Transdermal 17 beta-estradiol combined with oral progestogen increases plasma levels of insulin-like growth factor-I in postmenopausal women

A summary of the influence of exogenous estrogen administration across the lifespan on the GH/IGF-1 axis and implications for bone health

Bone growth, development, and remodeling are modulated by numerous circulating hormones. Throughout the lifespan, the extent to which each of the hormones impacts bone differs. Understanding the independent and combined impact of these hormones on controlling bone remodeling allows for the development of more informed decision making regarding pharmacology, specifically the use of hormonal medication, at all ages. Endocrine control of bone health in women is largely dictated by the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis and the hypothalamic-pituitary-ovarian (HPO) axis. Growth hormone, secreted from the pituitary gland, stimulates cells in almost every tissue to secrete IGF-1, although the majority of circulating IGF-1 is produced hepatically. Indeed, systemic IGF-1 concentrations have been found to be correlated with bone mineral density (BMD) in both pre- and post-menopausal women and is often used as a marker of bone formation. Sex steroids produced by the ovaries, namely estradiol, mediate bone resorption through binding to estrogen receptors on osteoclasts and osteoblasts. Specifically, by increasing osteoclast apoptosis and decreasing osteoblast apoptosis, adequate estrogen levels prevent excessive bone resorption, which helps to explain the rapid decline in bone mass that occurs with the menopausal decrease in estrogen production. Though there are documented correlations between endogenous estrogen concentrations and GH/IGF-1 dynamics, this relationship changes across the lifespan as sex-steroid dynamics fluctuate and, possibly, as tissue responsiveness to GH stimulation decreases. Aside from the known role of endogenous sex steroids on bone health, the impact of exogenous estrogen administration is of interest, as exogenous formulations further modulate GH and IGF-1 production. However, the effect and extent of GH and IGF-1 modulation seems to be largely dependent on age at administration and route of administration. Specifically, premenopausal women using combined oral contraceptive therapy (COC), post-menopausal women taking oral hormone therapy (HT), and both pre- and post-menopausal women using a transdermal form of estrogen therapy (COC or HT) demonstrate disparate GH/IGF-1 responses to exogenous estrogen. This review serves to summarize what is currently known regarding the influence of exogenous estrogen administration across the lifespan on the GH/IGF-1 axis and implications for bone health.

Estrogens and selective estrogen receptor modulators in acromegaly

Despite recent advances in acromegaly treatment by surgery, drugs, and radiotherapy, hormonal control is still not achieved by some patients. The impairment of IGF-1 generation by estrogens in growth hormone deficient patients is well known. Patients on oral estrogens need higher growth hormone doses in order to achieve normal IGF-1 values. In the past, estrogens were one of the first drugs used to treat acromegaly. Nevertheless, due to the high doses used and the obvious side effects in male patients, this strategy was sidelined with the development of more specific drugs, as somatostatin receptor ligands and dopamine agonists. In the last 15 years, the antagonist of growth hormone receptor became available, making possible IGF-1 control of the majority of patients on this particular drug. However, due to its high cost, pegvisomant is still not available in many centers around the world. In this setting, the effect of estrogens and also of selective estrogen receptor modulators on IGF-1 control was reviewed, and proved to be an ancillary tool in the management of acromegaly. This review describes data concerning their efficacy and place in the treatment algorithm of acromegaly.

APOE modulates the effect of estrogen therapy on Aβ accumulation EFAD-Tg mice

The post-menopausal loss of estrogen is key in the increased incidence of Alzheimer's disease (AD) in women. However, estrogen therapy (ET) clinical trials have produced conflicting results. The APOE gene of apolipoprotein E (apoE) likely modulates the effects of ET in AD. APOE4 is the greatest genetic risk factor for AD, increasing risk up to 15-fold compared with APOE3, and the negative effect of APOE4 on AD risk and neuropathology is greater in women than men. The interactive effects of APOE and ET may converge on modulation of amyloid-beta (Aβ) levels, as independently both the loss of estrogen and APOE4 increases Aβ accumulation. Thus, in this study, 3-month old female EFAD mice (5XFAD mice crossed with apoE-targeted replacement mice), which express increased levels of Aβ42 and human APOE were ovariectomized and treated for 3 months with either 17-β estradiol (OVX(ET+), 0.25mg total) or vehicle control (OVX(ET-)) and the effects on Aβ accumulation were determined. Compared to the OVX(ET-) cohort, in the OVX(ET+) cohort, extracellular amyloid and Aβ deposition in the hippocampus and cortex were decreased with APOE2 and APOE3, but were increased with APOE4 by IHC. Biochemical analysis demonstrated increased total and insoluble Aβ levels with APOE4, and decreased soluble Aβ42 levels with both APOE3 and APOE4, after ET. These data suggest that ET administered at menopause may benefit APOE4 negative women by decreasing extracellular and soluble Aβ42. However, for APOE4 carriers, the efficacy of ET will be dependent on the relative impact of extracellular and soluble Aβ on AD-induced neurodegeneration.

Bone accretion in adolescents using the combined estrogen and progestin transdermal contraceptive method Ortho Evra: a pilot study

OBJECTIVE

To date, there are no data regarding the effect of the transdermal combined estrogen and progestin contraceptive Ortho Evra on bone mineral content (BMC) and bone mineral density (BMD). We examined the effects of transdermally delivered ethinyl estradiol and norelgestromin on whole body (WB) BMC and BMD of the hip and lumbar spine (LS) of adolescent girls.

METHODS

In a matched case-control study, girls (n = 5) who applied Ortho Evra for days 1-21 followed by days 22-28 free of medication for 13 cycles (about 12 months) were compared with 5 age- and ethnicity-matched control girls. Evaluations of calcium intake; bone-protective physical activity; bone densitometry (DXA, QDR 4500A, Hologic); bone formation markers serum osteocalcin (OC) and bone-specific alkaline phosphatase (BAP); bone resorption marker urinary N-telopeptide (uNTX); insulin growth factor-1 (IGF-1); and sex hormone binding globulin (SHBG) were carried out at initiation, 6 months, and 12 months. Changes from baseline were compared using mixed models, adjusting for follow-up comparisons using the Holm Test (sequential Bonferroni).

RESULTS

There were no significant differences (SD) between groups at baseline in age, gynecologic age, WBBMC, hip BMD, and LSBMD. Girls on Ortho Evra did not change significantly in WBBMC (12-month mean increase 0.2% +/- 0.8%), whereas controls did (3.9% +/- 1.8%, P < or = .001, adjusted P = .002), with SD between the 2 groups (P = .007, adjusted P = .036). Adolescents on Ortho Evra did not change significantly in hip BMD (12-month mean increase 0.5% +/- 0.6%), whereas controls did (2.7% +/- 0.6%, P < or = .001, adjusted P = .004), with SD between the 2 groups (P = .024) prior to adjustment for multiple comparisons, but no SD after adjustment (P = .096). Similarly, although the increase in LSBMD within the control group after 12 months (mean increase 2.8% +/- 1.0%) was statistically significant (P = .009, adjusted P = .044), the change within the treatment group (12-month mean increase 0.8% +/- 0.8%) was not. However, percent LSBMD changes after 12 months did not significantly differ between the 2 groups before or after adjustment for multiple comparisons. Calcium intake and bone-protective physical activity did not significantly predict BMC and BMD changes of study participants. There was a significantly greater increase in SHBG levels in the treatment group after 6 months (P = .003, adjusted P = .013) and 12 months (P < or = .001, adjusted P < or = .001) than in controls. Changes in levels of OC, BAP, uNTX, and IGF-1 were not significantly different between the 2 groups.

CONCLUSIONS

Ortho Evra use attenuates bone mass acquisition in young women who are still undergoing skeletal maturation. This attenuation may be attributed in part to increased SHBG levels, which reduce the concentrations of free estradiol and free testosterone that are available to interact with receptors on the bone. Clinical implications remain to be determined in studies with a larger number of adolescents.

Role of androgens, progestins and tibolone in the treatment of menopausal symptoms: a review of the clinical evidence

Estrogen-containing hormone therapy (HT) is the most widely prescribed and well-established treatment for menopausal symptoms. High quality evidence confirms that estrogen effectively treats hot flushes, night sweats and vaginal dryness. Progestins are combined with estrogen to prevent endometrial hyperplasia and are sometimes used alone for hot flushes, but are less effective than estrogen for this purpose. Data are conflicting regarding the role of androgens for improving libido and well-being. The synthetic steroid tibolone is widely used in Europe and Australasia and effectively treats hot flushes and vaginal dryness. Tibolone may improve libido more effectively than estrogen containing HT in some women. We summarize the data from studies addressing the efficacy, benefits, and risks of androgens, progestins and tibolone in the treatment of menopausal symptoms.

Differential effects of various progestogens on metabolic risk factors for breast cancer

Biological and epidemiological findings suggest that metabolic factors - insulin, insulin-like growth factor-I (IGF-I) and sex hormone-binding globulin (SHBG) - are involved in the development and promotion of breast cancer. Estrogens, particularly if administered orally, counteract metabolic factors that increase breast cancer risk, i.e. they reduce insulin and IGF-I and increase SHBG. This could contribute toward explaining epidemiological data showing that unopposed oral estrogens do not increase breast cancer risk, or do so only modestly. In contrast to natural progesterone and progesterone-derived progestins, progestins endowed with androgenic (or glucocorticoid) activity negatively influence these metabolic factors, counteracting the favorable effects of estrogens. While most biological and epidemiological findings suggest that natural progesterone does not augment breast cancer risk, available data show an increased risk with synthetic progestins - with the possible exception of progesterone-derived dydrogesterone. Different mechanisms for different progestins could possibly be involved. Differences from progesterone with regard to pharmacokinetics and pharmacodynamics, potency, interaction with the two isoforms of the progesterone receptor, and binding to other steroid receptors could all be relevant. These remain theoretical speculations for the time being, but the possibility that some progestins increase breast cancer risk through their negative influence on metabolic factors cannot be rejected.

Treatment of menopausal symptoms: what shall we do now?

During the past few years, many women and doctors have revised their opinions of hormone replacement therapy (HRT) for menopausal symptoms, and a substantial number of individuals have discontinued its use because of concerns about side-effects. Numerous alternatives to HRT are promoted, and assessment of the quality of evidence about the safety and effectiveness of these compounds can be difficult. In this Review, we summarise the data from studies addressing the efficacy, risks, and benefits of frequently prescribed treatments, and offer evidence-based clinical guidelines for the management of menopausal symptoms. Although few comparative studies exist, oestrogen alone or combinations of oestrogen and progestagen are likely to be the most effective treatments for menopausal hot flushes and vaginal dryness. Tibolone is as effective as HRT, however, and might also improve libido. For those who wish to avoid hormonal treatments, there are few effective options. Selective serotonin reuptake inhibitors might be effective in the very short term (less than 12 weeks) and are well tolerated. There is not enough evidence that any of the complementary therapies available are any better than placebo for menopausal vasomotor symptoms, and few safety data exist.

The Insulin-Like Growth Factor I Generation Test in Adults

The insulin-like growth factor I (IGF-I) generation test has the potential to assess the ability of an individual to respond to an acute bolus of growth hormone (GH), in terms of IGF-I, IGF-binding protein 3 and acid-labile subunit responses. This article will discuss something of the history of the IGF-I generation test, and review some of the major studies to date. The IGF-I generation test was first used in adults by Lieberman et al., who studied the effects of ageing and oestrogen administration, and suggested that decreased responsiveness to GH occurs with increasing age and oral oestrogen administration. Our results, however, show that, while activity of the GH/IGF-I axis declines with age, peripheral responsiveness to GH is not affected. As in the Lieberman study, we found that oral oestrogen replacement reduces responses of GH-dependent peptides to GH stimulation in healthy post-menopausal women. Transdermal oestrogen administration also reduced responsiveness to GH, although to a lesser degree than orally administered oestrogen. In addition, utilizing a non-weight-based dose of GH we have demonstrated that obese individuals produce greater increases in IGF-I following an acute bolus of GH. In GH deficiency (GHD), data suggesting enhanced peripheral responsiveness should be interpreted with caution, and with awareness of differences between these groups in terms of age and obesity. The IGF-I generation test may allow a fresh approach to unanswered questions in the field of GHD, but as the IGF-I response to GH is not strictly associated with protein anabolism or clinical benefit, the question remains whether this test will predict the effect of longer-term GH administration.

