Androgen regulations of cellular events involve in bone perfusion

CAMPELO, A.; CUTINI, P.; RAUSCHEMBERGER, M.B.; MASSHEIMER, V.

Buenos Aires

Congreso; XXIX Reunion Anual AAOMM; 2012

AAOMM

We studied the effect of testosterone (T) on nitric oxide (NO) production, endothelial cell (EC) migration and VEGF synthesis; key factors for bone perfusion and vascularization. We previously reported that in rat aortic strips 1?20 min treatment with T (0.01?100 nM) significantly increased NO production in a non-gender specific manner. We found that the stimulatory action of T on NO synthesis decreased with age (7.84 ± 0.83 vs 3.82 ± 0.60 nmol NO/mg prot, young vs adult, p < 0.01). Evidence of the participation of Ca2 + influx from extracellular medium was obtained. Incubation of EC in Ca2 + free medium or in the presence of a calcium channel blocker (nifedipine) partially reduced the effect of T (79.0%, 26.5% and 28.3% above control; T, T + EGTA and T + nifedipine, p < 0.01). The mechanism of action of the steroid was investigated. The effect of T did not depend on its aromatization to estradiol since presence of the aromatase inhibitor anastrozole did not affect the stimulatory action of T on NO synthesis. In contrast, preincubation of EC with finasteride (fin), an inhibitor that blocks T conversion to DHT, partially suppressed T stimulus (4.20 ± 0.39 vs 7.34 ± 1.01, 4.32 ± 0.53 vs 6.00 ± 0.91 nmol NO/mg prot; C vs T; C + fin vs T + fin, p < 0.05) suggesting that both T and DHT mediate the androgen action. We observed that PI3K signal pathway is involved in the androgen-dependent NO synthesis since the inhibitor Wortmanin, completely suppressed the steroid action. In migration assays we determined that 72 h of T treatment stimulated EC migration (63 ± 7.8 vs 115 ± 15.8 migrated cells/field C vs T, p < 0.025). Indeed the androgen enhanced the expression mRNA for VEGF. These results indicate that Tregulates cellular and molecular events associated with bone perfusion.