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

Quercetin Attenuates Osteoporosis in Orchiectomy Mice by Regulating Glucose and Lipid Metabolism via the GPRC6A/AMPK/mTOR Signaling Pathway

Quercetin, a flavonoid found in natural medicines, has shown a role in disease prevention and health promotion. Moreover, because of its recently identified contribution in regulating bone homeostasis, quercetin may be considered a promising agent for improving bone health. This study aimed to elucidate the role of quercetin in androgen deprivation therapy-induced osteoporosis in mice. C57BL/6 mice were subjected to orchiectomy, followed by quercetin treatment (75 and 150 mg/kg/d) for 8 weeks. Bone microstructure was then assessed by micro-computed tomography, and a three-point bending test was used to evaluate the biomechanical parameters. Hematoxylin and eosin (H&E) staining was used to examine the shape of the distal femur, gastrocnemius muscle, and liver. The balance motion ability in mice was evaluated by gait analysis, and changes in the gastrocnemius muscle were observed via Oil red O and Masson's staining. ELISA and biochemical analyses were used to assess markers of the bone, glucose, and lipid metabolism. Western blotting analyses of glucose and lipid metabolism-related protein expression was performed, and expression of the GPCR6A/AMPK/mTOR signaling pathway-related proteins was also assessed. After 8 weeks of quercetin intervention, quercetin-treated mice showed increased bone mass, bone strength, and improved bone microstructure. Additionally, gait analysis, including stride length and frequency, were significantly increased, whereas a reduction of the stride length and gait symmetry was observed. H&E staining of the gastrocnemius muscle showed that the cross-sectional area of the myofibers had increased significantly, suggesting that quercetin improves balance, motion ability, and muscle mass. Bone metabolism improvement was defined by a reduction of serum levels of insulin, triglycerides, total cholesterol, and low-density lipoprotein, whereas levels of insulin-like growth factor-1 and high-density lipoprotein were increased after quercetin treatment. Expression of proteins involved in glucose uptake was increased, whereas that of proteins involved in lipid production was decreased. Moreover, the GPRC6A and the phospho-AMPK/AMPK expression ratio was elevated in the liver and tibia tissues. In contrast, the phospho-mTOR/mTOR ratio was reduced in the quercetin group. Our findings indicate that quercetin can reduce the osteoporosis induced by testosterone deficiency, and its beneficial effects might be associated with the regulation of glucose metabolism and inhibition of lipid metabolism via the GPCR6A/AMPK/mTOR signaling pathway.

Androgen receptor activation reduces the endothelial cell proliferation through activating the cSrc/AKT/p38/ERK/NFκB-mediated pathway

The effect of androgen on angiogenesis has been documented. However, its underlying molecular mechanisms have not been well illustrated. Here, we show that treatment with an androgen receptor (AR) agonist, metribolone (R1881; 0.05-5 nM), or dihydrotestosterone (DHT; 0.5-2 nM), concentration- and time-dependently inhibited proliferation in human umbilical venous endothelial cells (HUVEC). This inhibitory effect was confirmed in human microvascular endothelial cells (HMEC-1). Flow cytometric analysis demonstrated that R1881 induced G0/G1 phase cell cycle arrest in HUVEC. Blockade of the AR activity by pre-treatment with an AR antagonist, hydroxyflutamide (HF), or knockdown of AR expression using the shRNA technique abolished the R1881-induced HUVEC proliferation inhibition, suggesting that AR activation can inhibit endothelial cell proliferation. We further investigated the signaling pathway contributing to the proliferation inhibition induced by AR activation. Our data suggest that R1881 reduced the proliferation rate of HUVEC through activating the AR/cSrc/AKT/p38/ERK/NFκB pathway, subsequently up-regulating p53 expression, which in turn increased the levels of p21 and p27 protein, hence decreasing the activities of cyclin-dependent kinase 2 (CDK2) and CDK4, and finally reduced the cell proliferation rate. An extra-nuclear pathway involved in the proliferation inhibition induced by AR activation in vascular endothelial cells was confirmed by showing that membrane-impermeable testosterone-bovine serum albumin (BSA) treatment significantly increased the levels of p53, p27 and p21 protein and reduced cell proliferation. These data highlight the underlying molecular mechanisms by which AR activation induced proliferation inhibition in vascular endothelial cells.

Establishing normal values of total testosterone in adult healthy men by the use of four immunometric methods and liquid chromatography-mass spectrometry

BACKGROUND

The total testosterone (T) cutoffs clinically adopted to define late-onset hypogonadism (LOH) do not consider the differences that exist between different analytical platforms, nor do they consider the body mass index (BMI) or age of the patient. We aimed at providing method, age and BMI-specific normal values for total T in European healthy men.

