Sex differences in the participation of endothelial mediators and signaling pathways involved in the vasodilator effect of a selective GPER agonist in resistance arteries of gonadectomized Wistar rats.

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.

Effects of Drugs, Phytoestrogens, Nutrients and Probiotics on Endothelial Dysfunction in the Estrogen-Deficient State.

BACKGROUND: Endothelial dysfunction is commonly present in estrogen-deficient states, e.g., after menopause. In the search for alternatives to hormone replacement therapy (HRT), treatments based on phytoestrogens or in non-hormonal mechanisms have been under evaluation. OBJECTIVE: Here we aim to present an overview of innovative potential treatments for endothelial dysfunction in estrogen-deficient states, introducing our own preliminary data about the probiotic kefir. METHODS: We conducted a review based on a PubMed database search for keywords of interest (Menopause, Ovariectomy, Vascular dysfunction, Hot flashes, Metformin, Statins, Phytoestrogens, Omega-3, Vitamin D, Probiotics). RESULTS: Vascular parameters were found to be improved by both metformin and statins through pleiotropic effects, being related to a decrease in oxidative stress and restoration of the nitric oxide pathway. Phytoestrogens such as genistein and resveratrol have also been shown to improve vascular dysfunction, which seems to involve their estrogenic-like actions. Omega-3, vitamin D and its analogues, as well as probiotics, have shown similar vascular beneficial effects in both postmenopausal women and an animal model of ovariectomy (OVX), which could be related to antioxidant and/or anti-inflammatory effects. Moreover, our preliminary data on the probiotic kefir treatment in OVX rats suggested a vascular antioxidant effect. In particular, some evidence points to statins and vitamin D having anti-atherogenic effects. CONCLUSION: Pleiotropic effects of common medications and natural compounds could have therapeutic potential for endothelial dysfunction in estrogen-deficient states. They could, therefore, work as future complementary or alternative treatments to HRT.

Bothrops leucurus venom induces acute hypotension in rats by means of its phospholipase A2 (blD-PLA2).

Cardiovascular effects induced by snake venoms, in spite of having a crucial role in the outcome of the envenomation, have been less studied than other toxic activities displayed by these venoms. In this study we evaluated acute cardiovascular responses to Bothrops leucurus venom - Bl-V - both in vivo, in anesthetized rats, and in vitro, in isolated rat mesenteric resistance arteries. Bl-V (10-100 µg protein/kg) caused dose-dependent hypotension, followed by gradual recovery (2-20 min) to basal levels, and induced dose-dependent (1-20 µg/mL) vasodilation in pre-contracted arteries, what was more pronounced when the endothelium remained intact. These effects were partially counteracted by pre-treatment with indomethacin (cyclooxygenase inhibitor). Prior incubation of Bl-V with commercial pentavalent Bothrops antivenom also attenuated the cardiovascular effects induced by the venom, in spite of it not being among the venoms used for the development of the bothropic antivenom. Through an approach based on two chromatographic steps and mass spectrometry (MALDI-ToF and MALDI-ISD), a component with acute cardiovascular effects was isolated and identified as the basic phospholipase blD-PLA2, previously purified from the venom of B. leucurus. Taken together, our results show that, at low doses, the venom of B. leucurus induces transient, acute hypotension in anesthetized rats following systemic vasodilation in a dose-dependent way. In addition, we provide clear evidence of the involvement of the enzymatic activity of blD-PLA2 in this cardiovascular response, acting via the production of vasodilating prostanoids.

Telmisartan use in rats with preexisting osteoporotics bone disorders increases bone microarchitecture alterations via PPARγ.

AIMS: Telmisartan (TEL), an angiotensin II type I receptor blocker and PPARγ partial agonist, has been used for to treat hypertension. It is known that PPARγ activation induces bone loss. Therefore, we evaluate the effects of telmisartan on PPARγ protein expression, biomechanics, density and bone microarchitecture of femurs and lumbar vertebrae in SHR ovariectomized animals, a model of hypertension in which preexisting bone impairment has been demonstrated. MAIN METHODS: SHR females (3 months old) were distributed into four groups: sham (S), sham + TEL (ST), OVX (C) and OVX + TEL (CT). TEL (5 mg/kg/day) or vehicle were administered according to the groups. After the protocol, blood pressure was measured and density, microarchitecture and biomechanics of bone were analyzed. Western blotting analysis was performed to evaluate PPARγ protein expression in the bones. KEY FINDINGS: Castration induced a deleterious effect on mineral density and trabecular parameters, with telmisartan enhancing such effects. Telmisartan increased PPARγ levels, which were at their highest when the treatment was combined with castration. As to biomechanical properties, telmisartan reduced the stiffness in the castration group (CT vs. S or C group), as well as resilience and failure load in ST group (vs. all others groups). SIGNIFICANCE: These results demonstrated that telmisartan compromised bone density and microarchitecture in animals that shows preexisting osteoporotic bone disorders, probably via mechanisms associated with increased PPARγ. If this translates to humans, a need for greater caution in the use of telmisartan by patients that have preexisting bone problems, as in the postmenopausal period, may be in order.

Sex difference in GPER expression does not change vascular relaxation or reactive oxygen species generation in rat mesenteric resistance arteries.

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 (1 nM-10 µM), 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.

GPER agonist dilates mesenteric arteries via PI3K-Akt-eNOS and potassium channels in both sexes.

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.

Benefits of a memory game as a didactic strategy in the learning of human physiology / Benefícios de um jogo de memorização como estratégia didática no aprendizado da fisiologia humana

The diversification of teaching strategies helps students to learn by a more effective way of understanding and assimilating the themes seen in the classroom. This study aimed to develop an educational model of human physiology, based on memory stimulation, and evaluate the effectiveness of this model for undergraduate and high school students. The effectiveness of the model was evaluated by the application of two questionnaires in order to verify the assimilation of the theme seen in the classroom and the perception of the individuals about the model. The results confirm the effectiveness of this model pointing out the importance of these resources as motivational educational devices as well as the need to use innovative methodologies. Furthermore, the use of models with visual appeal and which do the learning in a playful way could improve the efficiency in the process of teaching and learning together with the traditional classroom model

A diversificação das estratégias de ensino ajuda os alunos a aprender através de uma forma mais eficaz para compreender e assimilar os temas vistos em sala de aula. Este trabalho teve por objetivo conceber e avaliar o uso de um jogo de memorização como estratégia auxiliar no processo de ensino e aprendizagem de alunos do ensino médio e do ensino superior, abordando o conteúdo de Fisiologia Humana, com foco no Sistema Excretor e Fisiologia Renal, respectivamente. A eficácia do modelo foi avaliada por meio da aplicação de dois questionários para verificar a assimilação dos conteúdos abordados em sala de aula e a percepção dos indivíduos sobre o modelo. Os resultados confirmam a eficiência do modelo apontando para a importância destes recursos como dispositivos educativos motivacionais, bem como a necessidade de utilizar metodologias inovadoras. Ademais, a utilização de modelos com apelo visual e que trabalhem o aprendizado de forma lúdica, podem agregar eficiência ao processo de ensino e aprendizagem ao tradicional modelo de sala de aula