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Abstracts

Life Extension Magazine June 2012
Abstracts

Testosterone

Testosterone supplementation in men with type 2 diabetes, visceral obesity and partial androgen deficiency.

The objective of this study was to assess the effects of oral testosterone supplementation therapy on glucose homeostasis, obesity and sexual function in middle-aged men with type 2 diabetes and mild androgen deficiency. Forty-eight middle-aged men, with type 2 diabetes, (visceral) obesity and symptoms of androgen deficiency, were included in this open-label study. Twenty-four subjects received testosterone undecanoate (TU; 120 mg daily, for 3 months); 24 subjects received no treatment. Body composition was analyzed by bio-impedance. Parameters of metabolic control were determined. Symptoms of androgen deficiency and erectile dysfunction were scored by self-administered questionnaires. TU had a positive effect on (visceral) obesity: statistically significant reduction in body weight (2.66%), waist-hip ratio (-3.96%) and body fat (-5.65%); negligible changes were found in the control group. TU significantly improved metabolic control: decrease in blood glucose values and mean glycated hemoglobin (HbA1c) (from 10.4 to 8.6%). TU treatment significantly improved symptoms of androgen deficiency (including erectile dysfunction), with virtually no change in the control group. There were no adverse effects on blood pressure or hematological, biochemical and lipid parameters, and no adverse events. Oral TU treatment of type 2 diabetic men with androgen deficiency improves glucose homeostasis and body composition (decrease in visceral obesity), and improves symptoms of androgen deficiency (including erectile dysfunction). In these men, the benefit of testosterone supplementation therapy exceeds the correction of symptoms of androgen deficiency and also includes glucose homeostasis and metabolic control.

Aging Male. 2003 Mar;6(1):1-7

Low testosterone levels are common and associated with insulin resistance in men with diabetes.

CONTEXT: Low testosterone levels are common in men with type 2 diabetes and may be associated with insulin resistance. OBJECTIVE: We investigated prevalence of testosterone eficiency and the relationship between testosterone and insulin resistance in a large cohort of men with type 2 and type 1 diabetes. DESIGN: The study was a cross-sectional survey of 580 men with type 2 diabetes and 69 men with type 1 diabetes. A subgroup of 262 men with type 2 diabetes was then reassessed after a median of 6 months. RESULTS: Forty-three percent of men with type 2 diabetes had a reduced total testosterone, and 57% had a reduced calculated free testosterone. Only 7% of men with type 1 diabetes had low total testosterone. By contrast, 20.3% of men with type 1 diabetes had low calculated free testosterone, similar to that observed in type 2 diabetes (age-body mass index adjusted odds ratio = 1.4; 95% confidence interval = 0.7-2.9). Low testosterone levels were independently associated with insulin resistance in men with type 1 diabetes as well as type 2 diabetes. Serial measurements also revealed an inverse relationship between changes in testosterone levels and insulin resistance. CONCLUSIONS: Testosterone deficiency is common in men with diabetes, regardless of the type. Testosterone levels are partly influenced by insulin resistance, which may represent an important avenue for intervention, whereas the utility of testosterone replacement remains to be established in prospective trials.

J Clin Endocrinol Metab. 2008 May;93(5):1834-40

The dark side of testosterone deficiency: III. Cardiovascular disease.

A considerable body of evidence exists suggesting that androgen deficiency contributes to the onset, progression, or both of cardiovascular disease (CVD). The aim of this review is to evaluate the relationships between testosterone (T) deficiency and risk factors of CVD and to discuss the implications of androgen deficiency in men with cardiovascular risk factors. The relationship between androgen deficiency and endothelial function, lipid profiles, inflammatory responses, altered vascular smooth muscle reactivity, and hypertension are discussed with regard to CVD. A comprehensive literature search was carried out with the use of Pub Med from 1980 through 2009, and relevant articles pertinent to androgen deficiency and vascular disease were evaluated and discussed. Low T, whether attributed to hypogonadism or androgen deprivation therapy, in men with prostate carcinoma, produces adverse effects on cardiovascular health. Androgen deficiency is associated with increased levels of total cholesterol, low-density lipoprotein, increased production of proinflammatory factors, and increased thickness of the arterial wall and contributes to endothelial dysfunction. Testosterone supplementation restores arterial vasoreactivity; reduces proinflammatory cytokines, total cholesterol, and triglyceride levels; and improves endothelial function but also might reduce high-density lipoprotein levels. Testosterone is an anabolic hormone with a wide range of beneficial effects on men’s health. The therapeutic role of T in men’s health, however, remains a hotly debated issue for a number of reasons, including the purported risk of prostate cancer. In view of the emerging evidence suggesting that androgen deficiency is a risk factor for CVD, androgen replacement therapy could potentially reduce CVD risk in hypogonadal men. It should be emphasized, however, that androgen replacement therapy should be done with very thorough and careful monitoring for prostate diseases.

