The effect of gonadotropin-releasing hormone agonists on growth hormone secretion in adult premenopausal women

Pelvic adhesion and gonadotropin-releasing hormone analogue: effects of triptorelin acetate depot on coagulation and fibrinolytic activities

The study investigated the impact of gonadotropin-releasing hormone analogue (GnRH-a) on coagulation and fibrinolytic activities and its effectiveness in the prevention of pelvic adhesion after myomectomy. Thirty-two infertile women underwent myomectomy followed by adhesion evaluation surgery with a second-look laparoscopy. Before myomectomy, 15 women were treated with triptorelin acetate for 3 months and 17 received no treatment. Plasminogen activator inhibitor (PAI), thrombin activatable fibrinolysis inhibitor (TAFI), protein C (PC), plasminogen, α2-antiplasmin were determined by enzyme-linked immunosorbent assays and the activity of coagulation factors V and VIII by coagulometric methods. Patients treated with GnRH-a showed significant decrease in PAI, TAFI, factors V, and VIII (P < .05) and increased PC (P < .05), but no significant change in plasminogen and α2-antiplasmin levels compared with control group. The incidence, extent, and severity of adhesions were significantly lower in GnRH-a-treated patients compared with control group (P < .05), suggesting a possible critical role of the GnRH-a therapy in preventing postoperative adhesion development.

Ovarian suppression with gonadotropin-releasing hormone agonist reduces whole body protein turnover in women

The age-related decline in fat-free mass is accelerated in women after menopause. The role of ovarian hormone deficiency in the regulation of fat-free mass, however, has not been clearly defined. To address this question, we examined the effect of ovarian hormone suppression on whole body protein metabolism. Whole body protein breakdown, oxidation, and synthesis were measured using [(13)C]leucine in young, healthy women with regular menstrual patterns before and after 2 mo of treatment with gonadotropin-releasing hormone agonist (GnRHa; n = 6) or placebo (n = 7). Protein metabolism was measured under postabsorptive and euglycemic-hyperinsulinemic-hyperaminoacidemic conditions. Ovarian suppression did not alter whole body or regional fat-free mass or adiposity. In the postabsorptive state, GnRHa administration was associated with reductions in protein breakdown and synthesis (P < 0.05), whereas no change in protein oxidation was noted. Under euglycemic-hyperinsulinemic-hyperaminoacidemic conditions, a similar reduction (P < 0.05) in protein synthesis and breakdown was noted, whereas, protein oxidation increased (P < 0.05) in the placebo group. Testosterone, steroid hormone precursors, insulin-like growth factor I, and their respective binding proteins were not altered by GnRHa administration, and changes in these hormones over time were not associated with GnRHa-induced alterations in protein metabolism, suggesting that changes in protein turnover are not due to an effect of ovarian suppression on other endocrine systems. Our findings provide evidence that endogenous ovarian hormones participate in the regulation of protein turnover in women.

Growth hormone response to clonidine in anovulatory infertile women resistant to clomiphene citrate stimulation

OBJECTIVE

To evaluate the GH response to the clonidine test in a group of infertile women and to determine their ovulatory response to clomiphene citrate (CC) stimulation.

DESIGN

Prospective study.

SETTING

Reproductive endocrinology unit.

PATIENT(S)

Thirty-three anovulatory infertile women (age range, 25-36 years) and 9 healthy controls with normal ovulation.

INTERVENTION(S)

In the early follicular phase, 0.3 mg of clonidine was administered between 8:30 and 9:00 A.M. and blood samples were collected for 120 minutes thereafter for measurement of serum GH levels. Plasma levels of insulin and glucose were measured after a 75-g glucose load, and CC was given at a dosage of 50-250 mg/d for ovulation-induction.

MAIN OUTCOME MEASURE(S)

Serum concentrations of GH, insulin-like growth factor I, insulin, and insulin-like growth factor binding protein-1.

