Effects of Bradykinin B2 Receptor Ablation from Tyrosine Hydroxylase Cells on Behavioral and Motor Aspects in Male and Female Mice.

The kallikrein-kinin system is a versatile regulatory network implicated in various biological processes encompassing inflammation, nociception, blood pressure control, and central nervous system functions. Its physiological impact is mediated through G-protein-coupled transmembrane receptors, specifically the B1 and B2 receptors. Dopamine, a key catecholamine neurotransmitter widely distributed in the CNS, plays a crucial role in diverse physiological functions including motricity, reward, anxiety, fear, feeding, sleep, and arousal. Notably, the potential physical interaction between bradykinin and dopaminergic receptors has been previously documented. In this study, we aimed to explore whether B2R modulation in catecholaminergic neurons influences the dopaminergic pathway, impacting behavioral, metabolic, and motor aspects in both male and female mice. B2R ablation in tyrosine hydroxylase cells reduced the body weight and lean mass without affecting body adiposity, substrate oxidation, locomotor activity, glucose tolerance, or insulin sensitivity in mice. Moreover, a B2R deficiency in TH cells did not alter anxiety levels, exercise performance, or motor coordination in female and male mice. The concentrations of monoamines and their metabolites in the substantia nigra and cortex region were not affected in knockout mice. In essence, B2R deletion in TH cells selectively influenced the body weight and composition, leaving the behavioral and motor aspects largely unaffected.

Interleukin-6 and the Gut Microbiota Influence Melanoma Progression in Obese Mice.

There is a strong correlation between obesity and cancer. Here, we investigated the influence of IL-6 and gut microbiota of obese mice in melanoma development. We first evaluated B16F10 melanoma growth in preclinical models for obesity: mice deficient for leptin (ob/ob) or adiponectin (AdpKO) and in wild-type mice (WT, C57BL/6J) fed a high-fat diet (HFD; 60% kcal from fat) for 12 weeks. The survival rates of ob/ob and HFD-fed mice were lower than those of their respective controls. AdpKO mice also died earlier than WT control mice. We then verified the involvement of IL-6 signaling in obese mice that were inoculated with melanoma cells. Both ob/ob and AdpKO mice had higher circulating IL-6 levels than wild-type mice. Melanoma tumor volumes in IL-6 KO mice fed an HFD were reduced compared to those of WT mice subjected to the same diet. Also evaluated the effect of microbiota in tumor development. Cohousing and fecal matter transfer experiments revealed that microbiota from ob/ob mice can stimulate tumor development in lean WT mice. Taken together, our data show that in some conditions IL-6 and the gut microbiota are key mediators that link obesity and melanoma.

Effects of 12†weeks of resistance training on rat gut microbiota composition.

In addition to its health benefits, exercise training has been noted as a modulator of the gut microbiota. However, the effects of resistance training (RT) on gut microbiota composition remain unknown. Wistar rats underwent 12 weeks of RT. Body mass, glucose tolerance, visceral body fat, triglyceride concentration and food consumption were evaluated. The gut microbiota was analyzed by 16S rRNA gene sequencing. Rats that underwent RT showed lower body mass (P=0.0005), lower fat content (P=0.02) and better glucose kinetics (P=0.047) when compared with the control. Improvements in the diversity and composition of the gut microbiota were identified in the RT group. The relative abundance of Pseudomonas, Serratia and Comamonas decreased significantly after 12 weeks of RT (P<0.001). These results suggest that RT has the potential to enhance the diversity of the gut microbiota and improve its biological functions.

The angiotensin-I-converting enzyme insertion/deletion in polymorphic element codes for an AluYa5 RNA that downregulates gene expression.

