No significant change in glucose homeostasis was observed, but HbA1c decreased by 9.5% (p = 0.004), circulating testosterone decreased by 22% (p = 0.0007) and dihydrotestosterone decreased by 12% (p = 0.007). The two vagal activity markers of plasma serotonin levels and the dopamine metabolite homovanillic acid decreased by 21% (p = 0.027) and 20% (p = 0.011), respectively. Adipose tissue concentrations of testosterone decreased by 18% (p = 0.049), and androstenedione decreased by 13% (p = 0.035), and mature NGF/proNGF ratio, a marker of sympathetic activity, increased (p = 0.04). These changes occurred without changes in anthropometrics. CONCLUSION: Five weeks of electroacupuncture treatment improves HbA1c and circulating and adipose tissue androgens in women with PCOS. This effect is mediated, at least in part, via modulation of vagal activity and adipose tissue sympathetic activity. Based on these findings, we have recently initiated a randomized controlled study (NTC02647827).

Placental STAT3 signaling is activated in women with polycystic ovary syndrome.

STUDY QUESTION: Does polycystic ovary syndrome (PCOS) in women without pregnancy complications affect placental signal transducer and activator of transcription 3 (STAT3) and mechanistic target of rapamycin (mTOR) signaling? SUMMARY ANSWER: Placental STAT3 signaling is activated but mTOR signaling is unaffected in PCOS. WHAT IS KNOWN ALREADY: Women with PCOS have increased risk of poor pregnancy outcomes (e.g. restricted or accelerated fetal growth), indicating placental dysfunction. Placental STAT3 and mTOR pathways regulate placental function and indirectly affect fetal growth. STUDY DESIGN, SIZE, DURATION: In a case-control study, placental tissue and maternal blood were collected at delivery from 40 control pregnant women and 38 PCOS women with uncomplicated pregnancy. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women with PCOS were recruited at two medical centers and pregnant controls were recruited at one of these centers. Placental mRNA expression of genes encoding proteins related to steroid action, metabolic pathways and cytokines was analyzed by quantitative RT-PCR. Phosphorylated placental STAT3 (P-STAT3) and mTOR targets was measured by western blot. Levels of sex steroids in serum were determined by mass spectrometry. MAIN RESULTS AND THE ROLE OF CHANCE: Placental P-STAT3 (Tyr-705) was increased in women with PCOS (P < 0.05) versus controls. Placental mTOR signaling was not affected in PCOS women when compared with controls. Circulating levels of androstenedione, androst-5-ene-3ß, 17ß-diol, testosterone, 5α-dihydrotestosterone and etiocholanolone glucuronide were higher and estradiol lower in women with PCOS than in controls (all P < 0.05). No correlation between sex steroid levels in serum and P-STAT3 was observed. LIMITATIONS, REASONS FOR CAUTION: Women with PCOS and pregnancy complications were excluded to avoid the confounding effects of placental pathologies, which could modify STAT3 and mTOR signaling. Moreover, 97.4% of women with PCOS in the study displayed oligoamenorrhea at diagnosis. Thus, the current findings could be restricted to PCOS women with the oligo-anovulatory phenotype without pregnancy complications. WIDER IMPLICATIONS OF THE FINDINGS: Phosphorylation of STAT3 is increased in the placenta from women with PCOS and uncomplicated pregnancies, indicating that specific metabolic placental pathways are activated in the absence of obstetric and perinatal complications. STUDY FUNDING/COMPETING INTERESTS: The work was supported by the Swedish Medical Research Council (Project No. 2011-2732 and 2014-2775); Jane and Dan Olsson Foundation, Wilhelm and Martina Lundgrens's Science Fund; Hjalmar Svensson Foundation (E.S.-V and M.M.); Adlerbert Research Foundation; Swedish federal government under the LUA/ALF agreement ALFFGBG-136481 and 429501 and the Regional Research and Development agreement (VGFOUREG-5171, -11296 and -7861). MM thanks the Becas Chile Programme (Chile) and University of Chile for financial support through a postdoctoral fellowship. There are no competing interests.

