M. Guido

Impact of insulin and body mass index on metabolic and endocrine variables in polycystic ovary syndrome

To assess the differential impact of the insulin secretory pattern and obesity on the endocrinometabolic features of the polycystic ovary syndrome (PCOS), we studied 110 PCOS women. Patients underwent a gonadotropin-releasing hormone (GnRH) test, an oral glucose tolerance test (OGTT), and basal evaluation of hormonal and biochemical parameters. Basal androgens and lipids, basal and stimulated gonadotropins, insulin, and glucose levels were measured. Patients were classified into four groups according to the body mass index (BMI) and insulin secretion: normoinsulinemic-lean ([NL] n = 24), normoinsulinemic obese ([NO] n = 24), hyperinsulinemic lean ([HL] n = 17), hyperinsulinemic obese ([HO] n = 45). HL patients showed a higher luteinizing hormone (LH) area under curve (AUC) after GnRH stimulus compared with NL patients (HL v NL, 4,285 +/- 348 v 3,377 +/- 314 IU/L x 120 min, P < .05), whereas we failed to find a statistically significant difference in a similar comparison among obese subjects (HO v NO, 3,606 +/- 302 v 3,129 +/- 602 IU/L x 120 min). A trend toward increased plasma testosterone and decreased sex hormone-binding globulin (SHBG) was found in relation to hyperinsulinemia and obesity, thus resulting in a higher free androgen index (FAI) in groups HL and NO versus NL (HL, 5.54 +/- 0.51; NO, 5.64 +/- 0.49; NL, 4.13 +/- 0.33; P < .05 and P < .01, respectively). The presence of both exaggerated insulin secretion and obesity resulted in a synergistic additive effect on the FAI in the HO group (6.81 +/- 0.34). Concerning the lipoprotein lipid profile, the NL group showed lower plasma triglyceride levels compared with the other three groups, whereas no significant differences were found for nonesterified fatty acid (NEFA) concentrations. Higher low-density lipoprotein cholesterol (LDL-C) and very-low-density lipoprotein cholesterol (VLDL-C) and lower high-density lipoprotein cholesterol (HDL-C) levels were found in the obese groups compared with the lean counterparts, whereas the same parameters did not significantly differ in a comparison between normoinsulinemic and hyperinsulinemic groups. In conclusion, our data suggest an important role of hyperinsulinemia in the LH response to a GnRH stimulus and an independent and synergistic additive effect of obesity and hyperinsulinemia on the FAI in PCOS.

Gonadotropin-releasing hormone agonist versus human chorionic gonadotropin as a trigger of ovulation in polycystic ovarian disease gonadotropin hyperstimulated cycles

OBJECTIVE To compare the use of GnRH agonist (GnRH-a) versus hCG in triggering the follicular rupture in patients with polycystic ovarian disease (PCOD) in whom ovulation was induced by gonadotropins. DESIGN Polycystic ovarian disease gonadotropin hyperstimulated cycles outcome was investigated in a prospective study. PATIENTS AND INTERVENTIONS Thirty-three PCOD patients (40 cycles) with gonadotropin-induced mild to moderate degree of ovarian hyperstimulation received 5,000 IU IM hCG or 200 microg [corrected] SC GnRH-a. A subgroup of GnRH-a-treated patients received P for luteal support. Five GnRH-a-treated patients underwent a GnRH test during luteal phase. MAIN OUTCOME MEASURES Echographic and endocrine characteristics both during the therapy and the luteal phase. RESULTS There was a similar percentage of ovulation and pregnancy rate in both groups of patients. The ovarian enlargement during the luteal phase in the GnRH-a-treated patients was lower than in the hCG group. Progesterone plasma levels (at midluteal phase) and the length of luteal phase was significantly lower in GnRH-a-treated patients with respect to the hCG-treated group. These differences disappeared in patients receiving luteal support. After GnRH injection, LH secretion decreased in GnRH-a-treated patients with respect to controls; however, corpus luteum was able to respond with a normal increase of P production. CONCLUSION The GnRH-a appears to be an effective alternative to hCG for inducing the follicular rupture in stimulated cycles in women who are at risk for developing ovarian hyperstimulation syndrome. However, GnRH-a administration can induce short luteal phase. This defect may be ascribed to the pituitary desensitization rather than to a direct effect on corpus luteum. Luteal phase support is needed to prevent luteal phase deficiency.

