Increased carotid atherosclerosis in andropausal middle-aged men

Testosterone deficiency syndrome and cardiovascular health: An assessment of beliefs, knowledge and practice patterns of general practitioners and cardiologists in Victoria, BC

INTRODUCTION

Testosterone deficiency syndrome (TDS) has been shown to be an independent cardiovascular risk factor and a predisposing factor for metabolic syndrome. As general practitioners and cardiologists primarily care for these patients, we sought to assess their knowledge, beliefs and practice patterns with respect to TDS and cardiac health.

METHODS

We distributed a questionnaire to all 20 cardiologists and a cohort of 128 family practitioners in Victoria, British Columbia. Of the 13 questions, 10 assessed knowledge and beliefs on TDS and 3 assessed current practice patterns.

RESULTS

Most respondents believed that TDS is a medical condition (66.7%) and could negatively affect body composition (62%), but a similar majority was unsure whether it was a cardiac risk factor (66.7%). While most believed that testosterone replacement therapy (TRT) could improve exercise tolerance (62%), most were unsure if it was beneficial in cardiac patients. Cardiologists were significantly less likely to believe that TRT was beneficial in preventing recurrent myocardial infarction and improving myocardial perfusion (p = 0.0133, 0.00186, respectively). The vast majority (88%) did not screen cardiac patients for TDS. If a patient was identified as having TDS, only10% of those surveyed would refer these patients to a urologist.

CONCLUSION

Despite its prevalence in cardiac patients, TDS is not well-understood by general practitioners and cardiologists; they lack knowledge on its deleterious cardiovascular effects. In their role as men's health advocates, urologists should educate our colleagues regarding the correlation between TDS and cardiovascular mortality and risk factors. Limitations of this study include small sample size and restricted geographic scope.

The Relationship between Testosterone Deficiency and Men's Health

Testosterone is important in the physiology of various organs and tissues. The serum testosterone concentration gradually declines as one of the processes of aging. Thus, the concept of late-onset hypogonadism has gained increasing attention in the last few years. Reported symptoms of late-onset hypogonadism are easily recognized and include diminished sexual desire and erectile quality, particularly in nocturnal erections, changes in mood with concomitant decreases in intellectual activity and spatial orientation, fatigue, depression and anger, a decrease in lean body mass with associated decreases in muscle volume and strength, a decrease in body hair and skin alterations, and decreased bone mineral density resulting in osteoporosis. Among these various symptoms, sexual dysfunction has been the most common and necessary to treat in the field of urology. It is well known that a low serum testosterone level is associated with erectile dysfunction and hypoactive sexual libido and that testosterone replacement treatment can improve these symptoms in patients with hypogonadism. Recently, in addition to sexual dysfunction, a close relationship between metabolic syndrome, characterized by central obesity, insulin resistance, dyslipidemia, and hypertension, and late-onset hypogonadism has been highlighted by several epidemiologic studies. Several randomized control trials have shown that testosterone replacement treatment significantly decreases insulin resistance in addition to its advantage for obesity. Furthermore, metabolic syndrome is one of the major risk factors for cardiovascular disease, and a low serum testosterone level is closely related to the development of atherosclerosis. Presently, it is speculated that a low serum testosterone level may increase the risk for cardiovascular disease. Thus, testosterone is a key molecule in men's health, especially that of elderly men.

Testosterone: a vascular hormone in health and disease

Coronary heart disease is a leading cause of premature death in men. Epidemiological studies have shown a high prevalence of low serum testosterone levels in men with cardiovascular disease (CVD). Furthermore, a low testosterone level is associated in some but not in all observational studies with an increase in cardiovascular events and mortality. Testosterone has beneficial effects on several cardiovascular risk factors, which include cholesterol, endothelial dysfunction and inflammation: key mediators of atherosclerosis. A bidirectional relationship between low endogenous testosterone levels and concurrent illness complicates attempts to validate causality in this association and potential mechanistic actions are complex. Testosterone is a vasoactive hormone that predominantly has vasodilatory actions on several vascular beds, although some studies have reported conflicting effects. In clinical studies, acute and chronic testosterone administration increases coronary artery diameter and flow, improves cardiac ischaemia and symptoms in men with chronic stable angina and reduces peripheral vascular resistance in chronic heart failure. Although the mechanism of the action of testosterone on vascular tone in vivo is not understood, laboratory research has found that testosterone is an L-calcium channel blocker and induces potassium channel activation in vascular smooth muscle cells. Animal studies have consistently demonstrated that testosterone is atheroprotective, whereas testosterone deficiency promotes the early stages of atherogenesis. The translational effects of testosterone between in vitro animal and human studies, some of which have conflicting effects, will be discussed in this review. We review the evidence for a role of testosterone in vascular health, its therapeutic potential and safety in hypogonadal men with CVD, and some of the possible underlying mechanisms.

Testosterone-induced effects on lipids and inflammation

Chronic pain has to be considered in all respects a debilitating disease and 10-20% of the world's adult population is affected by this disease. In the most general terms, pain is symptomatic of some form of dysfunction and (often) the resulting inflammatory processes in the body. In the study of pain, great attention has been paid to the possible involvement of gonadal hormones, especially in recent years. In particular, testosterone, the main androgen, is thought to play a beneficial, protective role in the body. Other important elements to be related to pain, inflammation, and hormones are lipids, heterogenic molecules whose altered metabolism is often accompanied by the release of interleukins, and lipid-derived proinflammatory mediators. Here we report data on interactions often not considered in chronic pain mechanisms.

Occurrence of erectile dysfunction, testosterone deficiency syndrome and metabolic syndrome in patients with abdominal obesity. Where is a sufficient level of testosterone?

AIM

The aim of this study was to determine the prevalence of erectile dysfunction (ED), testosterone deficiency syndrome (TDS), and metabolic syndrome in patients with abdominal obesity (AO) and the prevalence of morbidity at different levels of testosterone (TST).

BACKGROUND

Male sex hormones play an important role in ED and variety of TDS and may have influence on the development of metabolic syndrome. The number of men with AO which constitutes a serious health risk is continuously growing. Currently, there are different views that TST levels are already insufficient, and the patient should benefit from treatment.

OBJECTIVES

This study examined the association between ED, testosterone level and metabolic syndrome in men with AO.

DESIGN, SETTING, AND PARTICIPANTS

The study was carried out in an outpatient urology center of Urology Clinic and Obesity Center of the Clinic of Internal Medicine. There were 167 participants—men with AO which were examined as part of preventive examination.

METHODS

Hormonal, a complete urological and internal evaluation was carried out in every patient.

RESULTS AND LIMITATIONS

We found some degree of ED in 73% (122/167) in men with AO. The TST levels below 14 nmol/l had of these 122 patients 84 patients (68.9%) and 49 patients (40.2%) below 10 nmol/l. In this group of patients, we found 103/167 patients (61.7%) with metabolic syndrome. When we compared TST level and morbidity, we found significantly more patients with diabetes mellitus (DM), hypertension and dyslipidemia in group with TST below 10 nmol/l. We also found difference in the levels of HDL cholesterol and triglycerides in the group of patients with TST 10–14 and over 14 nmol/l.

CONCLUSION

Patients over 40 years of age with AO and ED should also be examined for TDS and metabolic syndrome. In this group of patients we found that 113/167 patients (67.6%) had total TST below 14 nmol/l, and sufficient level of TST seems to be above this level.

Do low testosterone levels contribute to ill-health during male ageing?

Testosterone regulates male sexual development and body composition. In adult men, testosterone levels exhibit a gradual decline with increasing age. Whether it is age per se or health and behaviour related factors that are responsible for this decline, and the implications thereof for subsequent health remain controversial. Observational studies report associations of lower testosterone levels with poorer health outcomes in ageing men, including frailty, reduced sexual activity, insulin resistance and cardiovascular events and mortality. However, outcome data from randomised clinical trials of testosterone are limited, and are lacking for major endpoints such as cardiovascular events. The risks and benefits of testosterone intervention in older men require further clarification. This article will review the role of testosterone in men, discuss epidemiological and interventional data illuminating its potential role to preserve health during male ageing, consider the limitations of the evidence base and implications for clinical practice, and explore future directions for research in this topical area.

The 20-year public health impact and direct cost of testosterone deficiency in U.S. men

INTRODUCTION

Testosterone deficiency (TD) imposes a substantial public health burden in the U.S. We modeled the costs associated with TD-related sequelae including cardiovascular disease (CVD), diabetes mellitus (DM), and osteoporosis-related fractures (ORFs).

AIM

To quantify the incremental cost burden imposed by TD's cardiometabolic sequelae.

METHOD

Incidence, prevalence, and mortality of these conditions were collected for men ages 45-74 from six national databases and large cross-sectional studies. Relative risk (RR) rates were determined for these sequelae in patients with T < 300 ng/dL. The prevalence of TD was determined for this cohort of men.

MAIN OUTCOME MEASURES

Adjusted incidence and prevalence were determined. Annual costs for the three TD-related sequelae were inflated at a real rate of 3% for 20 years.

RESULTS

Actual and adjusted (normalized for T deficiency) rates of CVD, DM, and ORFs in U.S. men aged 45-74 assuming a TD prevalence of 13.4% were calculated. We determined that, over a 20-year period, T deficiency is projected to be involved in the development of approximately 1.3 million new cases of CVD, 1.1 million new cases of DM, and over 600,000 ORFs. In year 1, the attributed cost burden of these diseases was approximately $8.4 billion. Over the entire 20-year period, T deficiency may be directly responsible for approximately $190-$525 billion in inflation-adjusted U.S. health care expenditures.

CONCLUSION

TD may be a significant contributor to adverse public health. Further study is needed to definitively describe the whether TD is a modifiable risk factor for CVD, DM, and ORFs. This may represent an opportunity for nationwide public health initiatives aimed at preventive care.

Endogenous androgen deficiency enhances diet-induced hypercholesterolemia and atherosclerosis in low-density lipoprotein receptor-deficient mice

BACKGROUND

Despite numerous clinical and animal studies, the role of sex steroid hormones on lipoprotein metabolism and atherosclerosis remain controversial.

OBJECTIVE

We sought to determine the effects of endogenous estrogen and testosterone on lipoprotein levels and atherosclerosis using mice fed a low-fat diet with no added cholesterol.

METHODS

Male and female low-density lipoprotein receptor-deficient mice were fed an open stock low-fat diet (10% of kcals from fat) for 2, 4, or 17 weeks. Ovariectomy, orchidectomy, or sham surgeries were performed to evaluate the effects of the presence or absence of endogenous hormones on lipid levels, lipoprotein distribution, and atherosclerosis development.

RESULTS

Female mice fed the study diet for 17 weeks had a marked increase in levels of total cholesterol, triglycerides, apolipoprotein-B containing lipoproteins, and atherosclerosis compared with male mice. Surprisingly, ovariectomy in female mice had no effect on any of these parameters. In contrast, castration of male mice markedly increased total cholesterol concentrations, triglycerides, apolipoprotein B-containing lipoproteins, and atherosclerotic lesion formation compared with male and female mice.