METHODS

A total of 351 eugonadal healthy men were recruited, and total T was measured with four automated immunometric assays (IMAs): ARCHITECT i1000SR (Abbott), UniCel DxI800 (Beckman Coulter), Cobas e601 (Roche), IMMULITE 2000 (Siemens) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Reference ranges (RRs) were calculated for each method.

RESULTS

Passing and Bablok regression analysis and Bland-Altman plot showed an acceptable agreement between Abbott and LC-MS/MS, but a poor one between LC-MS/MS and the other IMAs. Age-specific T concentrations in non-obese (BMI <29.9 kg/m2) men were greater than in all men. The total T normal range, in non-obese men aged 18-39 years, measured with LC-MS/MS was 9.038-41.310 nmol/L. RRs calculated with LC-MS/MS statistically differed from the ones calculated with all individual IMAs, except Abbott and among all IMAs. Statistically significant differences for both upper and lower reference limits between our RRs and the ones provided by the manufacturers were also noticed.

CONCLUSIONS

We calculated normal ranges in a non-obese cohort of European men, aged 18-39 years, with four commercially available IMAs and LC-MS/MS and found statistically significant differences according to the analytical method used. Method-specific reference values can increase the accuracy of LOH diagnosis and should be standardly used.

Androgens Ameliorate Impaired Ischemia-Induced Neovascularization Due to Aging in Male Mice

There is abundant evidence that low circulating testosterone levels in older men are associated with adverse cardiovascular outcomes; however, the direction of causality is unclear. Although there is burgeoning interest in the potential of androgen therapy in older men, the effect of androgens on cardiovascular regeneration in aging males remains poorly defined. We investigated the role of androgens in age-related impairment in ischemia-induced neovascularization. Castrated young (2 months) and old (24 months) male mice were subjected to unilateral hindlimb ischemia and treated with subdermal DHT or placebo Silastic implants. Blood flow recovery was enhanced by DHT treatment in young and old mice compared with age-matched placebo controls. DHT augmented angiogenesis in young mice and ameliorated age-related impairment in neovascularization in old mice. Administration of DHT was associated with increased hypoxia inducible factor-1α (HIF-1α) and stromal cell‒derived factor-1 expression in young mice, but not in old mice. In vitro, DHT-induced HIF-1α transcriptional activation was attenuated in fibroblasts from old mice. Interaction between androgen receptor (AR) and importins, key proteins that facilitate nuclear translocation of AR, was impaired with age. In contrast, DHT treatment stimulated the production and mobilization of Sca1+/CXCR4+ circulating progenitor cells in both young and old mice. DHT stimulated the migration and proangiogenic paracrine effect of ex vivo cultured bone marrow‒derived angiogenic cells from young and old mice. In conclusion, androgens ameliorated age-related impairment in ischemia-induced neovascularization. Although age-dependent dysfunction in androgen signaling attenuated some androgen effects on angiogenesis, provasculogenic effects of androgens were partially preserved with age.

Factors that may be influencing the rise in prescription testosterone replacement therapy in adult men: a qualitative study

OBJECTIVE

To explore and describe the factors that may be influencing the rise of prescribing and use of testosterone replacement therapy (TRT) in adult men.

DESIGN

A rapid qualitative research design using semi-structured interviews with providers and patients.

SETTING

Ontario, Canada.

PARTICIPANTS

Nine men who have used TRT (referred to as "patients"), and six primary care clinicians and seven specialists (collectively referred to as "providers") who prescribed or administered TRT.

METHOD

Patients' and providers' perspectives were investigated through semi-structured interviews. A purposive sampling approach was used to recruit all participants. We conducted qualitative analysis using the framework approach for applied health research.

MAIN FINDINGS

Participants perceived the following factors to have influenced TRT prescriptions and use in adult men: provider factors (diagnostic ambiguity of age-related hypogonadism and beliefs about appropriateness of TRT) and patient factors (access to information on TRT and drug seeking behavior). They perceived that these factors have perpetuated a rise in prescription in the absence of clear clinical guidelines and unclear research evidence on the safety and efficacy of TRT.

CONCLUSION

The findings of this study highlight that much work still needs to be done to improve diagnostic accuracy and encourage appropriate TRT prescription in adult men. In addition, both patients and providers need more information about the risks and long-term effects of TRT in men.

An investigation into the relationship between age and physiological function in highly active older adults

KEY POINTS

The relationship between age and physiological function remains poorly defined and there are no physiological markers that can be used to reliably predict the age of an individual. This could be due to a variety of confounding genetic and lifestyle factors, and in particular to ill-defined and low levels of physical activity. This study assessed the relationship between age and a diverse range of physiological functions in a cohort of highly active older individuals (cyclists) aged 55-79 years in whom the effects of lifestyle factors would be ameliorated. Significant associations between age and function were observed for many functions. V̇O2max was most closely associated with age, but even here the variance in age for any given level was high, precluding the clear identification of the age of any individual. The data suggest that the relationship between human ageing and physiological function is highly individualistic and modified by inactivity.

ABSTRACT

Despite extensive research, the relationship between age and physiological function remains poorly characterised and there are currently no reliable markers of human ageing. This is probably due to a number of confounding factors, particularly in studies of a cross-sectional nature. These include inter-subject genetic variation, as well as inter-generational differences in nutrition, healthcare and insufficient levels of physical activity as well as other environmental factors. We have studied a cohort of highly and homogeneously active older male (n = 84) and female (n = 41) cyclists aged 55-79 years who it is proposed represent a model for the study of human ageing free from the majority of confounding factors, especially inactivity. The aim of the study was to identify physiological markers of ageing by assessing the relationship between function and age across a wide range of indices. Each participant underwent a detailed physiological profiling which included measures of cardiovascular, respiratory, neuromuscular, metabolic, endocrine and cognitive functions, bone strength, and health and well-being. Significant associations between age and function were observed for many functions. The maximal rate of oxygen consumption (V̇O2max) showed the closest association with age (r = -0.443 to -0.664; P < 0.001), but even here the variance in age for any given level was high, precluding the clear identification of the age of any individual. The results of this cross-sectional study suggest that even when many confounding variables are removed the relationship between function and healthy ageing is complex and likely to be highly individualistic and that physical activity levels must be taken into account in ageing studies.

Testosterone level and the effect of levodopa and agonists in early Parkinson disease: results from the INSPECT cohort

Background

To determine if testosterone levels are influenced by dopaminergic therapy in Parkinson disease (PD) patients. Testosterone level has been reported to be low in patients with PD and other neurodegenerative diseases. In this study, we sought to determine whether dopaminergic therapy (i.e. levodopa and dopamine agonist) influenced testosterone levels. We used a cohort of consecutive male patients from the INSPECT trial--a multi-center, prospective, study that primarily investigated the effects of short-term treatment with pramipexole or levodopa on [¹²³I] B-CIT SPECT imaging in early PD.

Methods

Testosterone levels were drawn on consenting male subjects with early PD who enrolled in the INSPECT trial at three study visits (baseline, 12 weeks post-treatment, and 8–12 weeks post-washout). Subjects were randomized to: no treatment, pramipexole (up to 3 mg) or levodopa (up to 600 mg). Testosterone levels were obtained twice (prior to 10 AM) and averaged for each of three study visits.

Results

Thirty two male patients participated in this sub-study and there were no significant differences in disease characteristics in the 3 groups at baseline. Twenty-nine patients completed the follow-up visits and were suitable for analysis. There were statistically significant differences in the change in free testosterone level, increased in both the levodopa group and pramipexole group but decreased in the untreated group at 12-weeks post-treatment. There were no significant differences in the changes of UPDRS total or motor scores, although there was a strong trend toward improvement in motor scores. The testosterone level persisted in its increase only in the pramipexole group at the end of the washout period.

Conclusion

These preliminary data support the premise that dopaminergic medications do not reduce testosterone levels in early PD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/2054-7072-1-8) contains supplementary material, which is available to authorized users.

Prevalence of low testosterone levels in men with type 2 diabetes mellitus: a cross-sectional study

Background:

A high prevalence of low serum testosterone (LST) in men with type 2 diabetes have been reported worldwide. The aim of this study was to determine the prevalence and associated factors of LST in men with type 2 diabetes.

Materials and Methods:

This was a cross-sectional study, conducted among 1,089 men (aged 30-70 years) with type 2 diabetes who consecutively attended a major diabetes center in Amman, Jordan, between August 2008 and February 2009. The patients’ demographic characteristics were collected using a prestructured questionnaire. Duration of diabetes, smoking habits, presence of retinopathy, neuropathy, and nephropathy were collected from the medical records. All participants were asked to complete the Androgen Deficiency in Ageing Male (ADAM) questionnaire. Venous blood sample was collected to test for total testosterone (TT), free testosterone (FT), sex hormone binding globulin (SHBG), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), serum lipids, and glycosylated hemoglobin (HbA1c). LST was defined as TT <3 ng/ml.

