Testosterone differentially regulates targets of lipid and glucose metabolism in liver, muscle and adipose tissues of the testicular feminised mouse.

Testosterone deficiency is commonly associated with obesity, metabolic syndrome, type 2 diabetes and their clinical consequences-hepatic steatosis and atherosclerosis. The testicular feminised mouse (non-functional androgen receptor and low testosterone) develops fatty liver and aortic lipid streaks on a high-fat diet, whereas androgen-replete XY littermate controls do not. Testosterone treatment ameliorates these effects, although the underlying mechanisms remain unknown. We compared the influence of testosterone on the expression of regulatory targets of glucose, cholesterol and lipid metabolism in muscle, liver, abdominal subcutaneous and visceral adipose tissue. Testicular feminised mice displayed significantly reduced GLUT4 in muscle and glycolytic enzymes in muscle, liver and abdominal subcutaneous but not visceral adipose tissue. Lipoprotein lipase required for fatty acid uptake was only reduced in subcutaneous adipose tissue; enzymes of fatty acid synthesis were increased in liver and subcutaneous tissue. Stearoyl-CoA desaturase-1 that catalyses oleic acid synthesis and is associated with insulin resistance was increased in visceral adipose tissue and cholesterol efflux components (ABCA1, apoE) were decreased in subcutaneous and liver tissue. Master regulator nuclear receptors involved in metabolism-Liver X receptor expression was suppressed in all tissues except visceral adipose tissue, whereas PPARγ was lower in abdominal subcutaneous and visceral adipose tissue and PPARα only in abdominal subcutaneous. Testosterone treatment improved the expression (androgen receptor independent) of some targets but not all. These exploratory data suggest that androgen deficiency may reduce the buffering capability for glucose uptake and utilisation in abdominal subcutaneous and muscle and fatty acids in abdominal subcutaneous. This would lead to an overspill and uptake of excess glucose and triglycerides into visceral adipose tissue, liver and arterial walls.

Testosterone suppresses the expression of regulatory enzymes of fatty acid synthesis and protects against hepatic steatosis in cholesterol-fed androgen deficient mice.

AIMS: Non-alcoholic fatty liver disease and its precursor hepatic steatosis is common in obesity and type-2 diabetes and is associated with cardiovascular disease (CVD). Men with type-2 diabetes and/or CVD have a high prevalence of testosterone deficiency. Testosterone replacement improves key cardiovascular risk factors. The effects of testosterone on hepatic steatosis are not fully understood. MAIN METHODS: Testicular feminised (Tfm) mice, which have a non-functional androgen receptor (AR) and very low serum testosterone levels, were used to investigate testosterone effects on high-cholesterol diet-induced hepatic steatosis. KEY FINDINGS: Hepatic lipid deposition was increased in Tfm mice and orchidectomised wild-type littermates versus intact wild-type littermate controls with normal androgen physiology. Lipid deposition was reduced in Tfm mice receiving testosterone treatment compared to placebo. Oestrogen receptor blockade significantly, but only partially, reduced the beneficial effects of testosterone treatment on hepatic lipid accumulation. Expression of key regulatory enzymes of fatty acid synthesis, acetyl-CoA carboxylase alpha (ACACA) and fatty acid synthase (FASN) were elevated in placebo-treated Tfm mice versus placebo-treated littermates and Tfm mice receiving testosterone treatment. Tfm mice on normal diet had increased lipid accumulation compared to littermates but significantly less than cholesterol-fed Tfm mice and demonstrated increased gene expression of hormone sensitive lipase, stearyl-CoA desaturase-1 and peroxisome proliferator-activated receptor-gamma but FASN and ACACA were not altered. SIGNIFICANCE: An action of testosterone on hepatic lipid deposition which is independent of the classic AR is implicated. Testosterone may act in part via an effect on the key regulatory lipogenic enzymes to protect against hepatic steatosis.

Testosterone deficiency is associated with increased risk of mortality and testosterone replacement improves survival in men with type 2 diabetes.