Angiotensin-I-converting enzyme (ACE) is involved in the synthesis and degradation of important bioactive peptides. The ACE gene has a 287-bp insertion/deletion polymorphism that controls ACE expression through a mechanism that remains elusive. In this study, we found that the 287-bp polymorphic element of the ACE gene, a member of the AluYa5 sub-family of Alu elements, codes for an RNA molecule that controls the levels of ACE mRNA. Transient transfection of a plasmid containing a CMV promoter upstream of the ACE polymorphic element resulted in significant expression of an AluYa5 RNA and reduced ACE mRNA expression as well as ACE enzymatic activity in AD 293 cells. The AluYa5 element also independently reduced the expression of other genes, regardless of whether these genes harbored Alu elements within their genomic context. Interestingly, the CMV promoter was not required for the expression of the AluYa5 element in AD 293 cells. The 287-bp sequence was sufficient to produce AluYa5 RNA and led to a significant reduction in ACE gene expression. Moreover, the removal of an 11-bp fragment of the 3' end of the ACE polymorphic sequence, which is specific to this particular AluYa5 element, did not prevent this element from being expressed but did affect its ability to target ACE expression. Thus, the expression of the AluYa5 polymorphic element within the ACE gene could explain why patients carrying the ACE insertion polymorphism have reduced risk of developing several chronic diseases.

High aminopeptidase A activity contributes to blood pressure control in ob/ob mice by AT2 receptor-dependent mechanism.

Obesity is assumed to be a major cause of human essential hypertension; however, the mechanisms responsible for weight-related increase in blood pressure (BP) are not fully understood. The prevalence of hypertension induced by obesity has grown over the years, and the role of the renin-angiotensin-aldosterone system (RAAS) in this process continues to be elucidated. In this scenario, the ob/ob mice are a genetic obesity model generally used for metabolic disorder studies. These mice are normotensive even though they present several metabolic conditions that predispose them to hypertension. Although the normotensive trait in these mice is associated with the poor activation of sympathetic nervous system by the lack of leptin, we demonstrated that ob/ob mice present massively increased aminopeptidase A (APA) activity in the circulation. APA enzyme metabolizes angiotensin (ANG) II into ANG III, a peptide associated with intrarenal angiotensin type 2 (AT2) receptor activation and induction of natriuresis. In these mice, we found increased ANG-III levels in the circulation, high AT2 receptor expression in the kidney, and enhanced natriuresis. AT2 receptor blocking and APA inhibition increased BP, suggesting the ANG III-AT2 receptor axis as a complementary BP control mechanism. Circulating APA activity was significantly reduced by weight loss independently of leptin, indicating the role of fat tissue in APA production. Therefore, in this study we provide new data supporting the role of APA in BP control in ob/ob mouse strain. These findings improve our comprehension about obesity-related hypertension and suggest new tools for its treatment.NEW & NOTEWORTHY In this study, we reported an increased angiotensin III generation in the circulation of ob/ob mice caused by a high aminopeptidase A activity. These findings are associated with an increased natriuresis found in these mice and support the role of renin-angiotensin-aldosterone system as additional mechanism regulating blood pressure in this genetic obese strain.

MATE-1 modulation by kinin B1 receptor enhances cisplatin efflux from renal cells.

Cisplatin is a drug widely used in chemotherapy that frequently causes severe renal dysfunction. Organic transporters have an important role to control the absorption and excretion of cisplatin in renal cells. Deletion and blockage of kinin B1 receptor has already been show to protect against cisplatin-induced acute kidney injury. To test whether it exerts its protective function by modulating the organic transporters in kidney, we studied kinin B1 receptor knockout mice and treatment with a receptor antagonist at basal state and in presence of cisplatin. Cisplatin administration caused downregulation of renal organic transporters; in B1 receptor knockout mice, this downregulation of organic transporters in kidney was absent; and treatment by a B1 receptor antagonist attenuated the downregulation of the transporter MATE-1. Moreover, kinin B1 receptor deletion and blockage at basal state resulted in higher renal expression of MATE-1. Moreover we observed that kinin B1 receptor deletion and blockage result in less accumulation of platinum in renal tissue. Thus, we propose that B1 receptor deletion and blockage protect the kidney from cisplatin-induced acute kidney injury by upregulating the expression of MATE-1, thereby increasing the efflux of cisplatin from renal cells.

Lymphocyte glucose and glutamine metabolism as targets of the anti-inflammatory and immunomodulatory effects of exercise.

Glucose and glutamine are important energetic and biosynthetic nutrients for T and B lymphocytes. These cells consume both nutrients at high rates in a function-dependent manner. In other words, the pathways that control lymphocyte function and survival directly control the glucose and glutamine metabolic pathways. Therefore, lymphocytes in different functional states reprogram their glucose and glutamine metabolism to balance their requirement for ATP and macromolecule production. The tight association between metabolism and function in these cells was suggested to introduce the possibility of several pathologies resulting from the inability of lymphocytes to meet their nutrient demands under a given condition. In fact, disruptions in lymphocyte metabolism and function have been observed in different inflammatory, metabolic, and autoimmune pathologies. Regular physical exercise and physical activity offer protection against several chronic pathologies, and this benefit has been associated with the anti-inflammatory and immunomodulatory effects of exercise/physical activity. Chronic exercise induces changes in lymphocyte functionality and substrate metabolism. In the present review, we discuss whether the beneficial effects of exercise on lymphocyte function in health and disease are associated with modulation of the glucose and glutamine metabolic pathways.

Clinical impact of an angiotensin I-converting enzyme insertion/deletion and kinin B2 receptor +9/-9 polymorphisms in the prognosis of renal transplantation.

There is a consensus in the scientific literature that supports the importance of the kallikrein kinin and renin angiotensin systems in renal physiology, but few studies have investigated their importance after renal transplantation. The aim of this study was to investigate the clinical effects of the insertion/deletion polymorphism in the angiotensin I-converting enzyme (ACE) gene and the +9/-9 polymorphism in the kinin B2 receptor (B2R) gene in kidney-transplanted patients (n=215 ACE, n=203 B2R) compared with 443 healthy individuals. Demographic results showed that there is a higher frequency of the D allele (high plasma ACE activity) and +9 allele (lower B2R expression) in transplant patients compared with control individuals. We also observed a higher frequency of these alleles in patients who had an elevated level of plasma creatinine. At day 7 post-transplantation, we found a higher prevalence of individuals with the DD genotype with elevated plasma creatinine level. Furthermore, individuals with the DD genotype had a higher chronic allograft dysfunction and graft loss compared with the II patient genotype, which showed no loss of graft. Taken together, our data suggest that the DD genotype is an indicator of an unfavorable prognosis following renal transplantation and could be related to kinin modulation.

Exercise and caloric restriction alter the immune system of mice submitted to a high-fat diet.

As the size of adipocytes increases during obesity, the establishment of resident immune cells in adipose tissue becomes an important source of proinflammatory mediators. Exercise and caloric restriction are two important, nonpharmacological tools against body mass increase. To date, their effects on the immune cells of adipose tissue in obese organisms, specifically when a high-fat diet is consumed, have been poorly investigated. Thus, after consuming a high-fat diet, mice were submitted to chronic swimming training or a 30% caloric restriction in order to investigate the effects of both interventions on resident immune cells in adipose tissue. These strategies were able to reduce body mass and resulted in changes in the number of resident immune cells in the adipose tissue and levels of cytokines/chemokines in serum. While exercise increased the number of NK cells in adipose tissue and serum levels of IL-6 and RANTES, caloric restriction increased the CD4+/CD8+ cell ratio and MCP-1 levels. Together, these data demonstrated that exercise and caloric restriction modulate resident immune cells in adipose tissues differently in spite of an equivalent body weight reduction. Additionally, the results also reinforce the idea that a combination of both strategies is better than either individually for combating obesity.

Kinin B1 receptor controls maternal adiponectin levels and influences offspring weight gain.

Given the importance of the kinin B1 receptor in insulin and leptin hormonal regulation, which in turn is crucial in maternal adaptations to ensure nutrient supply to the fetus, we investigated the role of this receptor in maternal metabolism and fetoplacental development. Wild-type and kinin B1 receptor-deficient (B1KO) female mice were mated with male mice of the opposite genotype. Consequently, the entire litter was heterozygous for kinin B1 receptor, ensuring that there would be no influence of offspring genotype on the maternal phenotype. Maternal kinin B1 receptor blockade reduces adiponectin secretion by adipose tissue ex vivo, consistent with lower adiponectin levels in pregnant B1KO mice. Furthermore, fasting insulinemia also increased, which was associated with placental insulin resistance, reduced placental glycogen accumulation, and heavier offspring. Therefore, we propose the combination of chronic hyperinsulinemia and reduced adiponectin secretion in B1KO female mice create a maternal obesogenic environment that results in heavier pups.

Chronic conventional resistance exercise reduces blood pressure in stage 1 hypertensive men.

