Compared with age-matched men, premenopausal women are largely protected from coronary artery disease, a difference that is lost after menopause. The effects of oestrogens are mediated by the activation of nuclear receptors (ERα and ERβ) and by the G protein-coupled oestrogen receptor (GPER). This study aims to evaluate the potential role of GPER in coronary circulation in female and male rats. The baseline coronary perfusion pressure (CPP) and the concentration-response curve with a GPER agonist (G-1) were evaluated in isolated hearts before and after the blockade of GPER. GPER, superoxide dismutase (SOD-2), catalase and gp91phox protein expression were assessed by Western blotting. Superoxide production was evaluated '' via dihydroethidium fluorescence (DHE). GPER blockade significantly increased the CPP in both groups, demonstrating the modulation of coronary tone by GPER. G-1 causes relaxation of the coronary bed in a concentration-dependent manner and was significantly higher in female rats. No differences were detected in GPER, SOD-2 and catalase protein expression. However, gp91phox expression and DHE fluorescence were higher in male rats, indicating elevated superoxide production. Therefore, GPER plays an important role in modulating coronary tone and reactivity in female and male rats. The observed differences in vascular reactivity may be related to the higher superoxide production in male rats. These findings help to elucidate the role of GPER-modulating coronary circulation, providing new information to develop a potential therapeutic target for the treatment of coronary heart disease.

The present study aimed to determine the effects of chronic treatment with different doses of testosterone on endothelium–dependent coronary vascular reactivity in male rats. Adult male rats were divided into four experimental groups: control (SHAM), castrated (CAST), castrated and immediately treated subcutaneously with a physiological dose (0.5 mg/kg/day, PHYSIO group) or supraphysiological dose (2.5 mg/kg/day, SUPRA group) of testosterone for 15 days. Systolic blood pressure (SBP) was assessed at the end of treatment through tail plethysmography. After euthanasia, the heart was removed and coronary vascular reactivity was assessed using the Langendorff retrograde perfusion technique. A dose–response curve for bradykinin (BK) was constructed, followed by inhibition with 100 μM L-NAME, 2.8 μM indomethacin (INDO), L-NAME + INDO, or L-NAME + INDO + 0.75 μM clotrimazole (CLOT). We observed significant endothelium–dependent, BK–induced coronary vasodilation, which was abolished in the castrated group and restored in the PHYSIO and SUPRA groups. Furthermore, castration modulated the lipid and hormonal profiles and decreased body weight, and testosterone therapy restored all of these parameters. Our results revealed an increase in SBP in the SUPRA group. In addition, our data led us to conclude that physiological concentrations of testosterone may play a beneficial role in the cardiovascular system by maintaining an environment that is favourable for the activity of an endothelium–dependent vasodilator without increasing SBP.

Based on the antioxidant properties of pomegranate, this study was designed to investigate the effects of pomegranate peel extract on damage associated with hypertension and aging in a spontaneously hypertensive rat (SHR) model. The influence of pomegranate consumption was examined on systolic blood pressure (SBP), angiotensin-converting enzyme (ACE) coronary activity, oxidative stress, and vascular morphology. Four- or 28-wk-old SHR model rats were treated for 30 d, with terminal experimental animal age being 8 and 32 wk, respectively, with either pomegranate extract (SHR-PG) or filtered water (SHR). Data showed significant reduction in SBP and coronary ACE activity in both age groups. The levels of superoxide anion, a measure of oxidative stress, were significantly lower in animals in the SHR-PG group compared to SHR alone. Coronary morphology demonstrated total increases in vascular wall areas were in the SHR group, and pomegranate peel extract diminished this effect. Pomegranate peel extract consumption conferred protection against hypertension in the SHR model. This finding was demonstrated by marked reduction in coronary ACE activity, oxidative stress, and vascular remodelling. In addition, treatment was able to reduce SBP in both groups. Evidence indicates that the use of pomegranate peel extract may prove beneficial in alleviating coronary heart disease.

Decline in estrogen levels promotes endothelial dysfunction and, consequently, the most prevalent cardiovascular diseases in menopausal women. The use of natural therapies such as pomegranate can change these results. Pomegranate [Punica granatum L. (Punicaceae)] is widely used as a phytotherapeutic agent worldwide, including in Brazil. We hypothesized that treatment with pomegranate hydroalcoholic extract (PHE) would improve coronary vascular reactivity and cardiovascular parameters. At the beginning of treatment, spontaneously hypertensive female rats were divided into Sham and ovariectomized (OVX) groups, which received pomegranate extract (PHE) (250 mg/kg) or filtered water (V) for 30 days by gavage. Systolic blood pressure was measured by tail plethysmography. After euthanasia, the heart was removed and coronary vascular reactivity was assessed by Langendorff retrograde perfusion technique. A dose-response curve for bradykinin was performed, followed by L-NAME inhibition. The protein expression of p-eNOS Ser1177, p-eNOS Thr495, total eNOS, p-AKT Ser473, total AKT, SOD-2, and catalase was quantified by Western blotting. The detection of coronary superoxide was performed using the protocol of dihydroethidium (DHE) staining Plasma nitrite measurement was analyzed by Griess method. Systolic blood pressure increased in both Sham-V and OVX-V groups, whereas it was reduced after treatment in Sham-PHE and OVX-PHE groups. The baseline coronary perfusion pressure was reduced in the Sham-PHE group. The relaxation was significantly higher in the treated group, and L-NAME attenuated the relaxation in all groups. The treatment has not changed p-eNOS (Ser1177), total eNOS, p-AKT (Ser473) and total AKT in any groups. However, in Sham and OVX group the treatment reduced the p-eNOS (Thr495) and SOD-2. The ovariectomy promoted an increasing in the superoxide anion levels and the treatment was able to prevent this elevation and reducing oxidative stress. Moreover, the treatment prevented the decreasing in plasmatic nitrite. We observed a reduction in total cholesterol and LDL in the Sham-PHE group. The treatment with PHE enhances the endothelium-dependent coronary relaxation and improves cardiovascular parameters, which suggests a therapeutic role of PHE.

BackgroundThe protective effect of estrogen on the vasculature cannot be explained only by its action through the receptors ERα and ERβ. G protein-coupled estrogen receptors (GPER)—which are widely distributed throughout the cardiovascular system—may also be involved in this response. However, little is known about GPER actions in hypertension. Therefore, in this study we evaluated the vascular response mediated by GPER using a specific agonist, G-1, in spontaneously hypertensive rats (SHR). We hypothesized that G-1 would induce a relaxing response in resistance mesenteric arteries from SHR of both sexes.MethodsG-1 concentration-response curves (1 nM-10 μM) were performed in mesenteric arteries from SHR of both sexes (10–12-weeks-old, weighing 180–250 g). The effects of G-1 were evaluated before and after endothelial removal and incubation for 30 min with the inhibitors L-NAME (300 μM) and indomethacin (10 μM) alone or combined with clotrimazole (0.75 μM) or catalase (1,000 units/mL). GPER immunolocalization was also investigated, and vascular hydrogen peroxide (H2O2) and ROS were evaluated using dichlorofluorescein (DCF) and dihydroethidium (DHE) staining, respectively.ResultsGPER activation promoted a similar relaxing response in resistance mesenteric arteries of female and male hypertensive rats, but with the participation of different endothelial mediators. Males appear to be more dependent on the NO pathway, followed by the H2O2 pathway, and females on the endothelium and H2O2 pathway.ConclusionThese findings show that the GPER agonist G-1 can induce a relaxing response in mesenteric arteries from hypertensive rats of both sexes in a similar way, albeit with differential participation of endothelial mediators. These results contribute to the understanding of GPER activation on resistance mesenteric arteries in essential hypertension.

