Effects of GH and/or sex steroid administration on abdominal subcutaneous and visceral fat in healthy aged women and men

Cardiovascular safety of testosterone replacement therapy in men: an updated systematic review and meta-analysis

INTRODUCTION

The cardiovascular (CV) safety of testosterone (T) replacement therapy (TRT) is still conflicting. Recent data suggested a TRT-related increased risk of atrial fibrillation (AF). The aim of this study was to systematic review and meta-analyze CV risk related to TRT as derived from placebo controlled randomized trials (RCTs).

AREAS COVERED

An extensive Medline, Embase, and Cochrane search was performed. All placebo-controlled RCTs reporting data on TRT-related CV safety were considered. To better analyze the role of T on AF, population-based studies investigating the relationship between endogenous circulating T levels and AF incidence were also included and analyzed.

EXPERT OPINION

Out of 3.615, 106 studies were considered, including 8.126 subjects treated with TRT and 7.310 patients allocated to placebo. No difference between TRT and placebo was observed when major adverse CV events were considered. Whereas the incidence of non-fatal arrhythmias and AF was increased in the only trial considering CV safety as the primary endpoint, this was not confirmed when all other studies were considered (MH-OR 1.61[0.84;3.08] and 1.44[0.46;4.46]). Similarly, no relationship between endogenous T levels and AF incidence was observed after the adjustment for confounders Available data confirm that TRT is safe and it is not related to an increased CV risk.

Growth Hormone and Aging

Growth hormone (GH) secretion declines with aging (somatopause). One of the most controversial issues in aging is GH treatment of older adults without evidence of pituitary pathology. Although some clinicians have proposed reversing the GH decline in the older population, most information comes from not placebo-controlled studies. Although most animal studies reported an association between decreased GH levels (or GH resistance) and increased lifespan, human models have shown contradictory reports on the consequences of GH deficiency (GHD) on longevity. Currently, GH treatment in adults is only indicated for individuals with childhood-onset GHD transitioning to adulthood or new-onset GHD due to hypothalamic or pituitary pathologic processes.

Testosterone is associated with abdominal body composition derived from computed tomography: a large cross sectional study

The aim of this study was to evaluate the association between serum testosterone and abdominal body composition based on abdominopelvic computed tomography (APCT) measurements after adjusting for individual metabolic syndrome components. We performed a cross-sectional study using male subjects (age range: 22-84 years) who underwent a general health examination with abdominopelvic computed tomography and testosterone measurements. Body composition was evaluated with APCT. To confirm an association between testosterone and abdominal body composition, we conducted linear regression analysis. The effect of abdominal body composition was adjusted for important clinical factors such as age, albumin, and metabolic components in the multivariable regression analysis. Overall, 1453 subjects were included in the primary analysis. After adjustment for age, individual metabolic components, albumin, hemoglobin A1c, and C-reactive protein, we found that subcutaneous fat area index (β = - 0.042, p < 0.001), total abdominal muscle area index (β = 0.115, p < 0.001), normal attenuation muscle area index (β = 0.070, p < 0.001), and log_e-transformed lower attenuation muscle area index (β = 0.140, p = 0.002) had an association with log_e-transformed testosterone level. After adjusting for individual metabolic syndrome components, testosterone was associated negatively with subcutaneous fat, but not visceral fat. In addition, testosterone was positively correlated with abdominal muscle regardless of qualitative features such as fat-rich and fat-free.

Cardiovascular Disease Risk Among Transgender People with HIV

PURPOSE OF REVIEW

Transgender individuals are at disproportionate risk for HIV infection, with prevalence rates highest among transgender women of color. Antiretroviral therapy (ART)-treated people with HIV (PWH) are at increased risk for cardiovascular disease (CVD), in relation to persistent systemic immune activation and metabolic dysregulation. The purpose of this review is to examine parameters which may affect CVD risk among transgender PWH.

RECENT FINDINGS

Among transgender women and men, prospective longitudinal studies have shown that gender-affirming hormonal therapy (GAHT) is associated with select deleterious cardiometabolic effects such as increases in visceral adipose tissue. Retrospective studies among transgender women and men suggest an increase in CVD risk, such as venous thromboembolism, cerebrovascular accidents, and myocardial infarction. Studies among transgender PWH adhering to GAHT and ART suggest heightened systemic immune activation/inflammation. Prospective longitudinal studies assessing factors associated with increased CVD events among transgender PWH are needed to guide the development of CVD prevention strategies in this at-risk population.

Sleep Disorder and Heart Failure with Preserved Ejection Fraction

It is generally considered that obstructive sleep apnea is a potential cause of heart failure (HF), and insomnia and central sleep apnea are results of HF. However, the number of reports describing the bidirectional relationship between sleep disorder and HF has increased. Sleep disorder may contribute to left ventricular diastolic dysfunction via left atrial overload, left ventricular remodeling, pulmonary hypertension, and atrial fibrillation, which lead to HF with preserved left ventricular ejection fraction. Overnight rostral fluid shift and lung congestion may lead to airflow obstruction in the upper pharynx and stimulate pulmonary irritant receptors, which induce hyperventilation and sleep disorder.

Recent Update on the Molecular Mechanisms of Gonadal Steroids Action in Adipose Tissue

The gonadal steroids, including androgens, estrogens and progestogens, are involved in the control of body fat distribution in humans. Nevertheless, not only the size and localization of the fat depots depend on the sex steroids levels, but they can also highly affect the functioning of adipose tissue. Namely, the gonadocorticoids can directly influence insulin signaling, lipid metabolism, fatty acid uptake and adipokine production. They may also alter energy balance and glucose homeostasis in adipocytes in an indirect way, e.g., by changing the expression level of aquaglyceroporins. This work presents the recent advances in understanding the molecular mechanism of how the gonadal steroids influence the functioning of adipose tissue leading to a set of detrimental metabolic consequences. Special attention is given here to highlighting the sexual dimorphism of adipocyte functioning in terms of health and disease. Particularly, we discuss the molecular background of metabolic disturbances occurring in consequence of hormonal imbalance which is characteristic of some common endocrinopathies such as the polycystic ovary syndrome. From this perspective, we highlight the potential drug targets and the active substances which can be used in personalized sex-specific management of metabolic diseases, in accord with the patient's hormonal status.

Testosterone and Cardiovascular Risk: Meta-Analysis of Interventional Studies

BACKGROUND

The relationship between testosterone (T) and cardiovascular (CV) risk in men is conflicting.

AIM

To verify whether T therapy (TTh) represents a possible risk factor for CV morbidity and mortality.

METHODS

We conducted a random effect meta-analysis considering all available data from pharmaco-epidemiological studies as well as randomized placebo-controlled trials (RCTs).

OUTCOMES

CV mortality and morbidity were investigated.

RESULTS

After screening, 15 pharmaco-epidemiological and 93 RCT studies were considered. The analysis of pharmaco-epidemiological studies documented that TTh reduces overall mortality and CV morbidity. Conversely, in RCTs, TTh had no clear effect, either beneficial or detrimental, on the incidence of CV events. However, a protective role of TTh on CV morbidity was observed when studies enrolling obese (body mass index >30 kg/m²) patients were scrutinized (Mantel-Haenszel odds ratio 0.51 [95% CI 0.27-0.96]; P = .04), although this association disappeared when only high-quality RCTs were considered (Mantel-Haenszel odds ratio 0.64 [95% CI 0.22-1.88]; P = .42). Finally, an increased risk of CV diseases was observed in RCTs when T preparations were prescribed at dosages above those normally recommended, or when frail men were considered.

