The triad of erectile dysfunction, hypogonadism and the metabolic syndrome

Are men shortchanged on health? Perspective on life expectancy, morbidity, and mortality in men and women in the United States

BACKGROUND

Significant gender disparities exist in life expectancy and major disease morbidity. There is an urgent need to understand the major issues related to men's health that contributes to these significant disparities. It is hypothesized that men have higher and earlier morbidities, in addition to behavioral factors that contribute to their lower life expectancy.

METHODS

Data was collected from CDC: Health United States, 2007; American Heart Association, American Obesity Association, and American Cancer Society.

RESULTS

Men have lower life expectancy than women in most countries around the world including United States. This gender disparity is consistent regardless of geography, race and ethnicity. More men die of 12 out of the 15 leading causes of death than women. In addition, men have higher morbidity and mortality in coronary heart disease (CHD), hypertension, diabetes, and cancer.

CONCLUSIONS

Men's lower life expectancy may be explained by biological and clinical factors such as the higher incidence of cardiovascular metabolic disease and cancer. In the context of public health, raising awareness of cardiovascular and metabolic health is needed to reduce the gender disparity. In addition, consideration of preventive and early detection/intervention programs may improve men's health.

Androgens and male aging: Current evidence of safety and efficacy

Many signs of aging, such as sexual dysfunction, visceral obesity, impaired bone and muscle strength, bear a close resemblance to features of hypogonadism in younger men. The statistical decline of serum testosterone in aging men is solidly documented. It has been presumed that the above features of aging are related to the concurrent decline of androgens, and that correction of the lower-than-normal circulating levels of testosterone will lead to improvement of symptoms of aging. But in essence, the pivotal question whether the age-related decline of testosterone must be viewed as hypogonadism, in the best case reversed by testosterone treatment, has not been definitively resolved. Studies in elderly men with lower-than-normal testosterone report improvement of features of the metabolic syndrome, bone mineral density, of mood and of sexual functioning. But as yet there is no definitive proof of the beneficial effects of restoring testosterone levels to normal in elderly men on clinical parameters. Few of these studies meet as yet rigorous standards of scientific enquiry: double-blind, placebo-controlled design of the study. The above applies also to the assessment of safety of testosterone administration to elderly men. There is so far no convincing evidence that testosterone is a main factor in the development of prostate cancer in elderly men and guidelines for monitoring the development of prostate disease have been developed. It is of note that there are presently no long-term safety data with regard to the prostate. Polycythemia is another potential complication of testosterone treatment. It is dose dependent and can be managed with dose adjustment.

Abnormal protein expression in the corpus cavernosum impairs erectile function in type 2 diabetes

OBJECTIVE

To investigate the changes in corporal relaxation, intracavernous pressure (ICP) and associated protein expression that control normal erectile function in rats with type 2 diabetes (T2D), as this disease is part of the 'metabolic syndrome' associated with a high rate of erectile dysfunction (ED) in men, resulting from failure of corpus cavernosum-mediated processes.

MATERIALS AND METHODS

T2D was induced in rats by feeding them with a high-fat diet (HFD) followed by an injection with low-dose streptozotocin (STZ); they were then compared with rats that received a normal diet (ND).

RESULTS

Hyperglycaemia and dyslipidaemia were induced in HFD + STZ rats, suggesting that T2D was established. The rats with T2D had associated ED, as both nonadrenergic noncholinergic-mediated corporal relaxation and increased ICP by cavernous nerve stimulation were significantly attenuated compared to the ND group. Western blot analysis revealed diabetes-associated lower expression of endothelial and neuronal nitric oxide synthase (e and nNOS), and cGMP-dependent protein kinase (PKG)-1alpha/beta expression in penile tissue than in the ND group. Contrary to the proteins that regulate corporal relaxation, there were relatively high levels of RhoA/Rho kinase receptor 1 (ROCK1) and ET-A receptor (ETAR) in T2D rats. However, the expressed level of phosphodiesterase-5 and insulin-like growth factor binding protein 3 was not altered significantly in response to T2D.

CONCLUSION

Decreased expression of certain proteins that mediate the relaxant mechanism, associated with increased expression of certain proteins that mediate contractile mechanisms, might be important in the development of T2D-associated ED. In particular, down-regulated eNOS/nNOS/PKG1 as well as up-regulated ETAR/RhoA/ROCK1 might participate in the aetiology of ED in T2D.

Reversal of voltage-dependent erectile responses in the Zucker obese-diabetic rat by rosuvastatin-altered RhoA/Rho-kinase signaling

INTRODUCTION

The combination of independent risk factors for erectile dysfunction, obesity, hypertension, and diabetes are collectively manifested in a condition known as metabolic syndrome X (MSX). However, the regulatory mechanisms responsible for the erectile dysfunction (ED) are not fully understood. Clinical studies suggest that a pleiotropic effect of statin's ability to enhance vascular relaxation might be through an impact on nitric oxide signaling or through a regulation of RhoA activation.

AIM

We hypothesized that regulatory aspects of short-term statin therapy involve the alteration of the RhoA/Rho-kinase signaling cascade and will reverse the ED seen in a rat model of MSX.

MAIN OUTCOME MEASURES

The magnitude and sensitivity of the voltage-dependent maintenance of intracavernosal blood pressure and mean arterial blood pressure. These responses were correlated with tissue protein and mRNA expression levels of RhoA and Rho kinases.

METHODS

Erectile function was evaluated by assessing voltage-dependent stimulation of the cavernosal nerve in 16-20 weeks old lean and obese-diabetic Zucker rats treated with 5 mg/kg/day of rosuvastatin intraperitoneally for 3 days. Cavernosal tissue RhoA and Rho-kinases expression levels were evaluated by real-time reverse transcriptase-polymerase chain reaction, Western blot.

RESULTS

The voltage-dependent erectile responses were suppressed by >30% in the obese-diabetic Zucker rat. The 3-day treatment with rosuvastatin partially restored the erectile response. The Rho-kinase inhibitor, H-1152, dose dependently increased the erectile responses and shifted the voltage sensitivity with statin treatment. Analysis of protein expression levels suggested elevation of RhoA and Rho kinases in obese-diabetics and statin treatment lowering Rho-kinase II. The RhoA and Rho-kinase II mRNA levels were significantly reduced in the rosuvastatin-treated obese-diabetic animals.

CONCLUSIONS

These results support a hypothesis that short-term statin therapy may lower RhoA/Rho-kinase expression levels and improve cavernosal blood pressure response to Rho-kinase inhibition and voltage-stimulation, and reversing an augmented vasoconstricted state associated with diabetes and/or hypertension in MSX.

Pharmacogenetics of testosterone replacement therapy

Variable phenotypes of androgen insensitivity exist in humans, mainly owing to defective, mutated androgen receptors. A more subtle modulation of androgen effects is related to the CAG repeat polymorphism ([CAG]n) in exon 1 of the androgen receptor gene, in vitro, transcription of androgen-dependent target genes is attenuated with increasing length of triplets. As a clinical entity, the CAG repeat polymorphism can relate to variations of androgenicity in (apparently) eugonadal men in various tissues and psychological traits, the longer the (CAG)n, the less prominent the androgen effect when individuals with similar testosterone concentrations are compared. A strictly defined threshold to hypogonadism is likely to be replaced by a continuum spanned by genetics as well as symptom specificity. In addition, effects of externally applied testosterone can be markedly influenced by the (CAG)n and respective pharmacogenetic implications are likely influence indications as well as modalities of testosterone treatment of hypogonadal men.

Temporal trends in testosterone levels and treatment in older men

PURPOSE OF REVIEW

Longitudinal studies of testosterone concentrations have yielded sharper estimates of age-related androgen declines than their cross-sectional counterparts. A potential explanation for this phenomenon is a secular (age independent) mechanism acting to accelerate within-individual testosterone decreases with time. This article reviews the evidence in favor of such secular trends and discusses potential causes and implications.

RECENT FINDINGS

The magnitude of the proposed secular trend may be as much as 1% per calendar year in excess of per year cross-sectional trends. Current evidence suggests that body composition changes as expressed by BMI can in part account for the trend in testosterone. More speculative recent findings suggest a potential contributory role for environmental endocrine disruptors, but to date no longitudinal studies have examined this question. Symptomatic androgen deficiency as currently defined is associated with diverse downstream morbidity, but may not constitute a robust designation over longer term periods of time. Information concerning treatment patterns in the general population is limited.

SUMMARY

Existing evidence, though limited, supports the hypothesis of secular declines in serum testosterone levels in adult men. It is conceivable that these trends may influence the health of the public. Studies confirming and accounting for these trends are needed.

Clinical review: Prevalence and incidence of endocrine and metabolic disorders in the United States: a comprehensive review

CONTEXT

There has not been a comprehensive compilation of data regarding the epidemiology of all endocrine and metabolic disorders in the United States.

