Endogenous sex hormones, high density lipoprotein cholesterol, and other lipoprotein fractions in men

Unfavorably altered lipid profile in women with primary ovarian insufficiency

BACKGROUND

Hypoestrogenism related to the cessation of ovarian function increases the risk of metabolic disorders in postmenopausal women. Women with primary ovarian insufficiency (POI) are exposed to longer period of estrogen deficiency together with a subsequently higher risk of long-term comorbidities.

OBJECTIVE

To compare metabolic along with hormonal status among newly diagnosed women with POI with pre- and postmenopausal women. To investigate the impact of POI etiology on both metabolic and hormonal profiles.

METHODS

A case-control study with women assigned to one of the groups: 1) POI (n = 216), 2) age-matched premenopausal (n = 216), 3) postmenopausal (n = 227). Lipid profile, fasting glucose and insulin levels together with insulin resistance were determined among all participants.

RESULTS

POI women exhibited increased both total cholesterol (TC, p = 0.04) and low-density lipoprotein cholesterol (LDL-C, p < 0.01) compared to the premenopausal women and higher triglycerides (TG, p < 0.001) than postmenopausal women. POI group showed higher fasting glucose level (p = 0.04) differently to premenopausal women. The idiopathic POI group showed both lower sex hormone binding globulin (p = 0.02) and dehydroepiandrosterone sulfate (p = 0.04) along with reduced TC (p = 0.03) and TG (p = 0.01) together with increased high-density lipoprotein cholesterol (p = 0.04) levels than non-idiopathic POI women.

CONCLUSION

Women with newly diagnosed POI exhibited less favorable lipid profile than pre- or postmenopausal women. The association of negatively changed lipid profile in POI women is mostly mediated by women with unknown cause of premature ovarian cessation.

The incidence and aggravating factors of male hypogonadism in type 2 diabetes

BACKGROUND: Male hypogonadism is associated with type 2 diabetes mellitus (T2DM), therefore, it is of interest to study its frequency. The clinical symptoms of hypogonadism are not specific, and laboratory diagnostics is the basis for its detection. The optimal method for this diagnostics is isotope dilution liquid chromatography/tandem mass spectrometry, which was used in our study.

 AIMS: Assessment of the incidence and aggravating factors of male hypogonadism in type 2 diabetes

MATERIALS AND METHODS: A full-design, cross-sectional, screening, single-center, non-interventional study included men with T2DM, who were he was treated in Endocrinology Research Centre, Moscow. The study was conducted from October 2021 to January 2022. Medical history assessment, physical examination with determination of body mass index (BMI), measurement estimation of total testosterone by isotope dilution liquid chromatography/tandem mass spectrometry, glycated hemoglobin (HbA1c) and lipid profiles were performed. The groups were compared using the Mann-Whitney U-test for quantitative indicators and χ² with Yates’ correction for qualitative ones. Differences were considered statistically significant with p0,05.

RESULTS: Hypogonadism was detected in 355 (70.3%) men with T2DM. Patients with hypogonadism had statistically significantly higher BMI, worse glycemic control, lower HDL levels, and higher triglycerides than eugonadal men. An additional comparative analysis among non-obese individuals showed the presence of statistically significant differences in the level of HbA1c (higher in hypogonadal men) and HDL (lower in hypogonadal men). An analysis of hypogonadal patients depending on the presence of obesity showed statistically significant differences between groups in the level of total testosterone (lower in obese men) and triglycerides (higher in obese men).

CONCLUSIONS: The prevalence of male hypogonadism in type 2 diabetes was 70,3%. Its development was associated with obesity and poor glycemic control.

The Effects of Testosterone Treatment on Cardiovascular Health

Current evidence suggests that testosterone therapy has numerous benefits and risks on cardiovascular health. Examples of this include published data that support improvements in insulin sensitivity and body composition which may reduce the risk of diabetes. On the other hand, testosterone therapy may offset such benefits by mild impairments in lipid parameters. Consequently, controversy on the effects of testosterone therapy on cardiovascular health remains. Studies are underway to clarify this important question for the benefit of men with hypogonadism.

OX-HDL: A Starring Role in Cardiorenal Syndrome and the Effects of Heme Oxygenase-1 Intervention

In this review, we will evaluate how high-density lipoprotein (HDL) and the reverse cholesterol transport (RCT) pathway are critical for proper cardiovascular-renal physiology. We will begin by reviewing the basic concepts of HDL cholesterol synthesis and pathway regulation, followed by cardiorenal syndrome (CRS) pathophysiology. After explaining how the HDL and RCT pathways become dysfunctional through oxidative processes, we will elaborate on the potential role of HDL dysfunction in CRS. We will then present findings on how HDL function and the inducible antioxidant gene heme oxygenase-1 (HO-1) are interconnected and how induction of HO-1 is protective against HDL dysfunction and important for the proper functioning of the cardiovascular-renal system. This will substantiate the proposal of HO-1 as a novel therapeutic target to prevent HDL dysfunction and, consequently, cardiovascular disease, renal dysfunction, and the onset of CRS.

Basal Endogenous Steroid Hormones, Sex Hormone-Binding Globulin, Physical Fitness, and Health Risk Factors in Young Adult Men

Purpose: Few large-scale population-based studies have adequately examined the relationships between steroid hormones, health status and physical fitness. The purpose of the study was to describe the relationship of serum basal endogenous steroid hormones (testosterone, TES; empirical free testosterone, EFT; cortisol, COR) and sex hormone-binding globulin (SHBG) to body composition, cardiovascular risk factors, and physical fitness in young healthy men.

Methods: Male reservists (25 ± 4 years, N = 846) participated in the study. Basal TES, EFT, COR, and SHBG were measured in morning fasted blood. Stepwise regression analyses were used to examine associations between individual hormones to four separate categories: (1) body composition; (2) cardiovascular risk factors; (3) relative, and (4) absolute physical fitness.

Results: Higher TES, EFT, and SHBG were associated with lower waist circumference (TES: β = -0.239, p < 0.001; EFT: β = -0.385, p < 0.001), % body fat (TES: β = -0.163, p = 0.003), and body mass index (SHBG: β = -0.435, p < 0.001). Lower cardiovascular risk factors were associated with higher TES, EFT and SHBG concentrations, especially between SHBG and triglycerides (β = -0.277, p < 0.001) and HDL (β = 0.154, p < 0.001). Greater maximal relative aerobic capacity was concurrent with higher TES, EFT, and SHBG (β = 0.171, 0.113, 0.263, p < 0.001, =0.005, <0.001, respectively).

