Endocrine Abstracts

Introduction: Low endogenous testosterone is associated with atherosclerosis in elderly men. The aim of this study was to determine whether an inactive androgen receptor (AR) coupled with testosterone deficiency, inherent to the testicular feminised (Tfm) mouse, is associated with atherosclerosis following cholesterol feeding.Methods: Eight-week-old Tfm (n=34) and XY (n=32) littermate controls were fed for 16, 20, 24 or 28 weeks on either diet 1 (compris...

Vascular smooth muscle cells (VSMC) form a major constituent of the atherosclerotic plaque providing structural stability. However, increased cell number due to high proliferation rates can lead to greater artery occlusion. Testosterone replacement therapy improves exercise capacity and reduces symptoms of angina in men with coronary artery disease, although its effect upon VSMC growth is currently unknown. Testosterone deficiency is associated with increased atheroma burden a...

Several studies have demonstrated that atherosclerosis is associated with low serum levels of testosterone and replacement therapy reduces myocardial ischaemia in men. Vascular smooth muscle cell (VSMC) apoptosis reduces plaque stability. The role of testosterone if any, in this process is unknown. Testosterone has been demonstrated act via both the classic androgen receptor and by calcium channel antagonism. Calcium channel blockers have been shown to induce VSMC apoptosis. W...

Objective: The aim of this study was to determine dosing regimen to replace testosterone to physiological levels in the testicular feminised (Tfm) mouse, and also to produce similar supraphysiological testosterone concentrations in Tfm and XY littermates.Methods: Eight-week-old Tfm (n=66) and XY littermate controls (n=24) received a single 10 microlitre intramuscular injection of testosterone (Sustanon 100 - 100 milligrams testosterone per litre, or Sust...

Hypogonadism is difficult to confirm with standard assays. A large proportion of testosterone (T) is bound to sex hormone binding globulin (SHBG) and is biologically inert. Accurate measures of free and biological-available-testosterone (Bio-T) are largely unavailable. In this study we compared formulae calculated from the total testosterone (TT) and SHBG in their ability to predict hypogonadism and/or Bio-T.TT and SHBG were determined by ELISA and Bio-T...

Low testosterone levels in men are associated with increased atherosclerosis, and testosterone replacement therapy has been shown to reduce myocardial ischemia in men with coronary artery disease. Vascular smooth muscle cell (VSMC) apoptosis is proposed to reduce plaque stability, but the role of testosterone in this process is unknown. Testosterone causes vasodilatation via calcium channel antagonism and the calcium channel antagonist nifedipine induces VSMC apoptosis. We hav...

Atherosclerotic plaque smooth muscle cells (SMCs) are sensitive to apoptotic stimuli, increasing plaque instability. Testosterone replacement therapy is beneficial in men with coronary artery disease, although its effect upon plaque stability is unknown. We have utilised the rat A7r5 vascular SMC line to investigate the effects of testosterone on apoptosis induced by serum deprivation or the calcium channel antagonist nifedipine.Cells were plated at 1500...

Testosterone reduces myocardial ischaemia in men with coronary artery disease (CAD) and improves symptoms and exercise capacity in men with congestive heart failure (CHF), effects proposed to be due to testosterone-induced vasodilatation. Isolated vessel studies suggest this occurs via a calcium antagonistic action upon voltage-gated Ca2+ channels but this has yet to be investigated directly.We therefore employed patch clamp methodology to stu...

Low serum testosterone levels in men predict the future development of insulin resistance and Type 2 diabetes. Furthermore, men with Type 2 diabetes have lower testosterone levels than nondiabetic men. Testosterone is known to be positively correlated with insulin sensitivity. It has also been demonstrated that low levels of circulating androgens are associated with coronary artery disease, dyslipidaemia, hypertension and visceral obesity. The purpose of this study was to dete...

Evidence supports a protective role for testosterone in men with coronary artery disease (CAD) and in the regulation of cytokine function. This study examined the relationship between serum levels of inflammatory cytokines and testosterone in men with CAD. Serum was collected from 69 men (59+1 years) having >75% occlusion of 1 (n=20), 2 (n=18) or 3 (n=31) coronary arteries. Levels of total testosterone (TT), bioavailable testosterone (BT), tumour necrosis factor-alpha (TNFa...