OBJECTIVE: Men with type 2 diabetes are known to have a high prevalence of testosterone deficiency. No long-term data are available regarding testosterone and mortality in men with type 2 diabetes or any effect of testosterone replacement therapy (TRT). We report a 6-year follow-up study to examine the effect of baseline testosterone and TRT on all-cause mortality in men with type 2 diabetes and low testosterone. RESEARCH DESIGN AND METHODS: A total of 581 men with type 2 diabetes who had testosterone levels performed between 2002 and 2005 were followed up for a mean period of 5.81.3 S.D. years. mortality rates were compared between total testosterone 10.4nmol/l (300ng/dl; n=343) and testosterone 10.4nmol/l (n=238). the effect of TRT (as per normal clinical practise: 85.9% testosterone gel and 14.1% intramuscular testosterone undecanoate) was assessed retrospectively within the low testosterone group. RESULTS: Mortality was increased in the low testosterone group (17.2%) compared with the normal testosterone group (9%; P=0.003) when controlled for covariates. In the Cox regression model, multivariate-adjusted hazard ratio (HR) for decreased survival was 2.02 (P=0.009, 95% CI 1.2-3.4). TRT (mean duration 41.6±20.7 months; n=64) was associated with a reduced mortality of 8.4% compared with 19.2% (P=0.002) in the untreated group (n=174). The multivariate-adjusted HR for decreased survival in the untreated group was 2.3 (95% CI 1.3-3.9, P=0.004). CONCLUSIONS: Low testosterone levels predict an increase in all-cause mortality during long-term follow-up. Testosterone replacement may improve survival in hypogonadal men with type 2 diabetes.

Effect of Testosterone on Inflammatory Markers in the Development of Early Atherogenesis in the Testicular-Feminized Mouse Model.

BACKGROUND: Low levels of serum testosterone in men are associated with cardiovascular disease. Clinical studies show that testosterone replacement therapy (TRT) can improve symptoms of cardiovascular disease and reduce the inflammatory burden evident in atherosclerosis. AIM: We used an in vivo animal model to determine whether testosterone influences mediators of vascular inflammation as part of its beneficial effects on atherogenesis. METHODS: Testicular-feminized (Tfm) mice, which express low endogenous testosterone and a non-functional androgen receptor (AR), were used to assess the effect of androgen status on atheroma formation, serum lipids, and inflammatory mediators. Tfm mice were fed a high-cholesterol diet, received saline or physiological (TRT), and were compared to saline-treated XY littermates. RESULTS: A total of 28 weeks of high-cholesterol diet caused fatty streak formation in the aortic root of XY littermates and Tfm mice, an effect significantly amplified in Tfm mice. Tfm mice on normal diet showed elevated serum tumor necrosis factor-α (TFN-α) and interleukin-6 compared to XY littermates. High-cholesterol diet induced increased monocyte chemoattractant protein-1 (MCP-1) in Tfm mice, and TFN-α and MCP-1 in XY littermates. TRT reduced fatty streak formation and serum interleukin-6 in Tfm mice but had no significant effects on lipid profiles. Monocyte/macrophage staining indicated local inflammation in aortic root fatty streak areas of all mice, with TRT reducing local inflammation through plaque reduction in Tfm mice. Fractalkine (CX3CL1) and its receptor (CX3CR1) were present in fatty streaks of all mice fed a high-cholesterol diet, independent of androgen status. CONCLUSION: These results are consistent with AR-dependent and AR-independent anti-inflammatory actions of testosterone in atheroprotection, although the local anti-inflammatory mechanisms via which testosterone acts remain unknown.

Testosterone therapy during exercise rehabilitation in male patients with chronic heart failure who have low testosterone status: a double-blind randomized controlled feasibility study.

BACKGROUND: This study assessed the feasibility of a 12-week program of exercise, with and without intramuscular testosterone supplementation, in male patients with chronic heart failure (CHF) and low testosterone status and collected preliminary data for key health outcomes. METHODS: Male patients with CHF (n = 41, age 67.2 years, range 51-84 years) with mean ± SD testosterone levels of 10.7 ± 2.6 nmol/L (309 ± 76 ng/dL) were randomly allocated to exercise with testosterone or placebo groups. Feasibility was assessed in terms of recruitment, intervention compliance, and attrition. Outcomes included an incremental shuttle walk test, peak oxygen uptake, muscular strength, echocardiographic measures, N-terminal pro-brain natriuretic peptide, inflammatory markers, depression (Beck Depression Inventory), and health-related quality of life (Minnesota Living with Heart Failure Questionnaire and Medical Outcomes Study Short-Form). RESULTS: Attrition was 30% but with 100% compliance to exercise and injections in patients who completed the study. Similar improvements in shuttle walk test (18% vs 19%), body mass (-1.3 kg vs -1.0 kg), and hand grip strength (2.1 kg vs 2.5 kg) from baseline were observed in both groups. The exercise with testosterone group showed improvements from baseline in peak oxygen uptake (P < .01), Beck Depression Inventory (P < .05), leg strength (P < .05), and several Medical Outcomes Study Short-Form quality of life domains (P < .05), which were generally not apparent in the exercise with placebo group. Echocardiographic measures, N-terminal pro-brain natriuretic peptide, and inflammatory markers were mostly unchanged. CONCLUSIONS: This study shows for the first time that testosterone supplementation during a program of exercise rehabilitation is feasible and can positively impact on a range of key health outcomes in elderly male patients with CHF who have a low testosterone status.

Reversible heart failure: toxins, tachycardiomyopathy and mitochondrial abnormalities.

Heart failure is usually a relentless condition associated with a poor prognosis. Triggered by a physiological insult, maladaptive neurohumoral processes result in an ever-spiralling deterioration of cardiovascular function. However, there are certain underlying conditions which are associated with a temporary reduction in contractile function leading to reversible heart failure. These conditions affect a relatively small number of patients when compared with heart failure secondary to inherited cardiomyopathies and ischaemic heart disease. There are two broad mechanisms responsible for reversible myocyte dysfunction: acute inflammatory activation in which cytokines depress myocyte function, and toxic effects in which there is impairment of intra-cellular energetics. In this review, we discuss reversible heart failure caused by toxic effects. These effects can be caused by drugs (prescribed and illicit) and by tachycardic arrhythmia (tachycardiomyopathy), and are caused by abnormalities of mitochondrial function and myocytic calcium processing. The underlying pathological mechanisms, clinical features and management options are discussed, illustrated by clinical case studies.

Testosterone and cardiovascular disease in men.

Despite regional variations in the prevalence of coronary artery disease (CAD), men are consistently more at risk of developing and dying from CAD than women, and the gender-specific effects of sex hormones are implicated in this inequality. This 'Perspectives' article reviews the current evidence regarding the cardiovascular effects of testosterone in men including an examination of the age-related decline in testosterone, the relationship between testosterone levels and coronary disease, coronary risk factors and mortality. We also review the vaso-active effects of testosterone, and discuss how these have been used in men with heart failure and angina. We discuss the 'cause' versus 'effect' controversy, regarding low testosterone levels in men with coronary heart disease, as well as concerns over the use of testosterone replacement therapy in middle aged and elderly men. The article concludes with a discussion regarding the future direction for work in this interesting area, including the relative merits of screening for, and treating hypogonadism with testosterone replacement therapy in men with heart disease.

Testosterone replacement in hypogonadal men with type 2 diabetes and/or metabolic syndrome (the TIMES2 study).

OBJECTIVE: This study evaluated the effects of testosterone replacement therapy (TRT) on insulin resistance, cardiovascular risk factors, and symptoms in hypogonadal men with type 2 diabetes and/or metabolic syndrome (MetS). RESEARCH DESIGN AND METHODS: The efficacy, safety, and tolerability of a novel transdermal 2% testosterone gel was evaluated over 12 months in 220 hypogonadal men with type 2 diabetes and/or MetS in a multicenter, prospective, randomized, double-blind, placebo-controlled study. The primary outcome was mean change from baseline in homeostasis model assessment of insulin resistance (HOMA-IR). Secondary outcomes were measures of body composition, glycemic control, lipids, and sexual function. Efficacy results focused primarily on months 0-6 (phase 1; no changes in medication allowed). Medication changes were allowed in phase 2 (months 6-12). RESULTS: TRT reduced HOMA-IR in the overall population by 15.2% at 6 months (P = 0.018) and 16.4% at 12 months (P = 0.006). In type 2 diabetic patients, glycemic control was significantly better in the TRT group than the placebo group at month 9 (HbA(1c): treatment difference, -0.446%; P = 0.035). Improvements in total and LDL cholesterol, lipoprotein a (Lpa), body composition, libido, and sexual function occurred in selected patient groups. There were no significant differences between groups in the frequencies of adverse events (AEs) or serious AEs. The majority of AEs (>95%) were mild or moderate. CONCLUSIONS: Over a 6-month period, transdermal TRT was associated with beneficial effects on insulin resistance, total and LDL-cholesterol, Lpa, and sexual health in hypogonadal men with type 2 diabetes and/or MetS.

Reversible heart failure: the role of inflammatory activation.

Heart failure is increasingly common in western populations and is an inevitable consequence of the improved survival after myocardial infarction, and of an ageing population. Heart failure is usually relentlessly progressive as the maladaptive processes triggered by the physiological changes of the condition lead to further deterioration. However, in certain circumstances, heart failure is transient or potentially reversible when it occurs as part of intense systemic inflammatory activation. This review considers the role of inflammation in the aetiology of heart failure, and illustrates the strategies which have been used to modify the inflammatory response with anonymised clinical case reports.