Conclusion: Higher basal concentrations of TES, EFT, and SHBG were weakly associated with healthier body composition, fewer cardiovascular risk factors and greater relative aerobic capacity in healthy young men. It would be interesting to investigate whether these relationships are still evident after a few decades, and how different training modes (endurance, strength or their combination) positively affect physical fitness, body composition and their regulatory mechanisms over the decades.

Metabolic and affective consequences of fatherhood in male California mice

Physiological and affective condition can be modulated by the social environment and parental state in mammals. However, in species in which males assist with rearing offspring, the metabolic and affective effects of pair bonding and fatherhood on males have rarely been explored. In this study we tested the hypothesis that fathers, like mothers, experience energetic costs as well as behavioral and affective changes (e.g., depression, anxiety) associated with parenthood. We tested this hypothesis in the monogamous, biparental California mouse (Peromyscus californicus). Food intake, blood glucose and lipid levels, blood insulin and leptin levels, body composition, pain sensitivity, and depression-like behavior were compared in males from three reproductive groups: virgin males (VM, housed with another male), non-breeding males (NB, housed with a tubally ligated female), and breeding males (BM, housed with a female and their first litter). We found statistically significant (P<0.007, when modified for Adaptive False Discovery Rate) or nominally significant (0.007<P<0.05) differences among reproductive groups in relative testis mass, circulating glucose, triglyceride, and insulin concentrations, pain sensitivity, and anxiety-like behaviors. A priori contrasts indicated that VM produced significantly more fecal pellets than BM in the tail-suspension test, had significantly higher glucose levels than NB, and had significantly lower average testis masses than did NB and BM. A priori contrasts also indicated that VM had a nominally longer latency to the pain response than NB and that VM had nominally higher insulin levels than did NB. For breeding males, litter size (one to three pups) was a nominally significant positive predictor of body mass, food consumption, fat mass, and plasma leptin concentration. These results indicate that cohabitation with a female and/or fatherhood influences several metabolic, morphological, and affective measures in male California mice. Overall, the changes we observed in breeding males were minor, but stronger effects might occur in long-term breeding males and/or under more challenging environmental conditions.

Cross-sectional association between physical activity and serum testosterone levels in US men: results from NHANES 1999-2004

Testosterone levels and physical activity each play important roles in men's health, but the relationship between the two remains unclear. We evaluated the cross-sectional association between self-reported total physical activity and serum testosterone levels in 738 men (mean age 42.4 years, range 20-≥85 years) who participated in National Health and Nutrition Examination Survey 1999-2004. We compared geometric mean testosterone concentrations measured by radioimmunoassay (RIA) and calculated the odds ratio (OR) of having low or low normal testosterone (≤3.46 ng/mL) across tertiles of total physical activity in all men, and men stratified by age (20-49, ≥50 years), and obesity status (BMI < 30, ≥30 kg/m(2) ). The geometric mean testosterone concentration was 5.31 ng/mL; 18.6% of the men had low or low normal serum testosterone levels. Physical activity tertiles were not associated with testosterone levels overall, or when stratified by age or obesity status. Similarly, there was no association between physical activity tertiles and the odds of low or low normal testosterone, overall or by age. However, among non-obese men, those in the highest physical activity tertile were significantly less likely to have low or low normal testosterone than those in the lowest tertile (OR 0.50; 95% CI = 0.26-0.95); there was no association among obese men. Greater physical activity was not associated with testosterone levels, but may be associated with a reduced odds of low or low normal testosterone in non-obese men, but not in obese men.

Impact of Diet-Induced Obesity and Testosterone Deficiency on the Cardiovascular System: A Novel Rodent Model Representative of Males with Testosterone-Deficient Metabolic Syndrome (TDMetS)

INTRODUCTION

Current models of obesity utilise normogonadic animals and neglect the strong relationships between obesity-associated metabolic syndrome (MetS) and male testosterone deficiency (TD). The joint presentation of these conditions has complex implications for the cardiovascular system that are not well understood. We have characterised and investigated three models in male rats: one of diet-induced obesity with the MetS; a second using orchiectomised rats mimicking TD; and a third combining MetS with TD which we propose is representative of males with testosterone deficiency and the metabolic syndrome (TDMetS).

METHODS

Male Wistar rats (n = 24) were randomly assigned to two groups and provided ad libitum access to normal rat chow (CTRL) or a high fat/high sugar/low protein "obesogenic" diet (OGD) for 28 weeks (n = 12/group). These groups were further sub-divided into sham-operated or orchiectomised (ORX) animals to mimic hypogonadism, with and without diet-induced obesity (n = 6/group). Serum lipids, glucose, insulin and sex hormone concentrations were determined. Body composition, cardiovascular structure and function; and myocardial tolerance to ischemia-reperfusion were assessed.

RESULTS

OGD-fed animals had 72% greater fat mass; 2.4-fold greater serum cholesterol; 2.3-fold greater serum triglycerides and 3-fold greater fasting glucose (indicative of diabetes mellitus) compared to CTRLs (all p<0.05). The ORX animals had reduced serum testosterone and left ventricle mass (p<0.05). In addition to the combined differences observed in each of the isolated models, the OGD, ORX and OGD+ORX models each had greater CK-MB levels following in vivo cardiac ischemia-reperfusion insult compared to CTRLs (p<0.05).

CONCLUSION

Our findings provide evidence to support that the MetS and TD independently impair myocardial tolerance to ischemia-reperfusion. The combined OGD+ORX phenotype described in this study is a novel animal model with associated cardiovascular risk factors and complex myocardial pathology which may be representative of male patients presenting with TDMetS.

An update on testosterone, HDL and cardiovascular risk in men

Testosterone prescriptions have risen steadily and sharply in the USA despite a lack of clear understanding of the relationship between androgens and cardiovascular disease. In men with increasing age, testosterone levels decline and cardiovascular disease risk goes up. Ties between hypogonadism and cardiovascular disease are suggested by observational data, yet therapy with testosterone replacement has not been shown to mitigate that risk. To the contrary, recent literature has raised concern for increased cardiovascular disease in certain groups of men receiving testosterone therapy. In this article, we review current literature in an attempt to better understand what it suggests is the true relationship between testosterone and cardiovascular disease. We also take a closer look at effects of testosterone on lipids and HDL in particular, to see if this explains the cardiovascular effects seen in clinical studies.

