Effect of testosterone on plaque development and androgen receptor expression in the arterial vessel wall

Background-Recent studies have suggested that testosterone has a protective effect in the arterial vascular system. However, little is known about the molecular aspects of the mechanism(s) involved in these processes. The aim of the present study was to investigate the effect of testosterone on neoi ntimal plaque development and on the expression of the vascular androgen re ceptor. Methods and Results-Neointimal plaque formation was induced by endothelial denudation in the aortas of male New Zealand White rabbits. Aortic ring seg ments were cultured for 21 days after endothelial denudation. Testosterone was applied to the culture medium in different doses. Compared with the non -hormone-treated control group, a significant inhibition of neointimal plaq ue development (expressed as the intima/media ratio) was found at testoster one concentrations of 10 ng/mL (P=0.037) and 100 ng/mL (P=0.012; intima/med ia ratios: median of controls, 0.25; median of 10 ng/mL testosterone group, 0.15; median of 100 ng/mL testosterone group, 0.16). Associated with this inhibitory effect on plaque size was a 50% increase of the amount of androg en receptor mRNA in the arterial segments treated with testosterone. Conclusion-The beneficial effects of testosterone on postinjury plaque deve lopment underlines, at least in males, the important role of androgens in t he vascular system, As our data suggest, the vascular androgen receptor is probably involved in these processes. Further studies are required to chara cterize the androgen receptor-dependent pathways in the vascular system.