Growth hormone in serum of women during the menstrual cycle and during controlled ovarian hyperstimulation

Increased pulsatile, but not basal, growth hormone secretion rates and plasma insulin-like growth factor I levels during the periovulatory interval in normal women

The secretion of GH changes during the menstrual cycle, exhibiting high levels during the periovulatory phase (PO). Previous studies have not investigated whether this difference in GH status is due to increased secretion or reduced clearance of pituitary GH and amplified pulsatile vs. basal GH secretion. It is also unclear whether the PO phase is accompanied by changes in circulating insulin-like growth factor I (IGF-I). In this study we investigated the 24-h GH release patterns in the early follicular (EF) vs. the periovulatory menstrual phase in the same individuals. Ten young (aged 24-34 yr) healthy women with regular menses were studied with deconvolution analysis of GH profiles obtained by blood sampling every 20 min for 24 h, followed by an arginine stimulation test. A high sensitivity immunofluorometric GH assay was used. All women were studied in both the EF and PO phases in random order. There were no differences in the basal GH secretion rate or GH half-life during the two phases. The number of GH secretory bursts identified during the 24-h sampling period was significantly increased during the PO (13.3 +/- 0.5) compared to the EF (10.3 +/- 0.6) phase (P = 0.002); conversely, the mean interburst interval was shorter in the PO (107 +/- 5 min) than in the EF (134 +/- 8 min) phase (P = 0.004). There was no difference in GH pulse mass (P = 0.13) or amplitude (P = 0.21) between the two phases. The pulsatile GH production rate (milligrams per L/24 h) was significantly elevated during the PO (61 +/- 6) compared to that during the EF (37 +/- 8; P = 0.004). Increased total GH pulse area was confirmed by Cluster analysis (P = 0.027). Furthermore, the 24-h mean serum GH concentration was significantly increased in the PO (1.4 +/- 0.1 mg/L) vs. that in the EF (0.9 +/- 0.1 mg/L; P = 0.002). There was a positive correlation between estradiol (E2) and GH secretory pulse amplitude, frequency, and mean 24-h serum GH concentration in the PO cycle phase, indicating E2 to be a major statistical determinant of GH secretion. Serum GH increased significantly after arginine infusion in both phases (P < 0.001), whereas there was no difference between the two cycle phases (P = 0.20). Serum IGF-I levels were increased during the PO phase (253 +/- 20 mg/L) compared to those during the EF phase (210 +/- 16 mg/L; P = 0.03), whereas serum IGF-binding protein-3, IGF-II, and GH-binding protein were similar during the two phases. This study unequivocally documents elevated GH levels during the PO phase of the menstrual cycle, mediated by increased GH production rate and burst frequency. The concomitant increase in serum IGF-I suggests a central stimulation of the GH-IGF-I axis, which may be mediated by endogenous E2 levels.

Effect of growth hormone suppression on the serum levels of ovarian and adrenal sex steroid hormones in normal women and in women with polycystic ovary syndrome

We investigated the acute effect on the serum levels of ovarian and adrenal sex steroid hormones of the suppression of growth hormone during oral glucose tolerance test (OGTT). A standard 75 g OGTT was performed in 11 healthy women and eight women with polycystic ovary syndrome (PCOS). Another five controls were given a sham loading of oral distilled water. Blood samples were obtained immediately before and at 30-minute intervals after glucose or sham loading. Significant progressive declines in testosterone, estradiol, dehydroepiandrosterone sulfate (DHEAS) and growth hormone levels were observed during OGTT in both groups. In the PCOS and normal groups, respectively, at 120 min, testosterone levels were 75.8% and 64.4% of the baseline (0-time) value, estradiol levels were 83.4% and 83.1%, DHEAS levels were 79.3% and 79.1%, and growth hormone levels were 33.9% and 21.2%. Significant positive correlations were observed between the level of growth hormone and each of the testosterone, estradiol and DHEAS levels in both the groups. The area under the curve for growth hormone was significantly smaller in the PCOS group than in the normal group. Gonadotropins were not changed at any time during OGTT. It appears that growth hormone may modify ovarian and adrenal sex steroidogenic responses to tropic hormones directly or via local insulin-like growth factor-I. Women with PCOS may be relatively deficient in growth hormone, a deficiency which may play a role in the pathophysiology of ovulatory disturbance.

Growth hormone secretion timing in depression: clinical outcome comparisons

Growth hormone (GH) secretion in the 100 minutes preceding sleep onset (preSO), as well as in the first half of the night (1st HN), was examined for a group of 13 healthy women and 43 women with recurrent depression who participated in a 3-year maintenance therapy study. GH studies were obtained at several points during treatment and every 3 months during maintenance, during which patients were randomly assigned to active drug or drug-free maintenance treatment cells for 3 years, or until recurrence of depression. Depressed patients were divided into subgroups according to their maintenance treatment assignment (active drug or drug free) and treatment outcome (completing in remission or having a recurrence). Imipramine caused an increase in the GH ratio in all subgroups. Protocol completers had a significantly larger imipramine-induced increase in the GH ratio than did recurrers. The difference in time of GH secretion relative to sleep onset was found to correlate with treatment outcome and was independent of medication status during maintenance.

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.

Numbers and quality of oocytes after induction of multiple folliculogenesis in women and in mice with different lots of human menopausal gonadotropins

OBJECTIVE

To develop a murine in vivo bioassay that is sensitive to inherent variability of hMG.

DESIGN

Female F1 hybrid mice were mated after injection with fixed dosages of each of four lots of hMG. Oocytes/embryos were collected and monitored during 5 days of culture. Outcome measures were compared with retrospective outcomes of ovarian stimulation of women with the same hMG lots. The bioassay was then used to compare biopotencies of six different lots of hMG.

SETTING

Center for assisted reproductive technology.

INTERVENTIONS

None.

PATIENTS

Outcomes of controlled ovarian stimulation and IVF were retrospectively analyzed from 43 patients.

MAIN OUTCOME MEASURES

Numbers of oocytes/embryos recovered, numbers fertilized, and numbers progressing beyond fertilization.

RESULTS

Differences in biopotencies of hMG lots in the murine in vivo bioassay were consistent with differences in outcomes of patients treated with the same hMG lots during controlled ovarian stimulation. Bioassay outcomes also differed between different lots of hMG.

CONCLUSION

The bioassay described in this study is sensitive to between-lot differences in hMG that affect follicle recruitment and oocyte quality in women (and in mice). In this respect, the bioassay could be of value in screening hMG lots, before its exploitation in a patient population. One such application is explored.

Lack of impact of pharmacological growth hormone administration on circulating levels of reproductive hormones during the menstrual cycle in normal women

OBJECTIVE

To evaluate the effects of pharmacological growth hormone (GH) administration on the secretion of pituitary and gonadal hormones during the menstrual cycle in normal women.

DESIGN

Randomized, double-blind, placebo-controlled crossover design.

PATIENTS, PARTICIPANTS

Six normally menstruating, healthy women, 22 to 24 years of age and with a normal body mass index.

INTERVENTIONS

Each participant was treated with placebo and growth hormone (12 IU/d) during two different 14-day periods, separated by a 6-week washout period.

MAIN OUTCOME MEASURES

Serum insulin-like growth factor I (IGF-I), estradiol, progesterone, follicle-stimulating hormone, and luteinizing hormone.

RESULTS

Administration of GH for 14 days resulted in a significant increase in serum IGF-I, whereas no changes occurred in gonadotropin or sex steroid response.

CONCLUSIONS

Growth hormone treatment during the first 14 days of menstrual cycle in normal women does not affect gonadotropin or sex steroid patterns.

