Cellular and molecular actions of testosterone in vascular system

Abstract

Vascular function is regulated by various agonists including the sex steroid hormones estrogen, progesterone and androgens. In order to contribute to the knowledge of the role of androgens on vascular function, in this work we investigated the cellular and molecular actions of testosterone (T) on the regulation of cellular events involved in vascular physiology such as nitric oxide (NO) production, proliferation and migration of rat aortic endothelial cells (EC). We provide evidence that T (10-7 a 10-11M) induces an acute stimulation of NO production in EC (15 to 125% above/control, p<0.01), in a gene transcription independent manner and independently of aromatase action. The mechanism of action of the steroid involves the participation of the androgen receptor (82 vs 2% s/control, T vs T+Flutamide respectively, p<0.05), and is dependent on MAPK (4.24±1.11 vs 7.80±0.93; 4.51±0.73 vs 4.40±0.72 nmol NO/mg prot, C vs T; C+PD98059 vs T+PD98059,p<0.001) , PLC/PKC (4.25±1.10 vs 7.84±1.27; 4.62±0.87 vs 4.95±0.89 nmol NO/mg prot, C vs T; C+Chelerythrine vs T+Chelerythrine,p<0.001) and PI3K/Akt (4.30±0.83 vs 7.52±0.98; 4,82±0.77 vs 4.31±0.52 nmol NO/mg prot, C vs T -/+ LY294002) signaling pathways activation and dependent of the influx of extracellular calcium (82.6; 29.6; 23.2 % above/control, T; T+EGTA; T+Verapamil). Related to the cellular processes involved in vascular repair, we demonstrate that T promotes EC proliferation (3[H]-timidine incorporation) (17.3±1.4 vs 25.4±4.4, C vs T, p<0.05). The mitogenic action exhibited by the steroid is dependent on endothelial NO production since the proliferative effect is significantly reduced by the presence of the NOS inhibitor L-NAME. By means of wound healing essays it was also determined that T stimulates also EC migration. These results provide knowledge about vascular actions of T and the mechanisms of action involved