Effect of 17beta-oestradiol on cytokine-induced nitric oxide production in rat isolated aorta.
1. Studies were performed on isolated aortic rings without endothelium to investigate the effect of 17beta-oestradiol on cytokine-induced nitric oxide production by the inducible nitric oxide synthase (iNOS). 2. Treatment of the isolated aortic rings with interleukin-1beta (IL-1beta, 20 micro ml(-1)) led to the expression of iNOS mRNA and protein, as well as significant nitrite accumulation in the incubation media and suppression of phenylephrine (1 nM-10 microM)-evoked contraction. 3. Cycloheximide (1 microM), a protein synthesis inhibitor, prevented iNOS protein expression, nitrite accumulation and the suppression of contractility by IL-1beta on the isolated aortic rings. 17Beta-oestradiol (1 nM-10 microM) and the partial oestrogen receptor agonist 4-OH-tamoxifen (1 nM-10 microM) produced concentration-dependent inhibition of IL-1beta-induced nitrite accumulation and restored vasoconstrictor responsiveness to phenylephrine, similar to the iNOS inhibitor aminoguanidine (100 microM). 4. Semiquantitative PCR demonstrated decreased iNOS mRNA in the IL-1beta-induced and 17beta-oestradiol-treated rings. Western blot analysis of rat aorta homogenates revealed that 17beta-oestradiol treatment resulted in a reduction in IL-1beta-induced iNOS protein level. 5. Incubation with tumour necrosis factor alpha (TNF alpha, 1 ng ml(-1)) resulted in significant nitrite accumulation in the incubation media and suppression of the smooth muscle contractile response to phenylephrine, similar to IL-1beta. The effects of TNF alpha were also inhibited by co-incubation of the rings with 17beta-oestradiol and 4-OH-tamoxifen (1 microM). 6. The anti-transforming growth factor-beta1 (TGF-beta1) antibody, which inhibited TGF-beta1-induced suppression of nitrite production from IL-1beta-treated vascular rings, did not affect the inhibitory action of 17beta-oestradiol, suggesting that the effect of oestrogen on iNOS inhibition was not mediated by TGF-beta1. 7. These results show that the ovarian sex steroid, 17beta-oestradiol is a modulator of cytokine-induced iNOS activity in rat vascular smooth muscle and its mechanism of action involves decrease of iNOS mRNA and protein.
Kauser
K
K
Cardiovascular Department, Berlex Biosciences, Richmond, CA 94804-0099, USA.
Sonnenberg
D
D
Diel
P
P
Rubanyi
G M
GM
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001011:Aorta / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000276:immunology
D000906:Antibodies; D007375:Interleukin-1; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D013629:Tamoxifen; C016601:afimoxifene; D009569:Nitric Oxide; D004958:Estradiol; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat