RESUMEN
Ischemic preconditioning (IPC) describes a phenomenon wherein brief ischemia of the heart induces a potent cardioprotective mechanism against succeeding ischemic insult. Cyclooxygenase-2 (COX-2), a rate-limiting enzyme in prostanoid biosynthesis, is upregulated in the ischemic heart and contributes to IPC. Prostaglandin E2 (PGE2) protects the heart from ischemia-reperfusion (I/R) injury via its receptor subtype EP4. We sought to clarify the role of the PGE2/EP4 system in the late phase of IPC. Mice were subjected to four IPC treatment cycles, consisting of 5 min of occlusion of the left anterior descending coronary artery (LAD). We found that COX-2 mRNA was significantly upregulated in wild-type hearts at 6 h after IPC treatment. Cardiac PGE2 levels at 24 h after IPC treatment were significantly increased in both wild-type mice and mice lacking EP4 (EP4-/-). At 24 h after IPC treatment, I/R injury was induced by 30 min of LAD occlusion followed by 2 h of reperfusion and the cardiac infarct size was determined. The infarct size was significantly reduced by IPC treatment in wild-type mice; a reduction was not observed in EP4-/- mice. AE1-329, an EP4 agonist, significantly reduced infarct size and significantly ameliorated deterioration of cardiac function in wild-type mice subjected to I/R without IPC treatment. Furthermore, AE1-329 significantly enhanced the I/R-induced activation of Akt, a pro-survival kinase. We demonstrated that the PGE2/EP4 system in the heart plays a critical role in the late phase of IPC, partly by augmenting Akt-mediated signaling. These findings clarify the mechanism of IPC and may contribute to the development of therapeutic strategies for ischemic heart disease.
Asunto(s)
Precondicionamiento Isquémico Miocárdico , Infarto del Miocardio , Daño por Reperfusión Miocárdica , Ratones , Animales , Proteínas Proto-Oncogénicas c-akt/uso terapéutico , Ciclooxigenasa 2 , Prostaglandinas/uso terapéuticoRESUMEN
Cyclooxygenase 2 (COX-2) is an inducible rate-limiting enzyme for prostanoid production. Because COX-2 represents one of the inducible genes in mouse mesenchymal stem cells upon differentiation into Leydig cells, we investigated COX-2 expression and production of prostaglandin (PG) in Leydig cells. Although COX-2 was undetectable in mouse testis, it was transiently induced in Leydig cells by human chorionic gonadotropin (hCG) administration. Consistent with the finding that Leydig cells expressed aldo-keto reductase 1B7 (PGF synthase) and PGE synthase 2, induction of COX-2 by hCG caused a marked increase in testicular PGF 2α and PGE 2 levels. Using mouse Leydig cell tumor-derived MA-10 cells as a model, it was indicated by reporter assays and electron mobility shift assays that transcription of the COX-2 gene was activated by CCAAT/enhancer-binding protein ß (C/EBPß) with cAMP-stimulation. C/EBPß expression was induced by cAMP-stimulation, whereas expression of C/EBP homolog protein (CHOP) was robustly downregulated. Transfection of CHOP expression plasmid inhibited cAMP-induced COX-2 promoter activity. In addition, CHOP reduced constitutive COX-2 expression in other mouse Leydig cell tumor-derived TM3 cells. These results indicate that COX-2 is induced in Leydig cells by activation of C/EBPß via reduction of CHOP expression upon gonadotropin-stimulation to produce PGF 2α and PGE 2 .
Asunto(s)
Proteína beta Potenciadora de Unión a CCAAT/metabolismo , Gonadotropina Coriónica/farmacología , Ciclooxigenasa 2/metabolismo , Dinoprostona/metabolismo , Células Intersticiales del Testículo/metabolismo , Sustancias para el Control de la Reproducción/farmacología , Animales , Línea Celular Tumoral , AMP Cíclico/metabolismo , Ciclooxigenasa 2/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Regiones Promotoras Genéticas , Transducción de Señal/efectos de los fármacos , Factor de Transcripción CHOP/genética , Factor de Transcripción CHOP/metabolismo , Transcripción Genética , TransfecciónRESUMEN
Nonalcoholic steatohepatitis (NASH) is a hepatic manifestation of metabolic syndrome. Although the prostaglandin (PG)I2 receptor IP is expressed broadly in the liver, the role of PGI2-IP signaling in the development of NASH remains to be determined. Here, we investigated the role of the PGI2-IP system in the development of steatohepatitis using mice lacking the PGI2 receptor IP [IP-knockout (IP-KO) mice] and beraprost (BPS), a specific IP agonist. IP-KO and wild-type (WT) mice were fed a methionine- and choline-deficient diet (MCDD) for 2, 5, or 10 wk. BPS was administered orally to mice every day during the experimental periods. The effect of BPS on the expression of chemokine and inflammatory cytokines was examined also in cultured Kupffer cells. WT mice fed MCDD developed steatohepatitis at 10 wk. IP-KO mice developed steatohepatitis at 5 wk with augmented histologic derangements accompanied by increased hepatic monocyte chemoattractant protein-1 (MCP-1) and TNF-α concentrations. After 10 wk of MCDD, IP-KO mice had greater hepatic iron deposition with prominent oxidative stress, resulting in hepatocyte damage. In WT mice, BPS improved histologic and biochemical parameters of steatohepatitis, accompanied by reduced hepatic concentration of MCP-1 and TNF-α. Accordingly, BPS suppressed the LPS-stimulated Mcp-1 and Tnf-α mRNA expression in cultured Kupffer cells prepared from WT mice. PGI2-IP signaling plays a crucial role in the development and progression of steatohepatitis by modulating the inflammatory response, leading to augmented oxidative stress. We suggest that the PGI2-IP system is an attractive therapeutic target for treating patients with NASH.-Kumei, S., Yuhki, K.-I., Kojima, F., Kashiwagi, H., Imamichi, Y., Okumura, T., Narumiya, S., Ushikubi, F. Prostaglandin I2 suppresses the development of diet-induced nonalcoholic steatohepatitis in mice.
Asunto(s)
Epoprostenol/farmacología , Alimentos Formulados/efectos adversos , Hepatocitos/metabolismo , Macrófagos del Hígado/metabolismo , Hígado/metabolismo , Enfermedad del Hígado Graso no Alcohólico/prevención & control , Animales , Quimiocina CCL2/biosíntesis , Quimiocina CCL2/genética , Epoprostenol/análogos & derivados , Regulación de la Expresión Génica/efectos de los fármacos , Hepatocitos/patología , Macrófagos del Hígado/patología , Hígado/patología , Ratones , Ratones Noqueados , Enfermedad del Hígado Graso no Alcohólico/genética , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Enfermedad del Hígado Graso no Alcohólico/patología , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/genética , Receptores de Epoprostenol/agonistas , Receptores de Epoprostenol/genética , Receptores de Epoprostenol/metabolismo , Factores de Tiempo , Factor de Necrosis Tumoral alfa/biosíntesis , Factor de Necrosis Tumoral alfa/genéticaRESUMEN
To investigate the mechanisms underlying itching in atopic dermatitis, we examined whether thromboxane (TX) A2, an arachidonic acid metabolite, is involved in spontaneous scratching, an itch-related response, in NC mice with atopic dermatitis-like skin lesions. The TXA2 receptor (TP) antagonist ONO-3708 inhibited the spontaneous scratching. The mRNA expression of TX synthase (TXSyn) distributed mainly in epidermis and the concentration of TXB2, a metabolite of TXA2, were increased in lesional skin. Scratching caused by the PAR2 agonist SLIGRL-NH2 was suppressed by ONO-3708. SLIGRL-NH2-induced scratching decreased approximately 75% in TP-deficient mice, compared to wild-type mice. In primary cultures of mouse keratinocytes, SLIGRL-NH2 induced the production of TXA2, as evidenced by the increased TXB2, which was inhibited by the TXSyn inhibitor sodium ozagrel and a PAR2-neutralizing antibody. Taken together, these results suggest that epidermal TXA2, which may be produced via PAR2 activation, is involved in itching in atopic dermatitis.
Asunto(s)
Dermatitis Atópica/tratamiento farmacológico , Dermatitis Atópica/metabolismo , Prurito/tratamiento farmacológico , Prurito/metabolismo , Tromboxano A2/análogos & derivados , Tromboxano A2/metabolismo , Animales , Queratinocitos/metabolismo , Masculino , Metacrilatos/farmacología , Ratones , Oligopéptidos/efectos adversos , Oligopéptidos/farmacología , ARN Mensajero/metabolismo , Receptor PAR-2/antagonistas & inhibidores , Tromboxano A2/farmacologíaRESUMEN
ONO-1301 [(E)-[5-[2-[1-phenyl-1-(3-pyridyl)methylidene-aminooxy]ethyl]-7,8-dihydronaphthalene-1-yloxy]acetic acid] is a novel prostaglandin (PG) I2 mimetic with inhibitory activity on the thromboxane (TX) A2 synthase. Interestingly, ONO-1301 retains its inhibitory effect on platelet aggregation after repeated administration, while beraprost, a representative agonist for the PGI2 receptor (IP), loses its inhibitory effect after repeated administration. In the present study, we intended to clarify the mechanism by which ONO-1301 escapes desensitization of an antiplatelet effect. In platelets prepared from wild-type mice, ONO-1301 inhibited collagen-induced aggregation and stimulated cAMP production in an IP-dependent manner. In addition, ONO-1301 inhibited arachidonic acid-induced TXA2 production in platelets lacking IP. Despite the decrease in stimulatory action on cAMP production, the antiplatelet effect of ONO-1301 hardly changed after repeated administration for 10 days in wild-type mice. Noteworthy, beraprost could retain its antiplatelet effect after repeated administration in combination with a low dose of ozagrel, a TXA2 synthase inhibitor. Therefore, we hypothesized that chronic IP stimulation by beraprost induces an increase in TXA2 production, leading to reduction in the antiplatelet effect. As expected, repeated administration of beraprost increased the plasma and urinary levels of a TXA2 metabolite, while ONO-1301 did not increase them significantly. In addition, beraprost could retain the ability to inhibit platelet aggregation after repeated administration in mice lacking the TXA2 receptor (TP). These results indicate that TP-mediated signaling participates in platelet desensitization against IP agonists and that simultaneous inhibition of TXA2 production confers resistance against desensitization on IP agonists.
Asunto(s)
Inhibidores de Agregación Plaquetaria/farmacología , Piridinas/farmacología , Tromboxano A2/biosíntesis , Administración Oral , Animales , Presión Sanguínea/efectos de los fármacos , AMP Cíclico/biosíntesis , Epoprostenol/análogos & derivados , Epoprostenol/farmacología , Masculino , Ratones , Agregación Plaquetaria/efectos de los fármacos , Inhibidores de Agregación Plaquetaria/administración & dosificación , Piridinas/administración & dosificación , Receptores de Tromboxano A2 y Prostaglandina H2/metabolismo , Transducción de Señal/efectos de los fármacos , Tromboxano A2/metabolismo , Tromboxano-A Sintasa/antagonistas & inhibidoresRESUMEN
BACKGROUND: Prostacyclin (PGI2) enhances angiogenesis, especially in cooperation with bone marrow (BM)-derived endothelial progenitor cells (EPCs). However, the mechanisms of PGI2 in EPC-mediated angiogenesis in vivo remain unclear. The purpose of this study was to clarify the role of PGI2 in EPC-mediated angiogenesis using BM-specific IP deletion mice. METHODS AND RESULTS: Hind limb ischemia (HLI) was induced in wild-type (WT) mice transplanted with IP-deleted BM (WT/BM(IP(-/-)). Recovery of blood flow (RBF) in WT/BM(IP(-/-)) was impaired for 28 days after HLI, whereas RBF in IP(-/-)/BM(WT) was attenuated for up to 7 days compared with WT/BM(WT). The impaired RBF in WT/BM(IP(-/-)) was completely recovered by intramuscular injection of WT EPCs but not IP(-/-) EPCs. The impaired effects of IP(-/-) EPCs were in accordance with reduced formation of capillary and arterioles in ischemic muscle. An ex vivo aortic ring assay revealed that microvessel formation was enhanced by accumulation/adhesion of EPCs to perivascular sites as pericytes. IP(-/-)EPCs, in which expression of integrins was decreased, had impaired production of angiogenic cytokines, adhesion to neovessels and their angiogenic effects. The small-interfering RNA (siRNA)-mediated knockdown of integrin ß1 in WT EPCs attenuated adhesion to microvessels and their in vivo and in vitro angiogenic effects. CONCLUSIONS: PGI2 may induce persistent angiogenic effects in HLI through adhesion of EPCs to perivascular sites of neovessels via integrins in addition to paracrine effects.
Asunto(s)
Trasplante de Médula Ósea , Células Endoteliales/metabolismo , Epoprostenol/metabolismo , Isquemia/terapia , Microcirculación , Neovascularización Fisiológica , Células Madre/metabolismo , Animales , Adhesión Celular , Modelos Animales de Enfermedad , Células Endoteliales/patología , Epoprostenol/genética , Miembro Posterior/irrigación sanguínea , Miembro Posterior/metabolismo , Miembro Posterior/patología , Isquemia/genética , Isquemia/metabolismo , Masculino , Ratones , Ratones Noqueados , Pericitos/metabolismo , Pericitos/patología , Receptores de Prostaglandina/genética , Receptores de Prostaglandina/metabolismo , Células Madre/patologíaRESUMEN
Inflammatory responses in the kidney lead to tubulointerstitial fibrosis, a common feature of chronic kidney diseases. Here we examined the role of prostaglandin E(2) (PGE(2)) in the development of tubulointerstitial fibrosis. In the kidneys of wild-type mice, unilateral ureteral obstruction leads to progressive tubulointerstitial fibrosis with macrophage infiltration and myofibroblast proliferation. This was accompanied by an upregulation of COX-2 and PGE(2) receptor subtype EP(4) mRNAs. In the kidneys of EP(4) gene knockout mice, however, obstruction-induced histological alterations were significantly augmented. In contrast, an EP(4)-specific agonist significantly attenuated these alterations in the kidneys of wild-type mice. The mRNAs for macrophage chemokines and profibrotic growth factors were upregulated in the kidneys of wild-type mice after ureteral obstruction. This was significantly augmented in the kidneys of EP(4)-knockout mice and suppressed by the EP(4) agonist but only in the kidneys of wild-type mice. Notably, COX-2 and MCP-1 proteins, as well as EP(4) mRNA, were localized in renal tubular epithelial cells after ureteral obstruction. In cultured renal fibroblasts, another EP(4)-specific agonist significantly inhibited PDGF-induced proliferation and profibrotic connective tissue growth factor production. Hence, an endogenous PGE(2)-EP(4) system in the tubular epithelium limits the development of tubulointerstitial fibrosis by suppressing inflammatory responses.
Asunto(s)
Dinoprostona/metabolismo , Células Epiteliales/metabolismo , Enfermedades Renales/prevención & control , Túbulos Renales/metabolismo , Subtipo EP4 de Receptores de Prostaglandina E/metabolismo , Animales , Proliferación Celular , Células Cultivadas , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Quimiocina CCL5/genética , Quimiocina CCL5/metabolismo , Factor de Crecimiento del Tejido Conjuntivo/genética , Factor de Crecimiento del Tejido Conjuntivo/metabolismo , Ciclooxigenasa 2/genética , Ciclooxigenasa 2/metabolismo , Modelos Animales de Enfermedad , Células Epiteliales/efectos de los fármacos , Células Epiteliales/patología , Fibrosis , Ácido Fólico , Regulación de la Expresión Génica , Heptanoatos/farmacología , Enfermedades Renales/etiología , Enfermedades Renales/genética , Enfermedades Renales/metabolismo , Enfermedades Renales/patología , Túbulos Renales/efectos de los fármacos , Túbulos Renales/patología , Macrófagos/metabolismo , Macrófagos/patología , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Miofibroblastos/metabolismo , Miofibroblastos/patología , ARN Mensajero/metabolismo , Subtipo EP4 de Receptores de Prostaglandina E/agonistas , Subtipo EP4 de Receptores de Prostaglandina E/deficiencia , Subtipo EP4 de Receptores de Prostaglandina E/genética , Transducción de Señal , Factores de Tiempo , Factor de Crecimiento Transformador beta1/genética , Factor de Crecimiento Transformador beta1/metabolismo , Obstrucción Ureteral/complicacionesRESUMEN
Systemic inflammation induces various adaptive responses including tachycardia. Although inflammation-associated tachycardia has been thought to result from increased sympathetic discharge caused by inflammatory signals of the immune system, definitive proof has been lacking. Prostanoids, including prostaglandin (PG) D(2), PGE(2), PGF(2alpha), PGI(2) and thromboxane (TX) A(2), exert their actions through specific receptors: DP, EP (EP(1), EP(2), EP(3), EP(4)), FP, IP and TP, respectively. Here we have examined the roles of prostanoids in inflammatory tachycardia using mice that lack each of these receptors individually. The TXA(2) analog I-BOP and PGF(2alpha) each increased the beating rate of the isolated atrium of wild-type mice in vitro through interaction with TP and FP receptors, respectively. The cytokine-induced increase in beating rate was markedly inhibited in atria from mice lacking either TP or FP receptors. The tachycardia induced in wild-type mice by injection of lipopolysaccharide (LPS) was greatly attenuated in TP-deficient or FP-deficient mice and was completely absent in mice lacking both TP and FP. The beta-blocker propranolol did not block the LPS-induced increase in heart rate in wild-type animals. Our results show that inflammatory tachycardia is caused by a direct action on the heart of TXA(2) and PGF(2alpha) formed under systemic inflammatory conditions.
Asunto(s)
Dinoprost/farmacología , Inflamación , Taquicardia/metabolismo , Tromboxano A2/farmacología , Animales , Presión Sanguínea , Dinoprost/metabolismo , Electrocardiografía , Atrios Cardíacos/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Lipopolisacáridos/toxicidad , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Propranolol/farmacología , Receptores de Prostaglandina/metabolismo , Receptores de Tromboxano A2 y Prostaglandina H2/metabolismo , Taquicardia/inducido químicamenteRESUMEN
BACKGROUND: Microsomal prostaglandin E synthase-1 (mPGES-1) is a key enzyme that acts downstream of cyclooxygenase and plays a major role in inflammation by converting prostaglandin (PG) H2 to PGE2. The present study investigated the effect of genetic deletion of mPGES-1 on the development of immunologic responses to experimental colitis induced by dextran sodium sulfate (DSS), a well-established model of inflammatory bowel disease (IBD). METHODS: Colitis was induced in mice lacking mPGES-1 (mPGES-1-/- mice) and wild-type (WT) mice by administering DSS for 7 days. Colitis was assessed by body weight loss, diarrhea, fecal bleeding, and histological features. The colonic expression of mPGES-1 was determined by real-time PCR, western blotting, and immunohistochemistry. The impact of mPGES-1 deficiency on T cell immunity was determined by flow cytometry and T cell depletion in vivo. RESULTS: After administration of DSS, mPGES-1-/- mice exhibited more severe weight loss, diarrhea, and fecal bleeding than WT mice. Histological analysis further showed significant exacerbation of colonic inflammation in mPGES-1-/- mice. In WT mice, the colonic expression of mPGES-1 was highly induced on both mRNA and protein levels and colonic PGE2 increased significantly after DSS administration. Additionally, mPGES-1 protein was localized in the colonic mucosal epithelium and infiltrated inflammatory cells in underlying connective tissues and the lamina propria. The abnormalities consistent with colitis in mPGES-1-/- mice were associated with higher expression of colonic T-helper (Th)17 and Th1 cytokines, including interleukin 17A and interferon-γ. Furthermore, lack of mPGES-1 increased the numbers of Th17 and Th1 cells in the lamina propria mononuclear cells within the colon, even though the number of suppressive regulatory T cells also increased. CD4+ T cell depletion effectively reduced symptoms of colitis as well as colonic expression of Th17 and Th1 cytokines in mPGES-1-/- mice, suggesting the requirement of CD4+ T cells in the exacerbation of DSS-induced colitis under mPGES-1 deficiency. CONCLUSIONS: These results demonstrate that mPGES-1 is the main enzyme responsible for colonic PGE2 production and deficiency of mPGES-1 facilitates the development of colitis by affecting the development of colonic T cell-mediated immunity. mPGES-1 might therefore impact both the intestinal inflammation and T cell-mediated immunity associated with IBD.
RESUMEN
OBJECTIVE: Endothelial progenitor cells (EPCs) play an important role in the self-healing of a vascular injury by participating in the reendothelialization that limits vascular remodeling. We evaluated whether prostaglandin I(2) plays a role in the regulation of the function of EPCs to limit vascular remodeling. METHODS AND RESULTS: EPCs (Lin(-)cKit(+)Flk-1(+) cells) were isolated from the bone marrow (BM) of wild-type (WT) mice or mice lacking the prostaglandin I(2) receptor IP (IP(-/-) mice). Reverse transcription-polymerase chain reaction analysis showed that EPCs among BM cells specifically express IP. The cellular properties of EPCs, adhesion, migration, and proliferation on fibronectin were significantly attenuated in IP-deficient EPCs compared with WT EPCs. In contrast, IP agonists facilitated these functions in WT EPCs, but not in IP-deficient EPCs. The specific deletion of IP in BM cells, which was performed by transplanting BM cells of IP(-/-) mice to WT mice, accelerated wire injury-mediated neointimal hyperplasia in the femoral artery. Notably, transfused WT EPCs, but not IP-deficient EPCs, were recruited to the injured vessels, participated in reendothelialization, and efficiently rescued the accelerated vascular remodeling. CONCLUSIONS: These findings clearly indicate that the prostaglandin I(2)-IP system is essential for EPCs to accomplish their function and plays a critical role in the regulation of vascular remodeling.
Asunto(s)
Endotelio Vascular/metabolismo , Epoprostenol/metabolismo , Células Madre Mesenquimatosas/metabolismo , Neovascularización Fisiológica/fisiología , Animales , