Date Published: May 02, 2018
Publisher: Impact Journals
Author(s): Kamil Karolczak, Lucyna Konieczna, Tomasz Kostka, Piotr J. Witas, Bartlomiej Soltysik, Tomasz Baczek, Cezary Watala.
The cardiovascular effects of testosterone and dihydrotestosterone are generally attributed to their modulatory action on lipid and glucose metabolism. However, no ex vivo studies suggest that circulating androgen levels influence the activation and reactivity of blood platelets – one of the main components of the haemostasis system directly involved in atherosclerosis. The levels of testosterone, dihydrotestosterone and oestradiol in plasma from men and women aged from 60 to 65 years were measured by LC-MS; the aim was to identify any potential relationships between sex steroid levels and the markers of platelet activation (surface membrane expression of GPII/IIIa complex and P-selectin) and platelet reactivity in response to arachidonate, collagen or ADP, monitored with whole blood aggregometry and flow cytometry. The results of the ex vivo part of the study indicate that the concentrations of testosterone and its reduced form, dihydrotestosterone are significantly negatively associated with platelet activation and reactivity. These observations were confirmed in an in vitro model: testosterone and dihydrotestosterone significantly inhibited platelet aggregation triggered by arachidonate or collagen. Our findings indicate that testosterone and dihydrotestosterone are significant haemostatic steroids with inhibitory action on blood platelets in older people.
Testosterone (T) has recently been identified as a cardiovascular hormone, in addition to its basic role in the regulation of male reproduction [1,2].
Our results clearly show that T and DHT possess anti-platelet potential. Outcomes suggesting such a conclusion are derived not only from the in vivo/ex vivo findings presented in this study, but also from an in vitro model evaluating the effects of exogenous steroids on platelet reactivity. To ensure that the identified relationships remained valid upon adjustment for several confounders that are very likely to shape the extent of blood platelet reactivity, the in vivo findings were analysed using both simple association methods, without adjusting for numerous potential confounders, and multivariate approaches.