Serum adiponectin and lipid concentrations in pregnant women with polycystic ovary syndrome.

BACKGROUND: We aimed to evaluate the serum adiponectin and lipid concentrations in normal and polycystic ovary syndrome (PCOS) women during pregnancy in order to establish whether PCOS induces abnormal lipid and adiponectin levels that could constitute potential metabolic risk factors for pregnancy complications. METHODS: Women with singleton pregnancies and of similar age were included (48 pregnant PCOS and 51 normal pregnant women). During gestational weeks 10-16 and 22-28, a 2 h, 75 g oral glucose tolerance test was performed, with measurement of glucose and insulin in each sample. Adiponectin and lipid concentrations were determined in the fasting sample. RESULTS: The incidence of gestational diabetes mellitus (GDM) was significantly higher in the PCOS group (12.2%) compared with the control group (2%). In PCOS patients, triglyceride (TG) concentrations and area under the curve of glucose and insulin were higher in both study periods and adiponectin concentrations were significantly lower in the second period, compared with normal women. Moreover, adiponectin concentrations were lower in women with GDM than in those with normal glucose tolerance in the two study periods. CONCLUSION: Low adiponectin and high insulin levels are associated with GDM in pregnant PCOS patients. High TG levels seem not to be directly related to pregnancy complications in these patients.

Patterns of hormonal response to the GnRH agonist leuprolide in brothers of women with polycystic ovary syndrome: a pilot study.

BACKGROUND: The aim of this study was to evaluate the effect of a single dose of leuprolide acetate on gonadotrophin and gonadal steroid secretion in brothers of women with polycystic ovary syndrome (PCOS), in order to assess P450c17alpha activity. An oral glucose tolerance test (OGTT) and a lipid profile were also performed. METHODS: Twenty-two unrelated brothers of women with PCOS (PCOS(b)) and 14 brothers of normal cycling women (C(b)), matched for age, underwent a leuprolide acetate test (10 microg/kg s.c.) and an OGTT with measurement of circulating concentrations of gonadotrophins, steroid hormones, glucose, insulin and lipids. RESULTS: Clinical and basal hormonal parameters were similar in both groups. After leuprolide administration, PCOS(b) exhibited a significant increase of 17alpha-hydroxyprogesterone (17-OHP) compared to C(b) (P<0.05). However, only 45% of PCOS(b) showed a supranormal increase of 17-OHP (2 SD above the respective control group mean values, P<0.003) with a normal gonadotrophin response (group 1). The other 55% of the PCOS(b) exhibited a normal 17-OHP response to the analogue (group 2). However, in group 2, basal steroid concentrations did not show a uniform pattern: six of the PCOS(b) exhibited high basal androstenedione (2 SD above the respective control group mean values), three were very similar to C(b), and the other three presented lower basal testosterone concentrations (2 SD below the respective control group mean values) than those observed in C(b). CONCLUSIONS: This study shows that different responses to leuprolide in PCOS brothers make evident the heterogeneity of this syndrome in which P450c17alpha activity could be involved.

Proinsulin serum concentrations in women with polycystic ovary syndrome: a marker of beta-cell dysfunction?

BACKGROUND: The aim of this study was to establish the effect of polycystic ovary syndrome (PCOS) adjusted for adiposity on proinsulin concentrations. METHODS: Ninety-one women with PCOS and 72 normal cycling (NC) women were recruited. A 2 h, 75 g oral glucose tolerance test was performed. Glucose and insulin were measured in each sample. Proinsulin and C-peptide were determined at 0 and 30 min and the fasting proinsulin/insulin ratio (PI/I) was calculated. Insulin sensitivity was estimated by insulin sensitivity index (ISI) composite, and beta-cell function was estimated by insulinogenic index. RESULTS: Insulin, proinsulin and C-peptide concentrations were higher in women with PCOS than in NC women (P < 0.05). PI/I and insulinogenic index were similar in both groups. Proinsulin concentrations increased with body mass index (P < 0.05) only in women with PCOS; therefore, proinsulin concentrations were higher in obese PCOS patients compared with obese control women (P < 0.05). Moreover, a positive association between proinsulin concentrations and waist diameter adjusted for C-peptide (P < 0.05) and a negative association between proinsulin concentrations and ISI composite values were observed in PCOS patients (P < 0.05). CONCLUSIONS: Data suggest that in PCOS patients an elevated proinsulin concentration could reflect insulin resistance more than beta-cell dysfunction. However, the elevated concentration of proinsulin in these patients could also result from impaired beta-cell function resulting from intra-abdominal obesity independently of insulin resistance.

