Serum levels of insulin-like growth factor binding protein-1 and ovulatory responses to clomiphene citrate in women with polycystic ovarian disease

Insulin-like growth factor binding protein-1 and insulin in polycystic ovary syndrome: a systematic review and meta-analysis

Background

Insulin-like growth factor binding protein-1 (IGFBP-1) is considered a decline in polycystic ovary syndrome (PCOS), but it remains controversial that whether such reduction is attributed to obesity.

Aims

This systematic review aims to explore whether IGFBP-1 is reduced in PCOS, and whether such reduction is associated with obesity.

Results

Our pooled study included 12 studies with a total of 450 participants. IGFBP-1 levels in PCOS were significantly lower than that in non-PCOS (SMD (95%CI)=-0.49(-0.89, -0.09), P=0.02). No significant difference in IGFBP-1 levels between patients with or without PCOS classified by BMI. Whilst, stratification by PCOS status revealed a significant decrease in IGFBP-1 in overweight (SMD (95%CI)=-0.92(-1.46, -0.37), P=0.001). When comparing fasting insulin in the same way, PCOS patients had significantly elevated fasting insulin level but not statistically declined IGFBP-1 after classified by BMI.

Conclusion

This meta-analysis provides evidence that the decrease of IGFBP-1 in PCOS was more strongly influenced by comorbid obesity than by PCOS itself. Additionally, contrast to previous findings that insulin significantly suppresses IGFBP-1, our results suggested that the suppression of PCOS-related hyperinsulinemia on IGFBP-1 seemed diminished. Overall, our work may provide a novel perspective on the mechanism between insulin and IGFBP-1 underlying PCOS development.

Insulin-like growth factor binding protein-1 in PCOS: a systematic review and meta-analysis

BACKGROUND

Despite extensive research, the pathogenesis of polycystic ovary syndrome (PCOS) remains unclear. Putatively, an elevated circulating concentration of insulin inhibits the production of insulin-like growth factor binding protein-1 (IGFBP-1), thus increasing the level of free IGF-I in serum and stimulating ovarian androgen production. Decreased IGFBP-1 has been reported in PCOS and in obesity; however, there are inconsistencies in the evidence. This systematic review and meta-analysis aimed to determine whether IGFBP-1 is decreased in PCOS when controlling for the influence of BMI.

METHODS

Articles published between 1988 and 2008 were searched using MEDLINE, PubMed, SCOPUS and Web of Knowledge. Unpublished literature, trials in progress, and recent reviews were also searched. Original articles were selected by two investigators. To be included, the study must have compared serum IGFBP-1 in two populations: either PCOS versus controls, or an overweight subgroup versus the normal weight subgroup in either population. From 617 identified articles, 12 were included in the meta-analysis. Data were abstracted by two reviewers independently and standardized for errors.

RESULTS

The population difference is presented as the Weighted Mean Difference (95% CI). PCOS subjects had a significantly lower serum concentrations of IGFBP-1 compared with controls [P< 0.00001; -36.6 (-52.0, -21.2) µg/l]. Overweight PCOS subjects also had lower IGFBP-1 levels compared with normal weight PCOS subjects [P < 0.006; -30.6 (-52.3, -8.8) µg/l]. No significant difference was found between overweight PCOS patients and overweight controls [P = 0.23; -5.1 (-13.5, 3.2) µg/l] or between normal weight PCOS patients and normal weight controls [P = 0.50; -3.8 (-14.9, 7.3) µg/l]. Overweight controls had significantly lower IGFBP-1 concentrations than normal weight controls [P = 0.03; -18.0 (-34.4, - 1.5) µg/l].

CONCLUSION

These data indicate that a decreased serum level of IGFBP-1 is unlikely to be a mechanism for ovarian hyperandrogenism in PCOS. BMI may be the major determinant of serum IGFBP-1.

High dose of phytoestrogens can reverse the antiestrogenic effects of clomiphene citrate on the endometrium in patients undergoing intrauterine insemination: a randomized trial

OBJECTIVE

To compare the effectiveness of clomiphene citrate (CC) alone or combined with phytoestrogens (PE) in ovulation induction in patients who had intrauterine insemination in a randomized, double-blind study.

METHODS

A total of 134 women aged 25-35 years, who were infertile for at least 2 years and who had oligomenorrhea or amenorrhea associated with a positive menstrual response to the intramuscular progesterone-challenge test were enrolled. They were randomly treated with CC (100 mg daily for 5 days) and CC (100 mg daily for 5 days) in combination with PE (1500 mg daily for 10 days). We estimated the difference in uterine artery pulsatily index, number of preovulatory follicles, endometrial thickness, and pregnancy rate.

RESULTS

Both treatments increased follicle-stimulating hormone, luteinizing hormone, and 17beta-estradiol plasma concentrations, but the differences were not statistically significant. However, the differences in endometrial thickness of the two groups were statistically significant. No significant differences in the pulsatility index values and in the number of preovulatory follicles were noted.

CONCLUSION

A high dose of phytoestrogens can reverse the deleterious effects of clomiphene citrate on endometrial thickness and could contribute to higher pregnancy rates.

PCOS: an ovarian disorder that leads to dysregulation in the hypothalamic–pituitary–adrenal axis?

This review focuses on the role of the ovaries in the pathogenesis of the polycystic ovarian syndrome. In particular, the failure of follicular development, hypothalamo-pituitary dysregulation, alterations in adrenal steroid output and derangement of intermediary metabolism are discussed in the context of the ovaries. It is concluded that the central and adrenal alterations associated with PCOS are unlikely to be primary but rather are secondary to the events within the ovary.

Predictive value of serum androstenedione basal levels on the choice of gonadotropin or laparoscopic ovarian electrocautery as ovulation induction in clomiphene citrate-resistant patients with polycystic ovary syndrome

Therapeutic approaches to chronic anovulation from polycystic ovaries in clomiphene-resistant infertile patients are under debate. This study discusses evidence that supports the possible predictive value of serum basal level of androstenedione in the choice of the better therapy between laparoscopic ovarian electrocautery and ovulation induction. Lower androstenedione levels seem to be correlated with a better ovarian response after ovulation induction with gonadotropins, while high androstenedione levels are associated with a higher incidence of conception after laparoscopic ovarian electrocautery. Obesity does not seem to represent a hindrance to laparoscopic treatment.

Use of ethinyl estradiol to reverse the antiestrogenic effects of clomiphene citrate in patients undergoing intrauterine insemination: a comparative, randomized study

OBJECTIVE

To compare the effectiveness of clomiphene citrate used alone and in combination with ethinyl E2 for the induction of ovulation in patients undergoing IUI.

DESIGN

Randomized, double-blind study.

SETTING

Four infertility treatment centers.

PATIENT(S)

Women aged 25-35 years with infertility of at least 2 years' duration and oligomenorrhea or amenorrhea associated with a positive menstrual response to an IM progesterone challenge.

INTERVENTION(S)

A total of 64 patients were randomized to treatment with CC (100 mg daily for 5 days) or CC (100 mg daily for 5 days) plus ethinyl E2 (0.05 mg daily for 5 days).

MAIN OUTCOME MEASURE(S)

The uterine artery pulsatility index, number of preovulatory follicles, endometrial thickness, and pregnancy rate.

RESULT(S)

Both treatment regimens increased FSH, LH, and 17beta-E2 levels, with no statistically significant differences. There was a statistically significant difference in endometrial thickness between the two treatment groups. No statistically significant differences were noted in pulsatility index values or in the number of preovulatory follicles.

CONCLUSION(S)

Ethinyl E2 can reverse the deleterious effects of CC on endometrial thickness, which may contribute to higher pregnancy rates.

Octreotide is not useful for clomiphene citrate resistance in patients with polycystic ovary syndrome but may reduce the likelihood of ovarian hyperstimulation syndrome

OBJECTIVE

To determine whether octreotide is effective for ovulation induction in patients with polycystic ovary syndrome (PCOS) and clomiphene citrate resistance or for reduction of the risk of ovarian hyperstimulation syndrome (OHSS) with gonadotropin therapy.

DESIGN

Prospective, double-blind, placebo-controlled, crossover trial.

SETTING

Private infertility practice.

PATIENT(S)

Twelve patients with PCOS undergoing therapy for infertility.

INTERVENTION(S)

The patients were assigned randomly to receive either octreotide or placebo. Those with clomiphene citrate-resistant PCOS received clomiphene citrate, 150 mg. Patients at risk for the development of OHSS received urinary FSH for ovulation induction.

MAIN OUTCOME MEASURE(S)

Ovulation, pregnancy, the development of OHSS, and levels of fasting insulin, insulin-like growth factor 1, insulin-like growth factor binding proteins 1 and 3, testosterone, androstenedione, DHEAS, E2, LH, and FSH.

RESULT(S)

Octreotide significantly reduced levels of fasting insulin, insulin-like growth factor 1, and LH in both clomiphene citrate- and urinary FSH-stimulated cycles. Levels of insulin-like growth factor binding protein 3 were increased. Two of six clomiphene citrate-stimulated cycles reached ovulation with the use of either octreotide or placebo. In urinary FSH-stimulated cycles, patients who received octreotide had significantly lower E2 levels at the time of hCG administration and fewer mature follicles. No cases of OHSS occurred in either group. One pregnancy occurred in each group.

CONCLUSION(S)

Octreotide was no more effective than placebo for clomiphene citrate resistance in patients with PCOS, but it did reduce E2 levels and follicle numbers when combined with urinary FSH. Thus, octreotide may reduce the incidence of OHSS in patients with PCOS.

Insulin and insulin-like growth factor I stimulate the proliferation of human ovarian theca-interstitial cells

OBJECTIVE

To determine whether insulin and insulin-like growth factor I (IGF-I) affect the proliferation of human theca-interstitial cells.

DESIGN

In vitro assays.

SETTING

University laboratory.

PATIENT(S)

Premenopausal women undergoing oophorectomy for benign conditions.

INTERVENTION(S)

Purified theca-interstitial cells were cultured in chemically defined media with or without insulin and IGF-I.

MAIN OUTCOME MEASURE(S)

The proliferation of cells was evaluated by determination of [3H] thymidine incorporation and cell counting.

RESULT(S)

Insulin and IGF-I stimulated DNA synthesis by theca-interstitial cells in a dose-dependent fashion. Insulin-like growth factor I had a greater potency than did insulin. The effects of both approached, but did not reach, the level of DNA synthesis observed in cultures exposed to 10% fetal bovine serum. Direct counting of theca-interstitial cells revealed that IGF-I significantly increased the total number of cells (36% above control), whereas insulin induced a modest and statistically nonsignificant increase in the cell number (14% above control).

CONCLUSION(S)

The present results support the hypothesis that insulin and IGF-I promote the mitotic activity of theca-interstitial cells. These effects may represent mechanisms that lead to hyperplasia of the thecal/stromal compartment in polycystic ovary syndrome.

The relationship between insulin sensitivity and insulin-like growth factor-binding protein-1

Insulin has been shown to regulate insulin-like growth factor-binding protein-1 (IGFBP-1) in vivo and in vitro. Insulin resistance is a feature of the polycystic ovary syndrome (PCOS). We have studied the relationship between insulin sensitivity (S1) and the circulating concentration of IGFBP-1 in a group of young women and in some who had PCOS. A case-control study has been carried out comparing reproductively normal women with women with PCOS (defined as women with oligo- or amenorrhea associated with androgen excess). Fifteen women with clinical PCOS and ten age- and weight-matched controls were studied. S1 was measured by the frequently sampled intravenous glucose tolerance test (FSIGT) using the minimal model technique. IGFBP-1, insulin-like growth factor-I (IGF-I) and growth hormone levels were measured before and during the FSIGT. Circulating testosterone, dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) levels were measured while the subjects were fasting. S1 and IGFBP-1 levels were significantly lower in the PCOS group than in controls (S1/10(-5) min-1/pM] mean +/- SE 3.8 +/- 0.8 vs. 8.5 +/- 1.3, p < 0.03; IGFBP-1 [ng/ml] mean +/- SE 26.6 +/- 4.2 vs. 56.0 +/- 5.9, p < 0.005). In women with PCOS, IGFBP-1 concentrations related negatively to the body mass index (BMI) (r = -0.77, p < 0.003) and positively to S1 (r = 0.76, p < 0.003). S1 remained a significant predictor of IGFBP-1 concentrations when controlled for BMI (combined r2 = 0.35, p < 0.05). No relationship was found between androgen levels and IGFBP-1. Insulin sensitivity contributed to the difference in IGFBP-1 levels found in women with PCOS. Whether the reduced concentrations of IGFBP-1 play a role in the pathophysiology of PCOS is uncertain, but it may act to alter delivery of IGF to peripheral tissues in insulin-resistant individuals.