CLINICAL IMPLICATIONS

Pharmaco-epidemiological studies showed that TTh might reduce CV risk, but this effect was not confirmed when RCTs were considered.

STRENGTHS & LIMITATIONS

Meta-analysis of pharmaco-epidemiological studies indicates that TTh reduces overall mortality and CV morbidity. In addition, even in RCTs, a protective role of TTh on CV morbidity was envisaged when studies enrolling obese (body mass index >30 kg/m²) patients were considered. Pharmaco-epidemiological studies should be considered with caution due to the lack of completeness of follow-up and of the management of missing data. In addition, properly powered placebo-controlled RCTs with a primary CV end point, in men with late-onset hypo-gonadism, are not yet available. Finally, the duration of all studies evaluated in the present meta-analysis is relatively short, reaching a maximum of 3 years.

CONCLUSIONS

Data from RCTs suggest that treatment with T is not effective in reducing CV risk, however, when TTh is correctly applied, it is not associated with an increase in CV risk and it may have a beneficial effect in some sub-populations. Corona G, Rastrelli G, Di Pasquale G, et al. Testosterone and Cardiovascular Risk: Meta-Analysis of Interventional Studies. J Sex Med 2018;15:820-838.

Effects of growth hormone on hepatic insulin sensitivity and glucose effectiveness in healthy older adults

PURPOSE

Growth hormone (GH) replacement decreases insulin sensitivity in healthy individuals. However, the effects of GH on organ-specific insulin sensitivity and glucose effectiveness are not well characterized. The purpose of this study was to evaluate the effects of GH administration for 26 weeks on muscle and hepatic insulin sensitivity and glucose effectiveness in healthy older individuals.

METHODS

This report is from a 26-week randomized, double-blind, placebo-controlled parallel-group trial in healthy, ambulatory, community-dwelling older women and men. We compared surrogate indices of insulin sensitivity [quantitative insulin-sensitivity check index (QUICKI), muscle insulin sensitivity index (MISI), hepatic insulin resistance index (HIRI)] and glucose effectiveness [oral glucose effectiveness index (oGE)] derived from oral glucose tolerance tests (OGTTs) in subjects before and after 26 weeks of administration of GH (n = 17) or placebo (n = 15) as an exploratory outcome.

RESULTS

GH administration for 26 weeks significantly increased fasting insulin concentrations and HIRI but did not significantly change MISI or oGE compared to placebo.

CONCLUSIONS

GH administration for 26 weeks in healthy older subjects impairs insulin sensitivity in the liver but not skeletal muscle and does not alter glucose effectiveness.

Metabolic Disorders and Male Hypogonadotropic Hypogonadism

Several studies highlight that testosterone deficiency is associated with, and predicts, an increased risk of developing metabolic disorders, and, on the other hand, is highly prevalent in obesity, metabolic syndrome and type-2 diabetes mellitus. Models of gonadotropin releasing hormone deficiency, and androgen deprivation therapy in patients with prostate cancer, suggest that hypogonadotropic hypogonadism might contribute to the onset or worsening of metabolic conditions, by increasing visceral adiposity and insulin resistance. Nevertheless, in functional hypogonadism, as well as in late onset hypogonadism, the relationship between hypogonadotropic hypogonadism and metabolic disorders is bidirectional, and a vicious circle between the two components has been documented. The mechanisms underlying the crosstalk between testosterone deficiency and metabolic disorders include increased visceral adipose tissue and insulin resistance, leading to development of metabolic disorders, which in turn contribute to a further reduction of testosterone levels. The decrease in testosterone levels might be determined by insulin resistance-mediated and, possibly, pro-inflammatory cytokine-mediated decrease of sex hormone binding globulin, resulting in a temporary increased free testosterone available for aromatization to estradiol in visceral adipose tissue, followed by a subsequent decrease in free testosterone levels, due to the excess of visceral adipose tissue and aromatization; by a direct inhibitory effect of increased leptin levels on Leydig cells; and by a reduced gonadotropin secretion induced by estradiol, inflammatory mediators, leptin resistance, and insulin resistance, with the ultimate determination of a substantial hypogonadotropic hypogonadism. The majority of studies focusing on the effects of testosterone replacement therapy on metabolic profile reported a beneficial effect of testosterone on body weight, waist circumference, body mass index, body composition, cholesterol levels, and glycemic control. Consistently, several interventional studies demonstrated that correction of metabolic disorders, in particular with compounds displaying a greater impact on body weight and insulin resistance, improved testosterone levels. The aim of the current review is to provide a comprehensive overview on the relationship between hypogonadotropic hypogonadism and metabolism, by clarifying the independent role of testosterone deficiency in the pathogenesis of metabolic disorders, and by describing the relative role of testosterone deficiency and metabolic impairment, in the context of the bidirectional relationship between hypogonadism and metabolic diseases documented in functional hypogonadotropic hypogonadism. These aspects will be assessed by describing metabolic profile in men with hypogonadotropic hypogonadism, and androgenic status in men with metabolic disorders; afterwards, the reciprocal effects of testosterone replacement therapy and corrective interventions on metabolic derangements will be reported.

Sex-dependent Depot Differences in Adipose Tissue Development and Function; Role of Sex Steroids

Men and women are different in their fat mass and distribution pattern. The gynoid-type fat distribution, accumulation in lower-body, is considered to be protective while the android-type accumulation in upper-body, both in abdominal subcutaneous and visceral depots, is detrimental. Sex-dependent depot differences in adipose metabolic and endocrine functions are thought to contribute to the sexual disparity in fat distribution as well as its association with cardiometabolic risks. Although molecular details have not been completely elucidated, available evidence shows that sex steroid hormones are important factors governing sexual dimorphism in adipose tissue distribution and hence, risks for metabolic diseases. We will review sex-dependent heterogeneities in adipose tissue properties that can link their depot-specific biology to metabolic complications in men and women. In addition, we will also review how sex steroids regulate adipose tissue biology, both development and functional characteristics, with emphasis on their depot-dependent actions.

MR spectroscopy of hepatic fat and adiponectin and leptin levels during testosterone therapy in type 2 diabetes: a randomized, double-blinded, placebo-controlled trial

BACKGROUND

Men with type 2 diabetes mellitus (T2D) often have lowered testosterone levels and an increased risk of cardiovascular disease (CVD). Ectopic fat increases the risk of CVD, whereas subcutaneous gluteofemoral fat protects against CVD and has a beneficial adipokine-secreting profile.

HYPOTHESIS

Testosterone replacement therapy (TRT) may reduce the content of ectopic fat and improve the adipokine profile in men with T2D.

DESIGN AND METHODS

A randomized, double-blinded, placebo-controlled study in 39 men aged 50-70 years with T2D and bioavailable testosterone levels <7.3 nmol/L. Patients were randomized to TRT (n = 20) or placebo gel (n = 19) for 24 weeks. Thigh subcutaneous fat area (TFA, %fat of total thigh volume), subcutaneous abdominal adipose tissue (SAT, % fat of total abdominal volume) and visceral adipose tissue (VAT, % fat of total abdominal volume) were measured by magnetic resonance (MR) imaging. Hepatic fat content was estimated by single-voxel MR spectroscopy. Adiponectin and leptin levels were measured by in-house immunofluorometric assay. Coefficients (b) represent the placebo-controlled mean effect of intervention.

RESULTS

TFA (b = -3.3 percentage points (pp), P = 0.009), SAT (b = -3.0 pp, P = 0.006), levels of adiponectin (b = -0.4 mg/L, P = 0.045), leptin (b = -4.3 µg/mL, P < 0.001), leptin:adiponectin ratio (b = -0.53, P = 0.001) and HDL cholesterol (b = -0.11 mmol/L, P = 0.009) decreased during TRT compared with placebo. Hepatic fat content and VAT were unchanged.

CONCLUSIONS

The effects of TRT on cardiovascular risk markers were ambiguous. We observed potentially harmful changes in cardiovascular risk parameters, markedly reduced subcutaneous fat and unchanged ectopic fat during TRT and a reduction in adiponectin levels. On the other hand, the decrease in leptin and leptin:adiponectin ratio assessments could reflect an amelioration of the cardiovascular risk profile linked to hyperleptinaemia in ageing men with T2D.

Testosterone inhibits expression of lipogenic genes in visceral fat by an estrogen-dependent mechanism

The influence of the aromatase enzyme on the chronic fat-sparing effects of testosterone requires further elucidation. Our purpose was to determine whether chronic anastrozole (AN, an aromatase inhibitor) treatment alters testosterone-mediated lipolytic/lipogenic gene expression in visceral fat. Ten-month-old Fischer 344 rats (n = 6/group) were subjected to sham surgery (SHAM), orchiectomy (ORX), ORX + treatment with testosterone enanthate (TEST, 7.0 mg/wk), or ORX + TEST + AN (0.5 mg/day), with drug treatment beginning 14 days postsurgery. At day 42, ORX animals exhibited nearly undetectable serum testosterone and 29% higher retroperitoneal fat mass than SHAM animals (P < 0.001). TEST produced a ∼380-415% higher serum testosterone than SHAM (P < 0.001) and completely prevented ORX-induced visceral fat gain (P < 0.001). Retroperitoneal fat was 21% and 16% lower in ORX + TEST than SHAM (P < 0.001) and ORX + TEST + AN (P = 0.007) animals, while serum estradiol (E₂) was 62% (P = 0.024) and 87% (P = 0.010) higher, respectively. ORX stimulated lipogenic-related gene expression in visceral fat, demonstrated by ∼84-154% higher sterol regulatory element-binding protein-1 (SREBP-1, P = 0.023), fatty acid synthase (P = 0.01), and LPL (P < 0.001) mRNA than SHAM animals, effects that were completely prevented in ORX + TEST animals (P < 0.01 vs. ORX for all). Fatty acid synthase (P = 0.061, trend) and LPL (P = 0.043) mRNA levels were lower in ORX + TEST + AN than ORX animals and not different from SHAM animals but remained higher than in ORX + TEST animals (P < 0.05). In contrast, the ORX-induced elevation in SREBP-1 mRNA was not prevented by TEST + AN, with SREBP-1 expression remaining ∼117-171% higher than in SHAM and ORX + TEST animals (P < 0.01). Across groups, visceral fat mass and lipogenic-related gene expression were negatively associated with serum testosterone, but not E₂ Aromatase inhibition constrains testosterone-induced visceral fat loss and the downregulation of key lipogenic genes at the mRNA level, indicating that E₂ influences the visceral fat-sparing effects of testosterone.

Sex and sex steroids: impact on the kinetics of fatty acids underlying body shape

Adult humans have a remarkable sexual dimorphism in body shape. Men tend to store relatively more fat in the upper body whereas women store more fat in the lower body. We do not have a complete understanding of the mechanisms underlying these differences, but we know that people who preferentially store abdominal fat are at greater risk of metabolic disease. It is also known that the changes in sex steroid concentrations during puberty and again with advancing age are accompanied by changes in body fat distribution. The objective of this review is to describe what has been learned regarding the mechanisms underlying changes in regional body fat distribution that occur as a result of changes in sex hormones and to delineate effects of sex steroids in modulating body composition.

Testosterone and obesity

Testosterone is a key hormone in the pathology of metabolic diseases such as obesity. Low testosterone levels are associated with increased fat mass (particularly central adiposity) and reduced lean mass in males. These morphological features are linked to metabolic dysfunction, and testosterone deficiency is associated with energy imbalance, impaired glucose control, reduced insulin sensitivity and dyslipidaemia. A bidirectional relationship between testosterone and obesity underpins this association indicated by the hypogonadal-obesity cycle and evidence weight loss can lead to increased testosterone levels. Androgenic effects on enzymatic pathways of fatty acid metabolism, glucose control and energy utilization are apparent and often tissue specific with differential effects noted in different regional fat depots, muscle and liver to potentially explain the mechanisms of testosterone action. Testosterone replacement therapy demonstrates beneficial effects on measures of obesity that are partially explained by both direct metabolic actions on adipose and muscle and also potentially by increasing motivation, vigour and energy allowing obese individuals to engage in more active lifestyles. The degree of these beneficial effects may be dependent on the treatment modality with longer term administration often achieving greater improvements. Testosterone replacement may therefore potentially be an effective adjunctive treatment for weight management in obese men with concomitant hypogonadism.

Lowered testosterone in male obesity: mechanisms, morbidity and management

With increasing modernization and urbanization of Asia, much of the future focus of the obesity epidemic will be in the Asian region. Low testosterone levels are frequently encountered in obese men who do not otherwise have a recognizable hypothalamic-pituitary-testicular (HPT) axis pathology. Moderate obesity predominantly decreases total testosterone due to insulin resistance-associated reductions in sex hormone binding globulin. More severe obesity is additionally associated with reductions in free testosterone levels due to suppression of the HPT axis. Low testosterone by itself leads to increasing adiposity, creating a self-perpetuating cycle of metabolic complications. Obesity-associated hypotestosteronemia is a functional, non-permanent state, which can be reversible, but this requires substantial weight loss. While testosterone treatment can lead to moderate reductions in fat mass, obesity by itself, in the absence of symptomatic androgen deficiency, is not an established indication for testosterone therapy. Testosterone therapy may lead to a worsening of untreated sleep apnea and compromise fertility. Whether testosterone therapy augments diet- and exercise-induced weight loss requires evaluation in adequately designed randomized controlled clinical trials.

Cardiovascular risk associated with testosterone-boosting medications: a systematic review and meta-analysis

INTRODUCTION

Recent reports have significantly halted the enthusiasm regarding androgen-boosting; suggesting that testosterone supplementation (TS) increases cardiovascular (CV) events.

AREAS COVERED

In order to overcome some of the limitations of the current evidence, the authors performed an updated systematic review and meta-analysis of all placebo-controlled randomized clinical trials (RCTs) on the effect of TS on CV-related problems. Out of 2747 retrieved articles, 75 were analyzed, including 3016 and 2448 patients in TS and placebo groups, respectively, and a mean duration of 34 weeks. Our analyses, performed on the largest number of studies collected so far, indicate that TS is not related to any increase in CV risk, even when composite or single adverse events were considered. In RCTs performed in subjects with metabolic derangements a protective effect of TS on CV risk was observed.

EXPERT OPINION

The present systematic review and meta-analysis does not support a causal role between TS and adverse CV events. Our results are in agreement with a large body of literature from the last 20 years supporting TS of hypogonadal men as a valuable strategy in improving a patient's metabolic profile, reducing body fat and increasing lean muscle mass, which would ultimately reduce the risk of heart disease.

An update on male hypogonadism therapy

INTRODUCTION

Men who have symptoms associated with persistently low serum total testosterone level should be assessed for testosterone replacement therapy.

