RESUMO
The discovery of a receptor that binds prorenin and renin in human endothelial and mesangial cells highlights the possible effect of renin-independent prorenin in the resumption of meiosis in oocytes that was postulated in the 1980s.This study aimed to identify the (pro)renin receptor in the ovary and to assess the effect of prorenin on meiotic resumption. The (pro)renin receptor protein was detected in bovine cumulus-oocyte complexes, theca cells, granulosa cells, and in the corpus luteum. Abundant (pro)renin receptor messenger ribonucleic acid (mRNA) was detected in the oocytes and cumulus cells, while prorenin mRNA was identified in the cumulus cells only. Prorenin at concentrations of 10(-10), 10(-9), and 10(-8)M incubated with oocytes co-cultured with follicular hemisections for 15h caused the resumption of oocyte meiosis. Aliskiren, which inhibits free renin and receptor-bound renin/prorenin, at concentrations of 10(-7), 10(-5), and 10(-3)M blocked this effect (P<0.05). To determine the involvement of angiotensin II in prorenin-induced meiosis resumption, cumulus-oocyte complexes and follicular hemisections were treated with prorenin and with angiotensin II or saralasin (angiotensin II antagonist). Prorenin induced the resumption of meiosis independently of angiotensin II. Furthermore, cumulus-oocyte complexes cultured with forskolin (200µM) and treated with prorenin and aliskiren did not exhibit a prorenin-induced resumption of meiosis (P<0.05). Only the oocytes' cyclic adenosine monophosphate levels seemed to be regulated by prorenin and/or forskolin treatment after incubation for 6h. To the best of our knowledge, this is the first study to identify the (pro)renin receptor in ovarian cells and to demonstrate the independent role of prorenin in the resumption of oocyte meiosis in cattle.
Assuntos
Corpo Lúteo/transplante , Meiose/fisiologia , Ovário/fisiologia , Receptores de Superfície Celular/metabolismo , Renina/metabolismo , Reprodução/fisiologia , Amidas/farmacologia , Angiotensina II/metabolismo , Animais , Bovinos , Células Cultivadas , Colforsina/farmacologia , Corpo Lúteo/efeitos dos fármacos , Corpo Lúteo/fisiologia , Células do Cúmulo/citologia , Células do Cúmulo/efeitos dos fármacos , Células do Cúmulo/fisiologia , Feminino , Fumaratos/farmacologia , Células da Granulosa/citologia , Células da Granulosa/efeitos dos fármacos , Células da Granulosa/fisiologia , Humanos , Meiose/efeitos dos fármacos , Nucleotídeos Cíclicos/metabolismo , Oócitos/citologia , Oócitos/efeitos dos fármacos , Oócitos/fisiologia , Folículo Ovariano/citologia , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/fisiologia , Ovário/citologia , Ovário/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Superfície Celular/genética , Renina/antagonistas & inibidores , Renina/genética , Reprodução/efeitos dos fármacos , Saralasina/farmacologia , Células Tecais/citologia , Células Tecais/efeitos dos fármacos , Células Tecais/fisiologia , Receptor de Pró-ReninaRESUMO
Angiotensins (Angs) modulate blood pressure, hydro-electrolyte composition, and antinociception. Although Ang (5-8) has generally been considered to be inactive, we show here that Ang (5-8) was the smallest Ang to elicit dose-dependent responses and receptor-mediated antinociception in the rat ventrolateral periaqueductal gray matter (vlPAG). Ang (5-8) antinociception seems to be selective, because it did not alter blood pressure or act on vascular or intestinal smooth muscle cells. The non-selective Ang-receptor (Ang-R) antagonist saralasin blocked Ang (5-8) antinociception, but selective antagonists of Ang-R types I, II, IV, and Mas did not, suggesting that Ang (5-8) may act via an unknown receptor. Endopeptidase EP 24.11 and amastatin-sensitive aminopeptidase from the vlPAG catalyzed the synthesis (from Ang II or Ang III) and inactivation of Ang (5-8), respectively. Selective inhibitors of neuronal-nitric oxide (NO) synthase, soluble guanylyl cyclase (sGC) and a non-selective opioid receptor (opioid-R) inhibitor blocked Ang (5-8)-induced antinociception. In conclusion, Ang (5-8) is a new member of the Ang family that selectively and strongly modulates antinociception via NO-sGC and endogenous opioid in the vlPAG.
Assuntos
Angiotensina I/farmacologia , Guanilato Ciclase/metabolismo , Óxido Nítrico/metabolismo , Nociceptividade/efeitos dos fármacos , Peptídeos Opioides/metabolismo , Fragmentos de Peptídeos/farmacologia , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Receptores Citoplasmáticos e Nucleares/metabolismo , Transdução de Sinais/efeitos dos fármacos , Antagonistas de Receptores de Angiotensina/farmacologia , Animais , Aorta/efeitos dos fármacos , Relação Dose-Resposta a Droga , Frequência Cardíaca/fisiologia , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Peptídeos Opioides/antagonistas & inibidores , Ratos , Ratos Wistar , Saralasina/farmacologia , Guanilil Ciclase Solúvel , Teprotida/farmacologiaRESUMO
It is generally understood that angiotensin II (AngII) promotes follicle atresia in rats, although recent data suggested that this may not be true in cattle. In this study, we aimed to determine in vivo whether AngII alters follicle development in cattle, using intrafollicular injection of AngII or antagonist into the growing dominant follicle or the second largest subordinate follicle. Injection of saralasin, an AngII antagonist, into the growing dominant follicle inhibited follicular growth, and this inhibitory effect was overcome by systemic FSH supplementation. Injection of AngII into the dominant follicle did not affect follicular growth, whereas injection of AngII into the second largest follicle prevented the expected atresia of this subordinate follicle, and the treated follicle grew at the same rate as the dominant follicle for the next 24 h. Inhibition of AngII action in the dominant follicle decreased estradiol concentrations in follicular fluid and the abundance of mRNA encoding aromatase, 3ß-hydroxysteroid dehydrogenase, LH receptor, and cyclinD2 in granulosa cells, with minimal effects on theca cells. The effect of AngII on aromatase mRNA levels was confirmed using an in vitro granulosa cell culture system. In conclusion, these data suggest that AngII signaling promotes follicle growth in cattle and does so by regulating genes involved in estradiol secretion and granulosa cell proliferation and differentiation.
Assuntos
Angiotensina II/farmacologia , Folículo Ovariano/crescimento & desenvolvimento , Transdução de Sinais , Angiotensina II/administração & dosagem , Angiotensina II/fisiologia , Bloqueadores do Receptor Tipo 1 de Angiotensina II , Animais , Aromatase , Bovinos , Diferenciação Celular , Proliferação de Células , Estradiol , Feminino , Regulação da Expressão Gênica , Células da Granulosa/citologia , Células da Granulosa/efeitos dos fármacos , Folículo Ovariano/efeitos dos fármacos , Saralasina/administração & dosagem , Saralasina/farmacologia , Transdução de Sinais/efeitos dos fármacosRESUMO
Memory reconsolidation is a dynamic process in which a previously consolidated memory becomes labile following reactivation by a reminder. In a previous study in the crab Chasmagnathus memory model, we showed that a water-shortage episode, via angiotensin modulation during reconsolidation, could reveal a memory that otherwise remains unexpressed: weakly trained animals cannot reveal long-term memory (LTM) except when an episode of noticeable ethological meaning, water deprivation, is contingent upon reconsolidation. However, these results are at variance with two of our previous interpretations: weak training protocols do not build LTM and angiotensin II modulates the strength of the information storing process. A parsimonious hypothesis is that in Chasmagnathus angiotensins regulate LTM expression, but not LTM storage. Here, we tested three predictions of this hypothesis. First, the well-known retrograde amnesic effect of the angiotensin II antagonist saralasin is not due to interference on memory storage, but to modulation of memory expression. Second, the recovery of the LTM memory expression of the apparently amnesic retrograde effect produced by saralasin, through the water-shortage episode contingent upon reconsolidation, must be reconsolidation specific. Consequently, summation-like effects and retrieval deficits cannot explain these results because of the parametric conditions of reconsolidation. Third, weak training protocols build an unexpressed LTM that requires mRNA transcription and translation, a diagnostic characteristic of LTM. Results show that angiotensin modulates LTM expression but not LTM memory storage in the crab Chasmagnathus. The results lead us to suggest that, in Chasmagnathus, LTM expression - the process of gaining appreciable control over behavior of the reactivated trace in the retrieval session - may be considered a distinct attribute of its long-term storage. This strategy, a positive modulation during reconsolidation, is proposed to distinguish between memories that can be reactivated, labilized and are not expressed, and memories that are not stored long term, obliterated or altered in other retrieval mechanisms.
Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Angiotensina II/fisiologia , Braquiúros/fisiologia , Memória de Longo Prazo/fisiologia , Saralasina/farmacologia , Animais , Aprendizagem por Associação/efeitos dos fármacos , Aprendizagem por Associação/fisiologia , Meio Ambiente , Masculino , Memória de Longo Prazo/efeitos dos fármacos , Rememoração Mental/efeitos dos fármacos , Rememoração Mental/fisiologia , Reconhecimento Psicológico/efeitos dos fármacos , Reconhecimento Psicológico/fisiologia , Privação de Água/fisiologiaRESUMO
Diverse intracoronary agonists cause cardiac effects while acting on coronary endothelial luminal membrane (CELM) receptor. Our data show: a) the presence of AT(1)R in isolated CELM and in all cardiac cell types and b) sustained intracoronary infusions of Ang II-POL, a large sized molecule (approximately 15,000 kDa) confined to the vessel lumen that can only act on CELM's AT(1)R or Ang II (approximately 1 kDa); both exert the same maximum positive inotropic (PIE) and coronary constriction (CPP). The effects of these two agonists are blocked by Losartan and by Sar-POL; a large size antagonist (approximately 15,000 kDa) that acts only on CELM. Ang II effects are transient due to desensitization and cause tachyphylaxis to Ang II and toward Ang II-POL suggesting that both Ang II and Ang II-POL act on the same receptor group. In contrast, Ang II-POL effects are sustained and do not cause tachyphylaxis. The results show that intravascular Ang II and Ang II-POL act differentially by an unknown mechanism on CELM's AT(1)R and suggest that intravascular Ang II and Ang II-POL cause PIE and CCP by activation limited to CELM's AT(1)R through an unknown mechanism that is space-confined to the CELM's AT(1)R.
Assuntos
Vasos Coronários/efeitos dos fármacos , Endotélio Vascular/efeitos dos fármacos , Receptor Tipo 1 de Angiotensina/agonistas , Angiotensina II/farmacologia , Animais , Vasos Coronários/fisiologia , Endotélio Vascular/fisiologia , Losartan/farmacologia , Ratos , Ratos Wistar , Receptor Tipo 1 de Angiotensina/análise , Receptor Tipo 1 de Angiotensina/efeitos dos fármacos , Saralasina/farmacologia , Vasoconstrição/efeitos dos fármacosRESUMO
Angiotensin II (AngII) prevents the inhibitory effect of follicular cells on oocyte maturation, but its involvement in LH-induced meiotic resumption remains unknown. The aim of this study was to assess the involvement of AngII in LH-induced meiotic resumption and of prostaglandins (PGs) in the action of AngII. In the experiment I, seven cows were superovulated, intrafollicularly injected with 10 muM saralasin (a competitive AngII antagonist) or saline when the follicles reached a diameter larger than 12 mm, and challenged with a GnRH agonist to induce an LH surge. Fifteen hours after GnRH, the animals were ovariectomized and the oocytes were recovered to determine the stage of meiosis. The oocytes from follicles that received saline were in germinal vesicle (GV) breakdown (30.8%) or metaphase I (MI; 69.2%) stage while those that received saralasin were in the GV stage (100%; P<0.001) 15 h after GnRH agonist. In another experiment, oocytes were co-cultured with follicular hemisections for 15 h to determine whether PGs mediate the effect of AngII on meiotic resumption. Indomethacin (10 microM) inhibited AngII-induced meiotic resumption (13.4 vs 77.5% MI without indomethacin; P<0.001). Furthermore, the GV oocytes progressed to MI at a similar rate when PGE(2), PGF(2alpha) or AngII was present in the co-culture system with follicular cells (PGE(2) 77.4%, PGF(2alpha) 70.0%, and AngII 75.0% MI). In conclusion, our results provide strong evidence that AngII mediates the resumption of meiosis induced by an LH surge in bovine oocytes and that this event is dependent on PGE(2) or PGF(2alpha) produced by follicular cells.
Assuntos
Dinoprosta/metabolismo , Dinoprostona/metabolismo , Oócitos/citologia , Oócitos/metabolismo , Folículo Ovariano/metabolismo , Angiotensina II/antagonistas & inibidores , Angiotensina II/farmacologia , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Animais , Bovinos , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Técnicas de Cocultura , Inibidores de Ciclo-Oxigenase/farmacologia , Feminino , Hormônio Liberador de Gonadotropina/farmacologia , Indometacina/farmacologia , Hormônio Luteinizante/metabolismo , Meiose/efeitos dos fármacos , Saralasina/farmacologiaRESUMO
There is evidence that the renin-angiotensin system plays an important role in ovulation in cattle. Using an in vivo model, we investigated the role of angiotensin (Ang) II in bovine ovulation by injecting Ang II receptor antagonists into ovulatory follicles. Animals (n = 102) were pre-synchronized and, when the follicles reached 12 mm, they were given the respective treatment and the cows received GnRH agonist (i.m.) to induce ovulation. The ovulation rate was significantly lower when 100 mu M saralasin (Ang II receptor antagonist) was intrafollicularly injected (14.3%) in comparison with saline solution (83.3%). Based on these results, a second experiment was carried out to determine the timing of Ang II's critical role in ovulation. Saralasin inhibited ovulation only when applied at 0 and 6 h (16.7 and 42.9% ovulation rate in the 0- and 6-h groups respectively), but not at 12 h (100%) following GnRH agonist treatment. To investigate the subtypes of Ang II receptors implicated in the LH-induced ovulation, losartan (LO; AT(1)-Ang II receptor antagonist), PD123 319 (AT(2)-Ang II receptor antagonist), LO+PD123 319, or saline were intrafollicularly injected when the cows were challenged with GnRH agonist. Ovulation was inhibited by PD123 319 and LO+PD123 319 (50.0 and 33.3% on ovulation rate respectively), but not by LO or saline solution (100% ovulation in both groups). From these results, we suggest that Ang II plays a pivotal role in the early mechanism of bovine ovulation via the AT(2) receptor subtype.
Assuntos
Angiotensina II/fisiologia , Bovinos/metabolismo , Ovulação/fisiologia , Sistema Renina-Angiotensina/fisiologia , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Bloqueadores do Receptor Tipo 2 de Angiotensina II , Antagonistas de Receptores de Angiotensina , Animais , Feminino , Hormônio Liberador de Gonadotropina/farmacologia , Imidazóis/farmacologia , Injeções/métodos , Losartan/farmacologia , Hormônio Luteinizante/farmacologia , Folículo Ovariano/diagnóstico por imagem , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/fisiologia , Ovulação/efeitos dos fármacos , Piridinas/farmacologia , Distribuição Aleatória , Receptor Tipo 2 de Angiotensina/metabolismo , Sistema Renina-Angiotensina/efeitos dos fármacos , Saralasina/farmacologia , UltrassonografiaRESUMO
Se utilizó la saralasina, un bloqueador competitivo de la angiotensina II, con el propósito de incrementar el flujo sanguíneo renal y la tasa de filtración glomerular, para estudiar sus posibles consecuencias tubulares y sobre la presión arterial. Fueron divididas 40 ratas de la línea Wistar, inicialmente normotensas, en 4 grupos: saralasina, supresión, grupos controles corrieron paralelos. Se les realizaron a todos mediciones de variables hemodinámicas sistémicas y renales, así como morfométricas del riñón. Los resultados apoyaron la hipótesis de la participación de la hiperfunción tubular en la génesis de la hipertensión arterial primaria y propusieron un nuevo modelo de hipertensión arterial experimental en ratas
Assuntos
Animais , Ratos , Angiotensina II , Animais de Laboratório , Hipertensão , Rim , SaralasinaRESUMO
It has been suggested that low concentrations of angiotensin II cause vasoconstriction whereas high concentrations evoke vasodilation. Thus, this work aimed to functionally characterize the mechanisms underlying the relaxation induced by angiotensin II at high concentrations in isolated rat carotid rings. Experiments using standard muscle bath procedures showed that angiotensin II (0.01-3 microM) concentration dependently induces relaxation of phenylephrine-pre-contracted rings. No differences between intact or denuded endothelium were found. The angiotensin II-induced relaxation was strongly inhibited by saralasin, the non-selective antagonist of angiotensin II receptors but not by the selective antagonists of AT1 and AT2 receptors, losartan and PD123319, respectively. However, A-779, a selective angiotensin-(1-7) receptor antagonist, reduced the relaxation induced by angiotensin II. Administration of exogenous angiotensin-(1-7) on pre-contracted tissues produced concentration-dependent relaxation, which was also inhibited by A-779. HOE-140, the selective antagonist of the bradykinin in B2 receptor did not produce any significant effect on angiotensin II-induced relaxation. Pre-incubation of denuded-rings with N G-nitro-L-arginine methyl ester (L-NAME) or 1H-[1,2,4] Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) reduced angiotensin II-induced relaxation. On the other hand, neither indomethacin nor tetraethylammonium (TEA) produced any significant effect. The major new finding of this work is that high concentrations of angiotensin II induce relaxation of the rat carotid via activation of the NO-cGMP pathway through a mechanism that seems to be partially dependent on activation of angiotensin-(1-7) receptors.
Assuntos
Angiotensina II/farmacologia , Artérias Carótidas/fisiologia , Vasoconstritores/farmacologia , Vasodilatação/fisiologia , Angiotensina II/análogos & derivados , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Animais , Artérias Carótidas/efeitos dos fármacos , Relação Dose-Resposta a Droga , Antagonismo de Drogas , Técnicas In Vitro , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Oxidiazóis/farmacologia , Fragmentos de Peptídeos/farmacologia , Fenilefrina/farmacologia , Quinoxalinas/farmacologia , Ratos , Ratos Wistar , Saralasina/farmacologia , Vasodilatação/efeitos dos fármacosRESUMO
A considerable body of evidence reveals that consolidated memories, recalled by a reminder, enter into a new vulnerability phase during which they are susceptible to disruption again. Consistently, reconsolidation was shown by the amnesic effects induced by administration of consolidation blockers after memory labilization. To shed light on the functional value of reconsolidation, we explored whether an endogenous process activated during a concurrent real-life experience improved this memory phase. Reconsolidation of long-term contextual memory has been well documented in the crab Chasmagnathus. Previously we showed that angiotensin II facilitates memory consolidation. Moreover, water deprivation increases brain angiotensin and improves memory consolidation and retrieval through angiotensin II receptors. Here, we tested whether concurrent water deprivation improves reconsolidation via endogenous angiotensin and therefore strengthens memory. We show that memory reconsolidation, induced by training context re-exposure, is facilitated by a concurrent episode of water deprivation, which induces a raise in endogenous brain angiotensin II. Positive modulation is expressed by full memory retention, despite a weak training, 24 or 72 but not 4 h after memory reactivation. This is the first evidence that memory can be positively modulated during reconsolidation through an identified endogenous process triggered during a real-life episode. We propose that the functional value for reconsolidation would be to make possible a change in memory strength by the influence of a concurrent experience. Reconsolidation improvement would lead to memory re-evaluation, not by altering memory content but by modifying the behaviour as an outcome of changing the hierarchy of the memories that control it.