Androgen activity, ischaemic heart disease and risk factors among men in NHANES III

AIM

Observationally, low serum testosterone among men is associated with cardiovascular diseases and its risk factors, but it is unclear whether raising endogenous androgens would be protective. To clarify the role of androgens, the association of two different androgen biomarkers (serum testosterone and androstanediol glucuronide) with cardiovascular disease risk factors and mortality was examined in a nationally representative sample of US men.

RESEARCH DESIGN AND METHODS

Multivariable linear and proportion hazards regression were used to examine the adjusted associations of serum testosterone and androstanediol glucuronide with cardiovascular disease risk factors and death from major cardiovascular diseases in 1460 men from NHANES III phase 1 (1988-1991) followed-up through 2006.

RESULTS

Serum testosterone and androstanediol glucuronide were weakly correlated (0·13). Serum testosterone was associated with healthier values of most cardiovascular disease risk factors but not with death from ischaemic heart disease or stroke, adjusted for age, education, race/ethnicity, smoking and alcohol use. Similarly adjusted, androstanediol glucuronide was associated with unhealthier values of some cardiovascular risk factors and death from ischaemic heart disease (hazard ratio 1·16, 95% confidence interval 1·003-1·33 per standard deviation).

CONCLUSIONS

Androgen biomarkers had inconsistent associations with cardiovascular disease risk factors and ischaemic heart disease. Androstanediol glucuronide, rather than serum testosterone, had associations with cardiovascular disease risk factors more similar to those seen in randomized controlled trials of testosterone therapy, with corresponding implications for raising androgens.

Association of serum testosterone with lipid abnormalities in patients with angiographically proven coronary artery disease

CONTEXT

Low testosterone levels are associated with an atherogenic lipid profile and may contribute to the pathogenesis of atherosclerosis.

AIMS

Our study aimed to investigate the relationship between serum total testosterone (TT) levels and lipid profile in angiographically confirmed coronary artery disease (CAD) in men.

SETTINGS AND DESIGN

This is a case-control hospital-based study at Teaching Hospital, Karapitiya, Galle, Sri Lanka.

MATERIALS AND METHODS

Two hundred and six men, 103 with angiographically proven CAD and 103 healthy men as a control group were studied. The serum levels of TT and lipids were assessed.

STATISTICAL ANALYSIS

Data were analyzed using Minitab software (version 15 for Windows).

RESULTS

THE MEAN CONCENTRATIONS OF LIPID PARAMETERS OF PATIENTS AND CONTROLS WERE AS FOLLOWS: Serum total cholesterol (TCh), 5.9 ± 2.8 vs. 5.2 ± 1.6 mmol/l (P = 0.022), low-density lipoprotein cholesterol (LDL-Ch), 3.9 ± 1.2 vs. 3.1 ± 0.5 mmol/l (P = 0.001), high-density lipoprotein cholesterol (HDL-Ch), 1.1 ± 0.5 vs. 1.4 ± 0.6 mmol/l (P = 0.001), and TGs, 2.0 ± 1.0 vs. 1.5 ± 0.8 mmol/l (P = 0.001); lipid levels were significantly different between the two groups. The mean levels of TT in the patients and controls were 11.4 ± 2.7 vs. 18.1 ± 7.2 nmol/l (P = 0.001), significantly different. Among CAD patients, a significant positive association was found between testosterone and HDL-Ch (r = 0.623, P = 0.001), whereas a negative association was found with LDL-Ch (r = -0.579, P = 0.001).

CONCLUSIONS

Low levels of TT in men with CAD that appear together with an atherogenic lipid milieu may be involved in the pathogenesis of CAD. The observed association between testosterone and HDL-Ch suggests a protective effect of the hormone.

The Rancho Bernardo Study: 40 years studying why women have less heart disease than men and how diabetes modifies women's usual cardiac protection

Forty years ago, few cohort studies of cardiovascular disease (CVD) included women and fewer still included diabetes or glycemia as a risk factor. I describe here the Rancho Bernardo Study (RBS), a single-site, >40-year cohort study of sex differences in heart disease and how diabetes modifies women's natural cardioprotection. More than 6000 participants were followed for morbidity and mortality, with nearly 3000 survivors (and death certificates for >85% of decedents). In RBS more than half of diabetes was undiagnosed without an oral glucose tolerance test (OGTT); more women than men had isolated post-challenge hyperglycemia (IPH) as their only glucose evidence of diabetes; men had more diabetes than women, with higher fasting but lower post-challenge glucose levels than women; women with diabetes had more classical CVD risk factors than men; excess risk-factor clustering partially explained how diabetes eradicates female cardioprotection. Post-challenge glucose was a stronger CVD risk factor than fasting glucose. Endogenous insulin was not an independent CVD risk factor in women or men. Men with higher testosterone levels developed less diabetes and had fewer metabolic syndrome components. In men higher total testosterone levels predicted a reduced risk of all-cause and CVD but not cancer mortality. In women both extremes of bioavailable testosterone predicted fatal coronary heart disease but not all-cause mortality. Summary point estimates from large systematic reviews of individual data have replicated most RBS findings. Ongoing research can further clarify how diabetes modifies women's cardioprotection from mid-life to old age.

The effect of androgens on lipids

PURPOSE OF REVIEW

To review recent data concerning the relationship between endogenous testosterone and lipids as well as testosterone replacement therapy and lipids. To describe the effects of sex hormones on cardiovascular disease (CVD) that may act via serum lipids.

RECENT FINDINGS

Low endogenous testosterone is associated with high low-density lipoprotein and low high-density lipoprotein in both cross-sectional and prospective observational studies. Exogenous testosterone administration is associated with decreased high-density lipoprotein coupled with beneficial decreases in low-density lipoprotein and total cholesterol. The overall impact of testosterone administration on CVD is still unclear, with mixed safety results from recent randomized controlled trials.