CONCLUSIONS

These data suggest that endogenous androgens protect against diet-induced increases in cholesterol concentrations, formation of proatherogenic lipoproteins, and atherosclerotic lesions formation. Conversely orchidectomy, which decreases androgen concentrations, promotes increases in cholesterol concentrations, proatherogenic lipoprotein formation, and atherosclerotic lesion formation in low-density lipoprotein receptor-deficient mice in response to a low-fat diet.

Andropause and the development of cardiovascular disease presentation-more than an epi-phenomenon

Andropause refers to a generalized decline of male hormones, including testosterone and dehydroepiandrosterone in middle-aged and aging men. This decline in hormones has been associated with changes such as depression, loss of libido, sexual dysfunction, and changes in body composition. Aging has been associated with an abundance of concomitant diseases, in particular cardiovascular diseases, and although andropause is correlated to aging, a causal relationship between reduction of androgens and the development of chronic diseases such as atherosclerosis and heart failure has not been convincingly established yet. On the other hand, increasing data has emerged that revealed the effects of low levels of androgens on cardiovascular disease progression. As an example, low levels of testosterone have been linked to a higher incidence of coronary artery disease. Whether hormone replacement therapy that is used for andropausal men to alleviate symptoms of "male menopause" can halt progression of cardiovascular disease, remains controversially discussed, primarily due to the lack of well-designed, randomized controlled trials. At least for symptom improvement, the use of androgen replacement therapy in andropausal men may be clinically indicated, and with the appropriate supervision and follow up may prove to be beneficial with regard to preservation of the integrity of cardiovascular health at higher ages.

Low free testosterone in HIV-infected men is not associated with subclinical cardiovascular disease

OBJECTIVES

Low testosterone (T) is associated with cardiovascular disease (CVD) and increased mortality in the general population; however, the impact of T on subclinical CVD in HIV disease is unknown. This study examined the relationships among free testosterone (FT), subclinical CVD, and HIV disease.

METHODS

This was a cross-sectional analysis in 322 HIV-uninfected and 534 HIV-infected men in the Multicenter AIDS Cohort Study. Main outcomes were coronary artery calcification presence, defined as a coronary artery calcium (CAC) score  >10 (CAC score was the geometric mean of the Agatston scores of two computed tomography replicates), and far wall common carotid intima-media thickness (IMT)/carotid lesion presence by B-mode ultrasound.

RESULTS

Compared with the HIV-uninfected men in our sample, HIV-infected men were younger, with lower body mass index (BMI) and more often Black. HIV-infected men had lower FT (age-adjusted FT 88.7 ng/dL vs. 101.7 ng/dL in HIV-uninfected men; P=0.0004); however, FT was not associated with CAC, log carotid IMT, or the presence of carotid lesions. HIV status was not associated with CAC presence or log carotid IMT, but was associated with carotid lesion presence (adjusted odds ratio 1.69; 95% confidence interval 1.06, 2.71) in HIV-infected men compared with HIV-uninfected men.

CONCLUSIONS

Compared with HIV-uninfected men, HIV-infected men had lower FT, as well as more prevalent carotid lesions. In both groups, FT was not associated with CAC presence, log carotid IMT, or carotid lesion presence, suggesting that FT does not influence subclinical CVD in this population of men with and at risk for HIV infection.

Effects of androgens on cardiovascular remodeling

Androgens, the male sex hormones, exert various biological effects on many target organs through the transcriptional effects of the nuclear androgen receptor (AR). ARs are expressed not only in classical target organs, such as the brain, genital organs, bone, and skeletal muscles, but also in the cardiovascular system. Because the female sex hormones estrogens are well-known to protect against cardiovascular disease, sex has been considered to have a significant clinical impact on cardiovascular mortality. However, the influence of androgens on the cardiovascular system has not been fully elucidated. To clarify this issue, we analyzed the effects of administration of angiotensin II and doxorubicin, an anticancer agent, in a loading model in male wild-type and AR-deficient mice. In this review, we focus on the actions of androgens as potential targets for the prevention of cardiovascular diseases in males.

Low plasma testosterone and elevated carotid intima-media thickness: importance of low-grade inflammation in elderly men

CONTEXT AND OBJECTIVE

An inverse correlation between plasma testosterone levels and carotid intima-media thickness (IMT) has been reported in men. We investigated whether this association could be mediated or modified by traditional cardiovascular risk factors as well as inflammatory status.

METHODS

In the Three-City population-based cohort study, 354 men aged 65 and over had available baseline data on hormones levels and carotid ultrasonography. Plasma concentrations of testosterone (total and bioavailable), estradiol and sex hormone-binding globulin (SHBG), together with cardiovascular risk factors were measured. IMT in plaque-free site and atherosclerotic plaques in the extracranial carotid arteries were determined using a standardized protocol. Multiple linear regression models were used to analyze this association and interaction study.

RESULTS

Analyses with and without adjustment for cardiovascular risk factors showed that carotid IMT was inversely and significantly correlated with total and bioavailable testosterone levels but not with SHBG and estradiol levels. This association depended on C-reactive protein (CRP) levels (p for interaction <0.05). Among men with low-grade inflammation (CRP ≥2 mg/L), mean IMT was higher in subjects with bioavailable testosterone ≤ 3.2 ng/mL than in those with bioavailable testosterone > 3.2 ng/mL (0.76 mm and 0.70 mm respectively, p < 0.01). By contrast, among men with CRP ≤ 2 mg/L, mean IMT was similar in both groups (0.72 mm and 0.71 mm respectively, p = 0.77). Similar results were found for total testosterone although not significant. No association was found between plasma hormones levels and atherosclerotic plaques.

CONCLUSION

In elderly men, low plasma testosterone is associated with elevated carotid intima-media thickness only in those with low-grade inflammation. Traditional risk factors have no mediator role.

Inverse relationship between bioavailable testosterone and subclinical coronary artery calcification in non-obese Korean men

Although low testosterone levels in men have been associated with high risk for cardiovascular disease, little is known about the association between male sex hormones and subclinical coronary disease in men with apparently low cardiometabolic risk. This study was performed to investigate the association between male sex hormones and subclinical coronary artery calcification measured as coronary calcium score in non-obese Korean men. We examined the relationship of total testosterone, sex hormone-binding globulin, bioavailable testosterone and free testosterone with coronary calcium score in 291 non-obese Korean men (mean age: 52.8±9.3 years) not having a history of cardiovascular disease. Using multiple linear regression, we evaluated associations between log (sex hormone) levels and log (coronary calcium score) after adjusting for confounding variables in 105 men with some degree of coronary calcification defined as coronary calcium score ≥ 1. In multiple linear regression analysis, bioavailable testosterone was inversely associated with coronary calcium score (P=0.046) after adjusting for age, body mass index, smoking status, alcohol consumption, regular exercise, mean blood pressure, resting heart rate, C-reactive protein, fasting plasma glucose, total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, hypertension medication and hyperlipidemia medication, whereas total testosterone, sex hormone-binding globulin and free testosterone were not (P=0.674, P=0.121 and P=0.102, respectively). Our findings indicate that bioavailable testosterone is inversely associated with the degree of subclinical coronary artery calcification in non-obese men.

Clomiphene citrate is safe and effective for long-term management of hypogonadism

OBJECTIVE

To assess the efficacy and safety of long-term clomiphene citrate (CC) therapy in symptomatic patients with hypogonadism (HG).

PATIENTS AND METHODS

Serum T, oestradiol and luteinizing hormone (LH) were measured in patients who were treated with CC for over 12 months. Additionally, bone densitometry (BD) results were collected for all patients. Demographic, comorbidity, treatment and Androgen Deficiency in Aging Men (ADAM) score data were also recorded. Comparison was made between baseline and post-treatment variables, and multivariable analysis was conducted to define predictors of successful response to CC. The main outcome measures were predictors of response and long-term results with long-term CC therapy in hypogonadal patients.

RESULTS

The 46 patients (mean age 44 years) had baseline serum testosterone (T) levels of 228 ng/dL. Follow-up T levels were 612 ng/dL at 1 year, 562 ng/dL at 2 years, and 582 ng/dL at 3 years (P < 0.001). Mean femoral neck and lumbar spine BD scores improved significantly. ADAM scores (and responses) fell from a baseline of 7 to a nadir of 3 after 1 year. No adverse events were reported by any patients.

CONCLUSIONS

Clomiphene citrate is an effective long-term therapy for HG in appropriate patients. The drug raises T levels substantially in addition to improving other manifestations of HG such as osteopenia/osteoporosis and ADAM symptoms.

Men's health in primary care: an emerging paradigm of sexual function and cardiometabolic risk

An office evaluation of men's health in primary care requires a thorough understanding of the implications of male sexual dysfunctions, hypogonadism, and cardiometabolic risk stratification and aggressive risk management. The paradigm of the men's health office visit in primary care is the recognition and assessment of male sexual dysfunction, specifically erectile dysfunction, and its value as a signal of overall cardiometabolic health, including the emerging evidence linking low testosterone and the metabolic syndrome. Indeed, erectile dysfunction may now be thought of as a harbinger of cardiovascular clinical events and other systemic vascular diseases in some men.

Low serum free testosterone level is associated with carotid intima-media thickness in middle-aged Japanese men

In the present study, we measured carotid artery intima-media thickness (CIMT) and assessed several metabolic factors in middle-aged healthy Japanese men to clarify the relation between testosterone and atherosclerosis. The study comprised 176 male employees aged ≥40 years who visited Osaka University Healthcare Center for their annual health examinations. Serum total testosterone (TT) concentration was measured using radioimmunoassay (RIA) and serum free testosterone concentration was measured using analog ligand RIA (aFT). A multivariate model adjusted for age, body mass index, mean arterial pressure and treatment for hypertension demonstrated a significant association between aFT and CIMT. Even after adjustment for other clinically relevant factors, the significant association between aFT and CIMT was not attenuated. After adjustment for all other clinically relevant factors, both univariate and multivariate models ascertained the stepwise association that a level of aFT of ≤10.0 pg/mL was significantly associated with CIMT. However, the association between TT and CIMT was not significant in either univariate or multivariate models. We conclude that our finding showing that low serum aFT level is an influencing and independent risk factor for CIMT is of value in the clinical setting because no other studies, to our knowledge, have conducted multivariate analyses using the various metabolic factors included in the present analyses.