Results:

Overall, 36.5% of patients with diabetes had TT level <3 ng/ml and 29% had symptoms of androgen deficiency. Of those with serum testosterone level <3 ng/ml, 80.2% had symptoms of androgen deficiency, 16.9% had primary hypogonadism (HG), and 83.1% had secondary HG. Univariate analysis showed a significant relationship between age, income, education, body mass index (BMI), smoking, duration of diabetes, diabetic nephropathy, diabetic neuropathy, and HbA1c. Multivariate logistic regression analysis indicated age, income, BMI, and diabetic neuropathy as the independent risk factors of LST.

Conclusions:

The prevalence of LST among men with type 2 diabetes is high. Age, income, BMI, and diabetic neuropathy were found to be the independent risk factors for LST.

Population-based patterns of prescription androgen use, 1976-2008

PURPOSE

Prescription testosterone (T) has limited approved medical indications and is a controlled substance in Canada. Utilization studies in other Westernized countries have revealed sharp increases in T use in recent years. We examined medical use of androgens, including T, over a ≥30-year period among adult (18+) men in a population-based study set in a Canadian juridisdiction of universal health care.

METHODS

Analyses were based on data from electronic records of dispensed prescriptions during 1976-2008 in Saskatchewan, Canada. All formulations of androgens listed in the provincial formulary (oral and injectable) were included. We examined demographics of users, androgen types used, switching patterns, and trends in the annual rate of use over time.

RESULTS

There were 11 521 androgen users who were followed for an average of 11.8 years. Overall, 11 types of androgens were used, and there were 86 812 dispensing events. The mean age at first use was 56.4 years (median: 58). Men had 7.5 prescription dispensing events on average (median: 2). The most commonly used formulations were methyl-T (36.2% of users) followed by T-enanthate (32.5%), T-cypionate (22.3%), and T-undecanoate (20.0%). Most users (82%) did not switch among androgen types. The annual rate of use varied substantially over time, with a marked increase observed from 1994 to 1999 and a decrease from 2000 to 2008.

CONCLUSIONS

Androgen users were largely middle aged and had relatively few dispensings. We hypothesize that observed secular trends in androgen use may align with drug treatment pattern changes for erectile dysfunction, including the advent of phosphodiesterase type 5 inhibitors.

Aging effects on oxidative phosphorylation in rat adrenocortical mitochondria

Does aging in itself lead to alteration in adrenocortical mitochondrial oxidative phosphorylation? Mitochondria from Fischer 344 (F344) rats (6 and 24 months old), Brown Norway rats (6 and 32 months old) and F344-Brown Norway hybrid rats (6 and 30 months old) were compared. Mitochondria were isolated from extirpated adrenal cortex. The yields of mitochondria were quantitatively similar in all rat strains irrespective of age. In order to assess the activity of each mitochondrial complex, several different substrates were tested and the rate of oxidative phosphorylation measured. Aging does not affect mitochondrial activity except in the F344 rat adrenal cortex where the maximal ADP-stimulated oxidative phosphorylation decreased with age. We hypothesize that impaired synthesis of steroid hormones by the adrenal cortex with age in F344 rats might be due to decreased adrenocortical mitochondrial oxidative phosphorylation. We conclude that aging results in adrenocortical mitochondria effects that are non-uniform across different rat strains.

A Telfairia Occidentalis Seed-incorporated Diet May Be Useful in Inhibiting the Induction of Experimental Andropause

Background:

Andropause, a prevalent pathology of men, results from an imbalance in steroid hormone concentrations that often is associated with aging, and reduces the quality of life of the sufferer. This study investigates the usefulness of a diet containing 15% Telfairia occidentalis seeds in the inhibition of the induction of experimental andropause.

Materials and Methods:

Twenty male rats were divided into four equal groups. Rats in the test group received dihydrotestosterone and estradiol valerate (ratio 10:1) subcutaneously every other day for 28 days and were placed on the test diet. Those in control I received the hormones, but not the test diet. Rats in controls II and III received olive oil (vehicle) and were placed on the test diet and normal diet, respectively. Testes weights and relative weights, serum testosterone concentrations, and testosterone concentration per gram of testicular tissue were measured or determined in all rats using standard protocols. Data were analyzed and differences between means separated using one-way analysis of variance.

Results:

Rats in the test group had slightly larger mean relative testes weights compared to those in control I, though both were significantly (P<0.001) smaller than the values obtained in controls II and III, respectively. Rats in the test group had significantly higher (P=0.034) serum testosterone concentrations relative to the control I group 6.9(0.3) ng/ml vs. 4.7(0.1) ng/ml, while the testosterone relative to testes weight values (ng/ml/g) of the test group was 16.8(3.4), and for controls I, II, and III the values were 12.3(1.4), 5.5(0.4), and 4.6(0.7), respectively. The differences between the test and control groups were all significant (P=0.04 in control I, and <0.001 in controls II and III).

Conclusion:

The test diet resulted in a modest reduction of biochemical castration and an improvement in secretory capacity of the testes of the test rats, relative to the control group that received the hormones but was placed on a normal diet. T. occidentalis seeds-incorporated diet may be useful in inhibiting the induction of experimental andropause.

Aging biology and novel targets for drug discovery

Despite remarkable technological advances in genetics and drug screening, the discovery of new pharmacotherapies has slowed and new approaches to drug development are needed. Research into the biology of aging is generating many novel targets for drug development that may delay all age-related diseases and be used long term by the entire population. Drugs that successfully delay the aging process will clearly become "blockbusters." To date, the most promising leads have come from studies of the cellular pathways mediating the longevity effects of caloric restriction (CR), particularly target of rapamycin and the sirtuins. Similar research into pathways governing other hormetic responses that influence aging is likely to yield even more targets. As aging becomes a more attractive target for drug development, there will be increasing demand to develop biomarkers of aging as surrogate outcomes for the testing of the effects of new agents on the aging process.

Gender-based cardiometabolic risk evaluation in minority and non-minority men grading the evidence of non-traditional determinants of cardiovascular risk

Evaluation of cardiometabolic risk has become vital in primary prevention of adverse vascular events (coronary artery disease, heart attack, stroke or congestive heart failure), particularly in younger middle-aged men (40-60 years old). To discern the prevalence of events in these men, clinicians often stratify cardiovascular risk and treat according to traditional Framingham risk criteria. Yet it is evident that the traditional Framingham risk assigned to intermediate- and low-risk men will miss several of these individuals deemed at high 'cardiometabolic risk', also known as residual cardiovascular risk. This review will elaborate the definition of cardiometabolic risk and apply the use of surrogate markers for cardiovascular risk stratification in men in addition to the traditional Framingham-based markers. It will utilise both gender non-specific and gender-specific determinants of cardiometabolic risk. Lastly, it will examine minority men's health and racial differences in these determinants of cardiovascular risk. This analysis includes an electronic literature search utilising PubMed, EMBASE and MEDLINE databases to clarify the level of evidence for the stepwise utility of novel biomarkers for cardiometabolic risk in the male patient. This manuscript generates discussion of the utility of markers of cardiometabolic risk stratification. The following questions are summarised: (i) Are there non-traditional tests that might define this risk better than traditional markers? (ii) Will treatment based on this risk assessment augment present risk stratification and lower cardiovascular risk? (iii) What is known regarding racial differences surrounding cardiometabolic risk assessment? Traditional risk factors including Framingham Risk Score underestimate the overall 10 year and lifetime risk for the intermediate-risk younger middle-aged men<60 years of age. This fact is especially true in the minority population. We have graded the evidence of non-gender specific and gender-specific markers of cardiometabolic risk, thereby, allowing greater clarification of risk in this population. The pragmatic use of these novel markers of cardiometabolic risk may help stratify those individuals at greater lifetime risk than that noted by the Framingham Risk Score.

Adaptive senectitude: the prolongevity effects of aging

In the past, it has been assumed that all the biological and medical changes that occur in old age are deleterious. It has therefore been concluded that treatment and prevention of such changes in old age should increase healthspan and delay death. However, accruing epidemiological and clinical trial evidence in older humans suggests that this is not the case. Some studies have shown that antioxidants and hormone supplements increase mortality, whereas high blood pressure, obesity, and metabolic syndrome are often associated with improved outcomes in very elderly people. Perhaps, some of these supposedly detrimental changes accompanying old age are in fact evolutionary adaptations to prolong life after reproduction in humans. Indeed, a form of reverse antagonistic pleiotropy or adaptive senectitude might be occurring. Some common biological and medical changes in old age might actually enhance longevity and represent novel targets for improving health in older people.

Androgens, angiogenesis and cardiovascular regeneration

PURPOSE OF REVIEW

Striking sex differences exist not only in the incidence of cardiovascular disease, but also in the clinical outcomes. Although cardiovascular events occur earlier in men, in women, it appears they have poorer short-term and long-term outcomes following these events compared to men. Thus, intrinsic sex differences may exist not only in atherogenesis, but also with respect to cardiovascular adaptation/repair in response to ischemia and/or infarction. Angiogenesis, the growth of new blood vessels, is essential for organ development and is critical to cardiovascular repair/regeneration. Although the effect of estrogen on angiogenesis has been studied extensively, the role of androgens has remained largely unexplored.

RECENT FINDINGS

Multiple lines of evidence now suggest an important role for androgens in cardiovascular repair and regeneration. Studies suggest that androgens stimulate angiogenesis via vascular endothelial growth factor-related mechanisms and by the stimulation of erythropoietin production. Furthermore, endothelial progenitor cells, important in angiogenesis, appear to be hormonally regulated and an important target of androgen action.

SUMMARY

Given the age-related decline in androgens, the findings discussed here have implications for therapeutic angiogenesis and androgen replacement therapies in aging and hypogonadal men.

A sex-specific role for androgens in angiogenesis

Mounting evidence suggests that in men, serum levels of testosterone are negatively correlated to cardiovascular and all-cause mortality. We studied the role of androgens in angiogenesis, a process critical in cardiovascular repair/regeneration, in males and females. Androgen exposure augmented key angiogenic events in vitro. Strikingly, this occurred in male but not female endothelial cells (ECs). Androgen receptor (AR) antagonism or gene knockdown abrogated these effects in male ECs. Overexpression of AR in female ECs conferred androgen sensitivity with respect to angiogenesis. In vivo, castration dramatically reduced neovascularization of Matrigel plugs. Androgen treatment fully reversed this effect in male mice but had no effect in female mice. Furthermore, orchidectomy impaired blood-flow recovery from hindlimb ischemia, a finding rescued by androgen treatment. Our findings suggest that endogenous androgens modulate angiogenesis in a sex-dependent manner, with implications for the role of androgen replacement in men.

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.

Correlates of low testosterone and symptomatic androgen deficiency in a population-based sample

CONTEXT

Risk factors for low testosterone and symptomatic androgen deficiency (AD) may be modifiable.

OBJECTIVE

Our objective was to examine demographic, anthropometric, and medical correlates of low testosterone and symptomatic AD.

DESIGN

Data were used from the Boston Area Community Health Survey, an epidemiological study conducted from 2002-2005.

SETTING

Data were obtained from a community-based random sample of racially and ethnically diverse men.

PATIENTS OR OTHER PARTICIPANTS

Data were available for 1822 men.

MAIN OUTCOME MEASURES

Multivariate logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations of covariates with 1) low testosterone and 2) symptomatic AD. The operational definition of low testosterone was serum total testosterone less than 300 ng/dl and free testosterone less than 5 ng/dl; symptomatic AD was defined as the additional presence of symptoms: any of low libido, erectile dysfunction, or osteoporosis or two or more of sleep disturbance, depressed mood, lethargy, or diminished physical performance.

RESULTS

Factors associated with low testosterone included age (OR = 1.36; 95% CI= 1.11-1.66, per decade), low per-capita income ($6000 or less per household member vs. more than $30,000; OR = 2.86; 95% CI = 1.39-5.87), and waist circumference (per 10-cm increase; OR = 1.75; 95% CI = 1.45-2.12). Only age (OR = 1.36; 95% CI = 1.04-1.77), waist circumference (OR = 1.88; 95% CI = 1.44-2.47), and health status (OR = 0.21; 95% CI = 0.05-0.92, excellent vs. fair/poor) were associated with our construct of symptomatic AD. Of all variables, waist circumference was the most important contributor in both models.

CONCLUSIONS

Waist circumference is a potentially modifiable risk factor for low testosterone and symptomatic AD. Manifestation of symptoms may be a consequence of generally poor health status.

The natural history of symptomatic androgen deficiency in men: onset, progression, and spontaneous remission

OBJECTIVES

To describe the onset, progression, and remission of symptomatic androgen deficiency (SAD) using longitudinal data from the Massachusetts Male Aging Study (MMAS).

DESIGN

A prospective, population-based study of men living in Boston, Massachusetts. Data were collected in three waves: T1 (1987/89), T2 (1995/97), T3 (2002/04). Onset, progression, and remission were defined in terms of transitions in SAD status from one wave to the next.

SETTING

In-person, in-home interviews.

PARTICIPANTS

Seven hundred sixty-six community-dwelling men aged 40 to 70 at baseline (T1) contributed data from T1 to T2 and 391 from T2 to T3.

MEASUREMENTS

SAD was defined in terms of serum total and free testosterone (T) levels and symptoms associated with low circulating androgens. Total T and sex hormone-binding globulin (SHBG) were measured using radioimmunoassay. Free T was calculated from total T and SHBG measurements.