Low serum testosterone and increased mortality in men with coronary heart disease.

BACKGROUND: To examine the effect of serum testosterone levels on survival in a consecutive series of men with confirmed coronary disease and calculate the prevalence of testosterone deficiency. DESIGN: Longitudinal follow-up study. SETTING: Tertiary referral cardiothoracic centre. Patients 930 consecutive men with coronary disease referred for diagnostic angiography recruited between June 2000 and June 2002 and followed up for a mean of 6.9±2.1 years. OUTCOME: All-cause mortality and vascular mortality. Prevalence of testosterone deficiency. RESULTS: The overall prevalence of biochemical testosterone deficiency in the coronary disease cohort using bio-available testosterone (bio-T) <2.6 nmol/l was 20.9%, using total testosterone <8.1 nmol/l was 16.9% and using either was 24%. Excess mortality was noted in the androgen-deficient group compared with normal (41 (21%) vs 88 (12%), p=0.002). The only parameters found to influence time to all-cause and vascular mortality (HR ± 95% CI) in multivariate analyses were the presence of left ventricular dysfunction (3.85; 1.72 to 8.33), aspirin therapy (0.63; 0.38 to 1.0), ß-blocker therapy (0.45; 0.31 to 0.67) and low serum bio-T (2.27; 1.45 to 3.6). CONCLUSIONS: In patients with coronary disease testosterone deficiency is common and impacts significantly negatively on survival. Prospective trials of testosterone replacement are needed to assess the effect of treatment on survival.

Testosterone and heart failure.

PURPOSE OF REVIEW: Chronic heart failure (CHF) is a common condition with significant morbidity despite optimal medical therapy. Standard therapy involves inhibiting the maladaptive changes of metabolism and neuro-hormones that characterize the syndrome of CHF. Anabolic deficiency is a major component of the CHF syndrome and testosterone replacement therapy has been subject to recent trials. RECENT FINDINGS: The recent literature shows that physiological testosterone replacement therapy leads to modest improvements in voluntary muscle strength, lean muscle mass, endurance and positive effects on neuro-muscular and baro-receptor reflexes. Long-term efficacy and safety remain unstudied at present. SUMMARY: Testosterone replacement therapy appears to improve metabolism and endurance in patients with CHF; further trials will be necessary before widespread use. Physicians who regularly treat patients with CHF may consider testosterone therapy but it is likely that they will require the advice and support from endocrine specialists.

Neuroendocrine effects on the heart and targets for therapeutic manipulation in heart failure.

Chronic heart failure (CHF) involves derangements in multiple neurohormonal axes leading to a procatabolic state and wasting syndrome associated with significant mortality. Catabolic abnormalities include excess catecholamines and glucocorticoids. Anabolic defects include deficiencies of sex steroids, insulin resistance, and growth hormone (GH) resistance. These abnormalities are also correlated with increased morbidity and mortality in CHF. Anabolic axes have been augmented in pilot studies in CHF with testosterone, GH, insulin-like growth factor-1, and GH secretagogues. Results have been varied although some treatments have been associated with improved surrogate endpoints. This review article explores the current understanding of metabolic derangements in CHF and highlights potential neuroendocrine treatment strategies.

Mechanisms of agonist-induced constriction in isolated human pulmonary arteries.

We determined the calcium signalling pathways involved in the mechanisms of contraction of the vasoconstrictive agonists KCl, U46619 and PDBu in isolated human pulmonary arteries. The influence of gender, vessel diameter and age of the patients was also investigated. Human pulmonary arteries (n = 86) were loaded in a wire myograph and maintained at a tension equivalent to the in vivo pressure of 17.5 mm Hg, bubbled with 95%O2/5%CO2 to maintain pH 7.4 in physiological saline solution (PSS). Cumulative concentration-response curves were obtained to KCl (100 microM-100 mM), U46619 (1 nM-1 microM) or PDBu (1 nM-1 microM), before or after a 30 min incubation with either the voltage-gated calcium channel (VGCC) blocker nifedipine (10 microM), the store-operated calcium channel (SOCC) blocker SK&F96365 (50 microM) or in calcium-free PSS (-Ca2+PSS). The KCl response was partially blocked in -Ca2+PSS and with nifedipine. The U46619 response was partially blocked in -Ca2+PSS and with nifedipine and SK&F96365. Incubation in -Ca2+PSS had no effect on the response to PDBu. Endothelial intact arteries responded significantly higher to U46619 than endothelial denuded arteries. This study demonstrates that KCl induces pulmonary vasoconstriction via activation of extracellular calcium entry through VGCCs, U46619 induces pulmonary vasoconstriction predominantly via activation of VGCCs and PDBu induces pulmonary vasoconstriction via a calcium-independent pathway.

