Effects of root extracts of eurycoma longifolia jack on corpus cavernosum of rat

Objective: This study was conducted to investigate the mechanisms of action of Eurycoma longifolia in rat corpus cavernosum

Materials and Methods: Tincture of the roots was concentrated to dryness by evaporating the ethanol in vacuo. This ethanolic extract was partitioned into 5 fractions sequentially with hexane, dichloromethane [DCM], ethyl acetate, butanol, and water. The corpus cavernosum relaxant activity of each fraction was investigated

The DCM fraction which showed the highest potency in relaxing phenyleph-rine-precontracted corpora cavernosa was purified by column chromatography. The effects of the most potent DCM subfraction in relaxing phenylephrine-precontracted corpora cavernosa, DCM-I, on angiotensin I- or angiotensin ll-in-duced contractions in corpora cavernosa were investigated. The effects of DCM-I pretreatment on the responses of phenylephrine-precontracted corpora cavernosa to angiotensin II or bradykinin were also studied. An in vitro assay was conducted to evaluate the effect of DCM-I on angiotensin-converting enzyme activity

Results: Fraction DCM-I decreased the maximal contractions [100%] evoked by angiotensin I and angiotensin II to 30 +/- 14% and 26 +/- 16% [p < 0.001], respectively. In phenylephrine-precontracted corpora cavernosa, DCM-I pretreatment caused angiotensin II to induce 82 +/- 27% relaxation of maximal contraction [p < 0.01] and enhanced [p < 0.001] bradykinin-induced relaxations from 47 +/- 8% to 100+/-5%. In vitro, DCM-I was able to reduce [p < 0.001] the maximal angiotensin-converting enzyme activity to 78 +/-0.24%

Conclusion: Fraction DCM-I was able to antagonize angiotensin ll-induced contraction to cause corpus cavernosum relaxation via inhibition of angiotensin II type 1 receptor and enhance bradykinin-induced relaxation through inhibition of angiotensin-converting enzyme

Avaliação dos eixos ECA / ANG II / AT1 e ECA-2 / ANG (1-7) / MAS em fibroblastos de gengiva e ligamento periodontal humanos estimulados por IL-1ß e sua contribuição na produção e regulação de citocinas e quimiocinas / Evaluation ACE /ANG II /AT1 and ACE-2 /ANG (1-7) /MAS axis in gingival and periodontal ligament human fibroblasts stimulated with IL-1ß and its contribution in the production of cytokines and chemokines

O Sistema renina-angiotensina (SRA) tem sido relatado como um importante modulador de processos inflamatórios e imunológicos, incluindo a doença periodontal (DP). Estudos sugerem neste sistema um eixo alternativo (ECA-2 /ANG(1-7) /MAS) que atuaria como um contra-regulador de efeitos mediados pelo clássico eixo (ECA /ANGII /AT1). Sabe-se que bactérias periodontopatogênicas, como a Porphyromonas gingivalis (Pg), possuem componentes bioativos de membrana (ex. lipopolissacarídeos-LPS) capazes de induzir uma forte resposta imune no hospedeiro devido à liberação de citocinas nas células, entre elas Interleucina (IL)- 1ß. Neste contexto, fibroblastos são as células mais abundantes nos tecidos periodontais e possuem em sua superfície celular receptores necessários para o reconhecimento da invasão bacteriana, ativando cascatas intracelulares, que levam à produção de citocinas. O objetivo deste estudo foi verificar se os eixos ECA/ ANGII/ AT1 e ECA-2/ ANG(1-7)/ MAS contribuem para a produção e/ ou regulação de citocinas inflamatórias (CI) por fibroblastos de gengiva humana (HGF) e ligamento periodontal humano (HPLF) estimulados por IL-1ß. Após o pré-tratamento com Losartan e Ang (1-7) ou silenciamento mediado por RNA de interferência (RNAi) de AT1, HGF e HPLF foram estimulados por IL-1ß por 3 horas (RNAm) ou 24 horas (proteína). Expressão de RNAm para AT1, MAS, ECA, ECA-2, IL-1ß, TNF-α, IL-6, IL-8, IL-10, TGF-ß, CXCL12, RANK-L e OPG foram avaliados por RT-qPCR e das proteínas IL-6, IL-8, ECA e ECA-2 por ELISA. Foi realizado também Western Blot para detecção de AT1 e ECA nos extratos celulares e dosagem de nitrito no sobrenadante das culturas. Ambos os subtipos de fibroblastos mostraram aumento da expressão de RNAm para AT1, IL-1ß, IL-6, IL-8, TNF-α e OPG, quando estimulados por IL-1ß. No entanto, apenas em HPLF foi observado aumento para MAS, ECA e TGF-ß. Losartan e Ang (1-7) não modularam o transcrito, a secreção de CI e nem a produção de nitrito no sobrenadante das culturas, tanto em HGF como em HPLF. O silenciamento do receptor AT1 reduziu a secreção de IL-6 e IL-8 induzida por IL-1ß em cultura de HGF e HPLF e aumentou a expressão gênica de OPG somente em HGF. Estes resultados sugerem que o silenciamento de AT1, mas não o bloqueio farmacológico deste receptor pelo antagonista Losartan, em HGF e HPLF, pode controlar a produção de IL-6 e IL-8, que por sua vez contribuem para a patogênese periodontal.(AU)

