Barbara Bonacasa

2-Methoxyestradiol attenuates hypertension and coronary vascular remodeling in spontaneously hypertensive rats.

OBJECTIVES Accumulating data provide evidence that some metabolites of 17beta-estradiol are biologically active and mediate multiple effects on the cardiovascular and renal systems. We investigated the effect of 2-methoxyestradiol (an active metabolite of estradiol with non-feminizing activity) on the development of hypertension and myocardial vascular remodeling in male and female ovarectomized SHR. METHODS Rats were divided into five groups: intact females, ovarectomized (OVX), OVX+ 2-methoxyestradiol (2ME), control males, and male+2ME. Systolic blood pressure was determined from 10 to 18 weeks. Structural changes in coronary vessels were quantified by an image analyzer. Immunoblotting of phosphorylated ERK1/2 and NADPH oxidase activity were performed on mesenteric arteries. RESULTS Treatment with 2ME reduced the increase in systolic blood pressure in male and ovarectomized rats to values not different from those obtained in intact females. Myocardial arterioles and small arteries showed significant increases in wall-to-lumen ratio and perivascular fibrosis in male and ovarectomized rats when compared with intact females. NADPH oxidase activity was increased in mesenteric arteries from males and ovarectomized females as compared with intact females. Finally, the expression of phosphorilated ERK1/2 were significantly higher in mesenteric arteries from male and ovariectomized animals than in those from intact females. Those effects of ovarectomy and gender differences were totally or partially prevented by treatment with 2-methoxyestradiol. CONCLUSIONS These data demonstrate that 2-methoxyestradiol protects the vasculature from hypertension-induced myocardial arterial remodeling in male and ovarectomized SHR, and that might be in part related to decreased superoxide generation and ERK1/2 activation.

Reactive Oxygen and Nitrogen Species in the Renal Ischemia/Reperfusion Injury

Renal ischemia is the most common cause of acute kidney injury (AKI) still associated with high mortality rates of about 50% in the intensive care unit. Postischemic AKI is characterized by decreased glomerular filtration rate and high renal vascular resistance with endothelial activation and dysfunction, a process of critical importance that is followed by a reduction in microvascular blood flow mainly affecting the renal outer medulla. The pathophysiology of postischemic AKI remains incompletely understood, although it seems to be a phenomenon of altered renal hemodynamics, linked critically to the production of high amounts of nitric oxide and free radicals. On the other hand, and depending on the severity of renal ischemia, tubular epithelial cells undergo a varying degree of necrosis or apoptosis with tubular obstruction followed by both, anatomical and functional recovery. The way in which vascular and tubular epithelium recover determines the final status of the renal function, ranging from full recovery to chronic renal failure and ultimately to end-stage renal disease. In this review we will revise the mechanisms responsible for these pathophysiologic alterations, including the role of heme oxygenase system and sex differences in the susceptibility to ischemic acute renal failure, and we will also review the pre- and postconditioning phenomena, in which brief episodes of ischemia before (pre-conditioning) or after (post-conditioning) the prolonged ischemia have a protective effect on AKI after reperfusion. Interestingly, these protective responses can be elicited by ischemizing distant tissues (remote conditioning). A better understanding of these mechanisms may help to improve the clinical outcome of those patients.

Effect of estrogen and angiotensin-converting enzyme inhibitor on vascular remodeling in ovariectomized spontaneously hypertensive rats.

Objective: The present study evaluated whether estrogen influences the effect of angiotensin-converting enzyme inhibition in preventing the vascular remodeling induced by hypertension and also investigated the signal mechanism involved in that effect. Design: Ten-week-old female spontaneously hypertensive rats were ovariectomized (OVX) and randomly assigned to the groups: untreated OVX and treated with 17&bgr;-estradiol (estradiol, 1.5 mg) and/or captopril (5 mg/kg/day). Evolution of systolic blood pressure was determined until 18 weeks. At that time, the heart and mesentery were excised. Structural changes in coronary vessels were quantified by an image analyzer. Inmunoblotting was performed on mesenteric arteries for determination of phosphorylated (ERK1/2). Results: Estradiol treatment enhanced the antihypertensive effect of captopril in OVX rats. Treatment with captopril slightly modified the media cross-sectional area and wall-to-lumen of myocardial arterioles from OVX spontaneously hypertensive rats, whereas coadministration of captopril and estradiol significantly reduced the media cross-sectional area, wall-to-lumen ratio, and perivascular fibrosis in OVX spontaneously hypertensive rats. Captopril alone did not significantly inhibit extracellular signal-regulated kinase 1/2 phosphorylation, whereas coadministration of captopril and estradiol significantly attenuated this parameter. Conclusions: These results indicate that estrogen may enhance the angiotensin-converting enzyme inhibition-mediated improvement of vascular remodeling in hypertension, which may be partly mediated via inhibition of extracellular signal-regulated kinase 1/2.

17??-Estradiol exerts a beneficial effect on coronary vascular remodeling in the early stages of hypertension in spontaneously hypertensive rats

Objective:Estrogens may induce cardioprotective effects and prevent neointima formation in response to vascular injury in vivo. The present study evaluated the effect of 17β-estradiol on myocardial arterial remodeling and on vascular mitogen-activated protein kinase expression in experimental hypertension. Design:The experiments were performed in intact female spontaneously hypertensive rats (SHR), in SHR that were ovariectomized at 10 or 25 weeks of age, and in ovariectomized SHR that were supplemented with 17 β-estradiol (OVX + E2, 1.5 mg every 8 weeks, subcutaneous pellets). Results:At 18 weeks of age, in all myocardial arterioles and small arteries studied, we found significant increases in wall-to-lumen ratio in ovariectomized rats as compared with intact animals. 17β-estradiol significantly reduced the wall-to-lumen ratio in OVX + E2 rats. Perivascular fibrosis of small coronary arteries was significantly increased by ovariectomy, and this effect was prevented by long-term treatment with 17β-estradiol. Phosphorylated extracellular signal-regulated kinase 1/2 significantly increased in mesenteric arteries from ovariectomized animals and this effect was prevented by 17β-estradiol. Wall-to lumen ratio and perivascular fibrosis were significantly higher in older intact animals at 33 weeks of age. However, neither ovariectomy nor estradiol replacement had any effect on long-term hypertension-induced vascular remodeling. Conclusions:These data suggest that estradiol may exert a beneficial effect by protecting the vasculature from hypertension-induced myocardial arterial remodeling in the early stages of hypertension, but not when chronic alterations are established after a long-term period of hypertension.

17β-Oestradiol enhances the acute hypotensive effect of captopril in female ovariectomized spontaneously hypertensive rats

The objective of this study was to investigate whether the acute haemodynamic effects of angiotensin‐converting enzyme inhibition with captopril could be enhanced by oestrogen administration, and then to evaluate the mechanisms involved in this enhancement. All experiments were performed in 18‐week‐old female spontaneously hypertensive rats arranged in three experimental groups: intact; ovariectomized (OVX); and ovariectomized plus treatment with 17β‐oestradiol (OVX + E2). These groups were used to evaluate the effects of captopril administration alone, or following bradykinin B2 receptor blockade or nitric oxide synthase inhibition, on a number of haemodynamic parameters (mean arterial pressure, cardiac index, vascular resistance and heart rate). The drop in mean arterial pressure and vascular resistance index in response to captopril was more pronounced in intact and ovariectomized rats treated with 17β‐oestradiol than in ovariectomized animals. Blockade of bradykinin B2 receptors or inhibition of nitric oxide synthesis attenuated the synergy between 17β‐oestradiol and captopril. It is concluded that ovariectomy blunted the blood pressure and vascular resistance index drop observed in intact rats in response to captopril. Treatment with 17β‐oestradiol prevented the blunted response to captopril in ovariectomized rats. Kinins and nitric oxide may be involved in the mechanisms of 17β‐oestradiol potentiation of the haemodynamic effects of captopril.

Endothelial dysfunction in gestational hypertension induced by catechol‐O‐methyltransferase inhibition

•  What is the central question of this study? Gestational hypertension is a major obstetric problem of placental origin, associated with reduced production of 2‐methoxyestradiol. In this study, we evaluated in rats the consequences of pharmacological inhibition of catechol‐O‐methyltransferase, the enzyme that produces 2‐methoxyestradiol from 2‐hydroxyestradiol. •  What is the main finding and its importance? The present study provides evidence that inhibition of catechol‐O‐methyltransferase in pregnant rats produces arterial hypertension and endothelial dysfunction due to reduced nitric oxide bioavailability. The results help us to understand gestational hypertension and support a possible new approach to early diagnosis and treatment of the disease.

Effects of oestrogen treatment and angiotensin‐converting enzyme inhibition on the microvasculature of ovariectomized spontaneously hypertensive rats

We investigated the role of oestrogen in the function and structure of the microcirculation of female spontaneously hypertensive rats (SHRs), and evaluated the effect of 17β‐oestradiol on their cardiovascular response to pharmacological agents that block the formation of angiotensin II. Ten‐week‐old SHRs were randomly assigned to the following groups: intact, ovariectomized, and ovariectomized treated with 17β‐oestradiol (1.5 mg delivered over 60 days) and/or captopril (5 mg kg−1 day−1 for 8 weeks). Systolic blood pressure was determined from the time of ovariectomy up to 18 weeks of age, at which time endothelial function and microvascular density in skeletal muscle were evaluated. Both 17β‐oestradiol and captopril prevented development of hypertension in ovariectomized rats. Furthermore, coadministration of both drugs had a greater antihypertensive effect than either one alone. Acetylcholine‐induced vasodilatation was impaired in ovariectomized SHRs, and the response was improved by treatment with 17β‐oestradiol and/or captopril. In addition, 17β‐oestradiol replacement in ovariectomized rats enhanced the effect of captopril on acetylcholine‐induced vasodilatation. Ovariectomized rats also showed lower microvascular density than intact rats, an effect that was prevented by 17β‐oestradiol replacement or captopril treatment and, to a significantly larger extent, by coadministration of both. We concluded that both 17β‐oestradiol and captopril attenuated the development of hypertension and improved the impairment in microvascular density of ovariectomized SHRs. Moreover, when simultaneously administered, oestradiol and captopril had an additive effect on blood pressure and the microvasculature.