AREAS COVERED

Acute and chronic illnesses are associated with low serum testosterone and these should be recognized and treated. Once the diagnosis of male hypogonadism is made, the benefits of testosterone treatment usually outweigh the risks. Without contraindications, the patient should be offered testosterone replacement therapy. The options of testosterone delivery systems (injections, transdermal patches/gels, buccal tablets, capsules and implants) have increased in the last decade. Testosterone improves symptoms and signs of hypogonadism such as sexual function and energy, increases bone density and lean mass and decreases visceral adiposity. In men who desire fertility and who have secondary hypogonadism, testosterone can be withdrawn and the patients can be placed on gonadotropins. New modified designer androgens and selective androgen receptor modulators have been in preclinical and clinical trials for some time. None of these have been assessed for the treatment of male hypogonadism.

EXPERT OPINION

Despite the lack of prospective long-term data from randomized, controlled clinical trials of testosterone treatment on prostate health and cardiovascular disease risk, the available evidence suggests that testosterone therapy should be offered to symptomatic hypogonadal men.

[Androgenic treatment of male hypogonadism]

The diagnosis of male hypogonadism should be clearly established on a clinical and biological basis before considering the initiation of a substitutive treatment with androgens. A careful evaluation of advantages, constraints and limitations of the treatment should be done previously. The potential advantages of an androgenic substitution include an improvement of the symptoms of hypogonadism and the prevention of its bone and metabolic consequences. Absolute (namely prostatic) or relative contraindications should be detected before starting any substitution. The modalities of treatment will be adapted to both the patient's age and the goals to reach. The different available formulations do not induce a similar pattern of plasma testosterone levels. Patches, gel applications and long-acting intramuscular formulations [injected every 3 months] result in stable plasma levels in the physiologic range. The main limitation to their use is linked to a financial aspect as they are not the object of any refund. A careful survey (on clinical, biological and radiological basis) should be established after starting the substitutive treatment with androgens.

Neural growth hormone implicated in body weight sex differences

As for many human diseases, the incidence of obesity and its associated health risks are sexually dimorphic: worldwide the rate of obesity is higher in women. Sex differences in metabolism, appetite, body composition, and fat deposition are contributing biological factors. Gonadal hormones regulate the development of many sexually dimorphic traits in humans and animals, and, in addition, studies in mice indicate a role for direct genetic effects of sex chromosome dosage on body weight, deposition of fat, and circadian timing of feeding behavior. Specifically, mice of either sex with 2 X chromosomes, typical of normal females, have heavier body weights, gain more weight, and eat more food during the light portion of the day than mice of either sex with a single X chromosome. Here we test the effects of X chromosome dosage on body weight and report that gonadal females with 2 X chromosomes express higher levels of GH gene (Gh) mRNA in the preoptic area (POA) of the hypothalamus than females with 1 X chromosome and males. Furthermore, Gh expression in the POA of the hypothalamus of mice with 2 X chromosomes correlated with body weight; GH is known to have orexigenic properties. Acute infusion of GH into the POA increased immediate food intake in normal (XY) males. We propose that X inactivation-escaping genes modulate Gh expression and food intake, and this is part of the mechanism by which individuals with 2 X chromosomes are heavier than individuals with a single X chromosome.

Testosterone induces cell proliferation and cell cycle gene overexpression in human visceral preadipocytes

Evidence from the literature suggests that testosterone plays an important role in visceral fat accumulation since both men and women with hyperandrogenism accumulate more adipose tissue in the abdominal cavity than healthy women. However, the underlying mechanisms remain to be elucidated. To shed light on this issue, we have used an in vitro approach to examine the effect of testosterone on human visceral preadipocyte proliferation. Our results showed that testosterone treatment significantly increased proliferation of human visceral preadipocytes in proliferation assays using flow cytometric analysis. We next performed a microarray gene expression analysis of human visceral preadipocytes treated with testosterone or vehicle to identify which genes were involved in the testosterone-induced increase in preadipocyte proliferation. The results showed a total of 140 genes differentially expressed between testosterone vs. vehicle. Among the top 10 upregulated genes, 5 were involved in cellular cycle and proliferation, and 3 (APOBEC3b, CCNA2, and PRC1) were significantly overexpressed by testosterone treatment when analyzed by real-time PCR. We conclude that testosterone exerts a proliferative effect on preadipocytes that may participate in the sex differences in fat distribution and that it may explain visceral fat accumulation in women with hyperandrogenism.

Cardiometabolic risks during anabolic hormone supplementation in older men

OBJECTIVE

To determine the cardiometabolic risks of testosterone and growth hormone (GH) replacement therapy to youthful levels during aging.

DESIGN AND METHODS

A double-masked, partially placebo controlled study in 112 men 65-90 years-old was conducted. Transdermal testosterone (5 g vs. 10 g/day) using a Leydig Cell Clamp and subcutaneous recombinant GH (rhGH) (0 vs. 3 vs. 5 μg/kg/day) were administered for 16-weeks. Measurements included testosterone and IGF-1 levels, body composition by DEXA, and cardiometabolic risk factors (upper body fat, blood pressure, insulin sensitivity, fasting triglycerides, HDL-cholesterol, and serum adiponectin) at baseline and after 16 weeks of treatment.

RESULTS

Some cardiometabolic factors improved (total and trunk fat, triglycerides, HDL-cholesterol) and others worsened (systolic blood pressure, insulin sensitivity index [QUICKI], adiponectin). Cardiometabolic risk composite scores (CRCSs) improved (-0.69 ± 1.55, P < 0.001). In multivariate analyses, QUICKI, triglycerides, and HDL-cholesterol contributed 33%, 16%, and 14% of the variance in CRCS, respectively. Pathway analyses indicated that changes in fat and lean mass were related to individual cardiometabolic variables and CRCS in a complex manner. Changes in BMI, reflecting composite effects of changes in fat and lean mass, were more robustly associated with cardiometabolic risks than changes in fat mass or LBM individually.

CONCLUSIONS

Testosterone and rhGH administration was associated with diverse changes in individual cardiometabolic risk factors, but in aggregate appeared not to worsen cardiometabolic risk in healthy older men after 4-months. The long-term effects of these and similar anabolic therapies on cardiovascular events should be investigated in populations with greater functional limitations along with important health disabilities including upper body obesity and other cardiometabolic risks.

Effects of Growth Hormone Administration on Muscle Strength in Men over 50 Years Old

Growth hormone (GH) use has been speculated to improve physical capacity in subjects without GH deficiency (GHD) through stimulation of collagen synthesis in the tendon and skeletal muscle, which leads to better exercise training and increased muscle strength. In this context, the use of GH in healthy elderly should be an option for increasing muscle strength. Our aim was to evaluate the effect of GH therapy on muscle strength in healthy men over 50 years old. Fourteen healthy men aged 50-70 years were evaluated at baseline for body composition and muscle strength (evaluated by leg press and bench press exercises, which focus primarily on quadriceps-lower body part and pectoralis major-upper body part-muscles, resp.). Subjects were randomised into 2 groups: GH therapy (7 subjects) and placebo (7 subjects) and reevaluated after 6 months of therapy. Thirteen subjects completed the study (6 subjects in the placebo group and 7 subjects in the GH group). Subjects of both groups were not different at baseline. After 6 months of therapy, muscle strength in the bench press responsive muscles did not increase in both groups and showed a statistically significant increase in the leg press responsive muscles in the GH group. Our study demonstrated an increase in muscle strength in the lower body part after GH therapy in healthy men. This finding must be considered and tested in frail older populations, whose physical incapacity is primarily caused by proximal muscle weakness. The trial was registered with NCT01853566.

