RESUMO
AIMS: To evaluate the effects of testosterone on endothelium-dependent vasodilation and oxidative stress in mesenteric resistance arteries. MAIN METHODS: Spontaneously hypertensive rats (SHR), aged 8 to 10 weeks, were divided into four groups: intact (SHAM), intact treated with testosterone (TTO; 3 mg/kg/day) via subcutaneous route (s.c.), intact treated with testosterone and anastrozole [aromatase enzyme inhibitor (TTO + ANA; 0.1 mg/kg/day, s.c.)] and intact treated with testosterone and finasteride [5 α-reductase enzyme inhibitor (TTO + FIN; 5 mg/kg/day, s.c.)] for four weeks. Concentration-response curves to acetylcholine (ACh, 0.1 nmol/L - 10 µmol/L) were obtained in mesenteric resistance arteries previously contracted with phenylephrine (PE, 3 µmol/L), before and after the use of selective inhibitors. Reactive oxygen species (ROS) levels were assessed in the vessels and the endothelium analyzed by scanning electron microscopy. KEY FINDINGS: TTO group showed a lower participation of nitric oxide (NO), increased oxidative stress, and participation of prostanoids and endothelium-dependent hyperpolarization (EDH), possibly to maintain the vasodilator response. Lower participation of NO and prostanoids, combined to an increased participation of EDH, were observed in the TTO + ANA group, in addition to higher levels of ROS and altered endothelial morphology. The vasodilation to ACh was impaired in TTO + FIN, along increased participation of NO, reduction of prostanoids, and greater EDH-dependent vasodilation. SIGNIFICANCE: Testosterone contributes to endothelial vasodilation by enhancing EDH through an increased participation of epoxyeicosatrienoic acids. While the decrease in NO appears to involve the participation of dihydrotestosterone, 17 ß-estradiol seems to stimulate the action of the NO pathway and prostanoids.
Assuntos
Hipertensão , Vasodilatação , Ratos , Animais , Espécies Reativas de Oxigênio/metabolismo , Testosterona/farmacologia , Testosterona/metabolismo , Hipertensão/metabolismo , Ratos Endogâmicos SHR , Inibidores Enzimáticos/farmacologia , Acetilcolina/farmacologia , Acetilcolina/metabolismo , Artérias Mesentéricas , Óxido Nítrico/metabolismo , Prostaglandinas/metabolismo , Endotélio Vascular/metabolismoRESUMO
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 18w (week-old) 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 the 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.
Assuntos
Óxido Nítrico , Superóxidos , Masculino , Ratos , Animais , Peróxido de Hidrogênio , Artérias , Hormônios Esteroides GonadaisRESUMO
AIM: Endothelial mechanisms underlying the vascular effects of estrogen modulated by the G protein-coupled estrogen receptor (GPER) are not well understood, especially in gonadal sex hormone deprivation. Thus, we investigated vascular function and endothelial signaling pathways involved in the selective activation of GPER in resistance arteries of gonadectomized rats. METHODS: Gonadectomy was performed in Wistar rats of both sexes. After 21 days, the animals were euthanized. Concentration-response curves were obtained by cumulative additions of G-1 in third-order mesenteric arteries. The vasodilatory effects of G-1 were evaluated before and after endothelium removal or incubation with pharmacological inhibitors. Tissue protein expression was measured by western blotting. Assays with 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM) and 2',7' dichlorodihydrofluorescein-diacetate (H2DCF-DA) were performed in the arteries investigated. Immunolocalization was assessed by immunofluorescence. RESULTS: G-1 induced partially endothelium-dependent relaxation in both sexes. The three isoforms of the enzyme nitric oxide synthase contributed to the production and release of nitric oxide in both gonadectomized groups, but the role of inducible nitric oxide synthase is more expressive in males. The mechanistic pathway by which endothelial nitric oxide synthase is phosphorylated appears to differ between sexes, with the rapid signaling pathway phosphatidylinositol-3-kinase/protein kinase B/endothelial nitric oxide synthase (PI3k-Akt-eNOS) being identified for males and mitogen-activated protein kinase/extracellular signal-regulated kinase/endothelial nitric oxide synthase (MEK-ERK-eNOS) for females. The contribution of hydrogen peroxide as an endothelial relaxation mediator seems to be greater in females. CONCLUSION: These results provide new insights into the effects of estrogen-induced responses via GPER on vascular function in gonadal sex hormone deprivation.
Assuntos
Óxido Nítrico Sintase Tipo III , Proteínas Proto-Oncogênicas c-akt , Animais , Endotélio Vascular , Estrogênios/metabolismo , Estrogênios/farmacologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Proteínas de Ligação ao GTP/metabolismo , Hormônios Esteroides Gonadais/metabolismo , Peróxido de Hidrogênio/metabolismo , Masculino , Artérias Mesentéricas , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/farmacologia , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosfatidilinositóis/metabolismo , Fosfatidilinositóis/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Wistar , Receptores de Estrogênio/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Caracteres Sexuais , Transdução de Sinais , Vasodilatadores/farmacologiaRESUMO
BACKGROUND: The protective effect of estrogen on the vasculature cannot be explained only by its action through the receptors ERα and ERß. 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. METHODS: G-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. RESULTS: GPER 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. CONCLUSION: These 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.
RESUMO
Although progesterone has the ability to promote dilation of vascular smooth muscle, its role in coronary circulation is still poorly characterized, especially in essential hypertension and in a model of endogenous deficiency of ovarian hormones. Thus, this study evaluated the effect of progesterone treatment on endothelium-dependent coronary vascular reactivity in hypertensive (SHR) and ovariectomized rats. Adult SHR aged 8-10 weeks were divided into: SHAM, Ovariectomized (OVX) and Ovariectomized + treatment with 2 mg/kg/day of progesterone for 15 days (OVX-P4). Coronary vascular reactivity was investigated using the modified Langendorff method. After stabilization, baseline coronary perfusion pressure (CPP) was recorded and vascular reactivity to bradykinin (BK, 0.1-1000 ng) were assessed before and after infusion, either individually or in combination, with Nω-nitro-l-arginine methyl ester (l-NAME), indomethacin or clotrimazole. Scanning electron microscopy was used for qualitative analysis of the endothelium. OVX and OVX-P4 groups had a higher baseline CPP compared to that of the SHAM group. BK was able to promote vasodilation in all groups. However, relaxation to BK was less pronounced in the OVX group when compared to SHAM, with architecture loss and areas of cell atrophy having been observed. Progesterone treatment prevented this injury. Perfusion with l-NAME induced greater damage to the SHAM group, while the use of indomethacin led to a significant reduction in the vasodilator response to BK in the OVX-P4 group. Taken together, our results show that progesterone modulates endothelium-dependent coronary vasodilation in SHR ovariectomized, preventing damage caused by ovarian hormonal deficiency through a mechanism that involves prostanoid pathway.