Comparison of the effects of ovarian cauterization and gonadotropin-releasing hormone agonist and oral contraceptive therapy combination on endocrine changes in women with polycystic ovary disease

OBJECTIVE

To study the effects of laparoscopic ovarian cauterization and combination of long-acting GnRH agonist (GnRH-a) and oral contraceptive (OC) therapy on endocrine changes in women with clomiphene citrate (CC)- resistant polycystic ovary disease (PCOD).

DESIGN

Prospective, randomized.

SETTING

University-based infertility clinic.

PATIENTS

Seventeen women with CC-resistant PCOD were included randomly in the study to either laparoscopic ovarian cautery or GnRH-a and OC therapy for 3 months.

MAIN OUTCOME MEASURES

Serum concentrations of LH, FSH, androstenedione (A), T, and sex hormone-binding globulin (SHBG) were determined before each therapeutic approach and during the follicular phase of first menstrual cycle after the cessation of each treatment.

RESULTS

The mean serum concentrations and the clinical profiles were similar in both groups. Both groups showed significant changes in LH, FSH, A, T, and SHBG compared with pretreatment levels. There were no significant differences in the final concentrations of LH, FSH, and A between the two study groups after each treatment, whereas T and SHBG levels were significantly different in the goserelin and OC group. The decrease in LH and increase in SHBG serum concentrations were greater in the goserelin and OC-treated women [-59% and + 5.9% versus - 70% and + 13.5%, respectively]. Although the SHBG concentration increased in both groups, the serum SHBG concentration of the goserelin and OC group was significantly higher than the other group.

CONCLUSION

Both therapeutic modalities revealed similar effects on the endocrine profiles in women with CC-resistant PCOD. Considering the invasiveness, cost, and potential complications of laparoscopic ovarian cauterization, noninvasive medical treatment with GnRH-a and OC combination may be more effective in restoring the optimal follicular environment in women with PCOD.

Disturbances in insulin secretion and sensitivity in women with the polycystic ovary syndrome

