Both oral and transdermal estrogen increase growth hormone release in postmenopausal women--a clinical research center study

Body Composition Analysis of 10 Years versus 5 Years of Adjuvant Endocrine Therapy in Patients with Nonmetastatic Breast Cancer

Objective

Our study aims to investigate the association of extended adjuvant endocrine therapy with disease-free survival (DFS), muscle mass, muscle strength, and visceral adipose tissue in patients with nonmetastatic breast cancer and the effect of extended endocrine therapy on body composition. Patients and Methods. Patients (N = 90) with nonmetastatic breast cancer aged between 60 and 65 years old were prospectively recruited in this study, compromising a cohort of subjects rece iving 5 years or 10 years of adjuvant endocrine therapy. Patients' DFS was compared between these two groups. Patients' body composition including muscle and fat using CT scans, muscle strength, and gait speed was evaluated in these two groups.

Results

Dietary behavior was recorded with the food frequency questionnaire (FFQ). Patients' age, body weight, and body mass index (BMI) did not differ between the two groups. An extended adjuvant endocrine therapy into 10 years could translate into DFS benefit (123.8 vs. 102.2 months, P=0.038). Patients receiving 10 years of adjuvant endocrine therapy had less skeletal muscle and more visceral fat compared with patients receiving 5 years of adjuvant endocrine therapy. The skeletal muscle index was 50.3 ± 1.6 cm²/m² versus 46.5 ± 1.3 cm²/m² in the 10 years or 5 years of adjuvant endocrine therapy group (P=0.042). The visceral fat was 28.9 ± 2.9 cm²/m² versus 55.0 ± 3.2 cm²/m² in the 10 years or 5 years of adjuvant endocrine therapy group (P=0.011). The muscle strength, gait speed, and FFQ results in the two groups not reaching statistical difference.

Conclusion

In conclusion, breast cancer patients with 10 years of adjuvant endocrine therapy had DFS benefit, but with more muscle loss and adipose tissue deposits compared to patients receiving 5 years of adjuvant endocrine therapy.

Association Between Hormone Therapy and Muscle Mass in Postmenopausal Women: A Systematic Review and Meta-analysis

IMPORTANCE

Hormone therapy (HT) has been suggested for protection against age-related muscle weakness in women. However, the potential for HT-associated health risks necessitates a better understanding of the direction and magnitude of the association between HT and health outcomes, such as lean body mass (LBM).

OBJECTIVE

To determine whether HT was associated with reduced LBM loss compared with not receiving HT among postmenopausal women aged 50 years and older.

DATA SOURCES

MEDLINE, Embase, AgeLine, CINAHL, and SportDiscus (searched from inception until April 25, 2018).

STUDY SELECTION

For this systematic review and meta-analysis, randomized clinical trials including postmenopausal women undergoing HT and control groups of women not receiving HT were selected by 2 reviewers. Studies were included if LBM or fat-free mass were measured as an outcome. Studies with participants from hospitals, long-term care facilities, or with specific diseases were excluded.

DATA EXTRACTION AND SYNTHESIS

Information regarding study characteristics and outcome measures were extracted by 1 reviewer and verified by another. Risk of bias was evaluated. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used to abstract data and assess data quality/validity. Data were pooled using a fixed-effects model.

MAIN OUTCOMES AND MEASURES

The primary study outcome was the overall absolute change in LBM (measured in kilograms), captured by dual-energy x-ray absorptiometry, dual-photon absorptiometry, or bioelectrical impedance analysis imaging.

RESULTS

Of 8961 studies that met selection criteria, 12 were included, with a total of 4474 recruited participants. Of the participants, mean (SD) age was 59.0 (6.1) years. Data on ethnicity were collected by 2 of the studies. Of the 22 HT intervention arms, 15 used estrogen-progesterone combination HT and 7 used estrogen-only HT. Control participants were women who received no HT at all or who received placebo. The median follow-up duration was 2 years (range, 6 months to 6 years). Seven treatment arms showed a loss of LBM, and 14 were protective. Overall, HT users lost 0.06 kg (95% CI, -0.05 to 0.18) less LBM compared with control participants, but the difference was not statistically significant (P = .26). The results were unchanged when stratified based on treatment type and dosage, duration of follow-up, time since menopause, study quality, and type of LBM measurement, with HT users losing between 0.06 kg more to 0.20 kg less LBM compared with control participants for all strata. The quality of evidence based on GRADE was low.

CONCLUSIONS AND RELEVANCE

This systematic review and meta-analysis did not show a significant beneficial or detrimental association of HT with muscle mass. Although muscle retention in aging women is of crucial importance, these findings suggest that interventions other than HT should be explored.