SUMMARY

There may be CVD risk reduction benefits, including an improved lipid profile, from testosterone administration in hypogonadal men. The overall effect of testosterone on CVD risk has not been definitively determined.

Steroid sex hormones for lower limb atherosclerosis

BACKGROUND

There is accumulating evidence that steroid sex hormones have a beneficial effect on a number of risk factors for peripheral arterial disease.

OBJECTIVES

The objective of this review was to determine whether exogenous steroid sex hormones are an effective treatment for patients with lower limb atherosclerosis.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched August 2012) and CENTRAL 2012, Issue 7. There were no language restrictions.

SELECTION CRITERIA

We selected randomised or quasi-randomised controlled trials of steroid sex hormones in patients with lower limb atherosclerosis.

DATA COLLECTION AND ANALYSIS

Both authors extracted data and assessed trial quality independently. Whenever possible investigators were contacted to obtain information needed for the review that could not be found in published reports.

MAIN RESULTS

Four trials appeared to meet the inclusion criteria, but one was excluded because of poor methodology. The three remaining trials compared testosterone treatment with placebo in a total of 109 subjects with intermittent claudication or critical leg ischaemia. The most recent trial to meet the inclusion criteria dated from 1971. No trials were available which investigated the potentially beneficial effects of oestrogenic hormones in women with lower limb atherosclerosis.Testosterone therapy produced no significant improvement in tests of walking distance or in a variety of other objective tests for peripheral arterial disease, including venous filling time, muscle blood flow and plethysmography. The relative risk for subjective improvement in symptoms using the combined trial results was also non-significant (relative risk (RR) 1.10, 95% confidence interval (CI) 0.81 to 1.48).

AUTHORS' CONCLUSIONS

There is no evidence to date that short-term testosterone treatment is beneficial in subjects with lower limb atherosclerosis. However, this might reflect limited data rather than the lack of a real effect.

Plasma testosterone is associated with Framingham risk score

INTRODUCTION

The Framingham risk score predicts a patient's 10-year risk of developing cardiovascular disease. Many risk factors included in its calculation influence or are influenced by circulating testosterone. To investigate the possible association between testosterone and cardiovascular risk, as defined by the Framingham score, a Veterans Affairs (VA) database was analyzed.

METHODS

A retrospective chart review was performed. Inclusion criteria were male sex and age ≥ 20 years. Exclusion criteria included pre-existing cardiovascular disease, stroke, and diabetes. Data were collected on veterans who had total plasma testosterone checked in the year 2008.

RESULTS

The study included 1,479 patients (mean age 61 years). Framingham score was negatively associated with both total testosterone (p < 0.0001) and free testosterone (p = 0.0003). There was a positive association between total testosterone and high-density lipoprotein and negative associations between total testosterone and body mass index (BMI), total cholesterol, triglycerides, and blood pressure medication use. Free testosterone was positively associated with total cholesterol, low-density lipoprotein, and current smoking status and negatively associated with age, BMI, and blood pressure medication use. The BMI was not associated with Framingham score.

CONCLUSIONS

Lower plasma testosterone may suggest the presence of cardiovascular risk factors and potentially increased risk for heart disease.

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

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

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.

Plasma testosterone in adult normoglycaemic men: impact of hyperinsulinaemia

This study analysed the relationship of plasma testosterone with β-cell secretion, insulin sensitivity and other pituitary-target gland hormones in normoglycaemic adult men. The sample frame was the 'Offspring of individuals with diabetes study' database. A total of 358 offspring of individuals with type-2 diabetes (T2DM) and 287 individuals without known family history of T2DM were recruited for the study. Normoglycaemic men aged ≥18 years (maximum 55) were selected for this analysis. All participants underwent 75 g oral glucose tolerance test (OGTT); blood samples were collected at 0, 30, 60 and 120 min for plasma insulin and C-peptide. Total testosterone, cortisol, adrenocorticotropic hormone, thyroid stimulating hormone and thyroxine (T4) were measured in the fasting sample. A total of 164 men (age 28 ± 7.7 years) were included in analysis. Testosterone correlated negatively with BMI, waist to hip ratio (WHR), area under curve (AUC) of C-peptide and insulin (during OGTT) and was positively correlated with insulin sensitivity (r ~ 0.4). Cortisol and T4 positively correlated (weak) with testosterone (r ~ 0.2). In multivariate analysis, AUC C-peptide, BMI, WHR (negatively) and cortisol (positively) were related to testosterone. Concluding, testosterone correlated negatively with BMI and β-cell secretion. There was a positive association of testosterone with insulin sensitivity, cortisol and T4.

Ideal lipid profile and genes for an extended life span

PURPOSE OF REVIEW

The world population is aging and a rapid increase is being seen in the very elderly (aged >80 years). Cholesterol levels in general rise with age and high cholesterol has been associated with extreme longevity. The relationship between lipids and cardiovascular events in the extreme elderly is unclear.

RECENT FINDINGS

A number of genetic factors associated with lipid metabolism have also been described as having potential antiaging roles, including the genes encoding lipoprotein-associated factors - apolipoprotein E and cholesterol ester transfer protein; adipose tissue metabolism - adiponectin, leptin, glycaemia; and blood pressure - angiotensinogen. Clinical trials of lipid-lowering therapies have recruited subgroups of moderately elderly patients, but only the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) trial specifically recruited an elderly population. There is no direct equivalent of the Hypertension in the Very Elderly trial (HYVET) study of antihypertensive patients in the extreme elderly. No heterogeneity has been seen with the effects of statin therapy in the elderly compared with younger age groups on classical cardiovascular endpoints of coronary heart disease and stroke.

SUMMARY

The optimal cholesterol target, long-term tolerability and the specific effects of statins on other vascular-associated diseases of aging, for example arterial aneurysms, microvascular renal and cerebral disease (dementias), remain to be determined.

Prospective association of low total testosterone concentrations with an adverse lipid profile and increased incident dyslipidemia

BACKGROUND

Earlier studies have suggested that total testosterone concentrations influence the lipid metabolism. Whether these concentrations are prospectively associated with an adverse lipid profile and an increased risk of incident dyslipidemia has not yet been investigated.

METHODS AND RESULTS

Our study population consisted of 1468 men, aged 20–79 years, who were repeatedly examined as part of the population-based Study of Health in Pomerania. Serum total testosterone concentrations measured by the chemiluminescent enzyme immunoassays were categorized into age-specific quartiles. We used generalized estimating equations models to assess the prospective association between total testosterone concentrations and lipid profile components including total cholesterol (TC), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride (TG) concentrations, as well as incident dyslipidemia after 5 years of follow-up. Multivariate models revealed that total testosterone concentrations in the lowest quartile were associated with higher TC and TG concentrations in both cross-sectional [TC: 0.23 mmol/l (95% confidence interval, CI, 0.02–0.42); TG: 0.73 mmol/l (95% CI, 0.53–0.94)] and longitudinal analyses [TC: 0.20 mmol/l (95% CI, 0.03–0.27); TG: 0.62 mmol/l (95% CI, 0.43–0.80)], but not with high-density lipoprotein cholesterol or low-density lipoprotein cholesterol concentrations. Baseline prevalence of dyslipidemia was 57.1% with a crude incidence rate of 46.6 per 1000 person-years. Total testosterone concentrations in the lowest quartile predicted dyslipidemia; age-adjusted relative risks (RR) for men in quartiles 1, 2, and 3 as compared to quartile 4 (highest, reference) were 1.28 (95% CI, 1.06–1.54), 1.10 (95% CI, 0.91–1.33), and 1.05 (95% CI, 0.86–1.29), respectively. This effect was particularly strong among men aged 20–39 years (relative risk, 1.51; 95% CI, 1.08–2.10).

CONCLUSION

Low total testosterone concentrations are prospectively associated with an adverse lipid profile and increased risk of incident dyslipidemia. These findings are particularly interesting and may contribute to an explanation for the higher cardiovascular disease risk in men with lower total testosterone concentrations.

Bioactive androgens and glucuronidated androgen metabolites are associated with subcutaneous and ectopic skeletal muscle adiposity among older black men

Aging is associated with declining serum levels of androgenic hormones and with increased skeletal muscle fat infiltration, an emerging risk factor for type 2 diabetes mellitus (T2DM). Androgens regulate fat mass and glucose homeostasis, but the effect of androgenic hormones on skeletal muscle fat infiltration is largely unknown. Thus, the aim of the current study was to examine the association of serum androgens and their precursors and metabolites with skeletal muscle fat infiltration and T2DM in a black male population group at high risk of T2DM. Serum androgens, estrogens, and androgen precursors and metabolites were measured using mass spectrometry; and calf skeletal muscle fat distribution (subcutaneous and intermuscular fat; skeletal muscle density) was measured using quantitative computed tomography in 472 Afro-Caribbean men 65 years and older. Bioactive androgens, testosterone, free testosterone, and dihydrotestosterone were associated with less skeletal muscle fat infiltration (r = -0.14 to -0.18, P < .05) and increased skeletal muscle density (r = 0.10 to 0.14, P < .05), independent of total adiposity. In addition, glucuronidated androgen metabolites were associated with less subcutaneous fat (r = -0.11 to -0.15, P < .05). Multivariate logistic regression analysis identified an increased level of 3α-diol-3 glucuronide (odds ratio = 1.38, P < .01) and a decreased level of dihydrotestosterone (odds ratio = 0.66, P < .01) to be significantly associated with T2DM. Our findings suggest that, in elderly black men, independent of total adiposity, bioactive androgens and glucuronidated androgen metabolites may play previously unrecognized role in skeletal muscle fat distribution. Longitudinal studies are needed to further evaluate the relationship between androgens and androgen metabolites with changes in skeletal muscle fat distribution with aging and the incidence of T2DM.

Association of serum cholesterol and cholesterol-lowering drug use with serum sex steroid hormones in men in NHANES III

PURPOSE

Low cholesterol levels and statin drugs may protect against prostate cancer with a worse prognosis. Their protective mechanism is unknown, but has been hypothesized to be related to cholesterol's role as a sex steroid hormone precursor. We evaluated whether serum testosterone and estradiol differ by cholesterol or cholesterol-lowering drug use.

MATERIALS AND METHODS

Testosterone and estradiol were measured for 1,457 male participants in the Third National Health and Nutrition Examination Survey. We estimated multivariable-adjusted geometric mean hormone concentration by quintiles of cholesterol concentration and by cholesterol-lowering drugs use.

RESULTS

Across quintiles of cholesterol, testosterone level did not differ (mean, 95% confidence interval (CI); Q1: 5.25, 5.02-5.49, Q5: 5.05, 4.76-5.37 ng/ml; p-trend = 0.32), whereas estradiol levels were lower (Q1: 38.7, 36.9-40.5; Q5: 33.1, 31.8-34.5 pg/ml; p-trend < 0.0001). Neither testosterone (no: 5.12, 4.94-5.30, yes: 4.91, 4.33-5.57 ng/ml, p = 0.57) nor estradiol (no: 35.9, 34.8-37.1; yes: 33.9, 29.4-39.2 pg/ml; p = 0.39) differed by cholesterol-lowering drugs use.

CONCLUSION

Testosterone did not differ by cholesterol or cholesterol-lowering drug use. Estradiol was lower in men with higher cholesterol, but did not differ by cholesterol-lowering drug use. Our results suggest that the lower risk of advanced prostate cancer among statin users is not readily explained by a cholesterol-mediated effect of statins on sex hormone levels.

Aging Men and Lipids

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

Cardiovascular disease and androgens: a review

Globally, cardiovascular disease is the single largest cause of mortality. The differences in pattern of cardiovascular disease between the two genders have not been explained properly. The spotlight has largely been focused on estrogens but no conclusive evidence has proven its role in reducing the incidence of cardiovascular disease. Consequently, androgens have attracted significant interest in explaining the gender difference in cardiovascular disease. More studies in last two decades have increased our knowledge about the effects of androgens on cardiovascular disease progression. Evidence for age related fall in testosterone levels in males and increasing cardiovascular events with age had lead to the postulation of idea of 'andropause or male menopause'. Unfortunately, for the last few decades the androgens have been highlighted as agents of abuse among athletes all over the world. There have been multiple reports of their association with sudden cardiac death and adverse cardiovascular outcomes when abused. Contrastingly, there has been an increasing prescription use of testosterone supplementation in various conditions related to androgen deficiency state and for many other off-label indications. Human observational studies have mostly concluded that men with lower testosterone levels tend to have higher incidence of coronary artery disease. Emerging evidence supports that lower androgen levels predict poor cardiovascular risk profile. Role with supplementation of testosterone for cardiovascular disease is being studied in both primary and secondary prevention stages and its safety being evaluated. This is an appropriate time to review the role of androgens specifically from a cardiovascular standpoint.

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.

Association of cigarette smoking, alcohol consumption, and physical activity with sex steroid hormone levels in US men

BACKGROUND

We evaluated the associations of smoking, alcohol consumption, and physical activity with sex steroid hormone concentrations among 1,275 men > or =20 years old who participated in the Third National Health and Nutrition Examination Survey (NHANES III).

METHODS

Serum concentrations of testosterone, estradiol, and sex hormone-binding globulin (SHBG) were measured. We compared geometric mean concentrations across levels of smoking, alcohol, and physical activity using multiple linear regression.

RESULTS

Current smokers had higher total testosterone (5.42, 5.10, and 5.26 ng/ml in current, former, and never smokers), free testosterone (0.110, 0.102, and 0.104 ng/ml), total estradiol (40.0, 34.5, and 33.5 pg/ml), and free estradiol (1.05, 0.88, and 0.84 pg/ml) compared with former and never smokers (all p < or = 0.05). Men who consumed > or =1 drink/day had lower SHBG than men who drank less frequently (31.5 vs. 34.8 nmol/l, p = 0.01); total (p-trend = 0.08) and free testosterone (p-trend = 0.06) increased with number of drinks per day. Physical activity was positively associated with total (p-trend = 0.01) and free testosterone (p-trend = 0.05).

CONCLUSIONS

In this nationally representative sample of men, smoking, alcohol, and physical activity were associated with hormones and SHBG, thus these factors should be considered as possible confounders or upstream variables in studies of hormones and men's health, including prostate cancer.

Partial androgen deficiency, depression and testosterone treatment in aging men

This study provides a critical review of the literature on depressive symptoms of partial androgen deficiency (PADAM) and their treatment with Testosterone (T). PADAM in aging males is responsible for a variety of behavioral symptoms, such as weakness, decreased libido and erectile dysfunction, lower psychological vitality, depressive mood, anxiety, insomnia, difficulty in concentrating, and memory impairment. The psychological and behavioural aspects of PADAM may overlap with signs and symptoms of major depression. Evidence of the relationship between androgen deficiency and male depression comes from studies that have assessed depression in hypogonadal subjects, the association between low T level and male depressive illness, and the antidepressant action of androgen replacement. The etiology of depressive symptoms of PADAM is multifactorial, and results from the interaction of the biological and psychosocial changes that take place during the mid-life transition. Although data derived from androgen treatment trials and androgen replacement do not support T treatment or replacement as more efficacious than placebo for major depressive disorder (MDD), the clinical impression is that, in some sub-threshold depressive syndromes, T may lead to antidepressant benefits.

Postprandial triglyceride metabolism in elderly men with subnormal testosterone levels

AIM

To investigate the level of postprandial triglycerides (TG)s in elderly men with subnormal testosterone level (< or = 11.0 nmol/L) compared to men with normal testosterone level (> 11.0 nmol/L).

METHODS

Thirty-seven men with subnormal and 41 men with normal testosterone aged 60-80 years underwent an oral fat load and TG levels were measured fasting and 2, 4, 6 and 8 h afterwards.

RESULTS

Men with subnormal testosterone had significantly higher body mass index (BMI) and waist circumference (P < 0.001) than men with normal testosterone. They had significantly higher area under curve (AUC, P = 0.037), incremental area under curve (AUCi, P = 0.035) and TG response (TGR, P = 0.014) for serum-TG and significantly higher AUC (P = 0.023), AUCi (P = 0.023) and TGR (P = 0.014) for chylomicron-TG compared to men with normal testosterone level. Adjusting for waist circumference erased the significant differences between the groups in postprandial triglyceridemia.

CONCLUSION

Men with subnormal testosterone have increased postprandial TG levels indicating an impaired metabolism of postprandial TG-rich lipoproteins (TRL), which may add to an unfavourable lipid profile and promote development of atherosclerosis.

Rapid actions of androgens

The biological activity of androgens is thought to occur predominantly through binding to intracellular androgen-receptors, a member of the nuclear receptor family, that interact with specific nucleotide sequences to alter gene expression. This genomic-androgen effect typically takes at least more than half an hour. In contrast, the rapid or non-genomic actions of androgens are manifested within in seconds to few minutes. This rapid effect of androgens are manifold, ranging from activation of G-protein coupled membrane androgen-receptors or sex hormone-binding globulin receptors, stimulation of different protein kinases, to direct modulation of voltage- and ligand gated ion-channels and transporters. The physiological relevance of these non-genomic androgen actions has not yet been determined in detail. However, it may contribute to modulate several second messenger systems or transcription factors, which suggests a cross-talk between the fast non-genomic and the slow genomic pathway of androgens. This review will focus on the rapid effects of androgens on cell surface and cytoplasmic level.

Low serum testosterone in men is inversely associated with non-fasting serum triglycerides: the Tromsø study

OBJECTIVE

To study the relationships between endogenous testosterone, sex hormone-binding globulin (SHBG) and serum lipids in non-fasting men.

METHODS

We performed a cross-sectional study in 1274 men without known cardiovascular disease who participated in a population-based study, the 1994/1995 Tromsø study. Anthropometric characteristics were measured and questionnaires regarding lifestyle and medical history were completed. Non-fasting blood samples were drawn between 08.00 and 16.00h, and total testosterone, SHBG, triglycerides (TG), total cholesterol (TC) and high-density lipoprotein (HDL) were analyzed.

RESULTS

In stratified analyses based on sampling time, a linear increase in serum TG levels was found in men with total testosterone levels below the 50th percentile during the day (p for trend=0.004). In contrast, serum triglycerides did not change during the day in men with testosterone levels above the 50th percentile. In regression analyses, total testosterone and SHBG were inversely and independently associated with TG (p<0.001 and p<0.001 respectively), and positively and independently associated with HDL (p=0.005 and p<0.001, respectively). Men with an unfavorable lipid profile (HDL <0.90 and TG >1.8) had significantly lower levels of total testosterone and SHBG (p=0.004 and p<0.001, respectively) in age and BMI adjusted analyses, compared to men with a normal lipid profile.

CONCLUSIONS

Low serum total testosterone was associated with a linear increase in serum TG during the day, and was independently associated with an unfavorable lipid profile. Our findings may indicate that low total testosterone is associated with impaired TG metabolism in men.

Endogenous testosterone and serum lipids in middle-aged men

BACKGROUND

The role of decreasing testosterone levels influencing lipid metabolism in aging men is not well established.

METHODS

We studied 1619 40 to 69-year old men with andropausal symptoms, who underwent measurements of serum testosterone, triglycerides, total-, and HDL-cholesterol.

RESULTS

Testosterone (mean 15.25 nmol/l+/-5.43 S.D., range 3.6-45.0 nmol/l) correlated directly with HDL-cholesterol (r=0.24, p<0.0001) and inversely with total cholesterol (r=-0.06, p<0.03), triglycerides (r=-0.30, p<0.0001) and body mass index (r=-0.34, p<0.0001), but not with LDL-cholesterol (r=0.05, p=0.09). In multivariate analyses adjusted for age, body mass index, smoking, alcohol consumption, diabetes and cardiovascular diseases, the significant determinants for serum triglycerides were testosterone (beta=-0.03, p<0.0001), age (beta=-0.01, p<0.0001), body mass index (beta=0.039, p<0.0001) and cardiovascular diseases (beta=0.09, p<0.04). The multivariate correlates of HDL-cholesterol included testosterone (beta=0.007, p<0.0001), body mass index (beta=-0.02, p<0.0001) and alcohol consumption (beta=0.02, p<0.0001).

CONCLUSIONS

We conclude that in aging men low testosterone levels are associated with a potentially atherogenic lipid profile including high triglycerides and low HDL-cholesterol.

New Perspectives on Mars and Venus: Unravelling the Role of Androgens in Gender Differences in Cardiovascular Biology and Disease

There are substantial gender differences in the pattern, severity and clinical outcomes of coronary heart disease independent of environmental risk factor exposure. As a consequence, there has been considerable interest in the potential role of sex hormones in atherogenesis, particularly the potential protective effects of oestrogen. However, the failure of the recent clinical randomised trials to show a cardioprotective effect for oestrogen coupled with a growing interest in androgen replacement therapy in elderly men has refocused interest on the role of androgens in cardiovascular biology and disease. Over the last decade, compelling evidence has emerged that sex differences in vascular biology are not only determined by gender-related differences in sex steroid levels but also by gender-specific tissue and cellular characteristics which mediate sex-specific responses to a variety of stimuli. In the vasculature, androgens often act in a gender-specific manner, with differential effects in male and female cells. This gender-dependent regulation may have important implications for understanding the basis of the gender gap in atherosclerosis and may eventually lead to the development of sex-specific treatments for cardiovascular disease. This review will summarise the current data for the role of androgens in gender differences in coronary heart disease and cardiovascular biology.

Regulation of human CYP27A1 by estrogens and androgens in HepG2 and prostate cells

The regulation of the human CYP27A1 gene by estrogens and androgens was studied in human liver-derived HepG2 and prostate cells. Our results show that the promoter activity, enzymatic activity and mRNA levels of CYP27A1 in HepG2 cells are downregulated by estrogen in presence of ERalpha or ERbeta. Similar effects by estrogen were found in RWPE-1 prostate cells. In contrast, estrogen markedly upregulated the transcriptional activity of CYP27A1 in LNCaP prostate cancer cells. 5alpha-Dihydrotestosterone and androgen receptor upregulated the transcriptional activity of CYP27A1 in HepG2 cells. Progressive deletion experiments indicate that the ERbeta-mediated effects in HepG2 and LNCaP cells are conferred to the same region (-451/+42) whereas ERalpha-mediated effects on this promoter are more complex. The results indicate that the stimulating effect of androgen in HepG2 cells is conferred to a region upstream from -792 in the CYP27A1 promoter. In summary, we have identified the human CYP27A1 gene as a target for estrogens and androgens. The results imply that expression of CYP27A1 may be affected by endogenous sex hormones and pharmacological compounds with estrogenic or androgenic effects.

Testosterone Relaxes Isolated Human Radial Artery by Potassium Channel Opening Action

Preliminary clinical studies of testosterone therapy in male patients with coronary artery disease obtained promising results. However, little is known about the in vitro effects of testosterone in human isolated arteries. We investigated the effect of testosterone on contractile tone of human isolated radial artery (RA). Testosterone was added (0.1 - 300 microM ) cumulatively to organ baths after precontraction with KCl (45 mM) and phenylephrine (PE, 10 microM). Testosterone-induced relaxations were tested in the presence of the cyclooxygenase inhibitor indomethacin (10 microM), nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME, 100 microM), non-selective large conductance Ca(2+)-activated and voltage-sensitive K(+) channel inhibitor tetraethylammonium (TEA, 1 mM), ATP-sensitive K(+) channel inhibitor glibenclamide (GLI, 10 microM), and voltage-sensitive K(+) channel inhibitor 4-aminopyridine (4-AP, 1 mM). Testosterone produced relaxation in human RA (E(max): 53.03 +/- 2.76% and 66.83 +/- 1.97% of KCl and PE-induced contraction, respectively). Except for GLI, the relaxation to testosterone is affected by neither K(+) channel inhibitors (TEA, BaCl(2), and 4-AP), L-NAME, nor indomethacin. We report for the first time that supraphysiological concentrations of testosterone induces relaxation in RA. This response may occur in part via ATP-sensitive K(+) channel opening action.

