Dr. Ron’s Research Review – September 19, 2012

This week’s research review focuses on testosterone deficiency articles by Traish.

The dark side of testosterone deficiency: I. Metabolic syndrome and erectile dysfunction (Traish, Guay et al. 2009)

The dark side of testosterone deficiency: II. Type 2 diabetes and insulin resistance (Traish, Saad et al. 2009)

The dark side of testosterone deficiency: III. Cardiovascular disease (Traish, Saad et al. 2009)

Androgens play a pivotal role in maintaining penile tissue architecture and erection: a review (Traish 2009)

Dr. Ron


Articles

Androgens play a pivotal role in maintaining penile tissue architecture and erection: a review

            (Traish 2009) Download

Androgens are essential for development, growth, and maintenance of penile structure, and regulate erectile physiology by multiple mechanisms. Here we provide a concise overview of the basic research findings pertaining to androgen modulation of erectile tissue architecture and physiology. A significant body of evidence exists pointing to a critical role of androgens in erectile physiology. Studies in animal models have provided fundamental knowledge on the role of androgens in modulating tissue architecture and cellular, molecular, and physiological mechanisms. Based on data from our laboratory and those reported by others, we believe that androgens play a pivotal role in maintaining the structure and function of the peripheral penile nerve network, the structural integrity of the corpora cavernosa, the tunica albuginea, and the endothelium of the cavernous spaces. Further, androgens play an important role in regulating the differentiation of precursor cells into trabecular smooth muscle. In this review, we will focus our discussion on findings pertaining to the role of androgens in regulating penile tissue architectural elements in modulating penile function. This knowledge has a profound impact on the potential use of androgens in the clinical setting to treat patients with erectile dysfunction.

The dark side of testosterone deficiency: I. Metabolic syndrome and erectile dysfunction

            (Traish, Guay et al. 2009) Download

The metabolic syndrome (MetS) is considered the most important public health threat of the 21st century. This syndrome is characterized by a cluster of cardiovascular risk factors including increased central abdominal obesity, elevated triglycerides, reduced high-density lipoprotein, high blood pressure, increased fasting glucose, and hyperinsulinemia. These factors increase the risk of cardiovascular disease (CVD) and/or type 2 diabetes. Although the etiology of this syndrome is thought to stem from obesity and physical inactivity, the extent of interactions of the individual MetS components with one another remains poorly defined. Obesity, diabetes, hypogonadism, and specific hormone and metabolic profiles have been implicated in the pathophysiology of CVD. The evolving role of androgens in MetS and CVD is of paramount importance. Reduced androgen levels associated with hypogonadism or androgen deprivation therapy increase cardiovascular risk factors and produce marked adverse effects on cardiovascular function. MetS has been associated with hypogonadism and erectile dysfunction (ED), and MetS may be considered a risk factor for ED. It is suggested that MetS, diabetes, and CVD will increase in the upcoming decades. Thus, it is critically important to develop a better understanding of how obesity, diabetes and hypogonadism contribute to androgen deficiency and the various pathophysiologic states of vascular disease. In this review we discuss the current literature pertaining to androgen deficiency, MetS, and ED, because the relationship of these factors is of scientific and clinical importance. Specifically, we will focus on exploring the relationships between hypogonadism, obesity, MetS, and ED.

The dark side of testosterone deficiency: II. Type 2 diabetes and insulin resistance

            (Traish, Saad et al. 2009) Download

A considerable body of evidence exists suggesting a link among reduced testosterone plasma levels, type 2 diabetes (T2D), and insulin resistance (IR). Hypogonadal men are at higher risk for T2D. Here we evaluate the relationships between testosterone, metabolic syndrome (MetS), T2D, and IR and discuss the relationships among androgen deficiency and these factors, especially as it ultimately relates to the development of cardiovascular disease and erectile dysfunction (ED). Thus, a comprehensive literature search was carried out using PubMed, and relevant articles pertinent to androgen deficiency, T2D, IR, MetS, and ED were reviewed and discussed. Low testosterone precedes elevated fasting insulin, glucose, and hemoglobin A1c (HbA1C) values and may even predict the onset of diabetes. Treatment of prostate cancer patients with surgical or medical castration exacerbates IR and glycemic control, strengthening the link between testosterone deficiency and onset of T2D and IR. Androgen therapy of hypogonadal men improves insulin sensitivity, fasting glucose, and HbA1c levels. We suggest that androgen deficiency is associated with IR, T2D, MetS, and with increased deposition of visceral fat, which serves as an endocrine organ, producing inflammatory cytokines and thus promoting endothelial dysfunction and vascular disease.

The dark side of testosterone deficiency: III. Cardiovascular disease

            (Traish, Saad et al. 2009) Download

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.

References

Traish, A. M. (2009). "Androgens play a pivotal role in maintaining penile tissue architecture and erection: a review." J Androl 30(4): 363-9.

Traish, A. M., A. Guay, et al. (2009). "The dark side of testosterone deficiency: I. Metabolic syndrome and erectile dysfunction." J Androl 30(1): 10-22.

Traish, A. M., F. Saad, et al. (2009). "The dark side of testosterone deficiency: III. Cardiovascular disease." J Androl 30(5): 477-94.

Traish, A. M., F. Saad, et al. (2009). "The dark side of testosterone deficiency: II. Type 2 diabetes and insulin resistance." J Androl 30(1): 23-32.