Removal of ovarian hormones increased LV remodeling in the aged rat, which could be attenuated by estrogen replacement. Moreover, regulation of Ang II receptor expression could be a mechanism by which estrogen may modulate heart remodeling.

Abstract-Tumor necrosis factor-␣ (TNF-␣) is involved in the pathogenesis of vascular disease. Clinical studies have shown that postmenopausal women have higher serum TNF-␣ levels; however, whether this increase in TNF-␣ is associated with vascular dysfunction is unknown. We investigated whether estrogen deficiency is associated with increased serum TNF-␣ levels and tested the effects of in vivo TNF-␣ inhibition on vascular reactivity. Aged (12 to 15 months) Sprague-Dawley rats were ovariectomized and treated with placebo, estrogen, or a TNF-␣ inhibitor (Etanercept; 0.3 mg/kg) for 4 weeks. Serum TNF-␣ was determined by a bioassay, and vascular function was evaluated in the myograph system. Estrogen-deficient animals had higher serum levels of TNF-␣ compared with either estrogen-replaced animals or animals treated with Etanercept. Moreover, in estrogen-deficient rats, TNF-␣ inhibition reduced the constriction of mesenteric arteries to phenylephrine, increased the modulation of this vasoconstriction by the NO synthase inhibitor nitro-L-arginine methyl ester, and decreased the modulation by a superoxide scavenger (Mn(III)tetrakis(4-benzoic acid) porphyrin chloride). Furthermore, endothelium-dependent relaxation was also enhanced by TNF-␣ antagonism. Additionally, vascular expression of endothelial NO synthase was increased in animals treated with Etanercept, whereas the expression of NAD(P)H oxidase gp91phox and p22phox subunits was decreased. These data show that estrogen-deficient female rats have higher bioactive serum TNF-␣ levels compared with estrogen-replaced animals. Moreover, a decrease in serum bioactive TNF-␣ by a soluble TNF-␣ receptor (Etanercept) results in increased modulation of vascular function by NO. These observations suggest that TNF-␣ could be a mediator of vascular dysfunction associated with estrogen deficiency. Key Words: aging Ⅲ nitric oxide Ⅲ tumor necrosis factor Ⅲ estrogen Ⅲ vascular function C ardiovascular disease is the leading cause of death for women in developed countries. Although menopause is considered a major risk factor for vascular disease, the pathophysiological mechanisms linking the decrease in ovarian hormones that occurs in menopause with alterations in vascular function are still unclear.NO is an important vasodilator and has an important role in the control of vascular homeostasis, including its ability to modulate the actions of vasoconstrictors such as the ␣-1-adrenergic agonist phenylephrine (PE). 1 In fact, a decrease in NO modulation of vascular function is associated with higher risk of developing vascular disease. 2 Animal and human studies have shown that the decline of the ovarian function is associated with decreased NO. [3][4][5] Although the mechanisms remain unknown, the decrease in bioavailable NO seems to be attributable to a decrease in its production or enhanced inactivation by superoxide anion that results in formation of peroxynitrite.Tumor necrosis factor-␣ (TNF-␣) is a proinflammatory cytokine proposed to be involved in the pathogenesis of vascular...

These data indicate that estrogen modulates cardiac expression of TNFalpha and TNFalpha receptors. Moreover, the cardioprotective effects of estrogen are in part mediated by regulation of TNFalpha levels in the ischemic heart.

Aging and estrogen deficiency increase the risk for developing cardiovascular disease (CVD). Oxidative stress has also been implicated in the pathophysiology of CVD and in ischemia-reperfusion (I/R) injury. We tested the hypothesis that chronic in vivo estrogen treatment or superoxide inhibition with the SOD mimetic EUK-8 improves cardiac functional recovery after I/R in the aged female rat. Sprague-Dawley rats (12-14 mo) were used as follows: intact (n = 6), ovariectomized + placebo (OVX, n = 6), OVX + EUK-8 (EUK-8, 3 mg/kg, n = 6), and OVX + estrogen (1.5 mg/pellet, 60 days release, n = 6). Perfused isolated hearts were subjected to global ischemia (25 min) followed by reperfusion (40 min). Functional recovery after I/R and myocardial protein expression of NADPH oxidase (p22, p67, and gp91(phox)), inducible nitric oxide synthase (NOS), endothelial NOS, and SOD1, as well as nitrotyrosine levels (as a marker for peroxynitrite), were assessed. Compared with OVX, EUK-8 and estrogen markedly improved functional recovery after I/R, which was associated with a decrease in NADPH oxidase expression and nitrotyrosine staining. However, estrogen increased inducible NOS expression, whereas EUK-8 had little effect. There were no significant changes in endothelial NOS and SOD1 expression among the groups. These results indicate that EUK-8 and estrogen improved cardiac recovery after I/R. Given the controversy surrounding hormone replacement therapy, EUK-8 may be an alternative to estrogen in protecting those at risk for myocardial ischemia in the aging population.

Abstract-Alterations in the vascular angiotensin II system may play a role in the pathophysiology of vascular disease after menopause. In previous studies we have shown that an increase in tumor necrosis factor (TNF)-␣ levels in aging rats because of estrogen deficiency may result in vascular dysfunction. In this study we investigated the effect of TNF-␣ inhibition in angiotensin II modulation of vascular function in aging female animals. Female rats approaching reproductive senescence (12 to 15 months old) were ovariectomized and treated with placebo, estrogen, or a selective TNF-␣ inhibitor (etanercept) for 4 weeks. Expression of angiotensin II in mesenteric arteries was evaluated by immunofluorescence, and the expression of angiotensin-converting enzyme and angiotensin type I receptor (AT 1 R) was investigated by Western immunoblot. Vascular function was assessed in mesenteric arteries using the myograph system, and the role of endogenous angiotensin II on adrenergic vasoconstriction was evaluated in vitro by selective AT 1 R blockade (Candesartan; 10 mol/L). Our data demonstrate that estrogen-depleted rats have higher serum levels of TNF-␣ and greater sensitivity to phenylephrine vasoconstriction compared with estrogen-replaced animals, which was attenuated by AT 1 R blockade. In vivo TNF-␣ inhibition or estrogen replacement reduced phenylephrine constriction of mesenteric arteries and decreased the modulation of this vasoconstriction by candesartan. These functional changes were accompanied by a reduction in the vascular expression of angiotensin II, angiotensin-converting enzyme, and AT 1 R.