Comparison of Visceral Adipose Tissue Mass in Adult African Americans and Whites**

OBJECTIVE

Previous studies have reported racial differences in the amount of visceral adipose tissue (VAT), a risk factor for metabolic diseases. These results are equivocal and have not controlled for hormonal influences on VAT mass. This study was designed to measure the extent to which race is associated with VAT, controlling for total adipose tissue (TAT) mass and testosterone.

RESEARCH METHODS AND PROCEDURES

Using a cross-sectional study design, we measured TAT mass using DXA, VAT and subcutaneous adipose tissue mass using magnetic resonance imaging, and sex hormones using radioimmunoassay in 224 African-American and white men and women.

RESULTS

White men had increased VAT mass, even when controlling for TAT and age, compared with African-American men. White women also had a higher VAT mass compared with African-American women, but only when controlling for TAT and age. When multiple linear regression was used to evaluate the racial differences in VAT mass in a subset of subjects (n=80), controlling for sex hormones, it was found that white men, but not women, had increased VAT mass compared with their African-American counterparts.

DISCUSSION

Based on the results of this study, we conclude that, when controlling for TAT, sex hormone levels, and age, white men, but not women, have more VAT mass than African-American men and women. Additional studies are needed to explore possible environmental and genetic influences on fat distribution relative to race and sex.

Hormone replacement therapy and physical function in healthy older men. Time to talk hormones?

Improving physical function and mobility in a continuously expanding elderly population emerges as a high priority of medicine today. Muscle mass, strength/power, and maximal exercise capacity are major determinants of physical function, and all decline with aging. This contributes to the incidence of frailty and disability observed in older men. Furthermore, it facilitates the accumulation of body fat and development of insulin resistance. Muscle adaptation to exercise is strongly influenced by anabolic endocrine hormones and local load-sensitive autocrine/paracrine growth factors. GH, IGF-I, and testosterone (T) are directly involved in muscle adaptation to exercise because they promote muscle protein synthesis, whereas T and locally expressed IGF-I have been reported to activate muscle stem cells. Although exercise programs improve physical function, in the long-term most older men fail to comply. The GH/IGF-I axis and T levels decline markedly with aging, whereas accumulating evidence supports their indispensable role in maintaining physical function integrity. Several studies have reported that the administration of T improves lean body mass and maximal voluntary strength in healthy older men. On the other hand, most studies have shown that administration of GH alone failed to improve muscle strength despite amelioration of the detrimental somatic changes of aging. Both GH and T are anabolic agents that promote muscle protein synthesis and hypertrophy but work through separate mechanisms, and the combined administration of GH and T, albeit in only a few studies, has resulted in greater efficacy than either hormone alone. Although it is clear that this combined approach is effective, this review concludes that further studies are needed to assess the long-term efficacy and safety of combined hormone replacement therapy in older men before the medical rationale of prescribing hormone replacement therapy for combating the sarcopenia of aging can be established.

Effects of GH in women with abdominal adiposity: a 6-month randomized, double-blind, placebo-controlled trial

OBJECTIVE

Abdominal adiposity is associated with increased cardiovascular risk and decreased GH secretion. The objective of our study was to determine the effects of GH on body composition and cardiovascular risk markers in abdominally obese women.

MATERIALS AND METHODS

In this randomized, double-blind, placebo-controlled study, 79 obese premenopausal women received GH vs placebo for 6 months. Primary endpoints were i) total abdominal (total abdominal adipose tissue, TAT) fat by computed tomography (CT) (body composition) and ii) high-sensitivity C-reactive protein (hsCRP) (cardiovascular risk marker). Body composition was assessed by CT, dual-energy X-ray absorptiometry, and proton MR spectroscopy. Serum cardiovascular risk markers, carotid intima-media thickness, and endothelial function were measured.

RESULTS

Mean 6-month GH dose was 1.7±0.1 mg/day, resulting in a mean IGF1 SDS increase from -1.7±0.08 to -0.1±0.3 in the GH group. GH administration decreased TAT and hsCRP compared with placebo. In addition, it increased thigh muscle mass and lean body mass and decreased subcutaneous abdominal and trunk fat, tissue plasminogen activator, apoB, and apoB/low-density lipoprotein compared with placebo. Visceral adipose tissue (VAT) decreased and intramyocellular lipid increased within the GH group. Six-month change in IGF1 levels was negatively associated with 6-month decrease in TAT and VAT. One subject had a 2 h glucose >200 mg/ml at 3 months; four subjects, three of whom were randomized to GH, had 2 h glucose levels >200 mg/ml at the end of the study.

CONCLUSION

GH administration in abdominally obese premenopausal women exerts beneficial effects on body composition and cardiovascular risk markers but is associated with a decrease in glucose tolerance in a minority of women.

Hypogonadism in the aging male diagnosis, potential benefits, and risks of testosterone replacement therapy

Hypogonadism in older men is a syndrome characterized by low serum testosterone levels and clinical symptoms often seen in hypogonadal men of younger age. These symptoms include decreased libido, erectile dysfunction, decreased vitality, decreased muscle mass, increased adiposity, depressed mood, osteopenia, and osteoporosis. Hypogonadism is a common disorder in aging men with a significant percentage of men over 60 years of age having serum testosterone levels below the lower limits of young male adults. There are a variety of testosterone formulations available for treatment of hypogonadism. Data from many small studies indicate that testosterone therapy offers several potential benefits to older hypogonadal men. A large multicenter NIH supported double blind, placebo controlled study is ongoing, and this study should greatly enhance the information available on efficacy and side effects of treatment. While safety data is available across many age groups, there are still unresolved concerns associated with testosterone therapy. We have reviewed the diagnostic methods as well as benefits and risks of testosterone replacement therapy for hypogonadism in aging men.

Lean mass predicts hip geometry in men and women with non-insulin-requiring type 2 diabetes mellitus

Persons with type 2 diabetes mellitus (T2DM) are at increased risk for hip fracture despite normal bone mineral density (BMD). The contribution of body composition to hip geometry, a measure of hip strength, has not been studied in T2DM. We hypothesized that lean mass would predict hip geometry. Subjects (n=134) for this cross-sectional analysis were men and women aged 56 ± 6yr with non-insulin-requiring T2DM. Fat and lean mass were measured with dual-energy X-ray absorptiometry (DXA). Abdominal fat was measured with magnetic resonance imaging. Hip geometry parameters including section modulus, cross-sectional area, and buckling ratio were estimated from DXA using validated formulae. Subjects had normal BMD, elevated body mass indices (29-41 kg/m(2)), and controlled T2DM (hemoglobin A1c: 5.1-8.3%). In bivariate analysis, lean mass was positively associated with section modulus and cross-sectional area in both sexes (r=0.36-0.55, p<0.05). In multivariate analyses, lean mass remained a significant predictor of all hip strength estimates in both sexes. In women alone, fat mass predicted parameters of hip strength. These data demonstrate that lean mass is significantly associated with hip strength in subjects with non-insulin-requiring T2DM. Resistance exercises that build lean mass may be an intervention for hip fracture prevention in T2DM, although additional research is needed.

[Growth hormone therapy in adult patients: a review]

Growth hormone deficiency (GHD) can frequently be expected in hypopituitarism of adult patients. If GHD is proven by dynamic testing of the somatotrophic axis, growth hormone substitution is useful for improving quality of life, body composition, bone and lipid metabolism, and myocardial function according to the criteria of evidence-based medicine and is admitted by most national health authorities. There are no other reasonable indications for growth hormone treatment in adulthood.

The role of testosterone in the etiology and treatment of obesity, the metabolic syndrome, and diabetes mellitus type 2

Obesity has become a major health problem. Testosterone plays a significant role in obesity, glucose homeostasis, and lipid metabolism. The metabolic syndrome is a clustering of risk factors predisposing to diabetes mellitus type 2, atherosclerosis, and cardiovascular morbidity and mortality. The main components of the syndrome are visceral obesity, insulin resistance, glucose intolerance, raised blood pressure and dyslipidemia (elevated triglycerides, low levels of high-density lipoprotein cholesterol), and a proinflammatory and thrombogenic state. Cross-sectional epidemiological studies have reported a direct correlation between plasma testosterone and insulin sensitivity, and low testosterone levels are associated with an increased risk of type 2 diabetes mellitus, dramatically illustrated by androgen deprivation in men with prostate carcinoma. Lower total testosterone and sex hormone-binding globulin (SHBG) predict a higher incidence of the metabolic syndrome. Administration of testosterone to hypogonadal men reverses part of the unfavorable risk profile for the development of diabetes and atherosclerosis.

Effects of testosterone supplementation on markers of the metabolic syndrome and inflammation in hypogonadal men with the metabolic syndrome: the double-blinded placebo-controlled Moscow study

OBJECTIVE

Men with the metabolic syndrome (MetS) have low plasma testosterone (T) levels. The aim of this study was to establish whether the normalization of plasma T improves the features of the MetS.

DESIGN

A randomized, placebo-controlled, double-blinded, phase III trial of 184 men suffering from both the MetS and hypogonadism.

PATIENTS

One hundred and eighty-four men, aged 35-70, with the MetS and hypogonadism (baseline total T level <12·0 nm or calculated free T level <225 pm.), recruited in the outpatient andrology and urology clinic, Research Center for Endocrinology in Moscow, Russia.

INTERVENTION

Treatment for 30 weeks with either parenteral T undecanoate (n = 113; TU; 1000 mg IM) or placebo (n = 71), administered at baseline, and after 6 and 18 weeks. One hundred and five (92·9%) men receiving TU and 65 (91·5%) receiving placebo completed the trial.

MEASUREMENTS

Body weight, body mass index (BMI), waist circumference (WC), hip circumference, waist-to-hip ratio, insulin, leptin, glucose, cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, C-reactive protein (CRP), interleukin-1-beta (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10) and tumour necrosis factor-alpha (TNF-α).

RESULTS

There were significant decreases in weight, BMI and WC in the TU vs placebo group. Levels of leptin and insulin also decreased, but there were no changes in serum glucose or lipid profile. Of the inflammatory markers, IL-1β, TNF-α and CRP decreased, while IL-6 and IL-10 did not change significantly.

CONCLUSIONS

Thirty weeks of T administration normalizing plasma T in hypogonadal men with the MetS improved some components of the MetS and a number of inflammatory markers.

Androgens and obesity

PURPOSE OF REVIEW

As testosterone levels are frequently reduced in obesity, an understanding of the relationship between serum testosterone and adiposity is necessary in the clinical evaluation of these men, in particular when considering testosterone therapy.

RECENT FINDINGS

Population and interventional data suggest a bi-directional relationship exists between testosterone and obesity in men, with lower total testosterone and sex hormone binding globulin (SHBG) (and to a lesser extent free testosterone) levels than their nonobese peers; obesity having an impact at least as important as ageing. Abnormalities in the hypothalamo-pituitary-testicular axis are seen with increasing obesity. Weight loss in massive obesity increases testosterone levels but its role in mild-moderate obesity is unclear. Testosterone supplementation reduces total body fat in hypogonadal and ageing men although the effects on regional fat distribution are less well described.

SUMMARY

Favourable changes in total body fat and regional fat distribution suggest a potential role for testosterone in obesity. However, lifestyle advice to achieve sustained weight loss should be the mainstay of management. Obese men with confirmed androgen deficiency can be offered treatment, whereas in those with low-normal testosterone levels more research is needed.

Aging Men and Lipids

Many theories aim at explaining the mechanisms of aging and death in humans. Decreased levels of androgens, growth hormone, and insulin-like growth factor accompany natural aging in men. Androgens influence the growth and maturation of men in various stages of their life. The action of androgens is performed by binding or not binding to androgen receptors. However, various actions of androgens were clarified after the discovery and genotyping of the androgen receptor. The influence of androgens on the lipid profile was reported by several researchers. This negative influence of androgens in men and the positive influence of estrogens in women are responsible for the higher impact of atherogenesis in men compared with women. In aging men, this negative influence of androgens on the lipid profile is more pronounced. This review considers the influence of age on lipid metabolism in men.

Testosterone in older men after the Institute of Medicine Report: where do we go from here?

Despite nearly a half-century of research on aging and sex steroids in men, answers to key questions that would allow us to confidently assess risk:benefit ratios for androgen replacement in older men with the partial androgen deficiency of aging men (PADAM) syndrome remain uncertain. Although it is now reasonably clear that a significant percentage of otherwise healthy older men have decreases in testosterone and bioavailable testosterone to levels consistent with hypogonadism, the clinical implications of this change remain uncertain. Data suggest that low testosterone in older men is correlated to varying degrees with loss of lean body mass and muscle strength, and increased total and central body fat. Less certain, but suggestive, are data relating low testosterone levels to decreased bone density, loss of insulin sensitivity, and cognitive and affective deterioration, as well as reduced sexual function. Replacement of testosterone in older men has shown some positive effects on each of these variables, but findings have been inconsistent, perhaps because studies have employed different preparations and doses of androgens, treated for various durations, and defined their target populations in different ways. As important as beneficial effects is the potential for adverse effects, which may be greater in older men. Possible problems include sleep apnea, erythrocytosis, dyslipidemia with acceleration of atherosclerosis, and, of greatest concern, prostate cancer or hyperplasia. Studies to date have suggested that these outcomes are not major risks, but, in the absence of a large, randomized trial or trials, definitive information is not available. The US National Academies Institute of Medicine's recent report recommends that the National Institutes of Health support small efficacy trials aimed at treatment of androgen deficiency-related clinical conditions, but not a large, randomized trial to elucidate risk:benefit ratios. This recommendation, if adhered to, is likely to delay, rather than foster, progress in this important area.

Determinants of postexercise heart rate recovery in patients with the obstructive sleep apnea syndrome

BACKGROUND

Young patients with obstructive sleep apnea syndrome (OSAS) display an attenuated heart rate recovery (HRR) during the first minute (HRR-1) and the first 2 min (HRR-2) postexercise. We sought to compare determinants of HRR-1 and HRR-2 in OSAS and to assess whether these associations depend on age.

METHODS

Exercise testing with measurements of HRR-1 and HRR-2 was performed in 54 patients with untreated OSAS (median [interquartile range] apnea-hypopnea index 27.5 [12.0-42.4] h(-1), desaturation index [DSI] 10.6 [5.1-25.0] h(-1)).

