Dihydrotestosterone Suppresses Foam Cell Formation and Attenuates Atherosclerosis Development

Abstract

The role of testosterone in atherosclerosis remains unclear because it is aromatized to estrogen. We investigated the effect of the nonaromatized natural androgen 5α-dihydrotestosterone (DHT) on the rabbit atherogenesis in relation to the proatherogenic molecule lectin-like oxidized-low-density lipoprotein receptor-1 (LOX-1) and its downstream molecules. Thirty-nine male New Zealand white rabbits were divided into four groups: 1) noncastrated group with normal chow diet (n = 6); 2) noncastrated group with high-cholesterol diet (HCD) (n = 10); 3) castrated group with HCD plus sc placebo pellet (n = 11); and 4) castrated group with HCD plus sc 150 mg DHT pellet (n = 12). Implantation of sc DHT or placebo pellet was performed at the time of castration. After castration or sham operation, the rabbits were fed the HCD for 8 wk, and plaque areas were assessed in the entire aorta. The HCD-induced increase in plaque area, which was most aggravated in the castration plus placebo group, was attenuated in the castration plus DHT group. Microscopic examination of the proximal descending aorta revealed that DHT significantly reduced HCD-induced foam cell formation, which was mostly composed of macrophages in the intima layer, compared with the placebo group. The decreased accumulation of foam cells with DHT treatment was accompanied by a marked reduction in the expression of LOX-1 mRNA in these cells. In cultured macrophages prepared from male wild-type mice that express the androgen receptor (AR), 1 × 10−8m and 1 × 10−9m DHT inhibited the formation of foam cells induced by oxidized low-density lipoprotein. Moreover, the expression of LOX-1 and inflammatory cytokines in the cultured macrophages was significantly suppressed by DHT. Such suppressive effects of DHT on foam cell formation and cytokine expression were not observed in cultured macrophages prepared from male AR-null mice, suggesting an involvement of AR in the mechanism. In conclusion, physiological levels of DHT attenuated the development of atherosclerosis in rabbits through the suppression of intimal foam cell formation of macrophage partly via the suppression of LOX-1 expression.