Endogenous testosterone and brachial artery endothelial function in middle-aged men with symptoms of late-onset hypogonadism

In aging men, serum endogenous testosterone is inversely associated with common carotid intima-media thickness (IMT) and directly with beneficial plasma lipid levels; however, the relationship to endothelial function is poorly characterized. We examined the association between serum testosterone and endothelium-dependent brachial artery flow-mediated dilatation (FMD) in middle-aged to elderly men. A group of 83 men aged 40?69 years (mean 55.9 ± 7.5 [SD]) with andropausal symptoms were studied. We measured their serum lipids, testosterone, luteinizing hormone, mean carotid IMT and brachial artery FMD by high resolution B-mode ultrasound. Brachial FMD correlated inversely with vessel diameter (r = -0.38, p = 0.0004), alcohol consumption (r = -0.22, p = 0.047) and serum testosterone (r = -0.27, p = 0.01), but not with luteinizing hormone. In multivariate analysis, FMD was explained by testosterone (β = -0.17, p = 0.0226), high density lipoprotein cholesterol (β = 4.17, p = 0.0312) and vessel diameter (β = -4.37, p < 0.0001) when adjusted for age, body mass index, triglycerides, blood pressure, carotid IMT, smoking, alcohol consumption, cardiovascular diseases and use of lipid lowering medication (HMG-CoA reductase inhibitors). In middle-aged to elderly men, there is an inverse correlation between serum testosterone and brachial FMD. These data suggest that testosterone may have an adverse effect on systemic endothelial function.

Testosterone deficiency

Testosterone deficiency (TD) afflicts approximately 30% of men aged 40-79 years, with an increase in prevalence strongly associated with aging and common medical conditions including obesity, diabetes, and hypertension. A strong relationship is noted between TD and metabolic syndrome, although the relationship is not certain to be causal. Repletion of testosterone (T) in T-deficient men with these comorbidities may indeed reverse or delay their progression. While T repletion has been largely thought of in a sexual realm, we discuss its potential role in general men's health concerns: metabolic, body composition, and all-cause mortality through the use of a single clinical vignette. This review examines a host of studies, with practical recommendations for diagnosis of TD and T repletion in middle-aged and older men, including an analysis of treatment modalities and areas of concerns and uncertainty.

Vitamin E dose-dependently reduces aortic fatty lesion formation in orchidectomized aged rats

BACKGROUND AND AIMS

Although the cardioprotective effects of supplemental doses of vitamin E have been investigated in several conditions, its role in gonadectomy- induced fatty lesion formation is unclear. The present study was designed to examine the efficacy of vitamin E in a dose-dependent manner on indices of oxidative stress and in preventing the formation of aortic fatty lesions in orchidectomized (Orx) aged rats.

METHODS

Forty 12-month old male Sprague-Dawley rats were either sham-operated (Sham) or Orx and fed a semi-purified control diet for 120 days. Thereafter, rats were assigned to four treatment groups (n=10): Sham and one Orx group received 75 IU vitamin E and served as controls, and the other two Orx groups received either 250 or 500 IU vitamin E per kg diet for 90 days.

RESULTS

Vitamin E at the highest dose (500 IU) was able to lower serum total cholesterol by 16% and significantly increase superoxide dismutase by 9% compared to Orx controls. Similarly, this dose was able to significantly reduce the development of atherosclerotic lesion formation and aortic fatty streak area by 93% compared to Orx controls.

CONCLUSIONS

The findings of this study suggest that dietary vitamin E supplementation in Orx aged rats provide anti-atherogenic effects, in part, due to vitamin E's antioxidative properties. Clinical studies are needed to confirm whether supplemental doses of vitamin E can prevent the development of atherosclerosis in older men particularly with low testosterone level.

Androgen receptor-dependent and independent atheroprotection by testosterone in male mice

The atheroprotective effect of testosterone is thought to require aromatization of testosterone to estradiol, but no study has adequately addressed the role of the androgen receptor (AR), the major pathway for the physiological effects of testosterone. We used AR knockout (ARKO) mice on apolipoprotein E-deficient background to study the role of the AR in testosterone atheroprotection in male mice. Because ARKO mice are testosterone deficient, we sham operated or orchiectomized (Orx) the mice before puberty, and Orx mice were supplemented with placebo or a physiological testosterone dose. From 8 to 16 wk of age, the mice consumed a high-fat diet. In the aortic root, ARKO mice showed increased atherosclerotic lesion area (+80%, P < 0.05). Compared with placebo, testosterone reduced lesion area both in Orx wild-type (WT) mice (by 50%, P < 0.001) and ARKO mice (by 24%, P < 0.05). However, lesion area was larger in testosterone-supplemented ARKO compared with testosterone-supplemented WT mice (+57%, P < 0.05). In WT mice, testosterone reduced the presence of a necrotic core in the plaque (80% among placebo-treated vs. 12% among testosterone-treated mice; P < 0.05), whereas there was no significant effect in ARKO mice (P = 0.20). In conclusion, ARKO mice on apolipoprotein E-deficient background display accelerated atherosclerosis. Testosterone treatment reduced atherosclerosis in both WT and ARKO mice. However, the effect on lesion area and complexity was more pronounced in WT than in ARKO mice, and lesion area was larger in ARKO mice even after testosterone supplementation. These results are consistent with an AR-dependent as well as an AR-independent component of testosterone atheroprotection in male mice.

Androgens and cardiovascular disease

PURPOSE OF REVIEW

There is increasing interest in age-related changes in sex hormone levels as a potentially treatable cause of ill-health in men. Relationships between androgens and cardiovascular disease will be discussed, with particular attention to more recently published research.

RECENT FINDINGS

In middle-aged and older men, lower testosterone levels are associated with insulin resistance, metabolic syndrome and diabetes, interrelated conditions that predispose to cardiovascular disease. The relationship between androgens and preclinical atherosclerosis requires confirmation. Nevertheless, lower testosterone levels predict cardiovascular events, such as stroke and transient ischaemic attack, in older men and are associated with higher cardiovascular and overall mortality. Testosterone is aromatized to oestradiol, and both higher and lower oestradiol levels have been associated with cardiovascular risk. Randomized trials have shown that testosterone supplementation in men with existing coronary artery disease can be protective against myocardial ischaemia. However, additional interventional studies are needed with endpoints of cardiovascular events.