Maternal serum androgens in pregnant women with polycystic ovarian syndrome: possible implications in prenatal androgenization.

BACKGROUND: The aim of this study was to evaluate the peripheral serum androgen concentrations in normal and polycystic ovarian syndrome (PCOS) women during pregnancy, in order to establish if PCOS may induce gestational hyperandrogenism and therefore constitute a potential source of androgen excess for the fetus. METHODS: Twenty pregnant PCOS (PPCOS) women and 26 normal pregnant (NP) women of similar age with singleton pregnancies were selected for the study. During gestational weeks 10-16 and 22-28, a 2 h, 75 g oral glucose tolerance test (OGTT) was performed. For the OGTT, glucose and insulin were measured in each sample and testosterone, androstenedione, dehydroepiandrosterone sulphate (DHEAS), estradiol, progesterone and sex hormone-binding globulin were determined in the fasting sample. RESULTS: In the first study period (gestational weeks 10-16), the levels of androstenedione, testosterone and DHEAS and the free androgen index tended to be higher in the PCOS group. These differences became significant in the second study period (gestational weeks 22-28). In this second period, 2 h insulin concentrations were also significantly higher in PPCOS than in NP women. CONCLUSIONS: The present study demonstrates a significant increase in androgen concentrations during pregnancy in PCOS women. We propose that these androgen concentrations could provide a potential source of androgen excess for the fetus, without leading to fetal virilization.

Prevalence of Type II diabetes mellitus and insulin resistance in parents of women with polycystic ovary syndrome.

AIMS/HYPOTHESIS: Insulin resistance with increased risk of Type II (non-insulin-dependent) diabetes is a common feature of polycystic ovary syndrome (PCOS). To investigate antecedents of metabolic disorders in family members of patients with PCOS, we evaluated glucose tolerance and insulin resistance in parents of patients with PCOS compared to parents of healthy women. METHODS: A total of 200 parents of women with clinical and hormonal evidence of PCOS (PCOSp) and 120 parents of healthy normally cycling women (HWp) were studied. A 75-g OGGT was performed and subjects were classified according to the World Health Organization (WHO) criteria (1999). Serum glucose and insulin were measured before the glucose load and 30, 60 and 120 min after. C-peptide and sex hormone-binding globulin were also determined before the glucose load. Insulin resistance was assessed by HOMA model and ISI composite. RESULTS: The prevalence of Type II diabetes was 1.89-(1.06-3.38)-fold higher in PCOSp compared to HWp. Insulin resistance, evaluated by HOMA(IR)and ISI composite was also significantly higher in the PCOSp group compared to the HWp group. After both study groups were distributed by sex, and adjusted by age and BMI, the metabolic parameters were still significantly different between PCOSp and HWp. CONCLUSIONS/INTERPRETATION: The data suggest that parents of PCOS women exhibit insulin resistance and Type II diabetes more frequently than those of healthy women, thus constituting a high-risk group but an ideal cohort to detect and prevent the development of Type II diabetes.

[Prevalence of metabolic disorders among family members of patients with polycystic ovary syndrome]. / Prevalencia familiar de patologías metabólicas en pacientes con síndrome de ovario poliquístico.