EVIDENCE ACQUISITION

We included 54 disorders with clinical and public health significance. We identified population-based studies that provided U.S. prevalence and/or incidence data by searching PubMed in December 2007 for English-language reports, hand-searching reference lists of six textbooks of endocrinology, obtaining additional resources from identified experts in each subspecialty, and searching epidemiological databases and web sites of relevant organizations. When available, we selected articles with data from 1998 or later. Otherwise, we selected the article with the most recent data, broadest geographical coverage, and most stratifications by sex, ethnicity, and/or age. Ultimately, we abstracted data from 70 articles and 40 cohorts.

EVIDENCE SYNTHESIS

Endocrine disorders with U.S. prevalence estimates of at least 5% in adults included diabetes mellitus, impaired fasting glucose, impaired glucose tolerance, obesity, metabolic syndrome, osteoporosis, osteopenia, mild-moderate hypovitaminosis D, erectile dysfunction, dyslipidemia, and thyroiditis. Erectile dysfunction and osteopenia/osteoporosis had the highest incidence in males and females, respectively. The least prevalent conditions, affecting less than 1% of the U.S. population, were diabetes mellitus in children and pituitary adenoma. Conditions with the lowest incidence were adrenocortical carcinoma, pheochromocytoma, and pituitary adenomas. Certain disorders, such as hyperparathyroidism and thyroid disorders, were more common in females. As expected, the prevalence of diabetes mellitus was highest among ethnic minorities. Sparse data were available on pituitary, adrenal, and gonadal disorders.

CONCLUSIONS

The current review shows high prevalence and incidence of common endocrine and metabolic disorders. Defining the epidemiology of these conditions will provide clues to risk factors and identify areas to allocate public health and research resources.

Comparison of long-acting testosterone undecanoate formulation versus testosterone enanthate on sexual function and mood in hypogonadal men

OBJECTIVE

To compare the effects of two treatment modalities of testosterone on sexual functioning and mood. Design Forty men were randomized to receive either parenteral testosterone enanthate (TE) or long-acting parenteral testosterone undecanoate (TU) over a period of 30 weeks. Thereafter, 20 men who had received TU and 16 men who had received TE continued with TU and completed another 65 weeks to study longer-term effects of TU.

METHODS

The following variables of sexual functioning were studied: sexual thoughts and fantasy, sexual interest and desire, satisfaction with sex life, number of erections and ejaculations per week, and number of spontaneous morning erections per week. Also variables related to mood were analyzed.

RESULTS

Improvements in these variables were significant and were of a similar magnitude in the group treated with TU and TE for 30 weeks. Improvements were maintained at the same levels over a period of another 65 weeks when all men received TU. Effects on mood were recorded for 30 weeks, but were more difficult to establish in the study population. There were significant differences in baseline values between the two groups and scores showed wide s.d.

CONCLUSIONS

Both TE and TU were effective in improving sexual functions in hypogonadal men. An advantage of TU over TE is its lower frequency of administration and its better tolerability and safety profile.

Men's health, low testosterone, and diabetes: individualized treatment and a multidisciplinary approach

Testosterone plays a critical role in male reproductive and metabolic functioning. Serum testosterone levels decrease with age, and low testosterone is associated with a variety of comorbidities, including insulin resistance, type 2 diabetes, obesity, metabolic syndrome, and cardiovascular disease. Men with type 2 diabetes have been shown to have significantly lower testosterone levels than men without diabetes. Several forms of testosterone replacement therapy (eg, oral, injectable, buccal, transdermal preparations) are available for use in the United States. The primary goals of testosterone therapy are to restore physiologic testosterone levels and reduce the symptoms of hypogonadism. Testosterone therapy may be a viable option in some men with diabetes and low testosterone; however, clinicians must be aware of contraindications to therapy (eg, prostate cancer and male breast cancer), implement appropriate monitoring procedures, and ensure that patient expectations are realistic regarding treatment outcome. Data suggest that testosterone therapy may have a positive effect on bones, muscles, erythropoiesis and anemia, libido, mood and cognition, penile erection, cholesterol, fasting blood glucose, glycated hemoglobin, insulin resistance, visceral adiposity, and quality of life. Sexual health may be a window into men's health; thus, more effective communication strategies are needed between clinicians and men with diabetes to ensure that sexual health topics are adequately addressed. Diabetes educators can play a key role in screening for low testosterone, providing relevant information to patients, and increasing clinician awareness of the need to address men's sexual health and implement appropriate strategies. Multidisciplinary care and individualized treatment are needed to optimize outcome.