RESULT(S)

On the basis of their ovulatory response to CC, 15 patients were considered nonresponsive (group 1) and 18 patients were considered responsive (group 2). Baseline levels of GH, insulin-like growth factor I, and insulin-like growth factor binding protein-1 were similar in the two groups of patients and the controls. The GH response to clonidine was significantly greater in group 2 and in the controls than in group 1. Concentrations of insulin and glucose after the glucose load were not different among the three groups.

CONCLUSION(S)

Women who were resistant to CC had a reduced GH response to clonidine. These data suggest that adequate GH secretory capacity is important for CC action.

Pathophysiology of the neuroregulation of growth hormone secretion in experimental animals and the human

During the last decade, the GH axis has become the compelling focus of remarkably active and broad-ranging basic and clinical research. Molecular and genetic models, the discovery of human GHRH and its receptor, the cloning of the GHRP receptor, and the clinical availability of recombinant GH and IGF-I have allowed surprisingly rapid advances in our knowledge of the neuroregulation of the GH-IGF-I axis in many pathophysiological contexts. The complexity of the GHRH/somatostatin-GH-IGF-I axis thus commends itself to more formalized modeling (154, 155), since the multivalent feedback-control activities are difficult to assimilate fully on an intuitive scale. Understanding the dynamic neuroendocrine mechanisms that direct the pulsatile secretion of this fundamental growth-promoting and metabolic hormone remains a critical goal, the realization of which is challenged by the exponentially accumulating matrix of experimental and clinical data in this arena. To the above end, we review here the pathophysiology of the GHRH somatostatin-GH-IGF-I feedback axis consisting of corresponding key neurotransmitters, neuromodulators, and metabolic effectors, and their cloned receptors and signaling pathways. We propose that this system is best viewed as a multivalent feedback network that is exquisitely sensitive to an array of neuroregulators and environmental stressors and genetic restraints. Feedback and feedforward mechanisms acting within the intact somatotropic axis mediate homeostatic control throughout the human lifetime and are disrupted in disease. Novel effectors of the GH axis, such as GHRPs, also offer promise as investigative probes and possible therapeutic agents. Further understanding of the mechanisms of GH neuroregulation will likely allow development of progressively more specific molecular and clinical tools for the diagnosis and treatment of various conditions in which GH secretion is regulated abnormally. Thus, we predict that unexpected and enriching insights in the domain of the neuroendocrine pathophysiology of the GH axis are likely be achieved in the succeeding decades of basic and clinical research.

Neuroendocrine control of pulsatile growth hormone release in the human: relationship with gender

Gender has multiple significant influences on the human GH axis in the premenopausal age group (Table 1), and attenuates by approximately 50% the negative impact of age on daily GH secretion rates, the inverse association between total adiposity and GH production, and the positive effect of increased physical fitness on GH secretion. The sex differences in GH axis activity are highly specific mechanistically, and namely entail the mass of GH secreted per burst (greater in women than men), and the orderliness of the 24-hour GH release process (less orderly pattern in women). Moreover, physiological regulation of the GH-IGF-I axis is evident within the follicular phase of the normal human menstrual cycle, wherein mean serum GH and plasma IGF-I concentrations rise concurrently with increased oestradiol secretion in the preovulatory phase. Oestrogen, directly or indirectly (e.g. via long-term changes in visceral and subcutaneous fat distribution), serves as the proximate mediator of many gender differences, and probably mediates most of the acute sex-steroid effects of both testosterone and oestradiol on the human GH-IGF-I axis. In conclusion, oestrogen regulates the physiological output of the GH-IGF-I axis both quantitatively (daily GH secretion rate) and qualitatively (organization or orderliness of GH release). The actions of oestrogen are probably achieved via alterations in GHRH and somatostatin activities and their reciprocal interactions. Current evidence concerning the role of oestrogen favours an increase in somatotroph responsiveness to GHRH, with or without decreased effects of somatostatin. Whether putative GHRPs, galanin, etc., participate in the potent amplifying actions of oestrogen on the GH axis is not known. Thus, gender and sex steroids are potent pathophysiological regulators of the orderliness and pulsatile mass of GH secreted in humans.

The effect of gonadotropin-releasing hormone agonist on thyroid-stimulating hormone and prolactin secretion in adult premenopausal women

OBJECTIVE

To investigate the effects of chronic administration of GnRH agonists (GnRH-a) on pituitary TSH and PRL secretion in adult women.

DESIGN

Prospective case-controlled study.

SETTING

Academic division of Reproductive Endocrinology, Department of Obstetrics and Gynecology.

PATIENTS

Ten ovulatory women and 10 women treated with monthly depot injections of leuprolide acetate (3.75 mg) were studied.

INTERVENTIONS

All subjects underwent pituitary stimulation with human thyrotropin-releasing hormone (TRH), 500 micrograms IV.

MAIN OUTCOME MEASURES

Basal and post-TRH-stimulated serum levels of TSH and PRL at 15, 30, 45, 60, 90, 120, and 180 minutes were compared among the two groups. Also, basal of T4, triiodothyronine, and triiodothyronine resin uptake studies were obtained and compared among the GnRH-a-treated and control groups.

RESULTS

No statistically significant difference between baseline or TRH-stimulated serum TSH and PRL could be detected between control and GnRH-a-treated groups of women. Furthermore, these groups were similar with respect to routine thyroid function assays.

CONCLUSION

Gonadotropin-releasing hormone agonist does not significantly affect baseline or TRH-stimulated TSH and PRL levels nor basal serum T4 and triiodothyronine levels or triiodothyronine resin uptake in adult women.

Effect of combined treatment with gonadotropin releasing hormone analogue and growth hormone in patients with central precocious puberty who had subnormal growth velocity and impaired height prognosis

Growth hormone-insulin-like growth factor-I status and response to growth hormone therapy (0.6 IU/kg/week sc, six times a week for 12 months) were evaluated in 12 girls (chronological age 9.4 +/- 1.6 years) suffering from central precocious puberty with growth velocity less than 4 cm/year and no substantial increase or decrease in predicted adult height during gonadotropin releasing hormone Bn-RH) analogue treatment (D-Trp6-LH-RH, 60 micrograms/kg im/28 days). At baseline, large variations were observed in nocturnal growth hormone (GH) means (pathological values stimulated levodopa GH peaks (pathological values (< 10.0 micrograms/l) 28.6%) and serum insulin-like growth factor-I (IGF-I) levels. Neither GH-nor IGF-I levels were correlated with growth velocity. During recombinant GH therapy, growth velocity increased significantly (baseline 3.0 +/- 0.9 cm/year; 6 months 6.4 +/- 1.9 cm/year, p < 0.001 versus baseline; 12 months 6.0 +/- 1.3 cm/year, p < 0.0001 versus baseline). There was a significant increase in height SDS for bone age (baseline -1.6 +/- 0.5 SDS; 12 months -1.04 +/- 0.6 SDS; p < 0.002) and in predicted adult height (baseline 152.0 +/- 3.6 cm; 12 months 155.9 +/- 3.4 cm; p < 0.002). Our results suggest that combined therapy with Gn-RH analogues and recombinant GH can improve growth velocity and predicted adult height in girls with central precocious puberty and impaired height prognosis during Gn-RH analogue treatment.

The role of insulin in ovarian size in patients with the polycystic ovary syndrome

The objective of this study was to evaluate whether the degree of suppression of ovarian volume effected by a gonadotropin releasing hormone (GnRH) agonist in patients with polycystic ovary syndrome (PCOS) correlated with basal insulin secretion and insulin secretion provoked by a glucose challenge. Eighteen PCOS patients received the GnRH agonist D-tryptophan-6-LHRH (Decapeptyl, 3.75 mg monthly i.m.) for 6 months and had blood glucose and insulin measured during a 75 g oral glucose tolerance test (OGTT) prior to and at the end of therapy. According to ovarian volume suppression after GnRH agonist therapy, two groups were defined: in group A (n = 10; mean body mass index (BMI) +/- SEM, 25.6 +/- 1.6 kg/m2) ovarian volume regressed from 17.9 +/- 1.6 to 6.7 +/- 0.3 ml (full responders) and in group B (n = 8; mean BMI +/- SEM, 28.1 +/- 2.3 kg/m2) from 21.5 +/- 1.1 to 15.1 +/- 1.0 ml (partial responders). Results showed that GnRH agonist therapy did not affect significantly BMI or fasting levels and area under the curve (AUC) for glucose and insulin in the respective groups. Fasting insulin levels correlated positively with ovarian volume prior to (r = 0.56, p < 0.05) and after 6 months of GnRH agonist therapy (r = 0.80, p < 0.005). The suppressibility of ovarian volume with GnRH agonist therapy correlated negatively with the difference between maximal and basal levels (r = -0.68), the area under the curve (r = -0.62) and maximal levels (r = -0.72) for insulin during the OGTT.(ABSTRACT TRUNCATED AT 250 WORDS)

The response of the growth hormone and insulin-like growth factor I axis to medical castration in women with polycystic ovarian syndrome

OBJECTIVE

To assess the impact of ovarian hormone deprivation on serum concentrations of GH and insulin-like growth factor I (IGF-I) in women with polycystic ovarian syndrome (PCOS).

DESIGN

Growth hormone and IGF-I levels were measured before, during, and at the end of a 6-month period of treatment with leuprolide acetate (LA) depot. Normal cycling and ovariectomized women served as controls.

SETTING

The Clinical Research Center of Northwestern University Medical School.

PATIENTS

Six women with PCOS, seven normal cycling women, and six ovariectomized women.

INTERVENTIONS

The PCOS and normal cycling subjects were treated with six consecutive monthly injections of LA depot 3.75 mg IM.

MAIN OUTCOME MEASURES

Circulating concentrations of GH and IGF-I.

RESULTS

After 3 months of treatment, GH levels decreased modestly in the PCOS group; however, these changes were not significant. No further decline was observed at 6 months. Growth hormone levels were unaffected in the normal cycling group. Levels of IGF-I remained unchanged in both groups. Mean baseline levels of both GH and IGF-I in the ovariectomized group were lower than those of the normal cycling and PCOS groups at all time points, but not significantly so.

CONCLUSIONS

Medical castration fails to significantly alter serum GH and IGF-I levels in either normal cycling or women with PCOS. These data indicate that GH secretion is not modulated by hormones of ovarian origin in either group, at least over the period of time studied.

Ovulation induction in gonadotrophin-resistant women

The patient who has gonadotrophin-resistant ovaries and who requires ovulation induction or superovulation for IVF presents a serious problem. The diagnosis is usually made in the first treatment cycle which is either abandoned due to a failure of response, requires inordinately high doses of gonadotrophins to induce a response or fails to induce satisfactory oestradiol levels and/or follicular development. This situation is often associated with advanced maternal age and high day 3 concentrations of FSH. The possible treatment strategies that we have described seem to offer only a partial solution to specific subgroups of poor responders. These include protocols of clomiphene/hMG, mini-dose GnRH agonist regimens, and cotreatment with GH, each of which may be found to be effective in individual cases. Taking into account today's increasing demand for pregnancy in older aged women, more research is needed to evolve more efficient solutions for this difficult problem.

Growth velocity and serum aminoterminal propeptide of type III procollagen in precocious puberty during gonadotropin-releasing hormone analogue treatment

Growth velocity and serum aminoterminal propeptide of type III procollagen (P-III-NP) were evaluated in 11 girls (age 3.8-8.5 years) with central precocious puberty during luteinizing hormone releasing hormone (LH-RH) analogue treatment (D-Trp6-LH-RH, 60 micrograms/kg im for 28 days, n = 7; D-ser(TBU)6-LH-RH, 1600 micrograms/day intranasally, n = 4). Before treatment, growth velocity (10.2 +/- 1.9 cm/year) and P-III-NP concentrations (12.8 +/- 4.3 micrograms/l) were in the pubertal range. During therapy, growth velocity significantly decreased to the prepubertal levels. P-III-NP concentrations decreased significantly after six months of therapy (7.9 +/- 3.7 micrograms/l, p < 0.001). Three girls with low growth velocity ( < 4 cm/year), stimulated growth hormone peak < 10 micrograms/l, and altered 12-h nocturnal growth hormone secretion at 12 and/or 18 months of treatment, had a more marked decrease in P-III-NP concentrations (patient 3: -65.9%; patient 5: -58.7%; patient 10: -61.0%) after 6 months of therapy. Our results suggest that LH-RH analogue treatment in central precocious puberty may impair growth. In these cases, measurement of serum P-III-NP levels may be an additional marker to monitor growth.