Modulating Effects of Progesterone on Spontaneous Nocturnal and Ghrelin-Induced GH Secretion in Postmenopausal Women

BACKGROUND

Oral administration of estradiol (E2) generally increases GH secretion in postmenopausal women. Oral administration of E2 is associated with a decrease in IGF-1, whereas parenteral or transdermally administered E2 may have no effect on GH. The effect of progesterone (P4) on GH secretion has rarely been studied. We hypothesized that moderately increased serum E2 levels stimulate GH and that P4 modulates E2-stimulated GH secretion.

STUDY DESIGN

Four parallel groups of randomly assigned postmenopausal women (n = 40). Treatments were saline placebo and oral placebo, saline placebo and oral micronized P4 (3 × 200 mg/d IM), E2 (5 mg IM) and oral placebo, and E2 IM and oral micronized P4. Outcome measures were overnight GH secretion (10 hours), stimulated (ghrelin, 0.3 µg/kg IV bolus) GH secretion, and CT-estimated visceral fat.

RESULTS

Intramuscular E2 administration did not alter nocturnal and ghrelin-stimulated GH secretion. Nocturnal GH secretion was not changed by P4 administration. However, P4 diminished ghrelin-stimulated pulsatile GH release with or without E2 (average, 7.20 ± 2.14 and 9.58 ± 1.97 µg/L/2 h, respectively; P = 0.045). Respective outcomes for mean GH concentrations and GH peak amplitudes were 0.97 ± 0.31 and 1.52 μg/L ± 0.29 (P = 0.025) and 2.76 ± 1.04 and 3.95 μg/L ± 0.90 (P = 0.031). Ghrelin-stimulated GH secretion correlated negatively with P4 concentration with or without correction for visceral fat area in the regression equation (R = 0.49, P = 0.04, β = -0.040 ± 0.016).

CONCLUSIONS

Low-range physiological E2 concentrations do not affect spontaneous or ghrelin-stimulated pulsatile GH secretion. Conversely, P4 inhibits ghrelin-stimulated GH secretion in a concentration-dependent fashion. The mechanistic aspects and physiological significance of natural P4's regulation of ghrelin-evoked GH secretion require further study.

Evaluation of growth hormone response to GHRH plus arginine test in children with idiopathic short stature: role of peak time

PURPOSE

To describe the course of growth hormone response to growth hormone releasing hormone (GHRH) plus arginine provocative test in children with idiopathic short stature (ISS) and to evaluate the role of peak time.

METHODS

A retrospective study was performed analyzing 344 GHRH plus arginine provocative tests performed in children and adolescents with short stature. Serum GH levels were measured at four-time points (T0', T30', T45' and T60') and GH peak was defined as the maximum value at any time point. Mean (T30'-T60') GH value and area under the curve (AUC) were calculated.

RESULTS

When analyzing the time of peak at the provocative test, the most frequent peak time was T45' (53.8%) in the ISS group, with no differences in gender, age, and pubertal stage. Analyzing GHD subjects, the most frequent time of peak was T30 (50%). Analyzing the whole population, the GH T0' levels were significantly lower in subjects with the GH peak at T45' than those with the GH peak at T30' (1.7 ± 2.0 vs. 3.2 ± 4.0, p < 0.001). In subjects with GH peak at T45', the value of GH peak, AUC and mean GH were significantly higher than in those with GH peak at T30' and T60'. A direct correlation was found between the value of GH peak and growth velocity SDS (r = 0.127, p = 0.04) and a negative one between GH peak and GH level at T0' (r = - 0.111, p = 0.04), even when adjusted for gender, age, pubertal stage and BMI Z score.

CONCLUSIONS

The time peak at 45 min seems to be associated with a better response to the test considering GH peak, mean and AUC. Patients with a GH peak at 30 min more probably could have a derangement in GH secretion showing worst growth pattern and/or a GH deficiency and should be carefully observed.

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.

Type I insulin-like growth factor as a liver reserve assessment tool in hepatocellular carcinoma

Chronic liver diseases (CLDs) encompass a wide range of illnesses, including nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, and viral hepatitis. Deterioration of liver capacity, with subsequent progression into cirrhosis and hepatocellular carcinoma (HCC), ultimately leads to a further decrease in the hepatic reserve. The Child-Turcotte-Pugh scoring system is the standard tool for assessing underlying liver reserve capacity in routine practice and in clinical trials of CLD and HCC. In this review, we highlight the clinical significance of insulin-like growth factor-I (IGF-I) and the growth hormone (GH) signaling pathway in HCC. IGF-I could be a marker for liver reserve capacity in CLDs and HCC in clinical practice. This approach could improve the risk assessment and stratifications of patients on the basis of their underlying liver reserve, either before active treatment in routine practice or before they are enrolled in clinical trials.