J Androl. 2009 Sep-Oct;30(5):477-94

Low levels of endogenous androgens increase the risk of atherosclerosis in elderly men: the Rotterdam study.

In both men and women, circulating androgen levels decline with advancing age. Until now, results of several small studies on the relationship between endogenous androgen levels and atherosclerosis have been inconsistent. In the population-based Rotterdam Study, we investigated the association of levels of dehydroepiandrosterone sulfate (DHEAS) and total and bioavailable testosterone with aortic atherosclerosis among 1,032 nonsmoking men and women aged 55 yr and over. Aortic atherosclerosis was assessed by radiographic detection of calcified deposits in the abdominal aorta, which have been shown to reflect intimal atherosclerosis. Relative to men with levels of total and bioavailable testosterone in the lowest tertile, men with levels of these hormones in the highest tertile had age-adjusted relative risks of 0.4 [95% confidence interval (CI), 0.2-0.9] and 0.2 (CI, 0.1-0.7), respectively, for the presence of severe aortic atherosclerosis. The corresponding relative risks for women were 3.7 (CI, 1.2-11.6) and 2.3 (CI, 0.7-7.8). Additional adjustment for cardiovascular disease risk factors did not materially affect the results in men, whereas in women the associations diluted. Men with levels of total and bioavailable testosterone in subsequent tertiles were also protected against progression of aortic atherosclerosis measured after 6.5 yr (SD +/- 0.5 yr) of follow-up (P for trend = 0.02). No clear association between levels of DHEAS and presence of severe aortic atherosclerosis was found, either in men or in women. In men, a protective effect of higher levels of DHEAS against progression of aortic atherosclerosis was suggested, but the corresponding test for trend did not reach statistical significance. In conclusion, we found an independent inverse association between levels of testosterone and aortic atherosclerosis in men. In women, positive associations between levels of testosterone and aortic atherosclerosis were largely due to adverse cardiovascular disease risk factors.

J Clin Endocrinol Metab. 2002 Aug;87(8):3632-9

Testosterone and atherosclerosis in aging men: purported association and clinical implications.

Two of the strongest independent risk factors for coronary heart disease (CHD) are increasing age and male sex. Despite a wide variance in CHD mortality between countries, men are consistently twice as likely to die from CHD than their female counterparts. This sex difference has been attributed to a protective effect of female sex hormones, and a deleterious effect of male sex hormones, upon the cardiovascular system. However, little evidence suggests that testosterone exerts cardiovascular harm. In fact, serum levels of testosterone decline with age, and low testosterone is positively associated with other cardiovascular risk factors. Furthermore, testosterone exhibits a number of potential cardioprotective actions. For example, testosterone treatment is reported to reduce serum levels of the pro-inflammatory cytokines interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha, and to increase levels of the anti-inflammatory cytokine IL-10; to reduce vascular cell adhesion molecule (VCAM)-1 expression in aortic endothelial cells; to promote vascular smooth muscle and endothelial cell proliferation; to induce vasodilatation and to improve vascular reactivity, to reduce serum levels of the pro-thrombotic factors plasminogen activator inhibitor (PAI)-1 and fibrinogen; to reduce low-density lipoprotein-cholesterol (LDL-C); to improve insulin sensitivity; and to reduce body mass index and visceral fat mass. These actions of testosterone may confer cardiovascular benefit since testosterone therapy reduces atheroma formation in cholesterol-fed animal models, and reduces myocardial ischemia in men with CHD. Consequently, an alternative hypothesis is that an age-related decline in testosterone contributes to the atherosclerotic process. This is supported by recent findings, which suggest that as many as one in four men with CHD have serum levels of testosterone within the clinically hypogonadal range. Consequently, restoration of serum levels of testosterone via testosterone replacement therapy could offer cardiovascular, as well as other, clinical advantages to these individuals.

Am J Cardiovasc Drugs. 2005;5(3):141-54

Testosterone up-regulates scavenger receptor BI and stimulates cholesterol efflux from macrophages.

