Testosterone and the cardiovascular system are the effects that the male hormone

testosterone Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting se ...

has on the

cardiovascular system In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart a ...

. The predominant androgen in men, testosterone, has shown to substantially decline throughout the aging process. The decline in both serum and total testosterone with age have been linked to several disease states in men. In particular,

cardiac failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF typically pre ...

and

ischemic heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of heart disease involving the reduction of blood flow to the cardiac muscle due to a build-up of atheromatous plaque in the ...

have been linked to this natural biochemical decline in testosterone. Previously, the higher cardiovascular risk in men has been attributed in part to the negative effects of systemic testosterone, however, more recent research has highlighted the protective nature of testosterone against cardiovascular disease. The magnitude and mechanism of action by which low testosterone in men is influential in the pathogenesis of cardiovascular risk and the potential benefits of testosterone therapy has yet to be fully determined. __TOC__

Systemic effects

Low testosterone is associated with an increased risk for

coronary artery disease Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of cardiovascular disease, heart disease involving Ischemia, the reduction of blood flow to the cardiac muscle due to a build-up ...

through the promotion of a pro-atherosclerotic environment. Some research has identified testosterone as a

vasodilator Vasodilation, also known as vasorelaxation, is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. Blood vessel wal ...

and an

endothelium The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the r ...

-repairing hormone within many regions in the body, including the coronary arteries. Recent research depicts testosterone as important in decreasing the production of inflammatory cytokines such as tumor necrosis factor alpha, interleukin-1beta and interleukin-6, which are influential in atherosclerotic profiles. Although it is believed that the reduction in inflammatory cytokines is related to a decreased atherosclerotic profile, the full explanation of this mechanism requires further research. Testosterone has also shown to be effective as an anti-atherosclerotic through preventing aortic

cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...

deposition in both rabbits fed high cholesterol diets and mice with low-density lipoprotein gene knockout. Fatty deposition within the aorta associated with low endogenous testosterone has been determined to be independent of the androgen receptor. Although the mechanism has yet to be fully determined, aromatase activity and the activation of estrogen receptor alpha is partially responsible for the atherosclerotic profile characteristic of low testosterone. Decreased systemic testosterone in men has also been reported in men with heart failure, whereby the severity of the disease is proportional to the reduction in systemic testosterone levels. Although a direct mechanism of action is not fully understood, some research attribute low testosterone to advancing side effects of heart failure, such as decreased exercise ability, decreased muscle mass, fatigue/

dyspnea Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that ...

and

cachexia Cachexia () is a syndrome that happens when people have certain illnesses, causing muscle loss that cannot be fully reversed with improved nutrition. It is most common in diseases like cancer, Heart failure, congestive heart failure, chronic o ...

Replacement therapy

Physiological testosterone is crucial for normal functionality in men. Long-term administration of physiological testosterone in mouse models has shown to be atheroprotective by increasing the HDL portion of cholesterol (the anti-atherosclerotic cholesterol). The beneficial action of testosterone in elevating the HDL fraction can be attributed to its conversion via aromatase activity in adipose tissue into 17-beta estradiol and its subsequent activation of estrogen alpha-receptors; thus, more testosterone leads to greater conversion into estrogen and thus a healthier lipid profile. This understanding has been determined in several studies, although results of these studies are contradictory. Testosterone replacement therapy in men diagnosed with pre-existing heart disease has been related to an increased risk of myocardial infarction. Furthermore, recent research has linked testosterone replacement therapy to an increase in deaths and other cardiovascular occurrences in men whom document a history of coronary artery disease. Further research is required to determine the full extent to which testosterone replacement therapy in aging men plays a role in the risk and/or advantage of cardiovascular occurrences. However, when given to men with

hypogonadism Hypogonadism means diminished functional activity of the human gonad, gonads—the testicles or the ovary, ovaries—that may result in diminished biosynthesis, production of sex hormones. Low androgen (e.g., testosterone) levels are referred t ...

in the short- and medium-term, testosterone replacement therapy does not increase the risk of cardiovascular events (including strokes and heart attacks and other heart diseases). The long-term safety of the therapy for this condition is not known yet.

References

{{Reflist, 2 Cardiology Cardiovascular system Testosterone