BACKGROUND: About 60% of patients with polycystic ovary syndrome (PCOS) have insulin resistance, predisposing them to the premature coronary disease and type 2-diabetes mellitus. However, the history of metabolic disorders in family members of patients with PCOS has been seldom documented in the literature. AIM: To evaluate the family profile of metabolic disorders of PCOS patients and to determine their relative risk of developing one of them in comparison to a control group. PATIENTS AND METHODS: Sixty PCOS patients were evaluated. The control group were 60 normal women. The data were obtained from the clinical history and personal interview with the patients, the controls and their relatives (brothers, parents and grandparents). The metabolic disorders considered were: dyslipidemia, obesity, hypertension and diabetes. RESULTS: The ages were similar between groups (PCOS: 24.0 +/- 6.3; control group: 24.8 +/- 6.2 years). The prevalence of metabolic disorders was 62% in the relatives of the PCOS patients and 27.8% in the relatives of the control group (p < 0.005). The probability to develop a metabolic disorder within the family was 2.7 (2.2-3.3) fold higher in the PCOS group compared to the control group. The risk of developing hypertension, dyslipidemia, obesity and diabetes was 2.1 (1.5-2.9); 1.8 (1.5-2.7); 3.6 (2.6-4.9) and 2.7 (1.8-3.9), respectively, in the PCOS group compared to the control group. CONCLUSIONS: The probability of finding a metabolic disorder in the families of PCOS patients, is 2.7 fold higher than in the control group families. The metabolic disorders are more frequent in parents and grandparents of the PCOS patients than in those of normal women.

[Polycystic ovary syndrome: the importance of establishing diagnosis]. / Síndrome de ovario poliquístico: la importancia de establecer su diagnóstico.

Polycystic ovary syndrome (PCOS) is a very common disorder that occurs up to 10% of premenopausal women. Although PCOS is known to be associated with a higher reproductive morbility and increased risk of hormone dependent-cancer, its diagnosis is particularly important because PCOS is strongly linked to insulin resistance. This involves a major risk of early metabolic and cardiovascular complications. On the other hand, the prevalence of metabolic disorders associated with insulin resistance is higher in family members of patients with PCOS than in those of normal women, which suggests that the treatment of this syndrome should be preventive rather than symptomatic. For that reason, PCOS might be considered a signal of a family disorder, a route to diabetes and a public health problem.

Resumption of ovarian function during lactational amenorrhoea in breastfeeding women with polycystic ovarian syndrome: metabolic aspects.

BACKGROUND: Polycystic ovarian syndrome (PCOS) is a common endocrine-metabolic disorder in women, a high percentage of whom exhibit peripheral insulin resistance. After delivery, in normal women, lactation imposes a metabolic adaptation, the impact of which on the insulin resistance of PCOS patients is not known. The aim of this study was to evaluate the effect of lactation on insulin resistance, glucose and insulin metabolism, and sex hormone-binding globulin (SHBG) and insulin-like growth factor binding protein-1 (IGFBP)-1 concentrations in fully breast-feeding normal and PCOS women during the postpartum period (lactational amenorrhoea) and also after weaning. METHODS: Twelve lactating PCOS (LPCOS) women and six normal lactating (NL) women of similar age and body mass index (BMI) were selected for the study. At the 4th and the 8th week postpartum (pp), and 8 weeks after weaning, a 2 h, 75 g oral glucose tolerance test (oGGT) was performed, followed by an insulin tolerance test 2 days later. For the oGGT, glucose and insulin were measured in each sample and SHBG and IGFBP-1 were determined in the fasting sample. RESULTS: During lactation, fasting insulin levels were similar in both groups. In LPCOS women 2 h insulin concentrations were significantly higher, and SHBG and IGFBP-1 concentrations were significantly lower, than those observed in NL women. In both groups, insulin sensitivity evaluated by the insulin tolerance test was not modified. After weaning, in LPCOS women, SHBG and IGFBP-1 concentrations remained lower and insulin concentrations remained higher than those observed in NL women ( P < 0.05 ). CONCLUSIONS: In PCOS women, insulin resistance is not modified during lactation. Lactation has a transitory beneficial effect on insulin levels and biological markers of insulin resistance.

Resumption of ovarian function during lactational amenorrhoea in breastfeeding women with polycystic ovarian syndrome: endocrine aspects.