SUMMARY

Observational studies continue to relate reduced circulating testosterone to cardiovascular risk, atherosclerosis and mortality in men. The role of oestradiol as a marker for cardiovascular disease requires clarification. Larger randomized trials are needed to establish whether hormonal therapy would reduce the burden of cardiovascular disease in ageing men.

Endogenous estrogen levels are associated with endothelial function in males independently of lipid levels

Estrogens and androgens may play an important role in vascular health in both sexes. The aim of this study was to examine the relation of endogenous sex hormone levels with early markers of atherosclerosis in a cohort of apparently healthy males. 124 males (age 46.25 ± 9.56) attending a preventive medicine program were examined for unrecognised features of the metabolic syndrome. Flow-mediated dilatation (FMD) and intima-media thickness (IMT) of the common carotid artery were evaluated. Obesity parameters were recorded; estradiol, testosterone, SHBG, free testosterone, insulin, as well as glucose and lipid levels were measured. FMD was positively correlated with estradiol (r = 0.201, P = 0.041) and negatively with total cholesterol (r = -0.205, P = 0.022), low density lipoproteins (r = -0.232, P = 0.009), and triglyceride levels (r = -0.179, P = 0.046). In multivariate analysis, the association of FMD with estrogen was independent of BMI and lipid levels. No significant association between FMD and testosterone levels was found. Subjects with an increased mean IMT (> 0.73 mm, i.e., > 3rd tertile) had lower levels of free (P = 0.021) and bioavailable (P = 0.016) testosterone. In multivariate logistic regression analysis, this association was no longer significant when age or cholesterol levels were considered. Endogenous estrogen levels are associated with FMD, independently of age and lipid levels, showing a protective effect in middle-age male subjects. Circulating androgens are associated, although not independently, with structural changes such as the IMT of carotid artery; this effect is possibly influenced by lipid levels and age.

Adiposity predicts carotid intima-media thickness in healthy children and adolescents

OBJECTIVE

To examine whether anthropometric measurements, blood pressure (BP), fasting total cholesterol, and low-density lipoprotein are related to ultrasound measures of carotid intima-media thickness (CIMT) in children and teenagers with no known risk factors for cardiovascular disease.

STUDY DESIGN

This cross-sectional study included 599 subjects, 6 to 20 years of age (292 males, 307 females; 224 Hispanics, 210 European-Americans, 126 African-Americans, and 39 Asian-Americans) whose body mass index, waist circumference, BP, lipid profiles, and values for CIMT were determined.

RESULTS

Measures of CIMT were significantly greater in males than females (P=.006) and in African-Americans when compared with other ethnic groups (all P < .05). There were no relations between age, diastolic BP, or fasting levels of triglycerides, total cholesterol, or low-density lipoprotein values and CIMT measures, regardless of sex or ethnic background. Stratified multiple regression analysis indicated that body mass index and waist circumference independently predicted CIMT in both males and females, even after controlling for age, weight, BP, fasting lipid levels, and ethnic background.

CONCLUSION

Increased body mass and adiposity are associated with increased intima-media thickness in children and teenagers. This association is present in children not considered overweight, underscoring the need for the continued promotion of adequate nutritional and physical exercise behavior during childhood.

Androgen receptor-dependent transactivation of growth arrest-specific gene 6 mediates inhibitory effects of testosterone on vascular calcification

Recent epidemiological studies have found that androgen deficiency is associated with a higher incidence of cardiovascular disease in men. However, little is known about the mechanism underlying the cardioprotective effects of androgens. Here we show the inhibitory effects of testosterone on vascular calcification and a critical role of androgen receptor (AR)-dependent transactivation of growth arrest-specific gene 6 (Gas6), a key regulator of inorganic phosphate (P(i))-induced calcification of vascular smooth muscle cells (VSMC). Testosterone and nonaromatizable androgen dihydrotestosterone inhibited P(i)-induced calcification of human aortic VSMC in a concentration-dependent manner. Androgen inhibited P(i)-induced VSMC apoptosis, an essential process for VSMC calcification. The effects on VSMC calcification were mediated by restoration of P(i)-induced down-regulation of Gas6 expression and a subsequent reduction of Akt phosphorylation. These effects of androgen were blocked by an AR antagonist, flutamide, but not by an estrogen receptor antagonist, ICI 182,780. We then explored the mechanistic role of the AR in Gas6 expression and found an abundant expression of AR predominantly in the nucleus of VSMC and two consensus ARE sequences in the Gas6 promoter region. Dihydrotestosterone stimulated Gas6 promoter activity, and this effect was abrogated by flutamide and by AR siRNA. Site-specific mutation revealed that the proximal ARE was essential for androgen-dependent transactivation of Gas6. Furthermore, chromatin immunoprecipitation assays demonstrated ligand-dependent binding of the AR to the proximal ARE of Gas6. These results indicate that AR signaling directly regulates Gas6 transcription, which leads to inhibition of vascular calcification, and provides a mechanistic insight into the cardioprotective action of androgens.