RESULTS

Overall, higher DSI (P < .001) and higher total cholesterol ([TC] P = .02) were independent predictors of lower HRR-1, whereas lower peak heart rate (P < .001), higher resting heart rate (P = .006), and higher DSI (P = .01) were independently associated with lower HRR-2. In the below-median age group (age <or= 48 years; n = 27), higher DSI (P = .002) was the only independent predictor of lower HRR-1, and lower peak heart rate (P < .001) and higher DSI (P = .003) were independently associated with lower HRR-2. In contrast, in the above-median age group (age > 48 years; n = 27) higher TC (P = .006), higher insulin resistance (P = .009), and higher resting heart rate (P = .048) were independently associated with lower HRR-1, and lower estimated glomerular filtration rate (P = .001), higher resting heart rate (P = .002), higher TC (P = .005), and lower peak heart rate (P = .01) were independently associated with HRR-2.

CONCLUSIONS

Assessment of HRR-2 provides additional information on different aspects of OSAS compared with HRR-1. Markers of OSAS severity, such as DSI, are independently associated with HRR in younger patients only, whereas in older patients, HRR reflects OSAS-related metabolic and renal dysfunction.

Growth hormone and sex steroid effects on serum glucose, insulin, and lipid concentrations in healthy older women and men

CONTEXT

With aging, GH, IGF-I, and sex steroid concentrations and glucose tolerance decrease, and body fat and serum lipids increase.

OBJECTIVE

The aim of the study was to assess GH and/or sex steroid administration effects on serum glucose, insulin, insulin sensitivity, and lipids in older individuals.

DESIGN

A double-masked, 2 x 2 factorial, placebo-controlled, double-dummy design was used for the study.

INTERVENTION

GH and/or sex steroid [transdermal estradiol plus oral medroxyprogesterone acetate in women (HRT); testosterone enanthate (T) in men] were administered for 6 months.

PARTICIPANTS

Healthy, community-dwelling women (n = 57) and men (n = 74) ages 65-88 yr (mean, 72 yr) participated in the study.

MAIN OUTCOME MEASURES

We measured serum glucose, insulin, and insulin sensitivity [quantitative insulin sensitivity check index (QUICKI) and insulin sensitivity index (ISI)] before and during an oral glucose tolerance test and lipid profiles.

RESULTS

In women, GH did not alter oral glucose tolerance test 120 min or 2-h area under the curve (AUC) glucose values, but it increased 120 min insulin and AUC insulin. There were no significant effects of HRT or GH+HRT. ISI and QUICKI decreased after GH. In men, GH increased 120 min and AUC glucose and insulin AUC. GH+T increased 120 min glucose and glucose and insulin AUCs. T alone did not affect glucose or insulin. ISI decreased after GH and GH+T, whereas QUICKI decreased after GH. GH in women and men and GH+T in men decreased QUICKI by 4 wk. In women, HRT decreased total cholesterol and low-density lipoprotein (LDL)-cholesterol, and GH decreased LDL-cholesterol. In men, total cholesterol decreased after T and GH+T. LDL-cholesterol decreased after GH and GH+T. GH increased serum triglycerides.

CONCLUSIONS

GH administration to healthy older individuals for 6 months increased insulin resistance with moderately beneficial effects on lipids.

Cross-sectional analysis of testosterone therapies in hypopituitary men on stable pituitary hormone replacement

OBJECTIVE

The last decade has seen a proliferation in options for testosterone replacement. However, little is known as to the benefits of different treatment modalities. Our objective was to determine the testosterone prescription pattern and to examine the impact on various outcome measures.

SUBJECTS AND METHODS

A total of 816 adult-onset hypopituitary males on stable pituitary replacement for at least 1 year were identified from the KIMS database. Patients were classified as either eugonadal (n = 106), or hypogonadal (n = 710) on intramuscular (IM, n = 558), oral (n = 74), transdermal (n = 61), and depot (n = 17) testosterone.

RESULTS

After 1 year of stable pituitary replacement therapy, body composition, cardiovascular parameters, GH replacement and quality of life were not significantly different in androgen-replaced hypogonadal patients compared to eugonadal patients. There were no differences in outcome variables within the hypogonadal group according to the testosterone replacement regimen used and no difference in response to GH therapy.

CONCLUSIONS

The majority of hypopituitary patients in the last decade have received IM testosterone. Body composition, cardiovascular parameters, GH replacement and quality of life were not different between eugonadal and hypogonadal patients and were not differentially affected by the mode of testosterone replacement. These findings are reassuring that there is no major difference in response to different testosterone replacement regimens.

Testosterone and growth hormone improve body composition and muscle performance in older men

CONTEXT

Impairments in the pituitary-gonadal axis with aging are associated with loss of muscle mass and function and accumulation of upper body fat.

OBJECTIVES

We tested the hypothesis that physiological supplementation with testosterone and GH together improves body composition and muscle performance in older men.

DESIGN, SETTING, AND PARTICIPANTS

One hundred twenty-two community-dwelling men 70.8 +/- 4.2 yr of age with body mass index of 27.4 +/- 3.4 kg/m2, testosterone of 550 ng/dl or less, and IGF-I in lower adult tertile (< or =167 ng/dl) were randomized to receive transdermal testosterone (5 or 10 g/d) during a Leydig cell clamp plus GH (0, 3, or 5 microg/kg . d) for 16 wk.

MAIN OUTCOME MEASURES

Body composition by dual-energy x-ray absorptiometry, muscle performance, and safety tests were conducted.

RESULTS

Total lean body mass increased (1.0 +/- 1.7 to 3.0 +/- 2.2 kg) as did appendicular lean tissue (0.4 +/- 1.4 to 1.5 +/- 1.3 kg), whereas total fat mass decreased by 0.4 +/- 0.9 to 2.3 +/- 1.7 kg as did trunk fat (0.5 +/- 0.9 to 1.5 +/- 1.0 kg) across the six treatment groups and by dose levels for each parameter (P < or = 0.0004 for linear trend). Composite maximum voluntary strength of upper and lower body muscles increased by 14 +/- 34 to 35 +/- 31% (P < 0.003 in the three highest dose groups) that correlated with changes in appendicular lean mass. Aerobic endurance increased in all six groups (average 96 +/- 137 sec longer). Systolic and diastolic blood pressure increased similarly in each group with mean increases of 12 +/- 14 and 8 +/- 8 mm Hg, respectively. Other predictable adverse events were modest and reversible.

CONCLUSIONS

Supplemental testosterone produced significant gains in total and appendicular lean mass, muscle strength, and aerobic endurance with significant reductions in whole-body and trunk fat. Outcomes appeared to be further enhanced with GH supplementation.

Testosterone replacement therapy in hypogonadal men: assessing benefits, risks, and best practices

Hypogonadism is a common condition, especially among older men, but often goes undiagnosed and untreated. It can be associated with a number of signs and symptoms that affect health and quality of life, including feelings of low energy and fatigue; decreased sex drive and performance; decreased muscle mass and strength; decreased bone mineral density; and increased body fat, particularly abdominal fat, a putative risk factor for metabolic syndrome and type 2 diabetes mellitus. The evidence supporting testosterone replacement therapy (TRT) in improving these and related conditions is strong and consistent for body composition and sexual function; moderately consistent for bone mineral density; inconsistent for insulin sensitivity, glycemic control, and lipid profiles; and weak and inconsistent for mood and cognitive function. The concern of some physicians about the potential for TRT to stimulate prostate cancer is not supported by decades of data accumulated to date, though studies of longer duration (eg, 10 years or more) would be even more convincing. Other research needs are discussed. As the front line of health care delivery, primary care physicians need to be vigilant in diagnosing and treating symptomatic hypogonadism. Based on current guidelines, we recommend assessing testosterone levels when an adult man exhibits signs of hypogonadism, and as part of normal medical screening in men starting at age 40 to 50 years, to establish a baseline. A physician should discuss the possibility of TRT with symptomatic patients who have a serum total testosterone level < 300 ng/dL. If TRT is initiated, a patient's response and adverse events should be assessed every 3 to 6 months, and therapy adjusted accordingly.

Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial

BACKGROUND

Growth hormone secretion and muscle mass decline from midpuberty throughout life, culminating in sarcopenia, frailty, decreased function, and loss of independence. The decline of growth hormone in the development of sarcopenia is one of many factors, and its etiologic role needs to be demonstrated.

OBJECTIVE

To determine whether MK-677, an oral ghrelin mimetic, increases growth hormone secretion into the young-adult range without serious adverse effects, prevents the decline of fat-free mass, and decreases abdominal visceral fat in healthy older adults.

DESIGN

2-year, double-blind, randomized, placebo-controlled, modified-crossover clinical trial.

SETTING

General clinical research center study performed at a university hospital.

PARTICIPANTS

65 healthy adults (men, women receiving hormone replacement therapy, and women not receiving hormone replacement therapy) ranging from 60 to 81 years of age.

INTERVENTION

Oral administration of MK-677, 25 mg, or placebo once daily.

MEASUREMENTS

Growth hormone and insulin-like growth factor I levels. Fat-free mass and abdominal visceral fat were the primary end points after 1 year of treatment. Other end points were body weight, fat mass, insulin sensitivity, lipid and cortisol levels, bone mineral density, limb lean and fat mass, isokinetic strength, function, and quality of life. All end points were assessed at baseline and every 6 months.

RESULTS

Daily administration of MK-677 significantly increased growth hormone and insulin-like growth factor I levels to those of healthy young adults without serious adverse effects. Mean fat-free mass decreased in the placebo group but increased in the MK-677 group (change, -0.5 kg [95% CI, -1.1 to 0.2 kg] vs. 1.1 kg [CI, 0.7 to 1.5 kg], respectively; P < 0.001), as did body cell mass, as reflected by intracellular water (change, -1.0 kg [CI, -2.1 to 0.2 kg] vs. 0.8 kg [CI, -0.1 to 1.6 kg], respectively; P = 0.021). No significant differences were observed in abdominal visceral fat or total fat mass; however, the average increase in limb fat was greater in the MK-677 group than the placebo group (1.1 kg vs. 0.24 kg; P = 0.001). Body weight increased 0.8 kg (CI, -0.3 to 1.8 kg) in the placebo group and 2.7 kg (CI, 2.0 to 3.5 kg) in the MK-677 group (P = 0.003). Fasting blood glucose level increased an average of 0.3 mmol/L (5 mg/dL) in the MK-677 group (P = 0.015), and insulin sensitivity decreased. The most frequent side effects were an increase in appetite that subsided in a few months and transient, mild lower-extremity edema and muscle pain. Low-density lipoprotein cholesterol levels decreased in the MK-677 group relative to baseline values (change, -0.14 mmol/L [CI, -0.27 to -0.01 mmol/L]; -5.4 mg/dL [CI, -10.4 to -0.4 mg/dL]; P = 0.026); no differences between groups were observed in total or high-density lipoprotein cholesterol levels. Cortisol levels increased 47 nmol/L (CI, 28 to 71 nmol/L (1.7 microg/dL [CI, 1.0 to 2.6 microg/dL]) in MK-677 recipients (P = 0.020). Changes in bone mineral density consistent with increased bone remodeling occurred in MK-677 recipients. Increased fat-free mass did not result in changes in strength or function. Two-year exploratory analyses confirmed the 1-year results.

LIMITATION

Study power (duration and participant number) was insufficient to evaluate functional end points in healthy elderly persons.

CONCLUSION

Over 12 months, the ghrelin mimetic MK-677 enhanced pulsatile growth hormone secretion, significantly increased fat-free mass, and was generally well tolerated. Long-term functional and, ultimately, pharmacoeconomic, studies in elderly persons are indicated.

Growth hormone improves lipoprotein concentration and arylesterase activity in mice with an atherogenic lipid profile induced by lactalbumin

The effect of growth hormone (GH) on arylesterase (AE), one of the activities of paraoxonase, has never been studied. The aims of the present study in mice were: (a) to compare the effect of age and sex on serum lipid and lipoprotein levels after consumption of lactalbumin- v. chow-based diets and (b) to study the effect of GH administration, age and sex on serum AE activity, lipid and lipoprotein and body fat levels in mice fed a lactalbumin diet. Seventy-two mice were divided into three age- and sex-matched experimental groups: (1) control chow (CC), (2) non-GH lactalbumin (NGL) and (3) GH-treated lactalbumin (GL) mice. Lactalbumin increased total cholesterol, (LDL+VLDL)-cholesterol and TAG and diminished HDL-cholesterol in all animals (P<0.05). In comparison with their NGL counterparts, old GL males presented lower total cholesterol (15%) and (LDL+VLDL)-cholesterol (17%) levels (P<0.05), whereas values of the same parameters were higher in adult GL males (P<0.05) (22 and 23%, respectively). Adult GL females displayed higher serum HDL-cholesterol concentrations (26%) (P<0.05) than adult NGL females. AE activity was lower in old GL females (78%) and old GL males (20%) (P<0.05), but higher in adult GL males (100%) (P<0.01). GH, that was inversely related to food intake, decreased abdominal and gonadal fat in all mice (P<0.05). To conclude, lactalbumin induced an atherogenic lipoprotein profile in NGL mice that was reverted by GH, preferentially in old males, suggesting that GH therapy will be more effective in aged men. The present results suggest that AE activity was age-, sex- and body fat level-dependent and that it diminished as a consequence of improved antioxidant status.

Long-term testosterone supplementation augments overnight growth hormone secretion in healthy older men

Circulating testosterone (T) and GH/IGF-I are diminished in healthy aging men. Short-term administration of high doses of T augments GH secretion in older men. However, effects of long-term, low-dose T supplementation on GH secretion are unknown. Our objective was to evaluate effects of long-term, low-dose T administration on nocturnal GH secretory dynamics and AM concentrations of IGF-I and IGFBP-3 in healthy older men (65-88 yr, n = 34) with low-normal T and IGF-I. In a double-masked, placebo-controlled, randomized study we assessed effects of low-dose T supplementation (100 mg im every 2 wk) for 26 wk on nocturnal GH secretory dynamics [8 PM to 8 AM, Q(20) min sampling, analyzed by multiparameter deconvolution and approximate entropy (ApEn) algorithms]. The results were that T administration increased serum total T by 33% (P = 0.004) and E(2) by 31% (P = 0.009) and decreased SHBG by 17% (P = 0.002) vs. placebo. T supplementation increased nocturnal integrated GH concentrations by 60% (P = 0.02) and pulsatile GH secretion by 79% (P = 0.05), primarily due to a twofold increase in GH secretory burst mass (P = 0.02) and a 1.9-fold increase in basal GH secretion rate (P = 0.05) vs. placebo. There were no significant changes in GH burst frequency or orderliness of GH release (ApEn). IGF-I levels increased by 22% (P = 0.02), with no significant change in IGFBP-3 levels after T vs. placebo. We conclude that low-dose T supplementation for 26 wk increases spontaneous nocturnal GH secretion and morning serum IGF-I concentrations in healthy older men.