Assuntos
Vasos Coronários/patologia , Endotélio Vascular/patologia , Hipertensão/patologia , Progesterona/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Bradicinina/farmacologia , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/ultraestrutura , Endotélio Vascular/efeitos dos fármacos , Feminino , Tamanho do Órgão/efeitos dos fármacos , Perfusão , Ratos Endogâmicos SHR , Sístole/efeitos dos fármacos , Útero/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologiaRESUMO
Physiological or supraphysiological levels of testosterone appear to be associated with the development of risk factors for cardiovascular diseases such as hypertension, as this hormone modulates the release of endothelial factors. However, its actions are still controversial, especially in the coronary circulation of hypertensive animals. This study was designed to assess the effects of testosterone treatment (T) on endothelium-dependent coronary vascular reactivity in orchiectomized SHR. The animals were divided into SHAM, orchiectomized (ORX), ORX+T and ORX+T+aromatase inhibitor (AI). All treatments lasted 15 days. Blood pressure (BP) was measured. Dose-response curves to bradykinin (BK) were constructed using the Langendorff technique, followed by inhibition of endothelium mediators (NO, prostanoids, EETs) and potassium channels. The intensity of eNOS, COX-1, COX-2, Akt, and gp91phox protein expression was quantified by Western blotting. BP was elevated in SHAM, ORX+T, and ORX+T+AI groups. However, we did not observe differences in the ORX group. Baseline coronary perfusion pressure (CPP) remained unaffected. Orchiectomy did not change the BK-induced relaxation compared to the SHAM group, whereas testosterone treatment increased it. This response was diminished in the absence of NO, prostanoids, and EETs in the SHAM and ORX groups, while in ORX+T group the relaxation was diminished only in the absence of NO and EETs. There was no difference in eNOS, COX-1, COX-2, and gp91phox protein expression, though Akt expression was increased in ORX and ORX+T groups. These results show that testosterone treatment can modulate endothelial function, especially in the coronary circulation under hypertension conditions, via NO and EETs pathways.
Assuntos
Bradicinina/farmacologia , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/fisiopatologia , Testosterona/farmacologia , Vasodilatação/efeitos dos fármacos , Animais , Biomarcadores , Pressão Sanguínea , Modelos Animais de Doenças , Suscetibilidade a Doenças , Relação Dose-Resposta a Droga , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Hipertensão/etiologia , Hipertensão/metabolismo , Masculino , Ratos , Ratos Endogâmicos SHR , Transdução de Sinais/efeitos dos fármacosRESUMO
Diminazene aceturate (DIZE) has been described as an angiotensin-converting enzyme 2 (ACE2) activator. We aimed to investigate DIZE effects on blood pressure (BP) of spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats. BP was recorded in awake and unrestrained rats 24 hours after femoral artery catheterization. DIZE (15 mg/kg, s.c.) produced a fast BP decrease only in SHR (P < .01). Pre-treatment with L-NAME (10 mg/kg, iv) did not change the hypotensive effect on systolic BP whereas mitigated the DIZE effect on diastolic BP (∆ Emax: -31 ± 5 DIZE vs -15 ± 1 mm Hg DIZE + L-NAME, P < .05). BP changes after DIZE remained unchanged after the treatment of rats with A-779 (50 ug/kg, iv), a Mas receptor blocker. Vasodilatation curves to DIZE (10-9 to 10-4 mol/L) in mesenteric arteries confirmed the NO-mediation on DIZE effects in SHR, as L-NAME (300 µmol/L) reduced the vascular sensitivity (∆EC50: -5.12 ± 0.09 CONTROL vs -4.66 ± 0.08 L-NAME, P < .05) and the magnitude of DIZE effect (area under the curve (AUC), 357.5 ± 8.2 DIZE vs 424.7 ± 11.6 L-NAME; P < .001), whereas A-779 (1 µmol/L) enhanced DIZE response (AUC, 357.5 ± 8.2 DIZE vs 309.8 ± 14.7 A-779, P < .05). Our findings indicate that DIZE acutely reduces the BP in SHR possibly by a mechanism other than Mas receptor activation. This effect seems to be mediated, at least partially, by NO.
Assuntos
Diminazena/análogos & derivados , Hipertensão/induzido quimicamente , Hipertensão/fisiopatologia , Óxido Nítrico/metabolismo , Animais , Pressão Sanguínea/efeitos dos fármacos , Diminazena/farmacologia , Hipertensão/metabolismo , Masculino , RatosRESUMO
AIM: Although progesterone (P4) has a beneficial effect on the cardiovascular system, P4 actions on the coronary bed have not yet been fully elucidated. This study evaluated the effect of progesterone treatment on endothelium-dependent coronary vascular reactivity in Wistar rats. MAIN METHODS: Eight-week-old adult rats were divided into Sham, Ovariectomized (OVX), Ovariectomized and progesterone treated (OVX P4). The OVX P4 group received daily doses of progesterone (2 mg/kg/day). Vascular reactivity was assessed by a modified Langendorff technique. The intensity of eNOS, Akt, and gp91phox protein expression was quantified by Western blotting. Superoxide anion (O2â-) and hydrogen peroxide (H2O2) production was measured by dihydroethidium and 2',7'-dichlorofluorescein, respectively. KEY FINDINGS: Treatment with P4 was able to prevent the reduction in baseline coronary perfusion pressure induced by ovariectomy. We observed that endothelium-dependent coronary vasodilation was reduced in the OVX group and potentiated in the OVX P4 group. Following the inhibition of the nitric oxide (NO) pathway, the bradykinin-induced relaxing response was potentiated in the OVX P4 group. With regard to the combined inhibition of NO and prostanoids pathways, the OVX P4 group showed a greater relaxing response, similar to what was found upon individual inhibition of NO. After the combined inhibition of NO, prostanoids and epoxyeicosatrienoic acids' pathways, the vasodilatory response induced by BK was abolished in all groups. SIGNIFICANCE: Treatment with P4 prevented oxidative stress induced by ovariectomy. These results suggest that progesterone has a beneficial action on the coronary vascular bed.
Assuntos
Vasos Coronários/efeitos dos fármacos , Endotélio Vascular/efeitos dos fármacos , Progesterona/farmacologia , Vasodilatação/efeitos dos fármacos , Animais , Feminino , Peróxido de Hidrogênio/metabolismo , NADPH Oxidase 2/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Ovariectomia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Transdução de Sinais/efeitos dos fármacos , Superóxidos/metabolismoRESUMO
OBJECTIVES: The 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). METHODS: Male 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). RESULTS: MAP 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. CONCLUSIONS: Our 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.
Assuntos
Estradiol/farmacologia , Coração/efeitos dos fármacos , Hipertensão/fisiopatologia , Vasodilatação/efeitos dos fármacos , Animais , Feminino , Masculino , Orquiectomia , Ovariectomia , Ratos , Ratos Endogâmicos SHRRESUMO
Progesterone seems to play a role in cardiovascular physiology since its receptors are expressed on endothelial cells from both sexes of mammals. However, little is known about its role on the coronary circulation. Thus, this study aims to evaluate the effect of acute administration of progesterone on the coronary bed and the endothelial pathways involved in this action in normotensive rats of both sexes. A dose-response curve of progesterone (1-50 µmol/L) in isolated hearts using the Langendorff preparation was performed. Baseline coronary perfusion pressure (CPP) was determined, and the vasoactive effect of progesterone was evaluated before and after infusion with Nω-nitro-L-arginine methyl ester (L-NAME), indomethacin, catalase, and Tiron. The analysis of nitric oxide (NO) and superoxide anion (O2 · -) was performed by DAF-2DA and DHE, respectively. Female group showed higher CPP. Nevertheless, progesterone promoted a similar relaxing response in both sexes. The use of L-NAME increased vasodilatory response in both sexes. When indomethacin was used, only the males showed a reduced relaxing response, and in the combined inhibition with L-NAME, indomethacin, and catalase, or with the use of Tiron, only the females presented reduced responses. NO and O2 ·- production has increased in female group, while the male group has increased only NO production. Our results suggest that progesterone is able to modulate vascular reactivity in coronary vascular bed with a vasodilatory response in both sexes. These effects seem to be, at least in part, mediated by different endothelial pathways, involving NO and EDH pathways in females and NO and prostanoids pathways in males.