The renin-angiotensin system (RAS) has been reported as an important modulator of inflammatory and immune responses, including periodontal disease (PD). Studies suggest an alternative axis as part of this system (ACE-2 / ANG (1-7) / MAS) that would act as counter-regulatory to the classical axis (ECA / ANGII / AT1). It is known that periodontal bacteria such as Porphyromonas gingivalis (Pg) have bioactive components in their membrane (such as lipopolysaccharide-LPS) capable of inducing a strong immune response in the host due to the release of cytokines in cells, including interleukin (IL) - 1ß. In this regard, fibroblasts are the most abundant cells in periodontal tissues and receptors needed for the recognition of bacterial invasion by activating intracellular cascades that lead to cytokine production. The aim of this study was to determine whether the axes ACE / ANGII / AT1 and ACE-2 / ANG (1-7) / MAS contribute to the production and / or regulation of inflammatory cytokines (IC) by fibroblasts of human gingiva (HGF) and human periodontal ligament (HPLF) stimulated IL-1ß. After pre-treatment with Losartan, Ang (1-7) or silencing mediated by RNA interference (RNAi) of AT1, HGF and HPLF were stimulated by IL-1ß for 3 hours (RNAm) or 24 hours (protein). Expression mRNA for AT1, MAS, ACE, ACE-2, IL-1ß, TNF-α, IL-6, IL-8, IL-10, TGF-ß, CXCL12, RANK-L and OPG was assessed by RT- qPCR and proteins IL-6, IL-8, ACE and ACE-2 by ELISA. Western Blot for the detection of AT1 and ECA and dosage of nitrite was also performed. Experiments stimulated by IL-1ß showed a positive control for gene expression AT1, IL-1ß, IL-6, IL-8, TNF-α and OPG in HGF and HPLF and MAS, ACE and TGF-ß only HPLF. Losartan and Ang (1-7) did not modulate the transcription and secretion of IC and no nitrite production in the culture supernatant of HGF and HPLF. The silencing AT1 reduced IL-6 secretion and IL-8 induced by IL- ß in cultured HGF and HPLF and increased OPG gene expression only HGF. These results suggest that silencing AT1, but not pharmacological blockade of this receptor by Losartan in HPLF and HGF, can control the production of IL-6 and IL-8, which in turn contribute to the pathogenesis of periodontal disease.(AU)

Avances en el tratamiento de cáncer de próstata resistente a la castración: énfasis en nuevas terapias hormonales / Advances in the treatment of castration-resistant prostate cancer: emphasis in new hormonal therapies

Prostate cancer represents the second cancer-related cause of death in North American and Chilean men. The main treatment for incurable stages of disease is surgical or pharmacological castration. However, with time and despite the addition of anti-androgens, the disease progresses to a clinical state that has been commonly referred to as “hormone refractory”. In recent years, the concept of hormone refractoriness has been challenged and replaced by “castration resistance”, acknowledging that further and optimal hormonal manipulation can be attained, beyond achieving testosterone levels at castration range. The purpose of this review is to summarize the recent therapeutic breakthroughs in the management of metastatic castrate resistant prostate cancer (mCRPC), with greater emphasis in the newer hormonal therapy agents such as Abiraterone and Enzalutamide. Future combination and sequential treatment strategies are contextualized in the current era of personalized cancer medicine and genomic characterization of prostate cancer.

The effect of hypoxia and reoxygenation in the response of mesangial cells to angiotensin II in vitro / Efeito da hipóxia e reoxigenação na resposta à angiotensina II em células mesangiais in vitro

INTRODUCTION: Mesangial cells (MC) may be involved in the glomerular alterations induced by ischemia/reperfusion injury. OBJECTIVE: To evaluate the response of immortalized MC (IMC) to 30 minutes of hypoxia followed by reoxygenation periods of 30 minutes (H/R30) or 24 hours (H/R24). METHODS: The intracellular calcium concentration ([Ca+2]i) was measured before (baseline) and after adding angiotensin II (AII, 10-5 M) in the presence and absence of glybenclamide (K ATP channel blocker). We estimated the level of intracellular ATP, nitric oxide (NO) and PGE2. RESULTS: ATP concentration decreased after hypoxia and increased after reoxygenation. Hypoxia and H/R induced increases in basal [Ca+2]i. AII induced increases in [Ca+2]i in normoxia (97 ± 9%), hypoxia (72 ± 10%) or HR30 (85 ± 17%) groups, but there was a decrease in the response to AII in group H/R24 since the elevation in [Ca+2]i was significantly lower than in control (61 ± 10%, p < 0.05). Glybenclamide did not modify this response. It was observed a significant increase in NO generation after 24 hours of reoxygenation, but no difference in PGE2 production was observed. Data suggest that H/R injury is characterized by increased basal [Ca+2]i and by an impairment in the response of cells to AII. Results suggest that the relative insensibility to AII may be at least in part mediated by NO but not by prostaglandins or vasodilator K ATP channels. CONCLUSION: H/R caused dysfunction in IMC characterized by increases in basal [Ca+2]i during hypoxia and reduction in the functional response to AII during reoxygenation.