Differential effects of progestins on the circulating IGF-I system

OBJECTIVE

Circulating insulin-like growth factor-I (IGF-I) is mainly produced by the liver under GH stimulation and is influenced by nutrition and insulin. IGF-I bioavailability is regulated by interactions with specific binding proteins (IGFBPs). The objective of this paper is to review available data on modifications of the IGF-I system in menopausal women during HRT, with particular attention on the differential effects of progestins.

METHOD

All available reports on the effects of different forms of HRT have been taken into account.

RESULTS

Available data suggest that different kinds of HRT have different effect on the IGF-I system, depending on route of administration, oestrogen dose, basal IGF-I values and type of progestin. Oestrogen administration (oestrogen replacement therapy (ERT)) reduces circulating IGF-I mainly through a hepatocellular effect. The decrease is sharper when oral ERT is used (first pass hepatic effect) and in women with higher basal IGF-I levels. The progestins endowed with androgenic effects--the 19-nortestosterone derivatives and, to a lesser extent, medroxyprogesterone acetate (MPA)--tend to reverse the IGF-I decrease induced by oral oestrogens. In contrast, progestins devoid of androgen-like hepatocellular and metabolic actions (e.g. dydrogesterone) do not interfere with the IGF-I decrease induced by oral oestrogens. Data on the effect of ERT on IGFBP-3 level are not consistent. Oral ERT, via hepatocellular actions (amplified by the first pass hepatic effect) causes a two to three-fold increase in IGFBP-1 levels. Androgenic progestins oppose the IGFBP-1 increase induced by oral oestrogens. Data on the effect of ERT and different progestins on the level of free IGF-I are scant and inconsistent.

CONCLUSION

Even if some aspects need clarification, available data demonstrate that different progestins have differential effects on the circulating IGF-I system.

HRT opposed to low-dose tamoxifen (HOT study): rationale and design

The rationale for the HOT study is mainly based on the findings of the Italian Tamoxifen Prevention Study, where 5,408 healthy hysterectomized women aged 35-70 years were randomized to 20 mg/day of tamoxifen or placebo for 5 years. After 81.2 months median follow-up, 79 breast cancers occurred (34 on tamoxifen versus 45 on placebo, p=0.215). In the subgroup of 1,580 women who used estrogen replacement therapy (ERT) at some point during the study, 23 breast cancers were observed: 17 on placebo and 6 on tamoxifen (hazard ratio=0.35, 95% CI, 0.14-0.89). Pharmacokinetic and pharmacodynamic (surrogate endpoint biomarkers) studies showed that a lower dose of tamoxifen (such as 5 mg/day) does not affect the drug's activity on several biomarkers of both cardiovascular and breast cancer risk. We therefore propose a multicenter placebo-controlled phase III trial in postmenopausal healthy women on hormone replacement therapy (HRT) to assess whether the combination of HRT and low-dose tamoxifen retains the benefits while reducing the risks of either.

Body composition, visceral fat distribution and fat oxidation in postmenopausal women using oral or transdermal oestrogen

OBJECTIVES

The aim of this study was to observe hysterectomized postmenopausal women (without progestogen, which could interfere in the results), using oral-conjugated oestrogen 0.625 mg daily (n=13) or 17beta-estradiol transdermal patches delivering 50 microg daily (n=10) during 12 months, and to evaluate the treatment effects on body composition, visceral fat distribution, energy expenditure and substrate oxidation.

METHODS

We studied 23 postmenopausal women using oral-conjugated oestrogen (Premarin) 0.625 mg daily (n=13) or transdermal oestrogen patches (Systen TTS) 50 microg daily (n=10). Body composition was measured by DEXA, visceral adipose tissue areas were measured by abdominal computed tomography, and energy expenditure, fat oxidation and carbohydrate oxidation were measured by indirect calorimetry (Deltatrac Metabolic Monitor).

RESULTS

There were: (1) a decrease in IGF-I and an increase in GH levels in the oral group and no change in the transdermal group; (2) a increase in lean body mass in the transdermal group and a decrease in the oral group; (3) a increase in total body fat mass in the oral group and no change in the transdermal group; (4) an increases in total bone mass and in total bone mineral density in the transdermal group and no change in the oral group; (5) an increase in lipid oxidation in the transdermal group and a decrease in the oral group, and (6) no significantly change about weight, visceral adipose tissue areas and energy expenditure in both groups.

CONCLUSIONS

The administration route of oestrogen replacement therapy in postmenopausal women confers distinct and divergent effects on body composition and substrate oxidation during 12-months treatment.

Menopause: new therapies

The risk-benefit ratio of traditional postmenopausal hormone therapy is considered by many to be unacceptable. Low-dose oestrogen-progestin therapy (oral or non-oral and continuous or pulsatile) may have a better risk-benefit ratio, but this remains unproven. Steroids with selective tissue activation, such as tibolone, alleviate symptoms and protect against bone loss, but long-term safety data are lacking. Selective oestrogen receptor modulators (SERMs), such as raloxifene, prevent bone loss when used alone, and may soon be combined with oestradiol to treat symptoms and prevent osteoporotic fracture. Effects of SERMs on the cardiovascular system are currently being evaluated.

Hormone replacement therapy: current controversies

Postmenopausal hormonal therapy is used to manage the climacteric symptoms that impair the quality of life of a substantial number of women. The difficulty is achieving the desired effects with minimal side-effects and no adverse health risks. Fundamental to this is understanding the physiology of oestrogen in women and the metabolism of the therapeutic compounds. Although the effects of oral oestrogen therapy have been studied extensively, there is insufficient evidence to assess adequately the independent effects of progestin use, other oestrogen compounds, differing doses and duration of treatment. We have reviewed some basic concepts of oestrogen physiology and how these relate to exogenous oestrogen administration, the risks of greatest concern, and the role of androgens and newer treatment alternatives.

Pharmacotherapy and medical complications of eating disorders in children and adolescents

In this article, the authors cover two areas of interest regarding eating disorders in childhood and adolescence: (1) the detection of eating disorders in medical practice and their medical complications and (2) the psychopharmacologic treatment of patients with eating disorders.

The Italian breast cancer prevention trial with tamoxifen: findings and new perspectives

The Italian Tamoxifen Prevention Study includes 5408 healthy hysterectomized women aged 35-70 years who have been randomized to 20 mg/day of tamoxifen or placebo for 5 years. After 46 months median follow-up, an increased risk of venous vascular events (38 women on tamoxifen vs. 18 women on placebo, P = 0.0053), mainly consisting of superficial phlebitis, has been observed and 41 breast cancers have occurred (19 on tamoxifen vs. 22 on placebo, P = 0.64). However, subgroup analyses indicated a borderline significant reduction of breast cancer among women continuously on estrogen replacement therapy (ERT, mostly transdermal) and receiving tamoxifen, with 8 cases of breast cancer among 390 ERT users on placebo versus 1 case among 362 ERT users on tamoxifen (RR = 0.13, 95% CI = 0.02-1.02). Withdrawal rate (mainly due to menopausal symptoms) differed according to ERT use, with compliance being 78% and 75% at 3 and 5 years, respectively, for women who never took ERT, and 92% and 88% at 3 and 5 years, respectively, for women not on ERT at baseline, but who took ERT at some time during the trial. Pharmacokinetic and pharmacodynamic (surrogate end point biomarkers) studies showed that a lower dose of tamoxifen (such as 5 mg/day) does not affect the drug's activity on several biomarkers of both cardiovascular and breast cancer risk. We are therefore planning a multicenter placebo-controlled phase III trial in postmenopausal healthy women on hormone replacement therapy (HRT) to test whether the combination of HRT and low-dose tamoxifen retains the benefits while reducing the risks of either agent maintaining a high compliance rate.

Interactions of estrogens and insulin-like growth factor-I in the brain: implications for neuroprotection

Data from epidemiological studies suggest that the decline in estrogen following menopause could increase the risk of neurodegenerative diseases. Furthermore, experimental studies on different animal models have shown that estrogen is neuroprotective. The mechanisms involved in the neuroprotective effects of estrogen are still unclear. Anti-oxidant effects, activation of different membrane-associated intracellular signaling pathways, and activation of classical nuclear estrogen receptors (ERs) could contribute to neuroprotection. Interactions with neurotrophins and other growth factors may also be important for the neuroprotective effects of estradiol. In this review we focus on the interaction between insulin-like growth factor-I (IGF-I) and estrogen signaling in the brain and on the implications of this interaction for neuroprotection. During the development of the nervous system, IGF-I promotes the differentiation and survival of specific neuronal populations. In the adult brain, IGF-I is a neuromodulator, regulates synaptic plasticity, is involved in the response of neural tissue to injury and protects neurons against different neurodegenerative stimuli. As an endocrine signal, IGF-I represents a link between the growth and reproductive axes and the interaction between estradiol and IGF-I is of particular physiological relevance for the regulation of growth, sexual maturation and adult neuroendocrine function. There are several potential points of convergence between estradiol and IGF-I receptor (IGF-IR) signaling in the brain. Estrogen activates the mitogen-activated protein kinase (MAPK) pathway and has a synergistic effect with IGF-I on the activation of Akt, a kinase downstream of phosphoinositol-3 kinase. In addition, IGF-IR is necessary for the estradiol induced expression of the anti-apoptotic molecule Bcl-2 in hypothalamic neurons. The interaction of ERs and IGF-IR in the brain may depend on interactions between neural cells expressing ERs with neural cells expressing IGF-IR, or on direct interactions of the signaling pathways of alpha and beta ERs and IGF-IR in the same cell, since most neurons expressing IGF-IR also express at least one of the ER subtypes. In addition, studies on adult ovariectomized rats given intracerebroventricular (i.c.v.) infusions with antagonists for ERs or IGF-IR or with IGF-I have shown that there is a cross-regulation of the expression of ERs and IGF-IR in the brain. The interaction of estradiol and IGF-I and their receptors may be involved in different neural events. In the developing brain, ERs and IGF-IR are interdependent in the promotion of neuronal differentiation. In the adult, ERs and IGF-IR interact in the induction of synaptic plasticity. Furthermore, both in vitro and in vivo studies have shown that there is an interaction between ERs and IGF-IR in the promotion of neuronal survival and in the response of neural tissue to injury, suggesting that a parallel activation or co-activation of ERs and IGF-IR mediates neuroprotection.

Effects of HRT on serum levels of IGF-I in postmenopausal women

OBJECTIVES

It is thought that insulin-like growth factor-1 (IGF-I) stimulates bone formation. We aimed to determine the effects of oral and transdermal hormone replacement therapy (HRT) on serum IGF-I levels and to investigate the effects of basal IGF-I levels on the levels obtained at the end of the therapy.

METHODS

Sixty-six postmenopausal women were administered either oral (n=44) or transdermal (n=22) HRT for 6 months. Serum levels of IGF-I were determined before and after HRT in all subjects. Groups were divided into two subgroups according to the median value of serum IGF-I levels (basal IGF-I levels above or below the median value). The increase of IGF-I levels after HRT were calculated (%) for all women. Mean increases of subgroups were compared. Furthermore, study groups were divided into three subgroups according to the changing of IGF-I (increase>25%, between 25% increase and 25% decrease and decrease>25%). Mean basal IGF-I levels of these three subgroups were compared.

RESULTS

Mean serum levels of IGF-I before and after HRT were not significantly different in both oral and transdermal groups (P>0.05). Mean increases of IGF-I after HRT for the patients with low basal IGF-I levels, were 65% in oral and 77% in transdermal groups. However, mean increase of the patients with high basal IGF-I levels were -8 and -16% respectively. Moreover, mean level of basal IGF-I was significantly low in women who have more than a 25% increase after HRT (P<0.05).

CONCLUSION

HRT seems to significantly increase serum levels of IGF-I in postmenopausal women with low basal levels of IGF-I.