Longitudinal assessment of the menopausal transition, endogenous sex hormones, and perception of physical functioning: the Study of Women's Health Across the Nation

BACKGROUND

To evaluate the longitudinal associations between menopausal status, related hormonal changes, and level of self-reported physical functioning.

METHODS

Study included 2,495 women (age: 45-57 between 2000 and 2001) from the Study of Women's Health Across the Nation. Physical functioning scale of the Medical Outcomes Study Short-Form (SF-36; score 0-100) was categorized as: no limitation (86-100), moderate limitation (51-85), and substantial limitation (0-50). Study variables were collected between 2000 (visit-04) and 2011 (visit-12) at five timepoints. Statistical models were adjusted for age at visit-04, time since visit-04, ethnicity, site, economic status, level and change in body mass index, level and change in physical activity, and presence of comorbid conditions.

RESULTS

In final models, natural and surgical postmenopausal women had significantly higher odds of functional limitation, compared with premenopausal women. Less reduction in estradiol and testosterone since visit-04 were significantly associated with lower odds of functional limitation, while greater increase in sex hormone-binding globulin was associated with higher odds of functional limitation.

CONCLUSIONS

Our findings suggest the menopause-related changes in endogenous sex hormones as a possible mechanism of action to explain the greater limitation in physical functioning reported in women at midlife.

Hormone and genetic study in male to female transsexual patients

BACKGROUND

Data of the literature demonstrated controversial results of a correlation between transsexualism and genetic mutations.

AIM

To evaluate the hormone and gene profile of male-female (M-F) transsexual.

SUBJECTS AND METHODS

Thirty M-F transsexuals aged 24-39. Seventeen had already undergone sex reassignment surgery, 13 were awaiting. All subjects had been undergoing estrogen and antiandrogen therapy. We studied hormones of the hypothalamus- pituitary-testicular axis, thyroid and adrenal profile, GH basal and after GHRH stimulation, IGF-I. The gene study analyzed SRY, AR, DAX1, SOX9, AZF region of the Y chromosome.

RESULTS

Pre-surgery subjects had elevated PRL, reduced testosterone and gonadotropins. Post-surgery subjects showed reduced androgens, a marked increase in LH and FSH and normal PRL. Cortisol and ACTH were similar to reference values in pre- and post-surgery patients. There was a marked increase in the baseline and post-stimulation GH values in 6 of the 13 pre-surgery patients, peaking at T15. IGF-I was similar to reference values in both groups except for one post-surgery patient, whose level was below the normal range. There were no polymorphisms in the amplified gene region for SOX9, and a single nucleotide synonimous polymorphism for DAX1. No statistically significant differences were seen in the mean of CAG repeats between controls and transsexual subjects. SRY gene was present in all subjects. Qualitative analysis of the AZFa, AZFb, and AZFc regions did not reveal any microdeletions in any subject.

CONCLUSIONS

This gender disorder does not seem to be associated with any molecular mutations of some of the main genes involved in sexual differentiation.

Estrogen treatment for acromegaly

Estrogens have been used in patients with acromegaly since the 1930-1940s, suppressing plasma IGF-1 levels and improving clinical signs and symptoms of acromegaly. Estrogens antagonize GH function at the post-receptor level, inhibiting GH signaling, thus decreasing GH-induced hepatic IGF-1 synthesis. We report our experience with four female patients with active acromegaly, naïve to medical treatment or inadequately controlled by somatostatin receptor ligands (SRLs) or the GH-receptor antagonist. Adding estrogen treatment (contraceptive pills or transdermal estrogen patches) to their ongoing medical treatment, suppressed IGF-1 significantly in all patients, achieving hormonal remission in three of them. We review the available data on the use of estrogens and selective estrogen receptor modulators in acromegaly, and their mechanisms of action. Estrogens could be an alternative, inexpensive adjuvant treatment for females with active acromegaly, who are only partially responding to SRLs or to the GH-receptor antagonist.

Diagnosing growth hormone deficiency in adults

Adult growth hormone (GH) deficiency is a recognised syndrome associated with adverse phenotypic, metabolic, and quality-of-life features which improve in many patients when GH is substituted. The appropriate selection of patients at risk of growth hormone deficiency (GHD) is the crucial first step in arriving at a correct diagnosis. Although multiple diagnostic modalities are available including a 24-hour serum GH profile, stimulated GH levels, and insulin-like growth factor-1 (IGF-1) levels, the use of dynamic tests for GH reserves is required in most cases. This paper discusses the utility and drawbacks of the various testing modalities with reference to international guidelines. Regardless of the test chosen, clinical pitfalls including age and obesity must be taken into account. In addition, there is considerable analytical variation in the biochemical measurements of GH and IGF-1 which must be considered before making a diagnosis of GHD in adulthood.

Ovariectomy and overeating palatable, energy-dense food increase subcutaneous adipose tissue more than intra-abdominal adipose tissue in rats

BACKGROUND

Menopause is associated with increased adiposity, especially increased deposition of intra-abdominal (IA) adipose tissue (AT). This differs from common or 'dietary' obesity, i.e., obesity apparently due to environmentally stimulated overeating, in which IAAT and subcutaneous (S) AT increase in similar proportions. The effect of menopause on adiposity is thought to be due to the decreased secretion of ovarian estrogens. Ovariectomy in rats and other animals is a commonly used model of menopause. It is well known that ovariectomy increases adiposity and that this can be reversed by estradiol treatment, but whether ovariectomy selectively increases IAAT has not been measured directly. Therefore, we used micro-computed tomography (microCT) to investigate this question in both chow-fed and dietary-obese rats.

METHODS

Ovariectomized, ovariectomized and estradiol treated, and sham-operated (intact) rats were fed chow or chow plus Ensure (Abbott Nutrition; n = 7/group). Total (T) AT, IAAT and SAT were measured periodically by microCT. Regional distribution of AT was expressed as IAAT as a percentage of TAT (%IAAT). Excesses in these measures were calculated with respect to chow-fed intact rats to control for normal maturational changes. Chemical analysis of fat was done in chow-fed intact and ovariectomized rats at study end. Data were analyzed by t-tests and planned comparisons.

RESULTS

Body mass, TAT, total fat mass, fat-free body mass, and %IAAT all increased in chow-fed intact rats during the 41 d study. In chow-fed rats, ovariectomy increased excess body mass, TAT, fat mass, fat-free body mass, and SAT, but had little effect on IAAT, in chow-fed rats, leading to a decrease in %IAAT. Ensure feeding markedly increased SAT, IAAT and TAT and did not significantly affect %IAAT. Ovariectomy had similar effects in Ensure-fed rats as in chow-fed rats, although less statistically reliable. Estradiol treatment prevented all the effects of ovariectomy.

CONCLUSIONS

Both ovariectomy in rats and menopause are associated with increased TAT. After ovariectomy, fat is preferentially deposited as SAT and lean body mass increases, whereas after menopause fat is preferentially deposited as IAAT and lean body mass decreases. These opposite effects of ovariectomy and menopause on regional AT distribution and lean body mass indicate that ovariectomy in rats is not a homologous model of menopause-associated changes in body composition that should be used with great caution in investigations of adiposity-related diseases.

The neurotoxic effects of estrogen on ischemic stroke in older female rats is associated with age-dependent loss of insulin-like growth factor-1

Hormone therapy to postmenopausal females increases the risk and severity of ischemic stroke. Our previous work using an animal model of menopause (reproductive senescence) shows that middle cerebral artery occlusion (MCAo) causes a larger cortical-striatal infarct in this older acyclic group compared with younger females. Moreover, although estrogen treatment is neuroprotective in younger females, estrogen paradoxically increases infarct volume in acyclic females. We hypothesized that the neurotoxic effects of estrogen in older females occurs because of decreased availability of IGF-1, a neuroprotectant that decreases with advancing age and is downregulated by estrogen treatment. Our data show that plasma IGF-1 levels are significantly reduced in reproductive senescent females and further reduced by estrogen at all ages. The neuroprotective effect of estrogen on MCAo-induced cortical infarct volume in mature adult female is reversed by intracerebroventricular injections of IGF-1 receptor antagonist JB-1. Similarly, estrogens neurotoxic effects on cortical infarct volume in senescent females is attenuated by concurrent IGF-1 treatment, and reversed when IGF-1 is infused 4 h after the onset of ischemia (delayed IGF-1 treatment). Delayed IGF-1/estrogen treatment also suppressed ischemia-induced ERK1 phosphorylation, reduced protein oxidation, and stimulated an early increase in prostaglandin E(2) at the infarct site. IGF-1 treatment was only protective in senescent females that received estrogen, indicating that the neuroprotective actions of this peptide require interaction with the steroid hormone receptor. These data support the hypothesis that stroke severity in older females is associated with decreased IGF-1 and further indicate that short-term postischemic IGF-1 therapy may be beneficial for stroke.

Insulinlike growth factor-1, insulinlike growth factor binding protein-1, and cognitive function in older men and women

OBJECTIVES

To assess the association between insulinlike growth factor (IGF)-1 and IGF binding protein (IGFBP)-1 with three cognitive function tests in a healthy elderly population.

DESIGN

Cross-sectional analyses from the Rancho Bernardo Cohort Study.

SETTING

Southern California community of Rancho Bernardo.

PARTICIPANTS

Men (n=636) and women (n=899) from the Rancho Bernardo study (median age 74) were assessed between 1988 and 1992 for cognitive function using the Mini-Mental State Examination (MMSE), Verbal Fluency (VF) test, and Trail-Making Test Part B (Trails B). Blood samples were obtained at the same time for IGF-1 and IGFBP-1 levels. The association between biomarkers and cognitive function tests was assessed by dichotomizing tests at the clinically relevant cutoff using logistic regression and according to tertiles and continuous IGF-1 and IGFBP-1 levels using multivariate linear regression analyses.

RESULTS

The mean MMSE, VF and Trails B scores indicated better cognitive function with higher IGF-1 tertile. Multivariate analyses showed that VF and MMSE were each significantly associated with IGF-1 in a dose-response manner for men (P for trend=.001), but no cognitive function tests were related to IGF-1 in women. For men, the highest IGFBP-1 tertile was inversely and significantly different from the lowest tertile for the MMSE test only (P for trend=.02).

CONCLUSION

IGF-1 was independently and positively related to MMSE and VF in men, and IGFBP-1 was inversely associated with MMSE in men. Sex differences in the association should be further investigated.

Androgens may mediate a relative preservation of IGF-I levels in overweight and obese women despite reduced growth hormone secretion

CONTEXT

Obesity is characterized by reduced GH secretion, but data regarding IGF-I levels and their determinants are conflicting.

OBJECTIVES

The objectives were to determine whether IGF-I levels are reduced and to investigate determinants of GH and IGF-I in healthy overweight and obese women.

DESIGN

A cross-sectional study was performed.

SETTING

The study was conducted at a General Clinical Research Center.

STUDY PARTICIPANTS

Thirty-four healthy women without pituitary/hypothalamic disease participated, including 11 lean [body mass index (BMI) <25 kg/m(2)], 12 overweight (BMI > or =25 kg/m(2) and <30 kg/m(2)), and 11 obese (BMI > or =30 kg/m(2)) women of comparable age (overall mean age, 30.7 +/- 7.8 yr).

INTERVENTION

There was no intervention.

MAIN OUTCOME MEASURES

The main outcome measures were frequent sampling (every 10 min for 24 h) for GH, peak GH after GHRH-arginine stimulation, IGF-I, IGF binding protein-3, estrone, estradiol, testosterone, free testosterone, SHBG, homeostasis model assessment of insulin resistance, and abdominal fat.

RESULTS

Mean 24-h GH and peak stimulated GH were lower in overweight than lean women and lowest in obese women. Mean IGF-I levels trended lower in obese, but not overweight, compared with lean women. Free testosterone was positively associated with IGF-I (R = 0.36, P = 0.04) but not with GH measures. Visceral fat was the only determinant of mean 24-h GH (R(2) = 0.66, P < 0.0001) and of peak stimulated GH (R(2) = 0.63, P < 0.0001), and mean 24-h GH accounted for 39% of the variability of IGF-I (P = 0.0002), with an additional 28% (P < 0.0001) attributable to free testosterone levels.

CONCLUSIONS

Despite a linear decrease in GH secretion and peak stimulated GH levels with increasing BMI in healthy overweight and obese women, IGF-I levels were not commensurately reduced. Androgens may contribute to this relative preservation of IGF-I secretion in overweight and obese women despite reduced GH secretion.

Aging and hormones of the hypothalamo-pituitary axis: gonadotropic axis in men and somatotropic axes in men and women

Neuroendocrinology of the aging (male) gonadal and (male and female) somatotropic axes will be reviewed. A companion chapter discusses reproductive hormonal changes in aging women. Both the gonadal and growth-hormone/insulin-like growth factor (GH/IGF-I) axes function as ensembles. The ensembles comprise tripartite interactions among the brain (hypothalamus), anterior pituitary gland (gonadotrope and somatotrope cells) and target organs (testis, liver, muscle, fat and brain). Compelling evidence indicates that combined hypothalamic and gonadal adaptations operate in the reproductive axis of older men, and multiple hypothalamic adaptations prevail in the GH axis of elderly men and women. Evolving investigative methods allow more precise parsing of the particular mechanisms that subserve such age-related changes, and suggest novel interventional strategies to evaluate the physiological impact of the dynamic alterations discerned in aging individuals.

Leptin does not mediate short-term fasting-induced changes in growth hormone pulsatility but increases IGF-I in leptin deficiency states

CONTEXT

States of acute and chronic energy deficit are characterized by increased GH secretion and decreased IGF-I levels.

OBJECTIVE

The objective of the study was to determine whether changes in levels of leptin, a key mediator of the adaptation to starvation, regulate the GH-IGF system during energy deficit.

DESIGN, SETTING, PATIENTS, AND INTERVENTION

We studied 14 healthy normal-weight men and women during three conditions: baseline fed and 72-h fasting (to induce hypoleptinemia) with administration of placebo or recombinant methionyl human leptin (r-metHuLeptin) (to reverse the fasting associated hypoleptinemia). We also studied eight normal-weight women with exercise-induced chronic energy deficit and hypothalamic amenorrhea at baseline and during 2-3 months of r-metHuLeptin treatment.

MAIN OUTCOME MEASURES

GH pulsatility, IGF levels, IGF and GH binding protein (GHBP) levels were measured.

RESULTS

During short-term energy deficit, measures of GH pulsatility and disorderliness and levels of IGF binding protein (IGFBP)-1 increased, whereas leptin, insulin, IGF-I (total and free), IGFBP-4, IGFBP-6, and GHBP decreased; r-metHuLeptin administration blunted the starvation-associated decrease of IGF-I. In chronic energy deficit, total and free IGF-I, IGFBP-6, and GHBP levels were lower, compared with euleptinemic controls; r-metHuLeptin administration had no major effect on GH pulsatility after 2 wk but increased total IGF-I levels and tended to increase free IGF-I and IGFBP-3 after 1 month.

CONCLUSIONS

The GH/IGF system changes associated with energy deficit are largely independent of leptin deficiency. During acute energy deficit, r-metHuLeptin administration in replacement doses blunts the starvation-induced decrease of IGF-I, but during chronic energy deficit, r-metHuLeptin administration increases IGF-I and tends to increase free IGF-I and IGFBP-3.

Effects of GH and/or sex steroids on circulating IGF-I and IGFBPs in healthy, aged women and men

Circulating GH, IGF-I, IGFBP-3, and sex steroid concentrations decrease with age. GH or sex steroid treatment increases IGFBP-3, but little is known regarding the effects of these hormones on other IGFBPs. We assessed the effects of 26 wk of administration of GH, sex steroids, or GH + sex steroids on AM levels of IGF-I, IGFBPs 1-5, insulin, glucose, and osteocalcin and 2-h urinary excretion of deoxypyridinolline (DPD) cross-links in 53 women and 71 men aged 65-88 yr. Before treatment, in women and men, IGF-I was directly related to IGFBP-3 (P < 0.001 and P < 0.0001) and IGFBP-1 to IGFBP-2 (P = 0.0001). In women, IGFBP-1 was inversely related to insulin (P < 0.0005) and glucose (P < 0.005) and IGFBP-4 to osteocalcin (P < 0.01). IGFBP-4 and IGFBP-5 were not significantly related to DPD cross-links. GH and/or sex steroid increased IGF-I levels in both sexes, with higher concentrations in men (P < 0.001). In women, the IGF-I increment after GH was attenuated by hormone replacement therapy (HRT) coadministration (P < 0.05). Hormone administration also increased IGFBP-3. IGFBP-1 was unaffected by GH + sex steroids, whereas GH decreased IGFBP-2 by 15% in men (P < 0.05). Hormone administration did not change IGFBP-4, whereas in men IGFBP-5 increased by 20% after GH (P < 0.05) and 56% after GH + testosterone (P = 0.0003). These data demonstrate sexually dimorphic IGFBP responses to GH. Additionally, HRT attenuated or prevented GH-mediated increases in IGF-I and IGFBP-3. Whether GH and/or sex steroid administration alters local tissue production of IGFBPs and whether the latter influence autocrine or paracrine actions of IGF-I remain to be determined.

Association of serum proinsulin with hormone replacement therapy in nondiabetic older women: the Rancho Bernardo Study

OBJECTIVE

One putative benefit of hormone replacement therapy (HRT) is a reduced risk of diabetes or reduced fasting glucose level. We report here the association of HRT with proinsulin, insulin, and fasting and postchallenge glucose levels in older adults.

RESEARCH DESIGN AND METHODS

Current HRT use was validated and cross-sectionally compared with diabetes-related variables in 785 women without diabetes by history or glucose tolerance test.

RESULTS

Median age was 72 years (range 50-97); median value of fasting plasma glucose, postchallenge plasma glucose, and proinsulin was 5.08 mmol/l, 6.93 mmol/l, and 9.3 pmol/l, respectively. In age-adjusted comparisons, current HRT use was associated with significantly lower fasting plasma glucose and higher postchallenge plasma glucose compared with never/previous HRT use, as well as with lower LDL and higher HDL cholesterol and higher triglycerides. Fasting and postchallenge intact insulin did not differ by HRT group, but proinsulin was significantly lower in current HRT users than in previous and never HRT users. The significant association between proinsulin and HRT status persisted after adjustment for age, waist-to-hip ratio, pulse pressure, LDL-to-HDL cholesterol ratio, triglycerides, fasting and postchallenge glucose, and intact insulin.