The nuclear hormone receptor farnesoid X receptor (FXR) is activated by androsterone

Farnesoid X receptor (FXR) uses bile acids as endogenous ligands. Here, we demonstrate that androsterone, a metabolic product of testosterone, is also an FXR ligand. Treatment of castrated male mice with androsterone induced expression of the FXR target gene small heterodimer partner (SHP). In mouse AML-12 hepatocytes, chenodeoxycholic acid (CDCA) or androsterone induced SHP expression with a similar kinetic pattern. The FXR antagonist guggulsterone blocked the induction of SHP by androsterone in AML-12 cells. Nuclear magnetic resonance spectroscopy demonstrated the direct binding of androsterone to purified human FXR (hFXR) ligand-binding domain (LBD) protein, resulting in the recruitment of steroid receptor coactivator protein-1 (SRC-1) coactivator peptide. In HEK293 cells, androsterone activated gal4-mouse FXR-LBD and gal4-hFXR-LBD fusion proteins, although in contrast to CDCA, androsterone activation was significantly greater for the mouse FXR-LBD than for the hFXR-LBD. Site-directed mutagenesis of the hFXR-LBD defined amino acids Asn354 and Ser345 as critical for differential species sensitivity to CDCA and androsterone, respectively. Crystal structure studies suggest that the orientation of the steroid nucleus of bile acids within the binding pocket of FXR is reversed from all other nuclear hormone receptors. In support of this model, we show here that mutations M265I or R331H, residues predicted by crystal structure to interact with the carboxylic acid tail of CDCA but not with androsterone, altered CDCA activation but had no effect on androsterone activation. Activation of FXR by androsterone may provide an additional means for physiological or pharmacological modulation of FXR.

Epidemiology: testosterone and the metabolic syndrome

Low levels of testosterone, hypogonadism, have several common features with the metabolic syndrome. In the Tromsø Study, a population-based health survey, testosterone levels were inversely associated with anthropometrical measurements, and the lowest levels of total and free testosterone were found in men with the most pronounced central obesity. Total testosterone was inversely associated with systolic blood pressure, and men with hypertension had lower levels of both total and free testosterone. Furthermore, men with diabetes had lower testosterone levels compared to men without a history of diabetes, and an inverse association between testosterone levels and glycosylated hemoglobin was found. Thus, there are strong associations between low levels of testosterone and the different components of the metabolic syndrome. In addition, an independent association between low testosterone levels and the metabolic syndrome itself has recently been presented in both cross-sectional and prospective population-based studies. Thus, testosterone may have a protective role in the development of metabolic syndrome and subsequent diabetes mellitus and cardiovascular disease in aging men. However, clinical trials are needed to confirm this assumption.

Atherosclerosis is enhanced by testosterone deficiency and attenuated by CETP expression in transgenic mice

In this work, we investigated the impact of testosterone deficiency and cholesteryl ester transfer protein (CETP) expression on lipoprotein metabolism and diet-induced atherosclerosis. CETP transgenic mice and nontransgenic (nTg) littermates were studied 4 weeks after bilateral orchidectomy or sham operation. Castrated mice had an increase in the LDL fraction (+36% for CETP and +79% for nTg mice), whereas the HDL fraction was reduced (-30% for CETP and -11% for nTg mice). Castrated mice presented 1.7-fold higher titers of anti-oxidized LDL (Ox-LDL) antibodies than sham-operated controls. Plasma levels of CETP, lipoprotein lipase, and hepatic lipase were not changed by castration. Kinetic studies showed no differences in VLDL secretion rate, VLDL-LDL conversion rate, or number of LDL and HDL receptors. Competition experiments showed lower affinity of LDL from castrated mice for tissue receptors. Diet-induced atherosclerosis studies showed that testosterone deficiency increased by 100%, and CETP expression reduced by 44%, the size of aortic lesion area in castrated mice. In summary, testosterone deficiency increased plasma levels of apolipoprotein B-containing lipoproteins (apoB-LPs) and anti-OxLDL antibodies, decreased LDL receptor affinity, and doubled the size of diet-induced atherosclerotic lesions. The expression of CETP led to a milder increase of apoB-LPs and reduced atherosclerotic lesion size in testosterone-deficient mice.

Low testosterone levels are associated with carotid atherosclerosis in men

OBJECTIVE

To study the relationship between endogenous sex hormone levels and intima-media thickness (IMT) of the carotid artery measured by ultrasonography.

DESIGN

Population-based cross-sectional study.

METHODS

Sex hormone levels measured by immunoassay, anthropometric measurements and IMT was studied in 1482 men aged 25-84 years participating in the 1994-1995 Tromsø study. The data were analysed with partial correlation, multiple linear regression and logistic regression analysis.

RESULTS

Linear regression models showed that total testosterone and sex hormone-binding globulin levels, but not calculated free testosterone, serum oestradiol or dehydroepiandrosterone sulphate levels were inversely associated with the age-adjusted IMT (P = 0.008 and P < 0.001 respectively). These associations were independent of smoking, physical activity, blood pressure and lipid levels, but were not independent of body mass index (BMI). Excluding men with cardiovascular disease (CVD) did not materially change these results. In a logistic regression model adjusted for the confounding effect of CVD risk factors, men with testosterone levels in the lowest quintile (<9.0 nmol L(-1)) had an independent OR = 1.51 (P = 0.015) of being in the highest IMT quintile.

CONCLUSIONS

We found an inverse association between total testosterone levels and IMT of the carotid artery in men that was present also after excluding men with CVD, but was not independent of BMI. The clinical relevance of this, however, is uncertain and needs to be investigated in a clinical setting.

Effects of testosterone on lipid peroxidation, lipid profiles and some coagulation parameters in rabbits

The purpose of this study was to investigate the effects of testosterone on some risk factors of atherosclerosis. Twenty-four male New Zealand white rabbits were randomly divided into three groups of eight. The first group was used as control. Second group was injected with 10 mg of testosterone propionate. Third group was castrated bilaterally. At the end of 6 weeks, lipid peroxidation (LPO), lipid profile, fibrinogen (FBN) level and coagulation parameters were evaluated. Testosterone administration decreased the level of high-density lipoprotein cholesterol (HDL-C), while castration increased this level (P < 0.05). Triglyceride (TG) and total cholesterol (TC) levels in the castration group were significantly higher (P < 0.05) than those in the testosterone group. The ratio of HDL-C:low-density lipoprotein cholesterol (LDL-C) decreased, while TC:HDL-C ratio increased (P < 0.05) in the testosterone group. No significant differences were found in the LDL-C and FBN levels among groups. However, there was a tendency for higher FBN level in the testosterone group. Testosterone administration resulted in an increase in the level of LPO (P < 0.05). Clotting time and prothrombin time prolonged in the castration group compared with testosterone group (P < 0.05). As a result, testosterone has exacerbating effect on atherosclerosis risk factors including lipid profile, LPO, FBN and coagulation system.