Assuntos
Progesterona/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/metabolismo , Feminino , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Fatores Sexuais , Superóxidos/metabolismo , Esfregaço VaginalRESUMO
AIM: An imbalance between antioxidant and pro-oxidant factors, with a predominance of the latter, characterises oxidative stress and is indicative of a loss of vascular function. The beneficial vascular effects of oestrogen may be related to its ability to stimulate the G protein-coupled oestrogen receptor (GPER) and produce antioxidant activity. This study evaluated the GPER-dependent relaxation response in the mesenteric resistance arteries of female and male rats and measured the contributions of pro-oxidant and antioxidant enzymes in this response. MAIN METHODS: The relaxation response was characterised in third-order mesenteric arteries using concentration-response curves of the selective GPER agonist G-1 (1â¯nM-10⯵M), target protein levels were measured using Western blots, and vascular superoxide anion (O2-) and hydrogen peroxide (H2O2) levels were measured using dihydroethidium (DHE) and dichlorofluorescein (DCF) staining, respectively. KEY FINDINGS: The GPER agonist induced concentration-dependent vasorelaxation without showing differences between sexes. However, GPER expression was greater in male rats. No sex differences were detected in the expression of antioxidant proteins (catalase, SOD-1, and SOD-2). The basal vascular production of O2- and H2O2 was similar in the studied groups, and stimulation with G-1 maintained this response. SIGNIFICANCE: Together, our results show that the expression of GPER is greater in male mesenteric arteries, despite of the lack of a difference in vascular response. Nevertheless, antioxidant enzyme expression levels and the generation rates of pro-oxidants were similar between the studied groups. These results offer a new perspective for understanding GPER expression and functionality in resistance arteries.
Assuntos
Antioxidantes/metabolismo , Endotélio Vascular/metabolismo , Artérias Mesentéricas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Vasodilatação/fisiologia , Animais , Endotélio Vascular/citologia , Feminino , Masculino , Artérias Mesentéricas/citologia , Ratos , Ratos Wistar , Fatores Sexuais , Transdução de SinaisRESUMO
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 ERß) 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 'in situ' 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.
Assuntos
Vasos Coronários/metabolismo , Vasos Coronários/fisiologia , Receptores Acoplados a Proteínas G/metabolismo , Animais , Antioxidantes/metabolismo , Etídio/análogos & derivados , Etídio/metabolismo , Feminino , Fluorescência , Masculino , Estresse Oxidativo , Perfusão , Pressão , Ratos Wistar , Superóxidos/metabolismoRESUMO
AIM: The action of oestrogen has traditionally been attributed to the activation of nuclear receptors (ERα and ERß). A third receptor, the G protein-coupled oestrogen receptor (GPER), has been described as mediator of the rapid action of oestrogen. Based on the possible protective role of oestrogen in the cardiovascular system, the present study was designed to determine whether selective GPER activation induces relaxation of mesenteric resistance arteries in both sexes and which signalling pathways are involved. MAIN METHODS: Third-order mesenteric arteries were isolated, and concentration-response curves were plotted following the cumulative addition of the selective GPER agonist G-1 (1nM-10µM) following induction of contraction with phenylephrine (3µM). The vasodilatory effects of G-1 were assessed before and after removal of the endothelium or incubation for 30min with nitric oxide synthase (Nω-nitro-L-arginine methyl ester - L-NAME, 300µM) and cyclooxygenase (indomethacin - INDO, 10µM) inhibitors alone or combined, PI3K-Akt pathway inhibitor (LY-294,002, 2.5µM) or a potassium channel blocker (tetraethylammonium - TEA, 5mM). GPER immunolocalisation was also performed on the investigated arteries. KEY FINDINGS: The tested GPER agonist induced concentration-dependent relaxation of the mesenteric resistance arteries without differences related to sex that were partially endothelium dependent, mainly mediated by the PI3K-Akt-eNOS pathway and attenuated by nonspecific potassium channel blockade. In addition, the endothelial GPER immunolocalisation was stronger among females. SIGNIFICANCE: This evidence provides a new perspective for understanding the mechanisms involved in the vascular responses triggered by oestrogen via GPER in both sexes.