INTRODUÇÃO: Células mesangiais (CM) podem estar envolvidas na lesão glomerular induzida por hipoxia/reperfusão (H/R). OBJETIVO: Avaliar a resposta de CM imortalizadas (CMI) à hipoxia por 30 minutos seguida de reoxigenação por 30 minutos (H/R30) ou 24 horas (H/R24). MÉTODOS: Concentração de cálcio intracelular ([Ca+2]i) foi avaliada antes (basal) e após a adição de angiotensina II (AII, 10-5 M), na presença e na ausência de glibenclamida (bloqueador de canais K ATP). Foram estimados o nível de ATP intracelular, de óxido nítrico (NO) e de PGE2. RESULTADOS: Nível de ATP diminuiu após hipóxia e aumentou após a reoxigenação. H/R induziu aumento na [Ca+2]i basal. A AII elevou a [Ca+2]i nas condições de normoxia (97 ± 9%), hipoxia (72 ± 10%) ou HR30 (85 ± 17%), porém no grupo H/R24, houve diminuição significativa na resposta à AII, uma vez que a elevação da [Ca+2]i foi mais baixa do que no controle (61 ± 10%, p < 0,05). Glibenclamida não alterou esta resposta. Houve um aumento significativo na geração de NO após 24 horas de reoxigenação, mas não foi observada nenhuma diferença na produção de PGE2. Os dados indicam que a injuria celular causada pela hipoxia/reoxigenação é caracterizada pelo aumento na [Ca+2]i basal e por uma diminuição na reatividade celular à AII. Resultados sugerem que a insensibilidade ao agonista constritor pode ser pelo menos em parte, mediada pelo NO, mas não pelas prostaglandinas ou por canais K ATP. CONCLUSÃO: H/R resultou em disfunção das CMI, caracterizada pelo aumento na [Ca+2]i basal durante a hipóxia e redução da resposta funcional a AII durante a reoxigenação.

Angiotensin-II-induced reactive oxygen species along the SFO-PVN-RVLM pathway: implications in neurogenic hypertension

Neurogenic hypertension has been the subject of extensive research worldwide. This review is based on the premise that some forms of neurogenic hypertension are caused in part by the formation of angiotensin-II (Ang-II)-induced reactive oxygen species along the subfornical organ-paraventricular nucleus of the hypothalamus-rostral ventrolateral medulla pathway (SFO-PVN-RVLM pathway). We will discuss the recent contribution of our laboratory and others regarding the mechanisms by which neurons in the SFO (an important circumventricular organ) are activated by Ang-II, how the SFO communicates with two other important areas involved in sympathetic activity regulation (PVN and RVLM) and how Ang-II-induced reactive oxygen species participate along the SFO-PVN-RVLM pathway in the pathogenesis of neurogenic hypertension.

Menores niveles tisulares de la enzima convertidora de angiotensina I homologa (ECA-2) y angiotensina-(1-9) están asociados a mayor remodelamiento de la pared aórtica de ratas hipertensas / Lower tissue levels of homologous angiotensin I converting enzyme (ACE-2) and angiotensin 1-9 are associated to increased remodeling of the aortic wall of hypertensive rats

Antecedentes: Recientemente hemos propuesto en un modelo experimental de infarto al miocardio una significativa interregulación entre los niveles de la enzima convertidora de angiotensina I (ECA) y su homóloga (ECA-2), junto con que angiotensina (Ang)-(1-9) más que Ang-(1-7) actuaría como uncontrarregulador de Ang II. Sin embargo tal relación no se ha investigado en el remodelado aórtico hipertensivo. Objetivo: Determinar la expresión de ECA y ECA-2, los niveles de Angs I, II, (1-7) y (1-9) y los parámetros de remodelado de la pared aórtica de ratas hipertensas. Métodos: Ratas normotensas Lewis (n=18) fueron randomizadas a hipertensión (HTA) por sobrecarga de presión (modelo Goldblatt, GB, 2 riñones-1 pinzado, n=9). Ratas pseudo-operadas se usaron como controles (S, n=9). A las 6 semanas post cirugía, se determinó la masa cardíaca relativa (MCR) y la presión arterial sistólica (PAS). En la aorta torácica se determinó el grosor de la túnica media (GTM), área de la TM (ATM), niveles de mRNA de ECA y ECA-2, factor de crecimiento transformante tipo beta (TGF-beta), inhibidor del activador de plasminógeno (PAI-1) y de la proteína quimioatractante de monocitos (MCP-1) por RT-PCR. La actividad y niveles proteicos de ECA y ECA-2 por fluorimetría y Western blot y los niveles de Angs I, II, (1-7) y (1-9) por HPLC y radioinmunoensayo. Resultados: La MCR y la PAS aumentaron significativamente (p<0,05) en el grupo GB respecto a su control S. Las ratas hipertensas mostraron un aumento significativo (p<0.05) del GTM (18 por ciento), ATM (31 por ciento), niveles de mRNA de ECA (164 por ciento), TGF-beta (105 por ciento), PAI-1(51 por ciento), MCP-1 (53 por ciento) junto con mayor actividad (89 por ciento), niveles proteicos de ECA (130 por ciento) y Ang II (48 por ciento). Esos efectos se asociaron a una significativa disminución del mRNA, los niveles proteicos y actividad...

Background: In experimental models of myocardial infarction we have recently proposed a significantinter-regulation between levels of Angiotensin I converting enzyme (ACE) and its homologous, ACE-2; in addition, we have proposed that Angiotensin 1-9 (Ang-(1-9)) rather than Ang-(1-7) counter regulates Ang II. These relations have not been investigated in hypertensive aortic wall remodeling. Aim: To measure de expression of ACE and ACE-2, the aortic wall levels of Ang I, Ang II, Ang-(1-7) and Ang-(1-9), along with parameters of aortic wall remodeling in hypertensive rats. Methods: 18 Lewis rats were randomized to Goldblatt (2 kidneys, 1 clamped) induced hypertension (n=9) or sham operation (controls, n=9). Six weeks after surgery, relative cardiac mass (RCM), systolic blood pressure (SBP), medial layer aortic wall thickness (MLT) and ML area (MLA) were measured. The aortic wall levels of ACE and ACE-2, tissue growth factor beta (TGF- beta), plasminogen activator inhibitor (PAI-1) and monocyte chemoattractant protein (MCP-1) were determined by RT-PCR. Activity and protein levels of ACE and ACE-2 were measured by fluorometry and Western Blot and ANG I, Ang II, Ang-(1-7) and Ang-(1-9) levels were determined using HPLC and radioimmunoassay. Results: RCM and SBP increased significantly in hypertensive as opossed to sham operated rats...

Endogenous angiotensin II modulates nNOS expression in renovascular hypertension

Nitric oxide (NO) influences renal blood flow mainly as a result of neuronal nitric oxide synthase (nNOS). Nevertheless, it is unclear how nNOS expression is modulated by endogenous angiotensin II, an inhibitor of NO function. We tested the hypothesis that the angiotensin II AT1 receptor and oxidative stress mediated by NADPH oxidase contribute to the modulation of renal nNOS expression in two-kidney, one-clip (2K1C) hypertensive rats. Experiments were performed on male Wistar rats (150 to 170 g body weight) divided into 2K1C (N = 19) and sham-operated (N = 19) groups. nNOS expression in kidneys of 2K1C hypertensive rats (N = 9) was compared by Western blotting to that of 2K1C rats treated with low doses of the AT1 antagonist losartan (10 mg·kg-1·day-1; N = 5) or the superoxide scavenger tempol (0.2 mmol·kg-1·day-1; N = 5), which still remain hypertensive. After 28 days, nNOS expression was significantly increased by 1.7-fold in the clipped kidneys of 2K1C rats and by 3-fold in the non-clipped kidneys of 2K1C rats compared with sham rats, but was normalized by losartan. With tempol treatment, nNOS expression increased 2-fold in the clipped kidneys and 1.4-fold in the non-clipped kidneys compared with sham rats. The changes in nNOS expression were not followed by changes in the enzyme activity, as measured indirectly by the cGMP method. In conclusion, AT1 receptors and oxidative stress seem to be primary stimuli for increased nNOS expression, but this up-regulation does not result in higher enzyme activity.

Menor expresión de la enzima convertidora de angiotensinaI omóloga (ECA2) se asocia a mayor remodelamiento de la pared aórtica de ratas con niveles geneticamente elevados de angiotensina II / Decreased expression of homologous angiotensin I converting enzyme (ACE2) is associated to increased remodeling of the aortic arterial wall in rats with genetically elevated levels of angiotensin II

Introducción: El polimorfismo de la enzima convertidora de angiotensina I (ECA) determina mayor actividadde ECA y niveles de angiotensina (Ang) II en ratas Brown Norway (BN) y menor actividad de ECA y niveles de Ang II en ratas Lewis (L). La interregulación entre ECA, ECA2 y su relación con remodelamiento aórtico hipertensivo no ha sido explorada Objetivo: Determinar la expresión de ECA y ECA2 y los parámetros de remodelamiento vascular hipertensivo en la aorta de ratas con niveles genéticamente determinados de ECA. Métodos: A ratas macho homocigotas de 150 grs BN y LL, se les indujo HTA por 6 semanas por el procedimiento Goldblatt (GB, 2 K-1clip). Ratas pseudo-operadas se usaron como controles (sham). Se determinó la presión arterial sistólica (PAS), el grosor de la túnica media (GTM), área de la TM (ATM), expresión génica deECA, ECA2 ,TGF-beta, PAI-1 y MCP-1 por RT-PCR y también proteica de ECA y ECA2 por Western Blot. Resultados: La masa cardiaca relativa y la PAS aumentaron significativamente en los grupos GB respecto a sus controles Sham, sin diferencias por efecto del polimorfismo de la ECA. En condiciones de normotensión las ratas BN mostraron que la pared aórtica expresa mayores niveles génicos y proteicos de la ECA(60% y 134%, respectivamente) y menores de ECA2 (74% y 73%, respectivamente) respecto de las ratas L(p<0.05). Estos resultados se asociaron con mayores GTM y ATM como en los niveles de mRNA de TGF-beta y, PAI-1 en las aortas de ratas BN respecto de las ratas L (p<0,05). En respuesta a un estrés hipertensivo las ratas con mayores niveles de ECA y menores niveles de ECA2 mostraron mayor GTM (p<0,05, respecto de GB-L), sin diferencias en los otros parámetros evaluados...

Background: Angiotensin I converting enzyme (ACE) polymorphism determines increased ACE and Ang IIlevels in Brown Norway rats (BN) and decreased ACE and Ang II levels in Lewis (L) rats. The interactionbetween ACE and ACE2 in relation to aortic remodeling associated to hypertension has not been explored. Aim: to determine the expression of ACE and ACE2 along with parameters of remodeling in hypertensive rats with genetically determined levels of ACE. Methods: BN and L rats weighing 150 g were made hypertensive by the Goldblatt procedure (GB, 2K-1 clip). Sham operated rats were used as controls. Systolic blood pressure (SBP), media thickness (MT), and MT area were measured. RT-PCR was used to determine the genetic expression of ACE, ACE2, TGF-beta, PAI-1 and MCP-1. Western Blot was used to measure the protein fraction of ACE and ACE2 Results: Relative cardiac mass and SBP increases significantly in GB rats compared to controls; ACE polymorphism did not influence this effect. The aortic wall of normotensive BN rats expressed increased genic and protein levels of ACE (60% and 134%, respectively) and decreased levels of ACE2 (74% and 73%, respectively) compared to L rats (p<0.05). These findings were associated to increased MT and MT area as well as increased mRNA for TGF-beta and PAI 1 in BN rats compared to L rats (p<0.05). In response to hypertensive stress, rats with increased ACE and decreased ACE2 levels developed increased MT compared to GB-L rats; other parameters of remodeling were not affected...

Mineralocorticoid modulation of central angiotensin-induced neuronal activity, water intake and sodium appetite

Central angiotensin II (AngII) stimulates water and salt solution intake. Pretreatment with low-dose mineralocorticoid (DOCA) enhances this AngII-induced intake of salt solutions (the synergy theory) in Wistar and Sprague Dawley rats but not in Fischer rats. This response is mediated via the AT-1 receptor. Electrophysiological experiments using iontophoretic application of AngII and the AT-1 receptor-specific non-peptide antagonist losartan showed excitation of neurons in the preoptic/medial septum region of urethane-anesthetized male Wistar rats. DOCA pretreatment further enhances this neuronal excitation in response to AngII and reduces the responses to losartan. This generated the hypothesis that DOCA-enhanced AngII-induced neuronal excitation is the neural support for the synergy theory. AT-2 receptors modulate these intake responses depending on sodium in the diet, and diuretic-induced dehydration during pregnancy produces a higher salt intake in the offspring. AngII-induced salt and water intakes were tested in offspring from Sprague Dawley mothers with only 1.8 percent NaCl to drink in which half were treated with furosemide. The important observations were a) the AT-1 antagonist alone suppressed intakes in offspring from mothers not treated with furosemide, b) both AT-1 and AT-2 antagonists suppressed intakes in offspring from furosemide-treated mothers, and c) combined administration of AT-1 and AT-2 antagonists greatly suppressed water intake in offspring from mothers not treated with furosemide. These results suggest that AT-1 and AT-2 receptors have variable properties (receptor number and/or second messengers). Furthermore, the activity and function of these central AngII receptors depend on the background mineralocorticoid levels. The exact mechanism of this influence, however, remains to be determined.

Cross-talk das vias de sinalização de insulina e angiotensina II: implicações com a associação entre diabetes mellitus e hipertensão arterial e doença cardiovascular / Insulin and angiotensin II signaling pathways cross-talk: implications with the association between diabetes mellitus, arterial hypertension and cardiovascular disease

Insulina (Ins) e Angiotensina II (AII) são fundamentais no controle de dois sistemas vitais e inter-relacionados: o metabólico e o cardiocirculatório, respectivamente. A disfunção de qualquer um desses hormônios pode levar ao desenvolvimento de duas doenças de alta prevalência, muitas vezes concomitantes e, talvez, com fisiopatologia integrada - diabetes mellitus (DM) e hipertensão arterial (HA). Vários estudos mostram que os sistemas de sinalização intracelular de Ins e AII estão conectados e influenciam um ao outro. Esta comunicação molecular ocorre em diferentes etapas da sinalização celular e é importante para vários fenômenos fisiológicos, desde o desenvolvimento de hipertrofia cardíaca e aquisição de energia pelo coração, até a ação de drogas anti-hipertensivas. No nível extracelular, a enzima de conversão de angiotensina regula a síntese de AII e o acúmulo de bradicinina, e ambos desempenham papel regulador sobre a sinalização de Ins. No nível intracelular, a interação dos sinais de Ins e AII ocorre em dois momentos distintos. Inicialmente, em etapas mais precoces da sinalização celular, a AII, atuando através da cascata JAK-2/IRS-1/PI3-quinase, JNK e ERK, provoca a fosforilação em serina e a conseqüente inibição de elementos-chave da via de sinalização da Ins. Finalmente, a AII induz a expressão da proteína regulatória SOCS-3, que impõe um controle mais tardio sobre o sinal de Ins. Esta revisão discute os avanços mais recentes neste campo e a importância dessa interação molecular na fisiopatologia e na associação clínica de DM e HA.