By lowering high density lipoprotein (HDL) cholesterol, testosterone contributes to the gender difference in HDL cholesterol and has been accused to be pro-atherogenic. The mechanism by which testosterone influences HDL cholesterol is little understood. We therefore investigated the effect of testosterone on the gene expression of apolipoprotein A-I (apoA-I), hepatic lipase (HL), scavenger receptor B1 (SR-BI), and the ATP binding cassette transporter A1 (ABCA1), all of which are important regulators of HDL metabolism. In both cultivated HepG2 hepatocytes and primary human monocyte-derived macrophages, testosterone led to a dose-dependent up-regulation of SR-BI, which was assessed on both the mRNA and the protein levels. As a functional consequence, we observed an increased HDL(3)-induced cholesterol efflux from macrophages. At supraphysiological dosages, testosterone also increased the expression of HL in HepG2 cells. Testosterone had no effect on the expression of apoA-I in HepG2 cells and ABCA1 in either HepG2 cells or macrophages. These data suggest that testosterone, despite lowering HDL cholesterol, intensifies reverse cholesterol transport and thereby exerts an anti-atherogenic rather than a pro-atherogenic effect.

Biochem Biophys Res Commun. 2002 Sep 6;296(5):1051-7

Testosterone administration to men increases hepatic lipase activity and decreases HDL and LDL size in 3 wk.

Testosterone administration to men is known to decrease high-density lipoprotein cholesterol (HDL-C) and the subclasses HDL(2) and HDL(3). It also might increase the number of small, dense, low-density lipoprotein cholesterol (LDL-C) particles in hypogonadal men. The decrease in HDL-C and in LDL-C size is potentially mediated by hepatic lipase activity, which hydrolyzes lipoprotein phospholipids and triacylglycerol. To determine how HDL-C and LDL-C particles are affected by testosterone administration to eugonadal men, testosterone was administered as a supraphysiological dose (600 mg/wk) for 3 wk to elderly, obese, eugonadal men before elective hip or knee surgery, and lipids were measured by routine methods and by density gradient ultracentrifugation. Hepatic lipase activity increased >60% above baseline levels, and HDL-C, HDL(2), and HDL(3) significantly declined in 3 wk. In addition, the LDL-C peak particle density and the amount of LDL-C significantly increased. Testosterone is therefore a potent stimulator of hepatic lipase activity, decreasing HDL-C, HDL(2), and HDL(3) as well as increasing LDL particle density changes, all associated with increased cardiovascular risk.

Am J Physiol Endocrinol Metab. 2003 Jun;284(6):E1112-8

Serum testosterone level and related metabolic factors in men over 70 years old.

BACKGROUND: Sex hormone decline remarkably decreases metabolic function in elderly men. Many degenerative diseases may relate to testosterone deficiency. OBJECTIVE: To evaluate the serum testosterone concentration in elderly men, its related metabolic and inflammatory factors, and the relationship of metabolic syndrome to testosterone levels. METHODS: 381 elderly men (78.8+/-4.1 yr old) residing in a veterans’ nursing home were enrolled. We measured body height and weight, waist and hip circumferences, body fat, blood pressure, blood glucose and insulin, glycosylated hemoglobin (HbA1c), lipid profile, complete blood count, high sensitivity C-reactive protein (hsCRP), total testosterone, and SHBG. Free testosterone was calculated by Nanjee-Wheeler’s method. RESULTS: Serum total testosterone levels were 0.20-15.74 ng/ml (free testosterone 11.78-478.31 pmol/l). Total testosterone correlated negatively with body mass index (BMI), waist-hip ratio, body fat, blood glucose, blood insulin, HbA1c, serum triglyceride, white blood cell (WBC) count and hsCRP; but positively with HDL-cholesterol (HDL-C) and hemoglobin. Multiple regression stepwise forward analysis revealed that BMI values, fasting blood glucose, WBC count, fasting hsCRP and hemoglobin were independent factors related to total testosterone. Furthermore, total testosterone is lower in elderly men with metabolic syndrome, according to National Cholesterol Education Program criteria with a modification of waist circumference. However, free testosterone plays a small role in association with metabolic factors in this elderly men’s population. CONCLUSION: Total testosterone level is significantly related to metabolic and inflammatory factors in elderly men. Low total testosterone may be a significant indicator for development of metabolic syndrome in elderly men.

J Endocrinol Invest. 2007 Jun;30(6):451-8