17beta-Estradiol inhibits vascular smooth muscle cell proliferation and c -fos expression: role of nitric oxide.

Rat vascular smooth muscle cells (VSMC) were used to study the effect of 17beta -estradiol (E(2)) on cellular proliferation (cell counting), DNA synthesis ((3)H thymidine incorporation), MTT, c -fos mRNA expression and nitric oxide (NO) release. The results obtained showed that E(2) (10(-12) 10(-8) mol/L) induced NO release from VSMC in a concentration-dependent manner; 10(-8) mol/L E (2)significantly inhibited VSMC cellular proliferation and DNA synthesis induced by 10% FCS and 10(-7) mol/L ET-1, which was obviously reversed by 10(-7)mol/L tamoxifen and 10(-6) mol/L L-NAME; after a pretreatment for 24 hours, 10(-8)mol/L E(2) significantly inhibited VSMC c -fos mRNA expression induced by 10(-7)mol/L ET-1, which was also obviously reversed by 10(-6) mol/L L-NAME. These results suggest that the inhibitory effects of E(2) on VSMC cellular proliferation and c -fos mRNA expression are closely related with NO release in VSMC, which is, at least, partly medicated by ER.