Androgen deficiency and atherosclerosis: The lipid link

The relationship between androgen deficiency and atherosclerosis is complex, poorly understood, and remains controversial. The aim of this review is to evaluate the data in the literature to determine if androgen deficiency modulates lipid profiles and contributes to atherosclerosis development or progression. Studies in animals and humans suggest that androgen deficiency is associated with increased triglycerides (TGs), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C). Although the effects of androgen deficiency on high-density lipoprotein cholesterol (HDL-C) remains controversial, recent data suggest that androgen therapy is associated with increased levels of HDL-C and may improve reverse cholesterol transport. Animal studies suggested that androgen deprivation adversely affect lipid profiles and this was reversed by androgen treatment. Furthermore, androgen treatment of hypogonadal men significantly improved lipid profiles. Emerging data indicate that androgens play an important role in lipid metabolism. Therefore androgens are critical in the prevention and progression of atherosclerosis. Androgen deficiency contributes to increased TGs, TC, LDL-C and reduced HDL-C while androgen treatment results in a favorable lipid profile, suggesting that androgens may provide a protective effect against the development and/or progression of atherosclerosis.

Lower testosterone levels predict incident stroke and transient ischemic attack in older men

CONTEXT

Lower circulating testosterone concentrations are associated with metabolic syndrome, type 2 diabetes, carotid intima-media thickness, and aortic and lower limb arterial disease in men. However, it is unclear whether lower testosterone levels predict major cardiovascular events.

OBJECTIVE

We examined whether lower serum testosterone was an independently significant risk factor for symptomatic cerebrovascular events in older men.

DESIGN

This was a prospective observational study with median follow-up of 3.5 yr.

SETTING

Community-dwelling, stroke-free older men were studied.

PARTICIPANTS

A total of 3443 men at least 70 yr of age participated in the study.

MAIN OUTCOME MEASURES

Baseline serum total testosterone, SHBG, and LH were assayed. Free testosterone was calculated using mass action equations. Incident stroke or transient ischemic attack (TIA) was recorded.

RESULTS

A first stroke or TIA occurred in 119 men (3.5%). Total and free testosterone concentrations in the lowest quartiles (<11.7 nmol/liter and <222 pmol/liter) were associated with reduced event-free survival (P = 0.014 and P = 0.01, respectively). After adjustment including age, waist-hip ratio, waist circumference, smoking, hypertension, dyslipidemia, and medical comorbidity, lower total testosterone predicted increased incidence of stroke or TIA (hazard ratio = 1.99; 95% confidence interval, 1.33-2.99). Lower free testosterone was also associated (hazard ratio = 1.69; 95% confidence interval, 1.15-2.48), whereas SHBG and LH were not independently associated with incident stroke or TIA.

CONCLUSIONS

In older men, lower total testosterone levels predict increased incidence of stroke or TIA after adjusting for conventional risk factors for cardiovascular disease. Men with low-normal testosterone levels had increased risk. Further studies are warranted to determine whether interventions that raise circulating testosterone levels might prevent cerebrovascular disease in men.

Gender differences in the cardiovascular effect of sex hormones

The higher incidence of cardiovascular disease in men than in women of similar age, and the menopause-associated increase in cardiovascular disease in women, has led to speculation that gender-related differences in sex hormones have a key role in the development and evolution of cardiovascular disease. Compelling data have indicated that sex differences in vascular biology are determined not only by gender-related differences in sex steroid levels, but also by gender-specific tissue and cellular differences that mediate sex-specific responses. In this Review, we describe the sex-specific effects of estrogen and testosterone on cardiovascular risk, direct vascular effects of these sex hormones, and how these effects influence development of atherosclerosis. Cardiovascular effects of exogenous hormone administration are also discussed. Importantly, evidence has indicated that estrogens alone or in combination with progestins in postmenopausal women increase cardiovascular risk if started late after menopause, but that it possibly has beneficial cardiovascular effects in younger postmenopausal women, although data on long-term testosterone therapy are lacking. Hormone therapy should not be considered solely for primary prevention or treatment of cardiovascular disease at this time.

Androgen-androgen receptor system protects against angiotensin II-induced vascular remodeling

Age-related andropause promotes cardiovascular disease in males. Although we had previously reported that the androgen-androgen receptor (AR) system plays important roles in cardiac growth and remodeling, the system's involvement in vascular remodeling remains unclear. To clarify this role, 25-wk-old male AR knockout (ARKO) mice and littermate male wild-type (WT) mice were divided into two groups with and without angiotensin II (Ang II) administration (2.0 mg/kg . d) for 14 d, respectively. No morphological differences in the coronary artery and thoracic aorta were observed between the groups without Ang II. Ang II stimulation markedly increased medial thickness and perivascular fibrosis in ARKO mice, with enhanced TGF-beta1, collagen type I, and collagen type III gene expression in the aorta. Ang II stimulation also prominently increased superoxide production, lipid peroxidation, and gene expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase components in ARKO mice compared with WT mice. In addition, phosphorylation of c-Jun N-terminal kinase (JNK) and phosphorylated (Smad2/3) was remarkably enhanced in Ang II-treated ARKO mice compared with Ang II-treated WT mice. Notably, daily urinary nitric oxide (NO) metabolites excretion as a marker of NO bioavailability, aortic endothelial NO synthase expression and phosphorylation, and Akt phosphorylation were significantly reduced in ARKO mice compared with WT mice, regardless of Ang II stimulation. In conclusion, the androgen-AR system is required for the preservation of NO bioavailability through Akt-endothelial NO synthase system activation and exerts protective effects against Ang II-induced vascular remodeling by regulating oxidative stress, c-Jun N-terminal kinase (JNK) signaling, and the TGF-beta-phosphorylated Smad pathway.

The benefits and risks of testosterone replacement therapy: a review

Increased longevity and population aging will increase the number of men with late onset hypogonadism. It is a common condition, but often underdiagnosed and undertreated. The indication of testosterone-replacement therapy (TRT) treatment requires the presence of low testosterone level, and symptoms and signs of hypogonadism. Although controversy remains regarding indications for testosterone supplementation in aging men due to lack of large-scale, long-term studies assessing the benefits and risks of testosterone-replacement therapy in men, reports indicate that TRT may produce a wide range of benefits for men with hypogonadism that include improvement in libido and sexual function, bone density, muscle mass, body composition, mood, erythropoiesis, cognition, quality of life and cardiovascular disease. Perhaps the most controversial area is the issue of risk, especially possible stimulation of prostate cancer by testosterone, even though no evidence to support this risk exists. Other possible risks include worsening symptoms of benign prostatic hypertrophy, liver toxicity, hyperviscosity, erythrocytosis, worsening untreated sleep apnea or severe heart failure. Despite this controversy, testosterone supplementation in the United States has increased substantially over the past several years. The physician should discuss with the patient the potential benefits and risks of TRT. The purpose of this review is to discuss what is known and not known regarding the benefits and risks of TRT.

The effects of endogenous and exogenous androgens on cardiovascular disease risk factors and progression

Cardiovascular disease incidence rates have long been known to significantly differ between the two sexes. Estrogens alone fail to explain this phenomenon, bringing an increasing amount of attention to the role of androgens. Contrary to what was initially hypothesized, androgens seem to have an overall cardioprotective effect, especially in men. Recent studies and published data continue to support this notion displaying a consistent inverse correlation with atherosclerosis progression and cardiovascular disease both in regressive and prospective study models. Clinical studies have also revealed what seems to be a differential androgenic effect on various cardiovascular risk factors between men and women. Further insight indicates that in order to avoid confusion it may be also preferable to separately examine the effects of endogenous androgen levels from exogenous testosterone administration, as well as discern the differential results of low to normal and supraphysiological administration doses. This review summarizes old and recent data according to the above distinctions, in an attempt to further our understanding of the role of androgens in cardiovascular disease.

Hypogonadotrophic hypogonadism in type 2 diabetes

Recent work shows a high prevalence of low testosterone and inappropriately low luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations in type 2 diabetes. This syndrome of hypogonadotrophic hypogonadism (HH) is associated with obesity in patients with type 2 diabetes. However, the duration of diabetes or HbA1c are not related to HH. Furthermore, recent data show that HH is not associated with type 1 diabetes. C-reactive protein concentrations have been shown to be elevated in patients with HH and are inversely related to plasma testosterone concentrations. This inverse relationship between plasma free testosterone and C- reactive protein concentrations in patients with type 2 diabetes suggests that inflammation may play an important role in the pathogenesis of this syndrome. This is of interest since inflammatory mechanisms may have a cardinal role in the pathogenesis of insulin resistance. It is also relevant that in the mouse, deletion of the insulin receptor in neurons leads to HH in addition to a state of systemic insulin resistance. It has also been shown that insulin facilitates the secretion of gonadotrophin releasing hormone (GnRH) from neuronal cell cultures. Thus, HH may be the result of insulin resistance at the level of the GnRH secreting neuron. Low testosterone concentrations are also related to an increase in total and regional adiposity. This review discusses these issues and attempts to make the syndrome relevant as a clinical entity. Clinical trials are required to determine whether testosterone replacement alleviates insulin resistance and inflammation. In addition, low testosterone levels are associated with an increase in cardiovascular events. Testosterone therapy may therefore, reduce cardiovascular risk. This important aspect requires further investigation.

Need for research on estrogen receptor function: importance for postmenopausal hormone therapy and atherosclerosis

BACKGROUND

Cardiovascular disease is the leading cause of morbidity and mortality in men and women worldwide. Although rare in premenopausal women, its incidence rises sharply after menopause, indicating atheroprotective effects of endogenous estrogens.

OBJECTIVE

This review discusses the differential effects of estrogen receptor function on atherosclerosis progression in pre- and postmenopausal women, including aspects of gender differences in vascular physiology of estrogens and androgens.

METHODS

Recent advances in the understanding of the pathogenesis of atherosclerosis, estrogen receptor function, and hormone therapy are reviewed, with particular emphasis on clinical and molecular issues.

RESULTS

Whether hormone therapy can improve cardiovascular health in postmenopausal women remains controversial. Current evidence suggests that the vascular effects of estrogen are affected by the stage of reproductive life, the time since menopause, and the extent of subclinical atherosclerosis. The mechanisms of vascular responsiveness to sex steroids during different stages of atherosclerosis development remain poorly understood in women and men.

CONCLUSION

In view of the expected increase in the prevalence of atherosclerotic vascular disease worldwide due to population aging, research is needed to determine the vascular mechanism of endogenous and exogenous sex steroids in patients with atherosclerosis. Such research may help to define new strategies to improve cardiovascular health in women and possibly also in men.

Gender and the injured brain

Anesthesiologists are frequently confronted with patients who are at risk for neurological complications due to perioperative stroke or prior traumatic brain injury. In this review, we address the growing and fascinating body of data that suggests gender and sex steroids influence the pathophysiology of injury and outcome for these patients. Cerebral ischemia, traumatic brain injury, and epilepsy are reviewed in the context of potential sex differences in mechanisms and outcomes of brain injury and the role of estrogen, progesterone, and androgens in shaping these processes. Lastly, implications for current and future perioperative and intensive care are identified.