The effect of growth hormone supplementation on in vitro fertilization outcome: a prospective randomized placebo-controlled double-blind study

OBJECTIVE

To determine the effect of growth hormone (GH) supplementation to a long gonadotropin-releasing hormone agonist (GnRH-a)/human menopausal gonadotropin (hMG) treatment protocol, on ovarian response, embryo quality, and clinical outcome in in vitro fertilization (IVF).

DESIGN

Growth hormone or placebo were administered in a prospective randomized double-blind manner.

PATIENTS

Forty-two normal ovulatory, women who were 38 years of age or less with mechanical factor infertility and a normal male factor were selected for this study.

INTERVENTIONS

Gonadotropin-releasing hormone agonist, 0.5 mg/d, was initiated in the midluteal phase of the preceding cycle and continued until the day of human chorionic gonadotropin (hCG) administration. Ovulation induction with hMG was started 14 days after pituitary down regulation (17 beta-estradiol [E2] serum level less than 30 pg/mL). Growth hormone (12 IU/d) or placebo were administered on days 1, 3, 5, and 7 of hMG treatment.

RESULTS

Breaking the code at the completion of the study revealed that 20 women received GH and 22 placebo. The age and duration of infertility did not differ between the two groups. Follicular phase duration, hMG ampules used, serum E2, and number of follicles (greater than or equal to 14 mm) on day of hCG as well as number of oocytes and embryos achieved were similar in both groups. Embryo morphology and rate of cleavage were also similar. Insulin-like growth factor-I (IGF-I) serum levels did not change after pituitary down regulation and increased significantly both after GH/hMG and placebo/hMG ovulation induction treatment. Clinical pregnancy rate (PR) per embryo transfer and implantation rate were 40% versus 32% and 17.9% versus 11.3% in the GH and placebo groups, respectively, and were not statistically different.

CONCLUSIONS

In normo-ovulatory women undergoing ovulation induction for IVF, GH supplementation to hMG after GnRH-a pituitary down regulation does not seem to augment ovarian response or improve embryo quality. The effect of this regimen on actual PRs and implantation rates needs further clarification.

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

STUDY OBJECTIVE

To investigate the interrelationships between circulating levels of endogenous human growth hormone (hGH), gonadotropins, estradiol (E2), and progesterone (P).

DESIGN

Retrospective.

SETTING

Assisted reproductive technology center.

PATIENTS

Nine normally cycling women from whom blood samples were drawn daily; 18 patients undergoing controlled ovarian hyperstimulation.

RESULTS

During the menstrual cycle, average (+/-SE) hGH levels in serum ranged between 7.97 +/- 2.71 microIU/mL on day 11 and 2.11 +/- 0.38 microIU/mL on day 22. Serum hGH levels did not correlate with peripheral levels of follicle-stimulating hormone (FSH), luteinizing hormone, P, or E2 and were related to the serum E2:FSH ratio (adhibited as an index of ovarian response to FSH) on cycle day 10 only. Levels of hGH in sera of patients undergoing controlled ovarian hyperstimulation were near 4 microIU/mL and were directly related to peripheral E2 levels at the time of induction of oocyte maturity. When corrected for differences in follicle number between stimulated patients, changes in serum E2 content were independent of respective hGH levels.

CONCLUSION

The findings challenge speculation that endogenous peripheral hGH content might relate to ovarian responsiveness to FSH.