Insulin resistance, defined as a diminished effect of a given dose of insulin on glucose homeostasis, is a highly prevalent feature of women with PCOS. Insulin resistance in PCOS is closely associated with an increase in truncal-abdominal fat mass, elevated free fatty acid levels, increased androgens, particularly free testosterone through reduced SHBG levels, and anovulation. The causes for insulin resistance in PCOS are still unknown. One line of evidence suggests that an increase in truncal-abdominal fat mass and subsequently increased free fatty acid levels induce insulin resistance in women with PCOS. Increased effects of corticosteroids and a relative reduction in oestrogen and progesterone seem to be involved in the aberrant body fat distribution. Conversely, there are also results supporting primary, genetic target cell defects as a cause of insulin resistance in PCOS. An explanation for these seemingly contradictory results could be that the group of women with PCOS is heterogeneous with respect to the primary event in carbohydrate/insulin disturbances. Also insulin secretion in PCOS is characterized by heterogeneity. At one end of the spectrum is a large subgroup of mainly obese women with reduced insulin secretion, which appears to result from failure of the beta cells to compensate for insulin resistance in susceptible women, resulting in glucose intolerance and NIDDM. In the insulin-resistant patients with normal glucose tolerance, most of the hyperinsulinaemia is probably due to secondarily increased insulin secretion and decreased insulin degradation. However, a component of the increased first-phase insulin release is not due to measurable insulin resistance. Notably, this is also found in lean women with normal insulin sensitivity, and is not reversed after weight reduction, in contrast to the findings for insulin resistance. The implications of this enhanced insulin release are not fully clear, but it may tentatively be associated with carbohydrate craving and subsequently increased risks for development of obesity and insulin resistance. It may represent a primary disturbance of insulin secretion in PCOS or may be associated with the perturbed steroid balance in anovulation. The insulin-androgen connection in PCOS appears to be amplified by several different mechanisms, notably in both directions, the initiating event probably varying between individuals. Thus insulin increases the biological availability of potent steroids, primarily testosterone, through the suppression of SHBG synthesis. Insulin is also involved as a progonadotrophin in ovarian steroidogenesis, with the possible net result of interfering with ovulation and/or increasing ovarian androgen production in states of hyperinsulinaemia. Conversely, testosterone may indirectly contribute to insulin resistance through facilitating free fatty acid release from abdominal fat, but perhaps also through direct muscular effects at higher serum levels. It seems likely that this constitution, presumably genetic, would provide evolutionary advantages in times of limited nutrition, given the energy-saving effects of insulin resistance. Hypothetically, hyperinsulinaemia (primary) could provide a stimulus to ensure intake of nourishment, but unlimited food supplies could in some cases initiate a vicious 'anabolic' circle, in which several of the proposed amplifying mechanisms between insulin and androgens--in both directions--could take part.

Insulin-like growth factors: clinical experience in ovarian function

Insulin, insulin-like growth factor, and insulin-like growth factor binding proteins have been shown to play major roles in the modulation of both normal and disturbed ovarian physiology. Identification of many of the actions of these peptides was initially characterized using animal models. However, an increasing body of evidence has emerged to clarify their contributions in human reproductive function. It is clear that at various stages of folliculogenesis, local steroid production acts in concert with intraovarian peptides to promote dominant follicle development. This review will discuss the physiologic role(s) of the insulin-insulin-like growth factor-insulin-like growth factor binding protein family in reproductive function and disorders of androgen excess.

Transvaginal ultrasonic assessment of the response to clomiphene citrate in polycystic ovarian syndrome

OBJECTIVE

To study the relationship between some ovarian morphological findings based on transvaginal ultrasound (US) and the clomiphene citrate (CC) responsiveness in patients with polycystic ovarian syndrome (PCOS).

DESIGN

A comparative study of ovarian US features between the CC responders and the CC nonresponders.

SETTING

Infertility and Endocrine Clinic, Department of Obstetrics Gynecology, Shimane Medical University Hospital, Izumo, Japan.

PATIENTS

Forty-seven infertile patients with PCOS and 30 healthy volunteers.

INTERVENTIONS

A dose of 50 to 200 mg/d CC was given for ovulation induction in patients with PCOS.

MAIN OUTCOME MEASURES

Ovarian volume and number of follicles; serum LH, FSH, T, delta 4 androstenedione, and DHEAS.

RESULTS

The mean ovarian volume (11.9 mL) and the number of small follicles (13.0) were significantly larger in the CC nonresponders compared with those of the CC responders (7.9 mL and 7.0, respectively). Only 47% of the CC responders and 79% of the CC nonresponders had bilaterally enlarged ovaries (> 6.2 mL). Considerable overlap existed between the different groups. However, 96% of the CC nonresponders had a significantly increased number of follicles (> or = 10 follicles) in each ovary compared with that (16%) of the CC responders. Furthermore, with the combination of these parameters, none of the CC nonresponders had bilaterally normal ovaries, and 96% of patients with PCOS with bilaterally abnormal ovaries were CC nonresponsive.

CONCLUSIONS

Small multiple follicles (> or = 10) and enlarged ovarian volume (> 6.2 mL) were the most prominent transvaginal US features of ovaries in patients with PCOS with CC nonresponsiveness. These US features could be clinically useful for distinguishing clearly a CC nonresponder from a CC responder.