RESULTS

At T2 or T3, the likelihood of SAD was markedly greater for subjects who had exhibited SAD at the previous wave (odds ratio=3.8, 95% confidence interval=1.9-7.4), overall 55% of subjects who exhibited SAD experienced remission by the next study wave. The probability of SAD was greater with older age and greater body mass index. Multivariate models demonstrated that the likelihood of remission was at least 50% for most subpopulations.

CONCLUSION

Over approximately 15 years of follow-up, SAD did not represent a stable health state. The likelihood of SAD would remit exceeded the likelihood that it would not, particularly among younger and leaner men.

Androgen administration to aged male mice increases anti-anxiety behavior and enhances cognitive performance

Although androgen secretion is reduced with aging, and may underlie decrements in cognitive and affective performance, the effects and mechanisms of androgens to mediate these behaviors are not well understood. Testosterone (T), the primary male androgen, is aromatized to estrogen (E(2)), and reduced to dihydrotestosterone (DHT), which is converted to 5alpha-androstane, 3alpha, 17beta-diol (3alpha-diol). To ascertain whether actions of the neuroactive metabolite of T, 3alpha-diol, mediates cognitive and affective behaviors, intact, aged male C57/B6 mice (24 month old) as well as young, intact and gonadectomized (GDX; 12 week old) mice were administered s.c. T, 3alpha-diol, E(2), or sesame oil vehicle (1 mg/kg; n=4-5/group) at weekly intervals and 1 h later mice were tested in the activity box, roto-rod, open field, elevated plus maze, zero maze, mirror maze, dark-light transition, forced swim, or Vogel tasks. Mice were trained in the inhibitory avoidance or conditioned contextual fear and were administered hormones following training and then were tested. After the last test occasion, tissues were collected for evaluation of hormone levels and effects on gamma-aminobutyric acid (GABA)-stimulated chloride flux. T, 3alpha-diol, or E(2) increased anti-anxiety and antidepressant behavior of aged, intact mice in the open field, light-dark transition, mirror maze, and forced swim tasks. T or 3alpha-diol, but not E(2), enhanced anti-anxiety behavior in the elevated plus maze, zero maze, and the Vogel task, and increased motor behavior in the activity monitor, latency to fall in the Roto-rod task, and cognitive performance in the hippocampally-mediated, but not the amygdala-mediated, portion of the conditioned fear task and in the inhibitory avoidance task. Anti-anxiety and enhanced cognitive performance was associated with regimen that increased plasma and hippocampal 3alpha-diol levels and GABA-stimulated chloride flux. Similar patterns were seen among young, adult GDX but not in intact mice. Thus, 3alpha-diol can enhance affective and cognitive behavior of male mice.

Testosterone therapy and obstructive sleep apnea: is there a real connection?

INTRODUCTION

With the recent increased recognition and treatment of hypogonadism in men, a caution has been given that testosterone replacement therapy (TRT) may cause or aggravate obstructive sleep apnea syndrome (OSA).

AIM

To evaluate the scientific data behind the cautionary statements about TRT and OSA.

MAIN OUTCOME MEASURES

Methodology and criteria for such studies and evaluation of documents and results based on methodology, duration, and outcome of treatment.

METHODS

A review of the literature on the subject of TRT and OSA was performed. The possible mechanisms of action of TRT, on breathing and respiration during sleep were explored.

RESULT

Historically, the first such caution came in 1978. Since then, a few similar incidence reports have been cited. The total number of patients in such reports was very small, very disproportional to the millions of patients treated with TRT. Also, there was a lack of consistent findings connecting TRT to OSA. In addition, different results may occur with physiologic replacement vs. supraphysiologic doses in regard to breathing and OSA. The studies showing the effect of TRT on OSA and breathing were all case studies with small numbers of subjects and showed little effect of TRT on OSA in the majority of case reports. Only one study using supraphysiologic doses was a double-blind, placebo-controlled study, which showed a development of OSA in healthy pooled subjects. The other reports were case studies with limited numbers of subjects, suggesting an inconsistent effect of supraphysiologic TRT on OSA and breathing.

CONCLUSION

Cautionary statements about TRT in OSA appear frequently in the TRT literature and guidelines, despite lack of convincing evidence that TRT causes and/or aggravates OSA. Also, there is a lack of consistency in the findings connecting TRT to OSA. It is evident that the link between TRT and OSA is weak, based on methodological issues in many of the studies, and most studies involved small numbers of men. Further studies in this area are needed.

The relative contributions of aging, health, and lifestyle factors to serum testosterone decline in men

CONTEXT

Although it is known that serum testosterone (T) concentrations decline with age, the relative contributions of changes in health and lifestyle to that decline have not been adequately assessed.

OBJECTIVE

The objective of this study was to establish the relative importance of aging, health, and lifestyle in contributing to male T decline.

DESIGN

A prospective cohort study of health and endocrine functioning in randomly selected men with a baseline visit (T1, 1987-1989) and two follow-up visits (T2, 1995-1997; T3, 2002-2004) was conducted.

SETTING

An observational study of men residing in greater Boston, Massachusetts, was conducted.

PARTICIPANTS

Participants included 1667 men aged 40 to 70 at baseline; follow-up was conducted on 947 (57%) and 584 (35%) at T2 and T3, respectively.

MAIN OUTCOME MEASURES

Main outcome measures included total serum T, calculated free T (FT), and SHBG.

RESULTS

There were substantial declines in total serum T and FT levels associated with aging alone. However, many health and lifestyle changes were associated with accelerated decline. A 4- to 5-kg/m2 increase in body mass index or loss of spouse was associated with declines in total serum T comparable to that associated with approximately 10 yr of aging. Results were similar for FT, but fewer factors were associated with SHBG after age was taken into account.

CONCLUSIONS

Both chronological aging and changes in health and lifestyle factors are associated with declines in serum T. Comorbidities and lifestyle influences may be as strongly associated with declining T levels as is aging itself over the short- to midterm. These results suggest the possibility that age-related hormone decline may be decelerated through the management of health and lifestyle factors.

A population-level decline in serum testosterone levels in American men

CONTEXT

Age-specific estimates of mean testosterone (T) concentrations appear to vary by year of observation and by birth cohort, and estimates of longitudinal declines in T typically outstrip cross-sectional decreases. These observations motivate a hypothesis of a population-level decrease in T over calendar time, independent of chronological aging.

OBJECTIVE

The goal of this study was to establish the magnitude of population-level changes in serum T concentrations and the degree to which they are explained by secular changes in relative weight and other factors.

DESIGN

We describe a prospective cohort study of health and endocrine functioning in randomly selected men of age 45-79 yr. We provide three data collection waves: baseline (T1: 1987-1999) and two follow-ups (T2: 1995-1997, T3: 2002-2004).

SETTING

This was an observational study of randomly selected men residing in greater Boston, Massachusetts.

PARTICIPANTS

Data obtained from 1374, 906, and 489 men at T1, T2, and T3, respectively, totaling 2769 observations taken on 1532 men.

MAIN OUTCOME MEASURES

The main outcome measures were serum total T and calculated bioavailable T.

RESULTS

We observe a substantial age-independent decline in T that does not appear to be attributable to observed changes in explanatory factors, including health and lifestyle characteristics such as smoking and obesity. The estimated population-level declines are greater in magnitude than the cross-sectional declines in T typically associated with age.

CONCLUSIONS

These results indicate that recent years have seen a substantial, and as yet unrecognized, age-independent population-level decrease in T in American men, potentially attributable to birth cohort differences or to health or environmental effects not captured in observed data.

Influence of sex steroid hormones on cerebrovascular function

The cerebral vasculature is a target tissue for sex steroid hormones. Estrogens, androgens, and progestins all influence the function and pathophysiology of the cerebral circulation. Estrogen decreases cerebral vascular tone and increases cerebral blood flow by enhancing endothelial-derived nitric oxide and prostacyclin pathways. Testosterone has opposite effects, increasing cerebral artery tone. Cerebrovascular inflammation is suppressed by estrogen but increased by testosterone and progesterone. Evidence suggests that sex steroids also modulate blood-brain barrier permeability. Estrogen has important protective effects on cerebral endothelial cells by increasing mitochondrial efficiency, decreasing free radical production, promoting cell survival, and stimulating angiogenesis. Although much has been learned regarding hormonal effects on brain blood vessels, most studies involve young, healthy animals. It is becoming apparent that hormonal effects may be modified by aging or disease states such as diabetes. Furthermore, effects of testosterone are complicated because this steroid is also converted to estrogen, systemically and possibly within the vessels themselves. Elucidating the impact of sex steroids on the cerebral vasculature is important for understanding male-female differences in stroke and conditions such as menstrual migraine and preeclampsia-related cerebral edema in pregnancy. Cerebrovascular effects of sex steroids also need to be considered in untangling current controversies regarding consequences of hormone replacement therapies and steroid abuse.