CONCLUSIONS

Reduced fasting and increased 2-h glucose replicate findings in a randomized clinical trial. The proinsulin effect has not been previously reported. Decreased fasting glucose and proinsulin levels in current HRT use suggest a potential antidiabetes effect of HRT. Increased postchallenge glucose in HRT, however, suggests insulin resistance and would be expected to increase the risk of heart disease.

Testosterone and estradiol regulate free insulin-like growth factor I (IGF-I), IGF binding protein 1 (IGFBP-1), and dimeric IGF-I/IGFBP-1 concentrations

The present study tests the clinical postulate that elevated testosterone (Te) and estradiol (E2) concentrations modulate the effects of constant iv infusion of saline vs. recombinant human IGF-I on free IGF-I, IGF binding protein (IGFBP)-1, and dimeric IGF-I/IGFBP-1 concentrations in healthy aging adults. To this end, comparisons were made after administration of placebo (Pl) vs. Te in eight older men (aged 61 +/- 4 yr) and after Pl vs. E2 in eight postmenopausal women (62 +/- 3 yr). In the saline session, E2 lowered and Te increased total IGF-I; E2 specifically elevated IGFBP-1 by 1.5-fold and suppressed free IGF-I by 34%; and E2 increased binary IGF-I/IGFBP-1 by 5-fold more than Te. During IGF-I infusion, the following were found: 1) total and free IGF-I rose 1.4- to 2.0-fold (Pl) and 2.1-2.5-fold (Te) more rapidly in men than women; 2) binary IGF-I/IGFBP-1 increased 3.4-fold more rapidly in men (Te) than women (E2); and 3) end-infusion free IGF-I was 1.6-fold higher in men than women. In summary, E2, compared with Te supplementation, lowers concentrations of total and ultrafiltratably free IGF-I and elevates those of IGFBP-1 and binary IGF-I/IGFBP-1, thus putatively limiting IGF-I bioavailability. If free IGF-I mediates certain biological actions, then exogenous Te and E2 may modulate the tissue effects of total IGF-I concentrations unequally.

Determinants of dual secretagogue drive of burst-like growth hormone secretion in premenopausal women studied under a selective estradiol clamp

The present study tests the hypothesis that estradiol (E(2)), compared with placebo (Pl), amplifies combined-secretagogue stimulation of GH secretion in premenopausal women studied at comparable IGF-I and testosterone concentrations. To this end, 13 women underwent GnRH agonist-induced gonadal down-regulation followed by graded transdermal addback of E(2) or Pl and randomly ordered iv infusions of saline or paired secretagogues on separate morning fasting. GH secretion was assessed by frequent blood sampling, immunochemiluminometry, and variable-waveform deconvolution analysis. Two-way ANOVA revealed that specific secretagogue combination (P < 0.001), E(2) status (P = 0.012), and their interaction (P = 0.038) jointly determined GH secretory-burst mass. Compared with Pl, the E(2)-clamped milieu elevated mean fasting GH concentrations (P = 0.032), the mass of GH secreted in bursts (P = 0.037), and maximal stimulation by paired l-arginine/GH-releasing peptide (GHRP)-2 (P = 0.028). E(2) also markedly accelerated the initial release of GH induced by GHRH/GHRP-2 (P < 0.001) and l-arginine/GHRH (P < 0.01). By linear regression analysis, E(2) concentrations positively forecast 41% of intersubject variability in GH secretion stimulated by combined l-arginine/GHRP-2 (P = 0.018), whereas abdominal visceral-fat mass negatively predicted 49% of that due to l-arginine/GHRH (P = 0.012). These data indicate that pulsatile GH secretion in young women studied at constant IGF-I and testosterone concentrations is dictated 3-fold jointly by secretagogue pair, E(2) availability, and intraabdominal adiposity. Moreover, the rapidity of GH release is controlled 2-fold jointly by E(2) and GHRH.

Characteristics of adult patients with growth hormone deficiency who underwent neurosurgery for functioning and non-functioning pituitary adenomas and craniopharyngiomas

