Hormonal treatments modulate pulsatile plasma growth hormone, gonadotrophin and osteocalcin levels in postmenopausal women

Does tibolone affect serum leptin levels and body weight in postmenopausal women?

OBJECTIVES

Leptin has a significant role in body weight regulation and energy balance. We examined the effect of tibolone on the body weight and serum leptin levels in postmenopausal women.

STUDY DESIGN

Twenty women (aged 43-60 years) participated in this prospective study. All women in this study protocol received 2.5 mg/day of tibolone. Absolute and body mass index (BMI)-corrected serum leptin concentrations and BMI values were measured at baseline, after 3 months, and after 6 months of the tibolone therapy.

RESULTS

Tibolone did not affect absolute and BMI-corrected serum leptin levels, and BMI values during the treatment. A significant linear correlation between BMI values and serum leptin levels was observed (p<0.05, r=0.67).

CONCLUSIONS

Tibolone seems not to affect serum leptin levels, body weight and BMI values of postmenopausal women. There is a significant correlation between serum leptin levels and BMI values.

The influence of tibolone upon serum leptin levels in post-menopausal women

OBJECTIVE

To estimate serum leptin levels in post-menopausal women, to relate these to the duration of the post-menopausal period, and to body mass index (BMI), and to assess the influence of tibolone on them.

METHODS

Fifteen women (age 49-64 years) were included. Three groups were studied; I, those with normal BMI taking tibolone; II, those with a raised BMI taking tibolone, and III, a group with raised BMI not taking tibolone. Blood samples were drawn before and 1, 2, 6, 9 and 12 months after the initiation of tibolone or, in group III, after the start of the study.

RESULTS

Serum leptin concentrations were high in all women with abnormal BMI. Long-term tibolone administration did not have any significant effect on serum leptin concentrations. There was no correlation between serum leptin levels and the age and the duration of post-menopausal period. There was a high positive correlation between serum leptin levels and BMI values.

CONCLUSIONS

BMI values affect serum leptin concentrations but long-term tibolone administration does not seem to have any effect on serum leptin levels.

Effects of two oral contraceptives on plasma levels of insulin-like growth factor I (IGF-I) and growth hormone (hGH)

In 18 healthy women, the effect of two oral contraceptives (OCs) on insulin-like growth factor (IGF-I) and its binding protein-3 (IGFBP-3) and growth hormone (hGH) plasma level were studied before and after intake of either of two OC formulations over 21 days, one containing 2 mg dienogest and 0.03 mg ethinylestradiol (group A) and the other 0.125 mg levonorgestrel and 0.03 mg ethinylestradiol (group B). There was a reduction of the mean IGF-I concentration of 30% (p = 0.008) in the women receiving dienogest-containing pills and 12% (p = 0.006) in women taking the levonogestrel-containing preparation. This difference between drug groups was statistically significant (p = 0.002). A correlation between the control values and the basal-treatment difference (r = 0.945; p = 0.000) was observed only in women of group A. Between basal and treatment cycles the mean plasma levels of hGH remained unchanged in both groups tested, but the 23.5-h integrated mean hGH plasma concentrations (AUC(0-23.5h)) were significantly elevated by 36% (p = 0.016) in comparison to basal values before treatment only in women receiving the levonorgestrel-containing pills. Also, in the women who received the dienogest-containing preparation, the changes of integrated mean plasma level were inversely associated with the control values (r = -0.723; p = 0.025). Neither in group A nor in group B was the mean plasma level of IGFB-3 changed.

IN CONCLUSION

the results of the present analysis indicate that hormonal contraceptives can modulate the GH and IGF-I-axis in the reproductive age. Probably the androgenic progestogen levonorgestrel (0.125 mg/day) opposes the estrogen-induced action. In the women who took the dienogest-containing formulations (anti-androgenic progestogen-group A), the extent of individual changes (hGh and IGF-I) depends on the basal level prior to pill intake. Further studies, especially of long-term intake of OCs, are necessary to confirm these results and to assess the practical relevance for possible effects on connective tissue and bone.

Effect of menopause and different combined estradiol-progestin regimens on basal and growth hormone-releasing hormone-stimulated serum growth hormone, insulin-like growth factor-1, insulin-like growth factor binding protein (IGFBP)-1, and IGFBP-3 levels

OBJECTIVE

To determine the effects of menopause and three different formulations of E2 plus medroxyprogesterone acetate on serum concentrations of basal and growth hormone-releasing hormone (GHRH)-stimulated growth hormone (GH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein (IGFBP)-1, IGFBP-3, insulin, and C peptide.

DESIGN

Prospective, controlled trial.

SETTING

Menopausal outpatient clinic at an academic tertiary care hospital.

PATIENT(S)

Nineteen postmenopausal women with different menopausal ages. Seventeen premenopausal women were included as controls.

INTERVENTION(S)

Oral estrogen (E2 valerate, 2 mg/d) or transdermal estrogen (50-microg or 100-microg E2 patch) was administered for 8 weeks. Medroxyprogesterone acetate (5 mg/d) was administered during weeks 3, 4, 7, and 8 of each protocol. Blood samples were collected before treatment and after the completion of each protocol from postmenopausal women, and on cycle days 6-8 from premenopausal women.