Background: Punica granatum L. is an infructescence native of occidental Asia and Mediterranean Europe, popularly referred to as pomegranate. It has been used in ethnomedicine for several applications, including the treatment of obesity, inflammation, diabetes, and the regulation of blood lipid parameters. Thus, pomegranate has been linked, to the treatment of cardiovascular diseases that have endothelial dysfunction as a common factor acting mainly against oxidative stress due to its high polyphenol content. Its biocomponents have anti-hypertensive, antiatherogenic, antihyperglycemic, and anti-inflammatory properties, which promotes cardiovascular protection through the improvement of endothelial function. Method: Different electronic databases were searched in a non-systematic way to uncover the literature of interest. Conclusion: This review article presents updated information on the role of pomegranate in the context of endothelial dysfunction and cardiovascular diseases. We have shown that pomegranate, or rather its components (e.g., tannins, flavonoids, phytoestrogens, anthocyanins, alkaloids, etc.), has beneficial effects on the cardiovascular system, improving parameters such as oxidative stress and the enzymatic antioxidant system, reducing ROS formation and acting in an anti-inflammatory way. Thus, this review may contribute to a better understanding of pomegranate's beneficial actions on endothelial function and possibly to the development of strategies associated with conventional treatments of cardiovascular diseases.

ObjectivesThe effect of oestrogen in hormonal dysfunction is not clear, especially in the coronary vascular bed. This study aimed at estradiol action (E2) in the coronary vascular bed from sham-operated and gonadectomized female and male spontaneously hypertensive rats (SHRs).MethodsMale and female SHRs had their mean arterial pressure (MAP) and baseline coronary perfusion pressure (CPP) determined. The effects of E2 (10 μM) were evaluated in isolated hearts by in bolus infusion before and after endothelium denudation (0.25 μM sodium deoxycholate) or perfusion with 100 μM NG-nitro-l-arginine methyl ester (L-NAME), 2.8 μM indomethacin, 0.75 μM clotrimazole, L-NAME after endothelium denudation, L-NAME plus indomethacin, or 4 mM tetraethylammonium (TEA).ResultsMAP was higher in males than in females, with gonadectomy increasing in females and reducing in males. CPP was higher in female group, remaining unaltered after gonadectomy. E2-induced vasorelaxation was observed in all groups, with no differences having been found between sexes even after gonadectomy. Perfusion with TEA, L-NAME, L-NAME plus indomethacin, and L-NAME after endothelium removal attenuated the relaxing response in all groups. Clotrimazole inhibited vasorelaxation only in female groups, and indomethacin did so only in gonadectomized groups. Endothelium participation was confirmed in female groups and in the gonadectomized male group.ConclusionsOur results indicated that the vasodilator effect of E2 was mediated by an indirect mechanism – via endothelium – as well as by direct action – via vascular smooth muscle – in both groups. The characterization of these mechanisms in coronary arteries might shed light on the functional basis of hormonal dysfunction symptoms in hypertension.

The role of androgens in vascular reactivity is controversial, particularly regarding their age-related actions. The objective of this study was to conduct a temporal evaluation of the vascular reactivity of resistance arteries of young male rats, as well as to understand how male sex hormones can influence the vascular function of these animals. Endothelium-mediated relaxation was characterized in third-order mesenteric arteries of 10-, 12-, 16-, and 18-week-old (w) male rats. Concentration-response curves to acetylcholine (ACh, 0.1 nmol/L - 10 µmol/L) were constructed in arteries previously contracted with phenylephrine (PE, 3 µmol/L), before and after use of nitric oxide synthase or cyclooxygenase inhibitors. PE concentration-response curves (1 nmol/L - 100 μmol/L) were also built. The levels of vascular nitric oxide, superoxide anion, and hydrogen peroxide were assessed and histomorphometry analysis was performed. The 18w group had impaired endothelium-dependent relaxation. All groups showed prostanoid-independent and nitric oxide-dependent vasodilatory response, although this dependence seems to be smaller in the 18w group. The 18w group had the lowest nitric oxide and hydrogen peroxide production, in addition to the highest superoxide anion levels. Besides functional impairment, 18w animals showed morphological differences in third-order mesenteric arteries compared with the other groups. Our data show that time-dependent exposure to male sex hormones appears to play an important role in the development of vascular changes that can lead to impaired vascular reactivity in mesenteric arteries, which could be related to the onset of age-related cardiovascular changes in males.