Statin therapy is associated with lower total but not bioavailable or free testosterone in men with type 2 diabetes.

OBJECTIVE: There is a high prevalence of hypogonadism in men with type 2 diabetes. This will lead to an increase in assessments of hypogonadism. Statins could potentially decrease testosterone levels by reducing the availability of cholesterol for androgen synthesis. We compared testosterone levels and hypogonadal symptoms with statin use in a cross-sectional study of 355 men with type 2 diabetes. RESEARCH DESIGN AND METHODS: Total testosterone, sex hormone-binding globulin (SHBG), and estradiol were measured by an enzyme-linked immunosorbent assay. Bioavailable testosterone was measured by the modified ammonium sulfate precipitation method. Free testosterone was calculated using Vermeulen's formula. Symptoms of hypogonadism were assessed using the Androgen Deficiency in the Aging Male questionnaire. RESULTS: Statins were associated with lower total testosterone (11.9 vs. 13.4 nmol/l, P = 0.006) and a trend toward lower SHBG (29.4 vs. 35.3 nmol/l, P = 0.034) compared with no treatment. Bioavailable testosterone, free testosterone, estradiol, and hypogonadal symptoms were not affected. Subanalysis showed that atorvastatin was associated with reduced total testosterone (11.4 vs. 13.4 nmol/l, P = 0.006) and a trend toward reduced SHBG (27.6 vs. 35.3 nmol/l, P = 0.022) compared with no treatment, and there was an apparent dose-response effect with the lowest levels of total testosterone seen in men treated with >or=20 mg atorvastatin (9.6 nmol/l, P = 0.017). Simvastatin use was not associated with significant reductions in testosterone or SHBG levels. CONCLUSIONS: Assessing androgen status using total testosterone in men with type 2 diabetes treated with statins, particularly atorvastatin, may potentially lead to diagnostic error. Levels of bioavailable testosterone or free testosterone are recommended for the assessment of hypogonadism in this group if total testosterone levels are borderline.

Current issues in thromboprophylaxis in the elderly.

The elderly are at particularly high risk for arterial and venous thromboembolism, both of which are associated with significant morbidity and mortality in this age group. However, this age group often receives inadequate thromboprophylaxis because of concerns about bleeding risk, which is often over-estimated, denying patients the benefit of proven antithrombotic regimens. Guidelines advocate active and comprehensive thromboprophylactic strategies across all age groups and recent studies have addressed age considerations in both arterial and venous embolic disorders. Pharmacological thromboprophylaxis has repeatedly been shown to have a favourable risk-benefit profile, including in elderly populations. The benefits of thromboprophylaxis have long been recognized in surgical patients and recent studies have confirmed the safety and efficacy of thromboprophylaxis in medical patients, with most trials having included elderly cohorts. Given the difficulties and inconvenience associated with use of current anticoagulants, new drugs are under development and whilst some have been associated with significant adverse effects, others have demonstrated low bleeding risks without the need for coagulation monitoring. Meanwhile, other new agents currently on the market, such as fondaparinux sodium, have gained license for use in orthopaedic and general surgery patients, although clinical experience with these agents in elderly populations is limited. This article discusses the latest developments and current opinions regarding thromboprophylaxis, with particular emphasis on its relevance to the elderly population.

Rosiglitazone increases bioactive testosterone and reduces waist circumference in hypogonadal men with type 2 diabetes.

The purpose of this study was to assess the effect of rosiglitazone on bioavailable, free and total testosterone levels in hypogonadal men with type 2 diabetes. Sixteen type 2 diabetic men with hypogonadism were studied before and after administration of rosiglitazone (8 mg/day) for six months, with assessments performed every two months on two consecutive days. We measured testosterone and sex hormone binding globulin (SHBG), visceral adiposity, high-sensitivity CRP (hs-CRP), lipids, microalbuminuria and blood pressure. There was a significant increase in free (p=0.01), bioavailable (p=0.007) and total testosterone (p=0.002), as well as SHBG (p=0.03) levels, with rosiglitazone treatment. Waist circumference and waist / hip ratio decreased with the improvement in insulin sensitivity and glycaemic control (p=0.01). There was also a significant reduction in hs-CRP (p=0.02) and urinary albumin excretion. No significant effect on blood pressure or the ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (LDL to HDL) was seen. In conclusion, the insulin-sensitiser rosiglitazone increases bioavailable, free and total testosterone and SHBG levels in hypogonadal men with type 2 diabetes.