BACKGROUND: The aim of this study was to evaluate the changes in gonadotrophin concentrations and the dynamics of the episodic fluctuations of circulating LH during night-time, in fully breastfeeding normal women and in those with polycystic ovarian syndrome (PCOS) during lactational amenorrhoea and after weaning, in order to provide insights into the onset of this syndrome. Additionally, ovarian activity was evaluated by ultrasound examination and steroid concentrations. METHODS: Twelve lactating PCOS (LPCOS) women and six normal lactating (NL) women of similar age were selected. On the 4th and 8th week postpartum (PP) and eight weeks after weaning, blood samples were collected every 10 min (10.00--20.00h). Gonadotrophin concentrations were determined in all samples. Steroid hormones were measured in one fasting sample and ovarian morphology was assessed by ultrasound. RESULTS: On the 8th week PP, LH pulse frequency was higher and FSH concentrations were lower in LPCOS women compared with NL women, and steroid hormone concentrations remained low, except for androstenedione which was higher in LPCOS patients. After weaning, similar differences were observed between both groups. PCOS patients also showed enlarged ovaries with a PCOS pattern in the three study periods. CONCLUSIONS: The enlarged ovaries associated with higher androstenedione concentrations suggest that PCOS is a primary ovarian defect, making it difficult to establish if the abnormal LH pattern observed in these women is primary or secondary to the ovarian dysfunction.

Secretory pattern of leptin and LH during lactational amenorrhoea in breastfeeding normal and polycystic ovarian syndrome women.

Several studies have suggested that leptin modulates hypothalamic-pituitary-gonadal axis function. A synchronicity of LH and leptin pulses has been described in healthy women and in patients with polycystic ovarian syndrome (PCOS), suggesting that leptin may modulate the episodic secretion of LH. The aim of the present investigation was to assess the episodic fluctuations of circulating LH and leptin during lactational amenorrhoea in fully breastfeeding normal and PCOS women at 4 and 8 weeks postpartum, in order to establish LH-leptin interactions in the reactivation of the gonadal axis during this period. Six lactating PCOS patients and six normal lactating women of similar age and body mass index were studied. During a 12 h period on the 4th and 8th weeks postpartum, blood samples were collected at 10 min intervals for 12 h (22:00-10:00). Serum LH and leptin concentrations were measured in all samples. For pulse analysis, the cluster algorithm was used. To detect an interaction between LH and leptin pulses, an analysis of co-pulsatility was employed. LH concentrations tended to increase in both groups between the 4th and 8th weeks postpartum; however, serum leptin concentrations were not modified. Leptin pulse frequencies were similar at the 4th and 8th weeks postpartum, and did not differ between groups. Moreover, leptin pulse frequency was higher than LH pulse frequency in both groups, and in the two study periods. There was no synchronicity between LH and leptin pulses, and there were no increments in leptin concentration during the night. The fact that leptin concentrations were not modified and no synchronicity between LH and leptin pulses was observed suggests that, during lactational amenorrhoea, circulating leptin is probably not involved as a primary signal in promoting the reactivation of pulsatile LH secretion.

[Evaluation of acute effect of GnRH administration on leptin secretion in normal and hyperandrogenic women]. / Evaluación del efecto agudo de la administración de GnRH sobre la secreción de leptina en mujeres sanas e hiperandrogénicas.