Effects of the selective estrogen receptor modulator, raloxifene, on the somatotropic axis and insulin-glucose homeostasis

Raloxifene is the first selective estrogen receptor modulator registered for the prevention and treatment of postmenopausal osteoporosis. In addition to direct effects on bone cells, estrogen and raloxifene may act indirectly via changes in hormonal homeostasis. However, the menopause-related decrease in serum insulin-like growth factor I (IGF-I) and the increase in insulin or glucose are not always reversed by estrogen replacement. Especially orally administered estrogen was reported to decrease serum IGF-I levels. Understanding the effects of estrogens and raloxifene on the GH-IGF axis and insulin-glucose homeostasis are important because of their link to bone metabolism and cardiovascular health. We investigated the effects of raloxifene on the GH-IGF-I axis and insulin-glucose homeostasis in a cross-sectional study in the third year of the Multiple Outcomes of Raloxifene Evaluation trial, a double blind, placebo-controlled, prospective study in postmenopausal women with osteoporosis (T-score of -2.5 or less or at least two moderate vertebral fractures). Patients with diabetes mellitus were excluded from this additional study. A fasting blood sample was obtained (0 h), and women received an sc injection of 0.05 mg recombinant human GH (Humatrope)/kg BW. The second blood sample was obtained 24 h later (24 h). GH, IGF-I, IGF-binding protein-3 (IGFBP-3), insulin, and glucose were measured. Group characteristics were tested by nonparametric ANOVA. The dose-response to raloxifene was tested by linear regression models, with age and body mass as covariates. Seven women were taking placebo, 16 were taking raloxifene (60 mg/day), and 9 were taking raloxifene (120 mg/day). Patients from the 60 mg raloxifene group were the oldest (mean +/- SD, 64.4 +/- 4.2 vs. 69.3 +/- 6.9 and 63.3 +/- 5.9 yr for placebo, 60 mg/day raloxifene, and 120 mg/day raloxifene, respectively; P = 0.05). Compared with placebo users, patients taking raloxifene had higher body mass index (24.7 +/- 1.7 vs. 25.0 +/- 3.1 and 28.8 +/- 5.8 kg/m(2); P = 0.03). At 0 h, raloxifene use was associated with lower IGF-I/IGFBP-3 ratio (4.3 +/- 0.7 vs. 2.9 +/- 0.7 and 3.0 +/- 0.7 nmol/mg; P = 0.001) and insulin/glucose ratio (13.7 +/- 5.2 vs. 11.9 +/- 5.9 and 9.5 +/- 2.3 pmol/mmol; P = 0.04). Similarly, raloxifene use was associated with lower IGF-I/IGFBP-3 and insulin/glucose ratios at 24 h (P = 0.01 and 0.07). Glucose, GH, and IGFBP-3 levels were similar among the groups (0.12 < P < 0.67). In conclusion, raloxifene use is associated with decreased serum IGF levels and insulin/glucose ratio before and 24 h after one rhGH injection in nondiabetic postmenopausal women with osteoporosis. Therefore, raloxifene may decrease liver sensitivity to GH. Other explanations are increased clearance or increased tissue sensitivity to IGF-I or insulin. The raloxifene-induced increases in bone mineral density do not appear to be mediated by reversing the age- and menopause-related decreases in IGF-I levels. The results of this small cross-sectional study need confirmation by longitudinal studies.

The insulin-like growth factor-I system and hormone replacement therapy

OBJECTIVE

To determine the effects of hormone replacement therapy on plasma concentrations of free and total insulin-like growth factor (IGF)-I, IGF binding protein (BP)-1, and IGFBP-3.

DESIGN

Clinical study.

SETTING

Gynecologic clinic at a university hospital.

PATIENT(S)

Seventy-one postmenopausal women.

INTERVENTION(S)

Six cycles of four different hormonal replacement therapy regimens: oral conjugated estrogens, transdermal estradiol, oral conjugated estrogens and norethisterone, and transdermal estradiol and norethisterone acetate.

MAIN OUTCOME MEASURE(S)

Blood samples were collected before and after treatment for measurement of free and total IGF-I, IGFBP-1, and IGFBP-3.

RESULT(S)

Conjugated estrogen replacement therapy is associated with a decrease in plasma concentration of total IGF-I and increase in concentrations of free IGF-I and IGFBP-1. Transdermal estrogens have no effect on total and free IGF-I and IGFBP-1 concentrations. Oral norethisterone plus conjugated estrogens increased free IGF-I and IGFBP-1 concentrations but did not change IGF-I concentrations. Transdermal conjugated estrogens plus norethisterone acetate increased free IGF-I concentrations but not total IGF-I or IGFBP-1 concentrations. The plasma concentration of IGFBP-3 did not change in any group.

CONCLUSION(S)

Alterations in total IGF-I concentration can occur depending on the route of hormone replacement therapy administration. Free IGF-I concentrations were elevated in all study groups except that treated with transdermal estrogens.

Composição corpórea, distribuição de gordura e metabolismo de repouso em mulheres histerectomizadas no climatério: há diferenças de acordo com a forma da administração do estrogênio?

As mulheres no climatério sofrem inúmeras alterações metabólicas, cardiovasculares e de composição corporal. A terapêutica de reposição hormonal (TRH) vem alcançando importância na atualidade, tornando-se quase um consenso que a mulher após a menopausa deve receber hormônios, pelos benefícios que trazem para a saúde, tais como prevenção de doenças coronarianas e osteoporose. A forma de administração de estrogênios influi em uma série de parâmetros metabólicos; é sabido, por exemplo, que a administração oral provoca uma elevação no hormônio de crescimento (GH) e uma diminuição do IGFI: quanto à forma (transdérmica), os estudos ainda não são conclusivos quanto aos níveis do GH e IGFI. Por outro lado, o GH e o IGFI podem agir de maneiras diferentes no metabolismo lipídico, ósseo e na distribuição de gordura corpórea. O objetivo deste trabalho foi estudar as variações da distribuição visceral de gordura nas diferentes formas de administração estrogênica e, particularmente, verificar se a forma de administração do hormônio altera a quantidade de gordura visceral. Foram estudadas 33 mulheres no climatério, histerectomizadas, divididas em 3 grupos: 1) 13 pacientes recebendo estrogênio eqüino conjugado 0,625mg via oral diariamente; 2) 10 pacientes recebendo 17b estradiol TTS 50 2x/semana via transdérmica e; 3) 10 pacientes recebendo placebo. Estas pacientes foram submetidas: a) análise da composição corporal pelos métodos de bioimpedância (RJL 101-A) e densitometria óssea e corpórea (DEXA); b) análise da distribuição de gordura, particularmente de adiposidade visceral, pela tomografia computadorizada abdominal e; c) medida do metabolismo de repouso pelo calorímetro DELTA-TRAC. Foram ainda feitas dosagens laboratoriais de colesterol total e frações, triglicérides e glicemia aos 0,6 e 12 meses. Não observamos diferenças estatística significativas nos parâmetros estudados em nenhum dos 3 grupos (placebo, estrógeno oral e estrogênio transdérmico), embora notamos tendência a maior ganho de peso nos grupos com estrógenos e tendência a maior ganho de massa magra no grupo com estrogênio transdérmico.