2-methoxyestradiol plasma levels are associated with clinical severity indices and biomarkers of preeclampsia.

We investigated whether clinical severity indices and biomarkers for preeclampsia (PE) are associated with low plasmatic 2-methoxyestradiol (2ME) in the third trimester of gestation. Blood was collected from 53 women with PE and 73 control pregnant women before parturition. The concentration of 2ME was significantly higher in controls than in patients with PE (2906.43 ± 200.69 pg/mL vs 1818.41 ± 189.25 pg/mL). The risk of PE decreased as 2ME levels increased. The 2ME values were negatively correlated with systolic peak arterial pressure and proteinuria in PE. Additionally, those women with PE with lower 2ME had a more serious clinical situation and needed a more aggressive therapy. Finally, 2ME levels (in patients with PE and total population) were significantly correlated with concentrations of soluble fms-like tyrosine kinase 1 and placental growth factor . Summarizing, patients with PE had lower 2ME levels that were correlated with different clinical indices and biomarkers of severity, indicating that 2ME could be taken into account for the clinical management of this syndrome.

Fetal Val108/158Met catechol-O-methyltransferase (COMT) polymorphism and placental COMT activity are associated with the development of preeclampsia.

OBJECTIVE To evaluate the association between fetal and maternal catechol-O-methyltransferase (COMT) Val158Met and methyl tetrahydrofolate reductase (MTHFR) C677T functional polymorphisms and preeclampsia, examining its influence on placental COMT and in maternal 2-methoxyestradiol (2-ME) plasma levels. DESIGN Prospective case-control study. SETTING University hospital. PATIENT(S) A total of 53 preeclamptic and 72 normal pregnant women. INTERVENTION(S) Maternal and cord blood samples and placental tissue samples were obtained. MAIN OUTCOME MEASURE(S) Maternal and fetal COMT and MTHFR polymorphisms were genotyped. Maternal plasma 2-ME and homocysteine levels, and expression and activity of placental COMT were measured. RESULT(S) The odds ratio for the risk of preeclampsia for fetal COMT Met/Met was 3.22, and it increased to 8.65 when associated with fetal MTHFR TT. Placental COMT activity and expression were influenced by genotype, but COMT activity in preeclamptic placentas did not differ from control pregnancies. There was no association between any genotypes and maternal 2-ME. Homocysteine levels were higher in women with preeclampsia than in normal pregnancies, and were inversely correlated with 2-ME plasma levels, indicating that its altered metabolism may lower COMT activity in vivo. CONCLUSION(S) Fetal Met-Met COMT genotype reduces COMT placental expression and activity in vitro and increases preeclampsia, risk but it does not explain the difference in maternal 2-ME levels between preeclamptic and normal pregnancies. However, the preeclamptic patients had elevated homocysteine levels that correlated inversely with 2-ME, indicating that an altered methionine-homocysteine metabolism may contribute to reduce COMT activity in vivo and explain the decreased levels of 2-ME in preeclamptic women.

Sexual Dimorphism in Renal Heme-Heme Oxygenase System in the Streptozotocin Diabetic Rats

Heme Oxygenase (HO) -1 and -2 exert antioxidant, cytoprotective and vascular actions in male diabetic rats. However, there is no information about the expression and functional significance of the renal HO system in diabetic females. The present study tested the hypothesis that the HO system is differentially regulated in the kidney of female Sprague Dawley diabetic rats, protecting it from nitrosative and glomerular functional damage. Two weeks after the administration of streptozotocin (STZ; 65 mg/kg. i.p), males (DM) and females (DF) showed hyperglycemia, polyuria and elevated kidney/body weight ratio, compared to their control males (CM) and females (CF). In conscious animals, creatinine clearance was higher (0.5 ± 00 vs. 0.3 ± 00; ml/min/100g BW; p<0.05) and urinary albumin excretion was lower (0.7 ± 0.3 vs 3.1 ± 0.7; mg/day) in DF compared to DM. Acute administration of a HO inhibitor stannous mesoporphyrin (SnMP 40 mol/kg, i.v.) induced a greater renal vasoconstrictor response in DF than in DM. Western blot analysis of renal tissue revealed higher renal cortex HO-1 protein levels in DF compared to all other groups; by immunohistochemistry this induction of HO-1 in DF was localized in tubular segments and glomeruli. Furthermore, renal cortical concentration of nitrosylated protein was higher in DM than in DF animals and inversely related with HO-1 levels in both renal cortex and medulla. These data demonstrate that the HO-1 protein is induced in females, associated with renal vasodilation, decreased renal nitrosative stress and reduced albuminuria, indicating that the HO system is protecting the kidney from diabetes-induced damage specifically in females.