Endocrine Abstracts

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 and testosterone replacement in animal studies ameliorates plaque size. We have utilised the rat aortic cell line A7r5 to investigate the effect of testosterone on VSMC cell growth.

A7r5 cells were plated at 50000 cells per well in 24-well plates in DMEM supplemented with 10% foetal bovine serum (FBS) and left to adhere overnight. Media was then removed and replaced with serum-free phenol red-free DMEM to synchronise cells for 24-hours, after which media was replaced with phenol red-free DMEM supplemented with 2% FBS containing either ethanol vehicle control (0.1%) or testosterone (10^-9, 10^-8, 10^-7 10^-6 or 10^-5M) for 24, 48 or 72-hours. Following incubation, media was removed the cells trypsinised, resuspended into isoton II and cell number determined via coulter counting.

Compared to ethanol vehicle control, testosterone (10^-9, 10^-8, 10^-7, 10^-6 or 10^-5M) had no significant effect on cell number over either 24; 58117plus/minus2712, 58496plus/minus2183, 56447plus/minus1898, 56120plus/minus1919, 55902plus/minus1467 and 57320plus/minus1418 respectively, 48: 52718plus/minus2667, 54511plus/minus3921, 55756plus/minus3684, 55994plus/minus3445, 53125plus/minus3354 and 59070plus/minus2886 respectively, or 72-hours; 57270plus/minus3747, 50213plus/minus3054, 51587plus/minus1634, 51870plus/minus2743, 51876plus/minus2112 and 49654plus/minus1397 respectively. All p>0.05.

In conclusion, testosterone alone has no significant effects on the growth of A7r5 VSMCs in culture and therefore is unlikely to cause further artery occlusion by increasing cell number. However, other factors implicated in coronary artery disease, such as inflammatory mediators, may need to be present for any beneficial or adverse effects of testosterone on VSMC growth to be seen.