BACKGROUND: Several studies suggest that leptin modulates the reproductive axis function. Leptin may stimulate release of GnRH from hypothalamus and of gonadotrophins from the pituitary. A synchronicity of LH and leptin pulses has been described in healthy women and in patients with polycystic ovarian syndrome (PCOS), suggesting a relationship between the episodic secretion of LH and leptin. In vitro experimental studies have demonstrated that leptin administration promotes GnRH-LH release. However it is not established whether GnRH promotes the episodic secretion of leptin. AIM: To assess the response of LH and leptin to the administration of a GnRH bolus in hyperandrogenic and healthy women. PATIENTS AND METHODS: Eleven hyperandrogenic and eleven healthy women of similar age and body mass index (BMI) were studied. Under basal conditions three blood samples were collected every 30 min before and after the administration of a GnRH bolus (100 micrograms). LH and leptin concentrations were measured in all samples. Testosterone, SHBG and estradiol were determined in the first sample. For data analysis, the increment of LH and leptin between 0-30 and 0-60 min was calculated. The LH and leptin areas under the curve (AUC) before and after GnRH administration were also calculated in both groups. RESULTS: After GnRH administration an increment in LH concentrations was observed in both groups; however, leptin concentrations were not modified. In both groups LH area under the curve increased after GnRH administration; however, the leptin area was not modified. CONCLUSIONS: These results suggest that circulating leptin concentration is not modulated by GnRH-LH.

[Relationship between leptin and insulin sensitivity in patients with polycystic ovary syndrome]. / Relación entre leptina y sensibilidad a la insulina en mujeres con síndrome de ovario poliquístico.

BACKGROUND: The relationship between leptin and insulin sensitivity, sexual steroids and insulin concentrations in women with polycystic ovary syndrome is still controversial. The objective of this study was to assess the relationship between insulin levels, insulin resistance parameters and serum leptin concentrations in healthy and polycystic ovary syndrome women. PATIENTS AND METHODS: 33 hyperandrogenic polycystic ovary syndrome women (GHA) and 27 healthy women (GS) were included in this study. Leptin, insulin, sex-hormone binding globulin (SHBG), testosterone and estradiol concentrations were determined in a basal sample. Body mass index, waist diameter and waist to hip ratio were recorded. Insulin sensitivity was calculated by means of insulin tolerance test and glycemia/insulinemia ratio. RESULTS: The leptin concentration was not different between GHA and GS. Insulin levels and free testosterona index (FTI) were higher in GHA than GS (p < 0.01). The glycemia/insulinemia ratio, SHBG levels, and insulin sensitivity were lower in GHA (p < 0.01). In both groups positive correlations between leptin concentration and body mass index (p < 0.01), waist diameter (p < 0.01), insulin levels (p < 0.01) and glycemia/insulinemia ratio (p < 0.01) were observed. Only GHA showed correlation between insulin sensitivity and leptin concentration (p < 0.02). SHBG and leptin levels were not correlated. CONCLUSIONS: The leptin concentration was not different between GHA and healthy women, although they are metabolically different. This phenomenon could be due to the fact that in hyperandrogenic women the effects of insulin resistance and hyperandrogenemia counteract each other.

Episodic leptin release is independent of luteinizing hormone secretion.

Several studies suggest that leptin modulates hypothalamic-pituitary-gonadal axis functions. Leptin may stimulate release of gonadotrophin releasing hormone (GnRH) from the hypothalamus and of gonadotrophins from the pituitary. A synchronicity of luteinizing hormone (LH) and leptin pulses has been described in healthy women and in patients with polycystic ovarian syndrome, suggesting that leptin may modulate the episodic secretion of LH. However, it has not been established whether LH regulates the episodic secretion of leptin. To further examine LH-leptin interactions, we studied the episodic fluctuations of circulating LH and leptin in two patients with Kallmann's syndrome (KS) before and on day 7 of pulsatile GnRH administration, and compared these with those observed in the early follicular phase of 10 regularly menstruating women divided into two control groups according to the body mass index of each patient. To assess episodic hormone secretion, blood samples were collected at 10 min intervals for 6 h, before and on day 7 of GnRH administration in KS patients, and during days 3-7 of the follicular phase in normally cycling women. LH and leptin concentrations were measured in all samples. For pulse analysis, the cluster algorithm was used. Before treatment, an apulsatile pattern with no endogenous LH pulsations was observed in both KS patients. However, leptin pulses were assessed in both women. During GnRH administration, pulsatile LH activity was achieved in both patients with pulse characteristics similar to those of the respective control group. Serum leptin concentrations and leptin pulsatile patterns were not modified. These results suggest that circulating leptin is probably not modulated by pulsatile GnRH-LH secretion.