Effects of ghrelin administration on endocrine and metabolic parameters in obese women with polycystic ovary syndrome

Introduction: The novel peptide ghrelin displays multiple endocrine and non-endocrine actions. Its strong GH-releasing activity in humans has long been recognized. However, in obesity, ghrelin administration induces a blunted GH secretion, enhances glucose and reduces insulin levels. The effects of ghrelin administration have not been investigated in polycystic ovary syndrome (PCOS), which can be associated with obesity, hyperinsulinism, and GH hyposecretion. Leptin is a mediator for energy balance opposed to ghrelin; both of them are supposed to act as regulators of reproductive functions. Aim of the study: Evaluate the endocrine and metabolic response to ghrelin administration in PCOS obese patients compared to body mass index (BMI)-matched and normal weight women. Materials and methods: Nine obese PCOS patients (BMI: 35.4±1.2 kg/m2) (OB PCOS), 6 obese controls (BMI: 38.4±1.1 kg/m2) (Ob), and 6 normal-weight women (BMI: 23±0.6 kg/m2) (NW) were enrolled in the study. In all patients we performed: 1) basal hormonal evaluation including FSH, LH, estradiol, testosterone, androstenedione, DHEAS, SHBG, 17-hydroxyprogesterone (17OHP), IGF-I, free T3 (FT3), free T4 (FT4) and ghrelin levels; 2) metabolic evaluation as follows: concentration of non-esterified fatty acid (NEFA) and oral glucose tolerance test (OGTT) (75 g); homeostasis model assessment (HOMA); glucose and insulin response to ghrelin administration (1 µg/kg); 3) measurement of GH, PRL, TSH, and leptin levels after infusion of ghrelin. Results: Administration of ghrelin increased glucose and reduced insulin levels in both Ob and OB PCOS. Moreover, ghrelin enhanced GH and PRL levels in all groups but it did not modify TSH and leptin levels. GH peak and area under the curve (AUC) in OB PCOS and Ob were lower than controls (p<0.05). Similar PRL peak and AUC values were observed in all groups. Conclusions: In both obese and PCOS obese patients, leptin levels are not influenced by ghrelin administration. Moreover, the GH response after ghrelin administration is blunted. However, ghrelin exerts glucose-enhancing and insulin-lowering effects, the latter absent in NW.

Role of opioid tone in the pathophysiology of hyperinsulinemia and insulin resistance in polycystic ovarian disease.

Hyperinsulinemia secondary to a poorly characterized disorder of insulin action is a feature of polycystic ovarian disease (PCOD). On the other hand, being generally admitted that opioids may play a role in glycoregulation and that opioid tone is altered in PCOD, an involvement of the opioids in determining the hyperinsulinemia of PCOD patients could be suggested. The aim of this study was to evaluate the effect of a chronic opioid blockade on insulin metabolism and peripheral insulin sensitivity in PCOD hyperinsulinemic patients. Twenty-three women with PCOD were studied. An oral glucose tolerance test (OGTT) and a clamp study were performed at baseline (during the follicular phase) and after 6 weeks of naltrexone administration (50 mg/d orally). Based on the insulinemic response to the OGTT, 16 women were classified as hyperinsulinemic and seven as normoinsulinemic. Naltrexone treatment significantly reduced fasting (P < .05) and area under the curve (AUC) (P < .02) plasma insulin levels only in the hyperinsulinemic group. Moreover, hyperinsulinemic patients showed similar C-peptide incremental areas after naltrexone treatment, whereas in the same patients the fractional hepatic insulin extraction calculated from the incremental areas of insulin and C-peptide was found to be increased after chronic opioid blockade by naltrexone. For peripheral insulin sensitivity, the hyperinsulinemic group showed significantly lower (P < .01) total-body glucose utilization (M) compared with the normoinsulinemic group. No change in the M value was found after treatment in both groups. These data suggest that the insulin sensitivity and hyperinsulinemia after an OGTT are two distinct deranged features of the insulin disorder of PCOD patients.