To investigate the antihypertensive effects of conventional resistance exercise (RE) on the blood pressure (BP) of hypertensive subjects, 15 middle-aged (46 ± 3 years) hypertensive volunteers, deprived of antihypertensive medication (reaching 153 ± 6/93 ± 2 mm Hg systolic/diastolic BP after a 6-week medication washout period) were submitted to a 12-week conventional RE training program (3 sets of 12 repetitions at 60% 1 repetition maximum, 3 times a week on nonconsecutive days). Blood pressure was measured in all phases of the study (washout, training, detraining). Additionally, the plasma levels of several vasodilators or vasoconstrictors that potentially could be involved with the effects of RE on BP were evaluated pre- and posttraining. Conventional RE significantly reduced systolic, diastolic, and mean BP, respectively, by an average of 16 (p < 0.001), 12 (p < 0.01), and 13 mm Hg (p < 0.01) to prehypertensive values. There were no significant changes of vasoactive factors from the kallikrein-kinin or renin-angiotensin systems. After the RE training program, the BP values remained stable during a 4-week detraining period. Taken together, this study shows for the first time that conventional moderate-intensity RE alone is able to reduce the BP of stage 1 hypertensive subjects free of antihypertensive medication. Moreover, the benefits of BP reduction achieved with RE training remained unchanged for up to 4 weeks without exercise.

Bradykinin receptor 1 activation exacerbates experimental focal and segmental glomerulosclerosis.

Focal and segmental glomerulosclerosis (FSGS) is one of the most important causes of end-stage renal failure. The bradykinin B1 receptor has been associated with tissue inflammation and renal fibrosis. To test for a role of the bradykinin B1 receptor in podocyte injury, we pharmacologically modulated its activity at different time points in an adriamycin-induced mouse model of FSGS. Estimated albuminuria and urinary protein to creatinine ratios correlated with podocytopathy. Adriamycin injection led to loss of body weight, proteinuria, and upregulation of B1 receptor mRNA. Early treatment with a B1 antagonist reduced albuminuria and glomerulosclerosis, and inhibited the adriamycin-induced downregulation of podocin, nephrin, and α-actinin-4 expression. Moreover, delayed treatment with antagonist also induced podocyte protection. Conversely, a B1 agonist aggravated renal dysfunction and even further suppressed the levels of podocyte-related molecules. Thus, we propose that kinin has a crucial role in the pathogenesis of FSGS operating through bradykinin B1 receptor signaling.

Cortisol Dose-Dependently Impairs Migration and Tube-like Formation in a Trophoblast Cell Line and Modulates Inflammatory and Angiogenic Genes.

Several stimuli can change maternal hormone levels during pregnancy. These changes may affect trophoblastic cells and modulate the development of the embryo and the placental tissue itself. Changes in cortisol levels are associated with impaired trophoblast implantation and function, in addition to other pregnancy complications. This study aims to analyze the effects of low and high doses of cortisol on an extravillous trophoblast cell line, and the effects of various exposures to this hormone. SGHPL-4 cells were treated with cortisol at five doses (0-1000 nM) and two exposures (continuous: 24 h/day; and intermittent: 2 h/day). In intermittent treatment, cortisol acted mainly as an anti-inflammatory hormone, repressing gene expression of kinin B1 receptors, interleukin-6, and interleukin-1ß. Continuous treatment modulated inflammatory and angiogenic pathways, significantly repressing angiogenic factors and their receptors. Cortisol affected cell migration and tube-like structures formation. In conclusion, both continuous and intermittent exposure to cortisol repressed the expression of inflammatory genes, while only continuous exposure repressed the expression of angiogenic genes, suggesting that a sustained increase in the levels of this hormone is more harmful than a high short-term increase. Cortisol also impaired tube-like structures formation, and kinin receptors may be involved in this response.

Exercise prevents the effects of experimental arthritis on the metabolism and function of immune cells.

Active lymphocytes (LY) and macrophages (MPhi) are involved in the pathophysiology of rheumatoid arthritis (RA). Due to its anti-inflammatory effect, physical exercise may be beneficial in RA by acting on the immune system (IS). Thus, female Wistar rats with type II collagen-induced arthritis (CIA) were submitted to swimming training (6 weeks, 5 days/week, 60 min/day) and some biochemical and immune parameters, such as the metabolism of glucose and glutamine and function of LY and MPhi, were evaluated. In addition, plasma levels of some hormones and of interleukin-2 (IL-2) were also determined. Results demonstrate that CIA increased lymphocyte proliferation (1.9- and 1.7-fold, respectively, in response to concanavalin A (ConA) and lipopolysaccharide (LPS)), as well as macrophage H(2)O(2) production (1.6-fold), in comparison to control. Exercise training prevented the activation of immune cells, induced by CIA, and established a pattern of substrate utilization similar to that described as normal for these cells. Exercise also promoted an elevation of plasma levels of corticosterone (22.2%), progesterone (1.7-fold) and IL-2 (2.6-fold). Our data suggest that chronic exercise is able to counterbalance the effects of CIA on cells of the IS, reinforcing the proposal that the benefits of exercise may not be restricted to aerobic capacity and/or strength improvement.

Changes in glucose and glutamine lymphocyte metabolisms induced by type I interferon α.

In lymphocytes (LY), the well-documented antiproliferative effects of IFN-α are associated with inhibition of protein synthesis, decreased amino acid incorporation, and cell cycle arrest. However, the effects of this cytokine on the metabolism of glucose and glutamine in these cells have not been well investigated. Thus, mesenteric and spleen LY of male Wistar rats were cultured in the presence or absence of IFN-α, and the changes on glucose and glutamine metabolisms were investigated. The reduced proliferation of mesenteric LY was accompanied by a reduction in glucose total consumption (35%), aerobic glucose metabolism (55%), maximal activity of glucose-6-phosphate dehydrogenase (49%), citrate synthase activity (34%), total glutamine consumption (30%), aerobic glutamine consumption (20.3%) and glutaminase activity (56%). In LY isolated from spleen, IFNα also reduced the proliferation and impaired metabolism. These data demonstrate that in LY, the antiproliferative effects of IFNα are associated with a reduction in glucose and glutamine metabolisms.

Bradykinin B2 Receptor Signaling Increases Glucose Uptake and Oxidation: Evidence and Open Questions.

The Kinin B2 receptor (B2R) is classically involved in vasodilation and inflammatory responses. However, through the observation of hypoglycemic effects of Angiotensin-I-Converting Enzyme (ACE) inhibitors, this protein has been related to metabolic glucose modulation in physiological and pathophysiological contexts. Although several studies have evaluated this matter, the different methodologies and models employed, combined with the distinct target organs, results in a challenge to summarize and apply the knowledge in this field. Therefore, this review aims to compile human and animal data in order to provide a big picture about what is already known regarding B2R and glucose metabolism, as well to suggest pending investigation issues aiming at evaluating the role of B2R in relation to glucose metabolism in homeostatic situations and metabolic disturbances. The data indicate that B2R signaling is involved mainly in glucose uptake in skeletal muscle and adipose tissue, acting as a synergic player beside insulin. However, most data indicate that B2R induces increased glucose oxidation, instead of storage, via activation of a broad signaling cascade involving Nitric Oxide (NO) and cyclic-GMP dependent protein kinase (PKG). Additionally, we highlight that this modulation is impaired in metabolic disturbances such as diabetes and obesity, and we provide a hypothetic mechanism to explain this blockade in light of literature data provided for this review, as well as other authors.

Kinin B1 receptor stimulation modulates leptin homeostasis. Evidence for an insulin-dependent mechanism.

Kinins are potent vasoactive and inflammatory peptides generated by kallikreins in blood and tissues that bind to specific receptors named B1 and B2. On the other hand, leptin is an adipocytokine that displays broad effects on energy balance, inflammation and vascular tone. Here we demonstrate that the intravenous administration of the kinin B1 receptor agonist des-Arg9-bradykinin (DBK) in mice leads to significant increase in serum leptin levels. However, incubation of isolated white adipose tissue with DBK was not sufficient to induce leptin release or leptin mRNA overexpression. On the contrary, long-term DBK treatment in isolated fat tissue impaired insulin-mediated actions on leptin secretion and expression. In order to verify whether the in vivo effect of B1 receptor stimulation on leptin release was also dependent on blood insulin levels, DBK was injected in animals in hyperinsulinemic state. In this case, however, DBK was not able to potentiate leptinemia. Therefore, our results show that the B1 receptor stimulation may modulate leptin homeostasis in an insulin-dependent manner. These new findings contribute to a better understanding of the processes involving leptin regulation and highlight the involvement of kinins with metabolic processes.

Kallikrein kinin system activation in post-exercise hypotension in water running of hypertensive volunteers.

Previous studies demonstrated a reduction in blood pressure level immediately after different types of exercises, like running, cycling and resistance training, a phenomenon called post-exercise hypotension (PEH). Since PEH can persist for hours it could be suggested as a non-pharmacological therapy for hypertensive individuals. Unfortunately, usually running is not recommended due to the high impact caused by its practice. Therefore running in water treadmill should be a better option, since the environment is completely different and causes lower impact. However it is not known whether PEH occurs in this situation. The objective of this work was to evaluate the existence of PEH after water running and to compare PEH promoted by running in two different environments. In addition, changes in plasmatic concentrations of the kallikrein kinin system (KKS) components were also evaluated. Sixteen hypertensive subjects were submitted to two exercise sessions, conventional running and water running, in two different occasions. The pattern of heart rate, blood pressure and plasmatic concentrations of KKS components immediately after and one hour after exercise were investigated. Results showed a maximal reduction in systolic and diastolic blood pressure 30 min after both exercise models (P<0.001), indicating that moderate water running promotes PEH with similar magnitude as compared to conventional running. Plasma kallikrein activity and bradykinin concentration increased immediately after exercise (P<0.05), but these parameters were not different in both exercise models. In conclusion, our findings show that water running, similarly to conventional running, can also provoke PEH and alterations in the KKS components.

Swimming training exacerbates pathological cardiac hypertrophy in kinin B2 receptor-deficient mice.

Kallikrein-kinin system exerts cardioprotective effects against pathological hypertrophy. These effects are modulated mainly via B2 receptor activation. Chronic physical exercise can induce physiological cardiac hypertrophy characterized by normal organization of cardiac structure. Therefore, the aim of this work was to verify the influence of kinin B2 receptor deletion on physiological hypertrophy to exercise stimulus. Animals were submitted to swimming practice for 5 min or for 60 min, 5 days a week, during 1 month and several cardiac parameters were evaluated. Results showed no significantly difference in heart weight between both groups, however an increased left ventricle weight and myocyte diameter were observed after the 60 min swimming protocol, which was more pronounced in B2(-/-) mice. In addition, sedentary B2(-/-) animals presented higher left ventricle mass when compared to wild-type (WT) mice. An increase in capillary density was observed in exercised animals, however the effect was less pronounced in B2(-/-) mice. Collagen, a marker of pathological hypertrophy, was increased in B2(-/-) mice submitted to swimming protocol, as well as left ventricular thickness, suggesting that these animals do not respond with physiological hypertrophy for this kind of exercise. In conclusion, our data suggest an important role for the kinin B2 receptor in physiological cardiac hypertrophy.

Bradykinin B2 receptor is essential to running-induced cell proliferation in the adult mouse hippocampus.

Physical exercise is a strong external effector that induces precursor cell proliferation in the adult mouse hippocampus. Research into mechanisms has focused on central changes within the hippocampus and we have established that serotonin is the signaling factor that transduces physical activity into adult neurogenesis. Less focus has been given on potential peripheral signals that may cause pro-mitotic running effects. Vasoactive kinin peptides are important for blood pressure regulation and inflammatory processes to maintain cardiovascular homeostasis. Acting via the two receptors termed B1 (B1R) and B2R, the peptides also function in the brain. In particular, studies attribute B2R a role in cell proliferation and differentiation into neurons in vitro. Here, we determined B1R and B2R mRNA expression levels in the adult mouse hippocampus and prefrontal cortex in vivo, and in response to running exercise. Using mice depleted in either or both receptors, B1-knockout (KO), B2KO and B1/2KO we observed changes in running performance overnight and in running distances. However, voluntary exercise led to the known pro-mitotic effect in the dentate gyrus of B1KO mice while it was attenuated in B2KO accompanied by an increase in microglia cells. Our data identify B2R as an important factor in running-induced precursor cell proliferation.