Insulin (Ins) and angiotensin II (AII) play pivotal roles in the control of two vital and closely related systems: the metabolic and the circulatory, respectively. A failure in the proper action of each of these hormones results, to a variable degree, in the development of two highly prevalent and commonly overlapping diseases - diabetes mellitus (DM) and hypertension (AH). In recent years, a series of studies has revealed a tight connection between the signal transduction pathways that mediate Ins and AII actions in target tissues. This molecular cross-talk occurs at multiple levels and plays an important role in phenomena that range from the action of anti-hypertensive drugs to cardiac hypertrophy and energy acquisition by the heart. At the extracellular level, the angiotensin-converting enzyme controls AII synthesis but also interferes with Ins signaling through the proper regulation of AII and the accumulation of bradykinin. At an early intracellular level, AII, acting through JAK-2/IRS-1/PI3-kinase, JNK and ERK, may induce the serine phosphorylation and inhibition of key elements of the Ins-signaling pathway. Finally, by inducing the expression of the regulatory protein SOCS-3, AII may impose a late control on the Ins signal. This review will focus on the main advances obtained in this field and will discuss the implications of this molecular cross-talk in the common clinical association between DM and AH.

Acciones de endotelina 1 y angiotensina II en embarazos complicados con preeclampsia / Endothelin 1 and angiotensin II in preeeclampsia

Introduction. It is generally thought that development of hypertension in preeclampsia (PE) is due to generalized endothelial dysfunction and/or results from an imbalance in the production and/or action of vasoactive factors, resulting in higher citosolic Ca2+ concentration which in turn leads to vasoconstriction and decreased blood pressure perfusion in organs, including the fetoplacental unit. Among vasoactive factors involved in blood pressure regulation, endothelin 1 (ET-1) and angiotensin II (Ang II) regulate citosolic Ca2+ concentrations and therefore are considered in this review. PE is associated with higher circulating and placental ET-1 levels, observation that explains, at least in part, vasoconstriction and oxidative stress. Higher and lower Ang II sensitivity seen in PE and normal pregnancy, respectively, could not be explained by changes in renin-angiotensin system components, including Ang II receptors (ATI). During normal pregnancy, ATI receptors are found as monomers and are inactivated by reactive oxygen species (ROS) leading to lower Ang II sensitivity. In contrast, PE is associated with increased ATl/bradicinin receptors (B2) heterodimers which are resistant to inactivation by ROS, maintaining increased ATI-receptor stimulated signaling in PE. In adittion, AT-1 agonistic antibodies (AT1-AA) obtained from PE women increases intracellular Ca2+, NADPH oxidase components and ROS, effects not observed with normal pregnancy AT1-AA. Conclusion. High ET-1 levels, the presence of AT1/B2 receptor heterodimers and increased AT1-AA are involved, at least in part, in the hypertensive and oxidative stress states in PE.

Introducción. Se reconoce que el desarrollo de la hipertensión en la preeclampsia (PE) resulta del daño endotelial generalizado y/o de la falta de equilibrio en la producción y/o acción de agentes vasoactivos, lo que conlleva al incremento en la concentración citosólica de Ca2+ que resulta en vasoconstricción y disminución de la perfusión sanguínea en los órganos, incluyendo la unidad fetoplacentaria. Dentro de los factores vaso-activos que regulan la presión arterial, en la presente revisión se consideró a la endotelina 1 (ET-1) y a la angiotensina II (Ang II), factores que regulan la concentración citosólica de Ca2+. En comparación con el embarazo normal, la PE se asocia con mayor concentración en suero y placenta de ET-1, lo que explica en parte la vasoconstricción y el estado de estrés oxidativo. La respuesta exagerada en la PE y el estado de refractariedad en el embarazo normal a la Ang II no pueden explicarse por componentes del sistema renina-angiotensina, incluyendo a los receptores de Ang II (ATI). Durante el embarazo normal los receptores AT-1 se encuentran en forma de monómeros y son inactivados por las especies reactivas de oxígeno (ROS), lo que se asocia con menor respuesta a Ang II. En cambio, la respuesta exagerada a la Ang II durante la PE puede deberse a la heterodimerizacion de los receptores ATI con los de bradicinina (B2), estado que les confiere resistencia a la inactivación por las especies reactivas de oxígeno (ROS), lo que explica el incremento en la concentración del Ca2+ intracelular. Además, los anticuerpos agonistas del receptor ATI (AT1-AA) de mujeres PE aumenta la concentración de Ca2+ intracelular, de la NADPH oxidasa y de ROS, efectos que no se presentan al utilizar AT1-AA de embarazadas normotensas. Conclusión. Las altas concentraciones de ET-1, la presencia de receptores ATI en forma de heterodimeros ATI/ B2 y el aumento en los AT1-AA explican en parte, el estado de hipertensión y de estrés oxidativo de la PE.

Effects of captopril and losartan on thermal and chemical induced pain in mice.

Angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers antagonists (ARAs) are widely used compounds in various cardiovascular disorders. ACEIs, but not ARAs, inhibit the enzyme dipeptidyl carboxypeptidase which is involved in the conversion of angiotensin I to II and degradation of kinins like bradykinin and substance P. Bradykinin and substance P are potent mediators of inflammation and pain. Hence the study was undertaken to evaluate the effects of captopril (an ACEI) and losartan (an ARA-AT1 receptor antagonist) on thermal and chemical induced nocioception by employing hot plate and acetic acid induced writhing tests respectively in mice. Inbred albino mice weighing between 25-30 g were used and they were divided into two sets, each set containing 7 groups. Control groups received normal saline and the remaining six groups received three doses (0.5, 1 and 2 mg/kg) of captopril and three doses (0.5, 1 and 2 mg/kg) of losartan. Drugs were administered intraperitoneally fifteen minutes before placing the animal over the hot plate or 30 minutes before injecting 0.6% acetic acid. Both drugs dose dependently reduced the reaction time in hot plate method. In chemical induced writhing test, both the drugs reduced the latency of onset of writhing and in captopril pretreated groups, acetic acid induced sustained abdominal contraction without any intermittent relaxation. However, in losartan pretreated animals acetic acid just increased the number of writhings without sustained abdominal contraction. Thus, our study suggests that both drugs have hyperalgesic effects.

Why does diabetes mellitus increase the risk of cardiovascular disease?

The main etiology for mortality and a great percentage of morbidity in patients with diabetes mellitus is atherosclerosis. The pathogenesis of cardiovascular disease (CVD) in diabetes is multifactorial and can be affected by metabolic and other factors. A hypothesis for the initial lesion of atherosclerosis is endothelial dysfunction, defined pragmatically as changes in the concentration of the chemical messengers produced by the endothelial cell and/or by blunting of the nitric oxide-dependent vasodilatory response to acetylcholine or hyperemia. Endothelial dysfunction has been documented in patients with diabetes and in individuals with insulin resistance or at high risk for developing type 2 diabetes. The way endothelial function altered in diabetic patients is not yet fully understood, but the loss of normal endothelial function could be involved in the pathogenesis of diabetic angiopathy, as endothelial dysfunction is associated with diabetic microangiopathy and macroangiopathy. Factors associated with endothelial dysfunction in diabetes include activation of protein kinase C, overexpression of growth factors and/or cytokines, and oxidative stress. Changes in endothelium function may lead to the coronary artery circulation being unable to cope with the increased metabolism of myocardial muscle independently of a reduced coronary artery diameter. Finally, recent reports indicate that an improved metabolic control in diabetic patients, whatever the treatment used, is associated with near normalization or restoration of normal endothelial function.

A connection between extracellular matrix and hormonal signals during the development of the human fetal adrenal gland

The human adrenal cortex, involved in adaptive responses to stress, body homeostasis and secondary sexual characters, emerges from a tightly regulated development of a zone-specific secretion pattern during fetal life. Its development during fetal life is critical for the well being of pregnancy, the initiation of delivery, and even for an adequate adaptation to extra-uterine life. As early as from the sixth week of pregnancy, the fetal adrenal gland is characterized by a highly proliferative zone at the periphery, a concentric migration accompanied by cell differentiation (cortisol secretion) and apoptosis in the central androgen-secreting fetal zone. After birth, a strong reorganization occurs in the adrenal gland so that it better fulfills the newborn's needs, with aldosterone production in the external zona glomerulosa, cortisol secretion in the zona fasciculata and androgens in the central zona reticularis. In addition to the major hormonal stimuli provided by angiotensin II and adrenocorticotropin, we have tested for some years the hypotheses that such plasticity may be under the control of the extracellular matrix. A growing number of data have been harvested during the last years, in particular about extracellular matrix expression and its putative role in the development of the human adrenal cortex. Laminin, collagen and fibronectin have been shown to play important roles not only in the plasticity of the adrenal cortex, but also in cell responsiveness to hormones, thus clarifying some of the unexplained observations that used to feed controversies.

A emergência de um novo modulador cardiovascular - a 2ªenzima de conversão da angiotensina 2 (ECA2) / The emergenceof a new cardiovascular modulator 2ªangiostensin-converting enzyme 2 (ACE2)

O sistemarenina-angiotensina (SR-A) exerce um papel central no controle das várias alças de regulação cardiovascular. Muito dos seus efeitos são modulados pela enzima conversora de angiotensina (ECA) que remove dois aminoácidos da angiotensina I para formar a angiotensina II (AngII). A Ang II é o vasoconstrictor mais potente entre os que participam da fisiopatogenia da hipertensão arterial. Outros produtos do SR-A também contribuem para os mecanismos reguladores da perfusão tecidual. É o caso da angiotensina(1-7), gerada diretamente da Ang I por endopeptidases, e que é um potente vasodilatador, opondo-se às ações tróficas da Ang II. A partir de 2000, uma outra enzima do SR-A foi caracterizada; sua sequência genômica apresentou várias semelhanças estruturais com o gene da ECA humana. Por isso, foi denominada ECA2. É expressa principalmente pelas células endoteliais, coração e rim. A ECA2 tem atividades biológicas distintas da ECA, convertendo a Ang I em Ang(1-9), que é subsequentemente hidrolisada pela ECA em Ang(1-7). A ECA2 hidrolisa a Ang II, produzindo, também, a partir daí, a Ang II, produzindo, também, a partir daí, a Ang(1-7). A ECA2, além de ser uma enzima chave na geração de um potente vasodilatador [Ang(1-7)], é essencial para uma adequada função miocárdica. A perspectiva de se contar com uma droga que especificamente induza à formação de ECA2, atenuando, ao mesmo tempo, a atividade da Ang II poderá abrir novos horizontes terapêuticos para a hipertensão arterial e doenças cardiovasculares

Ligand-induced endocytosis and nuclear localization of angiotensin II receptors expressed in CHO cells

A construct (AT1R-NF) containing a "Flag" sequence added to the N-terminus of the rat AT1 receptor was stably expressed in Chinese hamster ovary cells and quantified in the cell membrane by confocal microscopy after reaction with a fluorescein-labeled anti-Flag monoclonal antibody. Angiotensin II bound to AT1R-NF and induced endocytosis with a half-time of 2 min. After 60-90 min, fluorescence accumulated around the cell nucleus, suggesting migration of the ligand-receptor complex to the nuclear membrane. Angiotensin antagonists also induced endocytosis, suggesting that a common step in the transduction signal mechanism occurring after ligand binding may be responsible for the ligand-receptor complex internalization

Regulation of the renal proximal tubule second sodium pump by angiotensins

For several years it was believed that angiotensin II (Ang II) alone mediated the effects of the renin-angiotensin system. However, it has been observed that other peptides of this system, such as angiotensin-(1-7) (Ang-(1-7)), present biological activity. The effect of Ang II and Ang-(1-7) on renal sodium excretion has been associated, at least in part, with modulation of proximal tubule sodium reabsorption. In the present review, we discuss the evidence for the involvement of Na+-ATPase, called the second sodium pump, as a target for the actions of these compounds in the regulation of proximal tubule sodium reabsorption

Acute AT1 receptor blockade does not improve the depressed baroreflex in rats with chronic renal hypertension

To assess the role of angiotensin II in the sensitivity of the baroreflex control of heart rate (HR) in normotensive rats (N = 6) and chronically hypertensive rats (1K1C, 2 months, N = 7), reflex changes of HR were evaluated before and after (15 min) the administration of a selective angiotensin II receptor antagonist (losartan, 10 mg/kg, iv). Baseline values of mean arterial pressure (MAP) were higher in hypertensive rats (195 ± 6 mmHg) than in normotensive rats (110 ± 2 mmHg). Losartan administration promoted a decrease in MAP only in hypertensive rats (16 percent), with no changes in HR. During the control period, the sensitivity of the bradycardic and tachycardic responses to acute MAP changes were depressed in hypertensive rats (~70 percent and ~65 percent, respectively) and remained unchanged after losartan administration. Plasma renin activity was similar in the two groups. The present study demonstrates that acute blockade of AT1 receptors with losartan lowers the MAP in chronic renal hypertensive rats without reversal of baroreflex hyposensitivity, suggesting that the impairment of baroreflex control of HR is not dependent on an increased angiotensin II level

Substâncias vasoativas e a modulaçäo do sistema microvascular hepático / Vasoactive substances and the modulation of the hepatic microvascular system

Objetivo. Revisão da filogênese e ontogênese hepáticas, do sistema microvascular hepático e da modulação do tônus deste sistema vascular por diferentes substâncias vasoativas. Método. Levantamento de artigos por meio do sistema Medline e consulta a livros-texto. Resultado. Foram selecionados 52 trabalhos publicados entre 1949, dos quais retiramos as informações a respeito de filogênese e ontogênese hepáticas, sistema microvascular hepático e mecanismos de controle do tônus vascular hepático. Conclusão. O fígado possui sistema vascular altamente especializado na promoção de mecanismos de troca entre hepatócitos e sangue. Diferentes fatores atuam continuamente sobre estruturas contrácteis deste sistema vascular adequando a perfusão do tecido hepático às necessidades homeostáticas de cada momento. O fígado é órgão eminentemente mantenedor do meio interno.

Role of angiotensin II and vasopressin receptors within the supraoptic nucleus in water and sodium intake induced by the injection of angiotensin II into the medial septal area

In this study we investigated the effects of the injection into the supraoptic nucleus (SON) of non-peptide AT1- and AT2-angiotensin II (ANG II) receptor antagonists, DuP753 and PD123319, as well as of the arginine-vasopressin (AVP) receptor antagonist d(CH2)5-Tyr(Me)-AVP, on water and 3 percent NaCl intake induced by the injection of ANG II into the medial septal area (MSA). The effects on water or 3 percent NaCl intake were assessed in 30-h water-deprived or in 20-h water-deprived furosemide-treated adult male rats, respectively. The drugs were injected in 0.5 µl over 30-60 s. Controls were injected with a similar volume of 0.15 M NaCl. Antagonists were injected at doses of 20, 80 and 180 nmol. Water and sodium intake was measured over a 2-h period. Previous administration of the AT1 receptor antagonist DuP753 into the SON decreased water (65 percent, N = 10, P<0.01) and sodium intake (81 percent, N = 8, P<0.01) induced by the injection of ANG II (10 nmol) into the MSA. Neither of these responses was significantly changed by injection of the AT2-receptor antagonist PD123319 into the SON. On the other hand, while there was a decrease in water intake (45 percent, N = 9, P<0.01), ANG II-induced sodium intake was significantly increased (70 percent, N = 8, P<0.01) following injection of the V1-type vasopressin antagonist d(CH2)5-Tyr(Me)-AVP into the SON. These results suggest that both AT1 and V1 receptors within the SON may be involved in water and sodium intake induced by the activation of ANG II receptors within the MSA. Furthermore, they do not support the involvement of MSA AT2 receptors in the mediation of these responses