The aim of the present study was to evaluate the characteristics of GH deficiency (GHD) in adult patients after neurosurgery for pituitary adenomas and craniopharingiomas. One hundred and one GHD patients, (42 F/59 M), aged 47.58+/-14.4 yr (mean+/-SD; range 21-78), body mass index (BMI) 28.6+/-0.6, with a history of adult-onset hypothalamic-pituitary disease, were recruited for the study. The whole group included: 45 non-functioning pituitary adenomas, 23 craniopharyngiomas, 16 PRLomas, 8 GHomas, 7 ACTHomas and 2 FSHomas; in particular 51 were macroadenomas and 27 microadenomas. At study entry, GHD diagnosis was carried out by assessing GH secretion after GHRH+arginine. All patients were submitted to the study at least 12 months after neurosurgery and, where needed, subjects were replaced with an appropriate treatment. GHD was mild in 3/101 (3%) and severe in 98/101 patients (97%). Other hormone deficiencies associated with GHD were considered: TSH, ACTH, FSH/LH, ADH. The distribution of peak GH among all patients, according to the type of disease before neurosurgery, showed that patients with Cushing disease were characterized by the presence of higher peak GH. According to the number of additional hormone deficits, the distribution of peak GH among all patients was as follows: GHD was isolated in 4/101 subjects (4%; group A), while it was associated with 1 (14/101, 14%; group B), 2 (22/101, 22%; group C), 3 (44/101, 43%; group D) and 4 hormone deficits (17/101, 16%; group E). GHD was severe in all patients in the panhypopituitaric group. Total IGF-I plasma levels in the whole group of GHD patients were 95.2+/-4.2 microg/l. In all groups of patients IGF-I was lower in subjects with severe GHD than in those with mild GHD (93.6+/-4.1 vs 148.6+/-33.6 microg/l, p<0.03). In particular, according to the type of disease presented before neurosurgery, patients with Cushing disease were characterized by the presence of higher IGF-I plasma levels compared to the other. According to the number of additional deficits, the distribution of IGF-I plasma levels was characterized by higher values when GHD was isolated than when it was associated with multiple hormone deficiencies. IGF-I plasma levels were positively associated to peak GH during GHRH+arginine (r=0.4, p<0.0005). We conclude that patients after neurosurgery approach for sellar and parasellar neoplasia, within an appropriate clinical context, and both the presence of additional pituitary hormone deficiency and low levels of IGF-I can be considered a clear GHD condition, and therefore do not require provocative tests evaluating GH secretion.

Gender and age in the biochemical assessment of cure of acromegaly

The principal biochemical criteria for cure in acromegaly are normalization of both glucose-suppressed GH levels and IGF-I levels. As we have reported previously, measurement of GH by highly sensitive assay in conjunction with IGF-I levels has led to a re-appraisal of "normal" GH suppression criteria during an OGTT in subjects with acromegaly. In some patients with active acromegaly, glucose-suppressed GH levels as measured by highly sensitive assay are much lower than could previously be appreciated with less sensitive GH assays and some other patients in apparent remission have subtle abnormalities of GH suppression. A question to arise is whether gender differences in glucose-suppressed GH levels as found by others in young healthy subjects should be considered in our interpretation of OGTT criteria for cure in acromegaly. Therefore, we have evaluated parameters of GH secretion in a larger number of subjects from our cohort of postoperative patients with acromegaly and in healthy subjects in order to determine if gender or age associated differences in these parameters exist. Ninety-two subjects with acromegaly (49 men, 43 women) and 46 age-matched healthy subjects (26 men, 20 women) were evaluated with baseline GH and IGF-I levels and nadir GH levels after a 100 g. OGTT. GH was assayed by highly sensitive IRMA (DSL). Basal GH levels were higher in female than in male healthy subjects, but the fall in GH from baseline (% suppression) was also greater in females resulting in no significant difference in mean nadir GH levels in female vs. male healthy subjects (0.09 vs. 0.08 microg/L). In the subjects with acromegaly, there were no significant gender differences in basal, %GH suppression or nadir GH levels. Basal and nadir GH levels correlated significantly only in subjects with active disease (r=0.84, p<.0001). Similarly, IGF-I levels correlated significantly with basal (r=0.573, p=.0012), and nadir (r=.702, p<.0001) GH levels only in subjects with active disease. Gender differences in IGF-I levels were not apparent in any group of subjects. As expected, IGF-I levels declined with age in those groups of subjects with normal IGF-I levels. Nadir GH levels did not vary with age. In conclusion, we have not found significant gender or age-related differences in nadir GH levels and thus our data does not support separate OGTT criteria for cure in men and women with acromegaly.

Insulin-Like growth factor I: implications in aging

According to the somatomedin model, growth hormone (GH)-dependent hepatic synthesis is responsible for maintaining circulating insulin-like growth factor (IGF)-I levels. On the other hand, the local autocrine/paracrine IGF-I expression in peripheral tissue is generally GH-independent and reflects the effects of various and tissue-specific trophic hormones. Circulating IGF-I levels undergo important age-related variations increasing at puberty and decreasing, thereafter, to low levels in the elderly. Low IGF-I levels in the elderly mainly reflect impaired somatotroph secretion but the decline in gonadal sex steroid levels, some protein and micronutrients malnutrition as well as age-dependent variations in IGF-binding proteins may also play a role in the age-related decrease in IGF-I activity. This, in turn, partially accounts for age-related changes in bones, muscles, cardiovascular system, central nervous system and the immune system. However, it is currently unclear whether treatment with exogenous IGF-I can retard or reverse age-related changes in body structure and function.