MAIN OUTCOME MEASURE(S)

Levels of GH, IGF-1, IGFBP-1, IGFBP-3, insulin, and C peptide.

RESULT(S)

Basal GH levels were negatively correlated with age in premenopausal women but not in postmenopausal women. The area under the GHRH-induced GH curve decreased in older postmenopausal women after the oral estrogen protocol. Levels of IGF-1 diminished after the oral E2 protocol in postmenopausal women.

CONCLUSION(S)

The administration of oral, but not transdermal, E2 plus medroxyprogesterone acetate at the usual clinical doses used in postmenopausal women decreased IGF-1 levels and the response of GH to GHRH in older women. No substantial changes were detected in IGFBP-1, IGFBP-3, insulin, or C peptide levels.

Insulin-like growth factor I (IGF-I) serum level modifications during transdermal estradiol treatment in postmenopausal women: a possible bimodal effect depending on basal IGF-I values

The objective of this study was to determine the influence of transdermal estradiol administration on insulin-like growth factor I (IGF-I) serum level in a series larger than those published to date. Thirty-nine postmenopausal women with vasomotor symptoms were studied; blood samples (after overnight fast) were obtained just before and at the 6th month of treatment with transdermal estradiol 0.05 mg/day, and serum levels of IGF-I, growth hormone and sex hormone binding globulin (SHBG) were evaluated. Sixteen of the 39 women did not show variations of IGF-I values (group A), while 11 showed an increase (group B) and 12 showed a decrease (group C) by at least 20% with transdermal estradiol treatment. IGF-I basal levels were higher in group C as compared to group A (p < 0.05) and to group B (p < 0.01), intermediate in group A, and lower in group B. Group C showed a significant increase of SHBG values with transdermal estradiol treatment. Transdermal estradiol seems to induce a bimodal effect on IGF-I serum levels, depending on IGF-I basal values. This could be caused by a different responsivity to estrogen action on the liver (the major site of circulating IGF-I production) and also, possibly, by a different degree in insulin sensitivity changes caused by estrogen.

Modulatory effects of a synthetic steroid (tibolone) and estradiol on spontaneous and GH-RH-induced GH secretion in postmenopausal women

OBJECTIVE

Since hormonal replacement therapy (HRT) affects plasma GH levels, the present study aimed to verify the effect of tibolone, a synthetic steroid, on modulating spontaneous and growth hormone releasing hormone (GH-RH) induced GH secretion.

METHODS

Postmenopausal women (n = 30) were enrolled and randomly subdivided in three groups (n = 10 each group): (1) treated with transdermal estradiol (50 micrograms) (Dermestrill, Rottapharm, Monza, Italy) biweekly; (2) treated with transdermal estradiol (100 micrograms) (Dermestrill, Rottapharm, Monza, Italy) biweekly; (3) treated with tibolone 2.5 mg/day (Livial, Organon Italia, Rome, Italy). Patients underwent a GH-RH test (1 microgram/kg) and 15 of them underwent to a pulsatility study before and 5 weeks after treatment.

RESULTS

Mean (+ S.E.M.) GH plasma levels increased in all patients after any type of HRT. GH response to GH-RH stimulation (expressed as maximal response to GH-RH or as delta value) was similar in the three groups while significant changes occurred in spontaneous pulsatile GH release. Tibolone and both dosages of transdermal estradiol significantly reduced GH pulse frequency and increased pulse amplitude.

CONCLUSIONS

The reduced plasma GH levels observed during postmenopause are probably related to a reduced endogenous GH-RH and not to a reduced pituitary ability to respond to GH-RH. In addition tibolone, as well as transdermal estradiol, are effective in restoring the spontaneous GH episodic release.

Effects of hormone replacement therapy on growth hormone secretion patterns in correlation to somatometric parameters in healthy postmenopausal women

OBJECTIVES

The aim of the present study was to investigate the influence of a continuous estrogen, cyclic progesterone replacement therapy on the secretion of growth hormone (GH) and IGF I as well as of somatometric-GH correlation patterns.

METHODS

The study included 23 healthy postmenopausal women. Of the proband group 13 randomly selected women were treated with orally applicated 2 mg estradiol-valerat (E2V) and 10 mg dydrogesterone for 10 months. Ten women did not receive any hormonal treatment during this time. After 10 months all probands were reexamined and their GH and IGF I secretion, as well as their somatometric-hormonal correlation patterns, compared with those of a fertile control group.

RESULTS

It could be shown, that in postmenopausal women a 10-month oral hormone replacement therapy led to a significant increase of GH- and IGF I levels, however, the treated postmenopausal women did not reach the levels of the fertile controls. Those women who did not receive any hormonal treatment and the postmenopausal women before HRT showed nearly identical GH- and IGF I levels as well as somatometric-GH correlation patterns.

CONCLUSIONS

The results of the present paper indicate a marked influence of estrogens on GH and IGF I secretion. Furthermore, hormonal replacement therapy (HRT) may influence somatometric GH correlation patterns too.