OPIOID BLOCKADE EFFECT ON INSULIN BETA -CELLS SECRETORY PATTERNS IN POLYCYSTIC OVARY SYNDROME ORAL GLUCOSE LOAD VERSUS INTRAVENOUS GLUCAGON BOLUS

In order to evaluate the involvement of endogenous opiates in the insulin disorders of polycystic ovary syndrome (PCOs) a total of 25 PCOs women and 11 normo-ovulatory controls were studied by comparing the effect of a chronic opioid blockade on β-cells responsiveness to oral glucose load and to intravenous glucagon bolus. Each patient, studied on follicular phase, underwent to oral glucose tolerance test (OGTT), and, 2 days later, to a glucagon intravenous bolus (1 mg); these tests were then repeated after 6 weeks of naltrexone treatment (50 mg orally). Naltrexone treatment did not modify the insulin secretory patterns of control subjects, whereas the same therapy significantly reduced, in hyperinsulinemic PCOs women, the β-cell hyperresponsiveness both to oral glucose load and to intravenous glucagon (p < 0.05 and p < 0.01, respectively), even if with different mean percent decrease (32% OGTT vs. 45% glucagon, p < 0.05). Moreover, normoinsulinemic PCOs patients showed a slight, but not significantly increase in the β-cells response to OGTT after opioid blockade, whereas, in the same situation, the insulin release after glucagon bolus was significantly reduced (p < 0.01). Chronic opioid blockade did not modify gonadotropins, steroids and SHBG levels in either group. Our data show that naltrexone treatment is able to reduce the β-cell response to a direct intravenous secretagogue stimulus in all PCOs patients, while only in hyperinsulinemic PCOs subjects the same treatment is effective in reducing the exaggerated insulin secretion after oral glucose load. The reason for such a discrepancy could be ascribed to a different effect of opioids on first- and second-phase insulin secretion, or, alternatively, to an involvement of other secretagogue factors, such as glucoincretins.In order to evaluate the involvement of endogenous opiates in the insulin disorders of polycystic ovary syndrome (PCOs) a total of 25 PCOs women and 11 normo-ovulatory controls were studied by comparing the effect of a chronic opioid blockade on beta-cells responsiveness to oral glucose load and to intravenous glucagon bolus. Each patient, studied on follicular phase, underwent to oral glucose tolerance test (OGTT), and, 2 days later, to a glucagon intravenous bolus (1 mg); these tests were then repeated after 6 weeks of naltrexone treatment (50 mg orally). Naltrexone treatment did not modify the insulin secretory patterns of control subjects, whereas the same therapy significantly reduced, in hyperinsulinemic PCOs women, the beta-cell hyperresponsiveness both to oral glucose load and to intravenous glucagon (p < 0.05 and p < 0.01, respectively), even if with different mean percent decrease (32% OGTT vs. 45% glucagon, p < 0.05). Moreover, normoinsulinemic PCOs patients showed a slight, but not significantly increase in the beta-cells response to OGTT after opioid blockade, whereas, in the same situation, the insulin release after glucagon bolus was significantly reduced (p < 0.01). Chronic opioid blockade did not modify gonadotropins, steroids and SHBG levels in either group. Our data show that naltrexone treatment is able to reduce the beta-cell response to a direct intravenous secretagogue stimulus in all PCOs patients, while only in hyperinsulinemic PCOs subjects the same treatment is effective in reducing the exaggerated insulin secretion after oral glucose load. The reason for such a discrepancy could be ascribed to a different effect of opioids on first- and second-phase insulin secretion, or, alternatively, to an involvement of other secretagogue factors, such as glucoincretins.

Influence of body mass on the hypothalamic-pituitary-adrenal–axis response to naloxone in patients with polycystic ovary syndrome

OBJECTIVE To evaluate the influence of body mass on the hypothalamic-pituitary-adrenal (HPA)-axis response to naloxone in polycystic ovary syndrome (PCOS). DESIGN Controlled clinical study. SETTING Academic research environment. PATIENT(S) Ten lean and 10 obese women with PCOS compared with 7 lean and 8 obese control subjects matched for body mass index. INTERVENTION(S) Each patient received an IV bolus of naloxone at a dosage of 125 microg/kg. MAIN OUTCOME MEASURE(S) Samples were collected 30 minutes before and 0, 15, 30, 60, 90, and 120 minutes after injection: ACTH and cortisol levels were measured in all plasma samples. RESULT(S) No significant differences were found in the ACTH and cortisol responses to opioid blockade between lean women with PCOS and lean as well as obese control subjects; conversely, obese patients with PCOS showed a higher ACTH and cortisol responses to naloxone compared with all other groups. CONCLUSION(S) Hypothalamic-pituitary-adrenal-axis abnormalities of PCOS may be central in origin and abdominal obesity seems to play a key role in the HPA-axis hyperactivity of women with PCOS when naloxone is administered.