Effect of short-term medroxyprogesterone acetate on left ventricular mass: role of insulin-like growth factor-1

Previous studies using 17beta-estradiol and medroxyprogesterone acetate (MPA) have shown that hormone replacement therapy (HRT) increases left ventricular mass (LVM). To determine if insulin-like growth factor-1 (IGF-1) is associated with the increase in LVM, we measured IGF-1 and IGF-binding protein-3 (IGFBP-3) levels in 19 postmenopausal women before and after 8 weeks of oral treatment with MPA 5 mg/d. LVM was measured by two-dimensional echocardiography. Changes in IGF-1, IGFBP-3, and LVM from baseline were analyzed by paired ttest. Regression analysis was used to determine if changes in the IGF-1 axis with MPA treatment affect the increase in LVM. LVM increased 4.4% during the study (P = .006 vbaseline). IGF-1 increased 17% with MPA (P = .008), whereas IGFBP-3 did not change. The IGF-1/IGFBP-3 ratio increased 16.8% (P = .0003). Regression analysis of LVM with IGF-1, IGFBP-3, and the IGF-1/IGFBP-3 ratio suggested that IGF-1 during MPA therapy explains 2.4% and the IGF-1/IGFBP-3 ratio explains 3.2% of the variation in LVM. There was no effect of IGFBP-3 on LVM. Most of the variation in LVM with MPA (90.5%) was explained by baseline LVM. The IGF-1/IGFBP-3 ratio on MPA treatment was inversely related to the change in LVM: women with a lower LVM at baseline had the greatest increase in LVM with MPA. These findings suggest that MPA increases IGF-1 and LVM. Because the increase in IGF-1 with MPA treatment explains a fraction of the increase in LVM, other mechanisms must also be operative.

Postmenopausal osteoporosis is more related to hormonal aberrations than to lifestyle factors

OBJECTIVE

Serum insulin-like growth factor-1 (IGF-1) decreases with increasing age and this process is more pronounced in women after the menopause in parallel with the increasing prevalence of osteoporosis. This study was designed to compare IGF-1 concentrations, vitamin D, intact parathyroid hormone (PTH) and lifestyle factors in postmenopausal, osteoporotic women with and without oestrogen replacement therapy (HRT), with an age-matched random population sample of women.

DESIGN

Case control study.

PATIENTS

Postmenopausal, osteoporotic women, n = 128, mean age 59 +/- 6 years, were compared with a female random population sample matched for age, n = 227, mean age 59 +/- 5 years, from the WHO MONICA Project, Göteborg, Sweden. Osteoporotic fractures had occurred in 56% of the patients compared with 4% of the controls (P < 0.001).

MEASUREMENTS

Anthropometry, occupation, smoking habits, physical activity, blood pressure, IGF-1, vitamin D, intact PTH, blood lipids.

RESULTS

There were no differences in occupational class, current or previous smoking habits, degree of physical activity during occupational or leisure time between the patients and controls. Osteoporotic women had lower body weight and body mass index than the controls (P < 0.001). Height, waist/hip ratio and osteocalcin were similar. 25(OH) vitamin D and 1,25(OH)2 vitamin D were lower (P < 0.05 and P < 0.01, respectively), PTH was higher (P < 0.001) and IGF-1 lower (P < 0.01) in osteoporotic women compared with the controls. IGF-1 was lower (P < 0.05), in spite of similar bone mineral density, in osteoporotic women without HRT than in those with HRT, who had IGF-1 concentrations similar to those of the population sample, of whom fewer than 10% had HRT. Among patients, IGF-1 did not correlate with serum oestradiol or bone mineral density. PTH correlated negatively to bone mineral density at the femoral site (r = - 0.29; P = 0.003).

CONCLUSION

Osteoporosis in postmenopausal women is more related to hormonal aberrations than to lifestyle factors.

Cognitive and neuroendocrine response to transdermal estrogen in postmenopausal women with Alzheimer's disease: results of a placebo-controlled, double-blind, pilot study

Preliminary evidence from clinical studies indicates that treatment with estrogen augments cognitive function for women with Alzheimer's disease (AD). The neurobiology of estrogen, particularly its neuromodulatory and neuroprotective actions, provide a viable basis to support such cognition-enhancing effects. We conducted a placebo-controlled, double-blind, parallel-group design pilot clinical study to evaluate the cognitive and neuroendocrine response to estrogen administration for postmenopausal women with AD. Twelve women with probably AD of mild-moderate severity completed the study. During an eight week treatment period, six women received 0.05 mg/day dosage of 17 beta-estradiol via a skin patch and the remaining six wore a placebo skin patch. Subjects were randomized to equal distribution, and evaluated at baseline, at weeks 1, 3, 5, and 8 on treatment, and at weeks 9, 10, 11, and 13 off treatment. On each day of evaluation, cognition was assessed using a battery of neuropsychological tests, and blood samples were collected to measure plasma concentrations of estradiol and estrone. In addition, several neuroendocrine markers were measured in plasma to evaluate the relationship between estrogen-induced cognitive effects and fluctuations in the catecholaminergic and insulin-like growth factor systems. Significant effects of estrogen treatment were observed on attention (i.e. Stroop: number of self-corrections in the Interference condition, F[1,8] = 8.22, P < 0.03) and verbal memory (i.e., Buschke: delayed cued recall, F[3,30] = 4.31, P < 0.02). The salutary effects of estrogen on cognition were observed after the first week of treatment, and started to diminish when treatment was terminated. For women treated with estrogen, enhancement in verbal memory was positively correlated with plasma levels of estradiol (r = 0.96, P < 0.02) and negatively correlated with concentrations of insulin-like growth factor binding protein-3 (IGFBP-3) in plasma (r = -0.92, P < 0.03). Furthermore, a trend in the data was evident to suggest a negative relationship between plasma levels of insulin-like growth factor-1 (IGF-1) and verbal memory (r = -0.86, P = 0.06). Estrogen administration suppressed peripheral markers of the IGF system, as evidenced by a negative correlation between plasma concentration of estradiol and IGF-1 (r = -0.93, P < 0.03), and a trend for a similar relationship between plasma levels of estradiol and IGFBP-3 (r = -0.86, P = 0.06). With respect to the catecholamines assayed, norepinephrine was positively correlated with verbal memory (r = 0.95, P < 0.02) for women who were treated with estrogen. Furthermore, there was a trend to suggest a negative relationship between plasma epinephrine levels and the number of errors committed on a test of attention (r = -0.84, P = 0.07). In the placebo group, no significant effects of estrogen replacement were evident either on measures of cognition or on any of the neuroendocrine markers. The results of this study suggest that estrogen replacement may enhance cognition for postmenopausal women with AD. Furthermore, several markers of neuroendocrine activity may serve to index the magnitude of estrogen-induced facilitation on cognition. In addition, research findings from the present study will provide important information for the design of larger prospective clinical studies that are essential to definitively establish the therapeutic role of estrogen replacement for postmenopausal women with AD.

Effect of tamoxifen and transdermal hormone replacement therapy on cardiovascular risk factors in a prevention trial. Italian Chemoprevention Group

The combination of tamoxifen and transdermal hormone replacement therapy (HRT) may potentially reduce risks and side-effects of either agent, but an adverse interaction could attenuate their beneficial effects. We assessed the effects of their combination on cardiovascular risk factors within a prevention trial of tamoxifen. Baseline and 12-month measurements of total, low-density lipoprotein (LDL)- and high-density lipoprotein (HDL)-cholesterol, platelets and white blood cells were obtained in the following four groups: tamoxifen (n = 1117), placebo (n = 1112), tamoxifen and HRT (n = 68), placebo and HRT (n = 87). The analysis was further extended to women who were on HRT at randomization but discontinued it during the 12-month intervention period (n = 33 on tamoxifen and n = 35 on placebo) and to women who were not on HRT but started it during intervention (n = 36 in both arms of the study). Compared with small changes in the placebo group, tamoxifen was associated with changes in total, LDL- and HDL-cholesterol of approximately -9%, -19% and +0.2% in continuous HRT users compared with -9%, -14% and -0.8% in never HRT users. Similarly, there was no interaction on platelet count. In contrast, the decrease in total and LDL-cholesterol levels induced by tamoxifen was blunted by two-thirds in women who started HRT while on tamoxifen (P = 0.051 for the interaction term). We conclude that the beneficial effects of tamoxifen on cardiovascular risk factors are unchanged in current HRT users, whereas they may be attenuated in women who start transdermal HRT while on tamoxifen. Whereas a trial of tamoxifen in women already on transdermal HRT is warranted, prescription of HRT during tamoxifen may attenuate its activity.

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.

Twenty two weeks of transdermal estradiol increases sex hormone-binding globulin in surgical menopausal women

OBJECTIVE

To compare the effects of continuous noncombined transdermal estradiol versus oral conjugated estrogen on serum sex hormone-binding globulin (SHBG) levels prior to and during the 10th and 22nd weeks of therapy in patients with surgical menopause.

STUDY DESIGN

Open, comparative trial. Patients were consecutively assigned to three groups: group 1 (n = 18) received continuous transdermal estradiol (0.050 mg/day), group 2 (n = 18) continuous oral conjugated estrogens (0.625 mg/day), whereas group 3 (n = 15) received no treatment. Serum SHBG levels were determined before treatment and after 10 and 22 weeks of treatment.

RESULTS

Serum SHBG increased significantly with oral conjugated estrogens at 10 (p < 0.01) and 22 weeks (p < 0.01) compared with baseline. With transdermal estrogens there was a much smaller increase of SHBG. At 22 weeks, this increase was significant compared with baseline (p < 0.05), but not compared with the control group (p > 0.05).

CONCLUSION

Transdermal estrogen has no effect on SHBG, whereas oral conjugated estrogens causes considerable increase.

Effects of hormonal replacement therapy on plasma sex hormone-binding globulin, androgen and insulin-like growth factor-1 levels in postmenopausal women

Plasma sex hormone-binding globulin (SHBG) levels are important in the regulation of plasma free and albumin-bound androgens and estrogens. In postmenopausal women associated to the decrease of estrogen production, a decrease of plasma SHBG levels occurs. Hormone replacement therapy (HRT) in postmenopausal women modulates plasma SHBG levels, in relationship with the different regimens and routes of administration. The present study aimed to compare the effect of different HRT on plasma SHBG levels in relationship with the changes of plasma androgen [dehydroepiandrosterone sulphate (DHEAS), testosterone (T), androstenedione (A)] and insulin-like growth factor-1 (IGF-1) levels. In a retrospective study 443 postmenopausal women were studied and divided into 2 groups. The group 1 (n = 170) was subdivided in 4 groups of women as follows: A) treated with transdermal 17-beta estradiol + medroxyprogesterone acetate, B) treated with oral conjugated estrogens, C) treated with sequential HRT (estradiol valerate (EV) + norgestrel), and D) treated with a combined HRT (micronized estradiol (E2) + noretisterone acetate). Women of group 2 (n = 273) did not receive HRT and served as controls. All groups of women treated with different HRT showed plasma estradiol levels significantly higher than controls (p < 0.01), showing the highest values in women treated with oral HRT. Plasma SHBG levels were not significantly different between patients treated with transdermal 17-beta estradiol + medroxyprogesterone acetate and controls. On the other hand, all the groups of patients treated with oral conjugated estrogen with or without progestagens showed plasma SHBG levels significantly higher than controls (p < 0.01). Plasma SHBG levels were higher in the group treated with estrogen alone than in groups of women treated with sequential or combined HRT. Plasma DHEAS, T and A levels in patients treated with different HRT regimens were in the same range of levels as control women. Plasma IGF-1 levels were not significantly affected by the various HRT regimens and remained in the same range as controls. In conclusion, plasma SHBG levels increase following oral HRT while are not affected by transdermal HRT. Plasma IGF-1 and androgen levels are not influenced from oral or transdermal HRT.