Conventional and nonconventional uses of growth hormone

Although GH has been available as a therapeutic agent for the GH-deficient child for more than 30 years, the conditions of its use have yet to be optimized. The availability of biosynthetic material has provided researchers with the opportunity to develop the protocols necessary to begin to finally answer the most fundamental questions pertaining to dose, frequency, and duration of treatment. It has also permitted the initiation of prospective trials in a large number of conditions that result in childhood short stature, with the expectation that some or many of them will be treated effectively and safely. Finally, it has opened the door to an entire spectrum of potentially new uses of GH and other growth factors for so-called nonconventional indications. That these have implications that range from the short-term rapid healing of a burn graft site, to the more efficient induction of ovulation, to the long-term preservation of lean body mass has excited the interest of investigators in many fields of medicine and physiology. Thus, the recent progress reported in this paper is really the beginning of the new research that will take place with GH and growth factors.

The potential relevance of growth hormone to female reproductive physiology and pathophysiology

OBJECTIVE

To assess possible interfacing between the somatotrophic and reproductive axes.

DESIGN

Literature review.

MAIN OUTCOME MEASURES

Ovarian growth hormone reception and action.

RESULTS

The available literature strongly supports a permissive role for the somatotrophic axis in the reproductive process.

CONCLUSIONS

Although a role for growth hormone in reproductive biology appears highly likely, its relevance to the process of puberty and to the normal workings of the menstrual cycle, as well as its possible application in reproductive pathology must await further investigation.

Absence of effect of adjuvant growth hormone therapy on follicular responses to exogenous gonadotropins in women: normal and poor responders

OBJECTIVE

To examine the effects of growth hormone (GH) on ovarian responses to exogenous gonadotropins after pituitary desensitization in normal and poor responder patients undergoing in vitro fertilization.

DESIGN

A prospective study with comparison of control and GH-treated cycles.

PATIENTS

Poor responder patients (n = 10) required > 44 ampules of human menopausal gonadotropin (hMG) to achieve criteria for administration of human chorionic gonadotropin (hCG) on day 0 or cancellation in control cycles, and normal responder patients (n = 10) required < 45 ampules.

MAIN OUTCOME MEASURES

Ovarian responses to hMG assessed by duration of stimulation required to achieve first significant estradiol (E2) response and hCG criteria. Total doses and duration of hMG, follicular development and E2 concentrations on day 0, and embryology were also assessed.

RESULTS

Growth hormone showed no effect on any of the parameters studied in either patient group.

CONCLUSION

Follicular recruitment, E2 secretion by mature follicles, and oocyte yield and quality were uninfluenced by GH treatment.

Ovarian responses to menopausal gonadotropins in groups of patients with differing basal growth hormone levels

OBJECTIVE

To investigate the relationship between endogenous serum levels of human growth hormone (hGH) and ovarian response to human menopausal gonadotropins (hMG).

DESIGN

Retrospective analysis of patient response to hMG.

SETTING

Center for assisted reproductive technology.

PATIENTS

Eighty women who had undergone controlled ovarian hyperstimulation with hMG. Basal levels of hGH in sera from 40 of these patients were less than 5.0 microIU/mL (low hGH), values for the remaining 40 were greater than 5.0 microIU/mL (high hGH). Levels of hGH in day 2 sera were analyzed against numbers of oocytes recovered in an additional 182 patients.

MAIN OUTCOME MEASURES

Serum estradiol (E2) levels and numbers of oocytes recovered at oocyte pick-up.

RESULTS

Average (+/- SE) levels of hGH in sera of high-hGH and low-hGH patients were 10.2 +/- 0.6 and 2.47 +/- 0.3 microIU/mL, respectively (P less than 0.05). Respective peripheral levels of insulin-like growth factor-I were 105.3 +/- 2.9 and 97.2 +/- 2.8 ng/mL. Levels of E2 in serum of high-hGH patients exceeded respective (P less than 0.05) low-hGH values throughout folliculogenesis, and more oocytes were recovered from high-hGH patients (8.1 +/- 0.9 versus 4.7 +/- 0.5 for low-hGH patients; P less than 0.05). Serum progesterone values did not differ. Higher day 2 hGH levels were associated with higher numbers of oocytes recovered after controlled ovarian hyperstimulation.

CONCLUSIONS

The present findings indicate that endogenous hGH may augment gonadotropins during follicle recruitment and during multiple folliculogenesis in women. The phase of maximum ovarian sensitivity to hGH/gonadotropin synergism and the nature of synergism remain unclear.