Assuntos
Ciclopentanos/farmacologia , Estrogênios/metabolismo , Artérias Mesentéricas/efeitos dos fármacos , Canais de Potássio/efeitos dos fármacos , Quinolinas/farmacologia , Receptores Acoplados a Proteínas G/agonistas , Animais , Ciclopentanos/administração & dosagem , Relação Dose-Resposta a Droga , Feminino , Masculino , Artérias Mesentéricas/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Fosfatidilinositol 3-Quinase/metabolismo , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Quinolinas/administração & dosagem , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Vasodilatação/efeitos dos fármacosRESUMO
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.
Assuntos
Sistema Cardiovascular/efeitos dos fármacos , Castração/efeitos adversos , Vasos Coronários/efeitos dos fármacos , Testosterona/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Bradicinina/farmacologia , Clotrimazol/farmacologia , Endotélio Vascular/efeitos dos fármacos , Coração/efeitos dos fármacos , Terapia de Reposição Hormonal/métodos , Indometacina/farmacologia , Lipídeos/fisiologia , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Ratos , Ratos Wistar , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologiaRESUMO
Triorganotins, such as tributyltin (TBT), are environmental contaminants that are commonly used as antifouling agents for boats. However, TBT is also known to alter mammalian reproductive functions. Although the female sex hormones are primarily involved in the regulation of reproductive functions, 17ß-estradiol also protects against cardiovascular diseases, in that this hormone reduces the incidence of coronary artery disease via coronary vasodilation. The aim of this study was to examine the influence of 100 ng/kg TBT administered daily by oral gavage for 15 d on coronary functions in female Wistar rats. Findings were correlated with changes in sex steroids concentrations. Tributyltin significantly increased the baseline coronary perfusion pressure and impaired vasodilation induced by 17ß-estradiol. In addition, TBT markedly decreased serum 17ß-estradiol levels accompanied by a significant rise in serum progesterone levels. Tributyltin elevated collagen deposition in the heart interstitium and number of mast cells proximate to the cardiac vessels. There was a positive correlation between the increase in coronary perfusion pressure and incidence of cardiac hypertrophy. In addition, TBT induced endothelium denudation (scanning electron microscopy) and accumulation of platelets. Moreover, TBT impaired coronary vascular reactivity to estradiol (at least in part), resulting in endothelial denudation, enhanced collagen deposition and elevated number of mast cells. Taken together, the present results demonstrate that TBT exposure may be a potential risk factor for cardiovascular disorders in rats.
Assuntos
Vasos Coronários/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Estradiol/farmacocinética , Compostos de Trialquitina/toxicidade , Vasodilatação/efeitos dos fármacos , Animais , Vasos Coronários/fisiologia , Interações Medicamentosas , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/ultraestrutura , Estradiol/administração & dosagem , Feminino , Ratos , Ratos WistarRESUMO
BACKGROUND: Ultrasound lipoclasia (USL) on white adipose tissue (WAT) has been largely used in the treatment of cellulite. Nevertheless, the acute consequences of this therapy on metabolism and biochemical profile are significant and should be taken into account. OBJECTIVES: To analyze the acute metabolic effects of USL in WAT of healthy rats using analyses of body composition, biochemical profile, and inflammatory markers. METHODS: Female Wistar rats weighing approximately 250 g were divided into two groups (n=10 each): control and treated. The treated group was submitted to USL, a single 3-MHz ultrasound application (5.6 W/cm(2)), in gluteal-femoral WAT (3 cm(2)) for 3 minutes. Animals were subjected to glycemic control. Body composition was analyzed using bio-impedance, and lipid profile, insulinemia, C-reactive protein (CRP), and lactate dehydrogenase (LDH) were measured. RESULTS: USL reduced (p<.05) body fat mass. The basal metabolic rate was found to have increased (p<.05). Basal insulin and the lipoprotein profile were not different, although the glycemic curve and CRP and LDH (p<.05) levels were higher. CONCLUSIONS: Fat mobilization using USL provokes acute hyperglycemia and enhances an acute inflammatory response, producing cardiometabolic risk in female rats.