Mechanisms of action of endocrine treatment in breast cancer

Endocrine treatment plays an important role in the therapy of breast cancer. While the basic mechanisms are understood, additional mechanisms may be of importance to their action and they may also contribute to the mechanism(s) of acquired resistance. Currently, several novel drugs are entering into clinical trials. Observations of the absence or presence of cross resistance to novel 'pure' steroidal antiestrogens and the non-steroidal tamoxifen may add important information to our understanding of the mechanisms of action of both classes of drugs. Similarly, exploration of different aromatase inhibitors in sequence or concert, as well as the combining of different endocrine treatment options may be warranted. Additionally, alterations in different biochemical parameters such as growth factors should not only be carefully explored in relation to treatment options but should also be followed during the course of treatment to asess alterations over time and in relation to the development of drug resistance.

Potential impact on breast cancer risk of circulating insulin-like growth factor I modifications induced by oral HRT in menopause

Unlike parenteral estrogens, oral estrogen administration in menopause causes, through its hepatocellular action, a significant decrease of circulating insulin-like growth factor I (IGF-I) levels; this effect is opposed by the addition of an androgenic progestogen. In vitro studies show that IGF-I is a potent mitogen for 'estrogen responsive' breast cancer cells. Moreover, some findings in breast cancer patients and in women treated with tamoxifen suggest that reduction of circulating IGF-I could be protective to the breast. However, by also considering (1) the potential action on breast cancer cells of IGF-II, (2) the possible consequences of the growth hormone (GH) increase caused by the IGF-I reduction and (3) the fact that in vitro results are not simply transferable to the in vivo condition, other 'scenarios' can be envisaged, besides the favorable one. In support of the latter, there are epidemiologic data which suggest that oral estrogen use could have some favorable peculiarities with regards to breast cancer risk. The associated decrease in circulating IGF-I level could well be one of these peculiarities.

Relations between sex hormones, sex hormone binding globulin, insulin-like growth factor-I and insulin-like growth factor binding protein-1 in post-menopausal breast cancer patients

OBJECTIVE

Oestrogens, androgens and anti-endocrine drugs such as tamoxifen and aminoglutethimide influence plasma insulin-like growth factor-I (IGF-I). IGF-I, in turn, has been found to stimulate the peripheral aromatase in vitro. The aim of this study was to examine relations between sex hormones, IGF-I and insulin-like growth factor binding protein-1 (IGFBP-1) in post-menopausal women with breast cancer.

DESIGN

To measure plasma sex steroids, sex hormone binding globulin (SHBG), IGF-I, IGFBP-1, insulin and urinary oestrogen metabolites in post-menopausal women with breast cancer not receiving any endocrine therapy.

PATIENTS

Thirty-two patients had fasting blood samples obtained between 0800 and 1000 h. A sub-group of 10 patients had 24-hour urine oestrogen metabolites determined.

MEASUREMENTS

Plasma steroids and proteins were measured by radioimmunoassays. Urinary oestrogens were measured by GC-MS.

RESULTS

SHBG correlated negatively with plasma androstenedione (P < 0.001), insulin (P < 0.001), IGF-I, height and plasma oestrone sulphate (P < 0.025 for all), but positively with plasma IGFBP-1 (P < 0.025). IGFBP-1 correlated negatively with IGF-I (P < 0.001) and the testosterone/SHBG ratio (P < 0.05). Neither IGF-I nor IGFBP-1 correlated with any of the plasma or urinary sex hormones or with the oestrone/androstenedione and oestradiol/testosterone ratios. Multivariate analysis revealed plasma SHBG to correlate positively with IGFBP-1 (P = 0.029) and negatively with insulin (P = 0.031). Plasma IGFBP-1 correlated negatively with IGF-I (P < 0.0001) but not with insulin.

CONCLUSION

Our results do not suggest any influence of plasma sex steroids in physiological concentrations on IGF-I or IGFBP-1 in post-menopausal breast cancer patients, nor do they indicate IGF-I at physiological concentrations influences the ratios between plasma oestrogens and their androgen precursors.

Androgenic progestogens oppose the decrease of insulin-like growth factor I serum level induced by conjugated oestrogens in postmenopausal women. Preliminary report

Oral oestrogen treatment in postmenopausal women causes a decrease of insulin-like growth factor I (IGF-I) serum level, probably through a hepatocellular effect. To explore the possibility that the androgenic progestogens oppose this effect, serum IGF-I and sex hormone binding globulin (SHBG) were evaluated in two groups of patients treated respectively with oral conjugated oestrogens (oCE) or transdermal oestradiol (tdE2), in a first phase with the addition of dydrogesterone (DYDR), a non-androgenic progestogen, and subsequently with the addition of norethisterone acetate (NETA). With respect to basal values, treatment with oCE+DYDR caused an increase of SHBG (P < 0.002) and a decrease of IGF-I serum levels (P < 0.05); the shift to NETA addition opposed both effects: SHBG levels decreased partially but significantly (P < 0.01 vs. oCE + DYDR) and IGF-I returned to basal values with a significant increase with respect to the oCE + DYDR phase (P < 0.02). No changes were observed in the tdE2 + DYDR treated women; in this group the shift to NETA addition caused a significant decrease of SHBG values (P < 0.001 vs. before treatment and vs. tdE2 + DYDR phase) and a slight increase of IGF-I values. These differential effects on IGF-I and SHBG serum levels might be relevant as far as breast cancer risk is concerned.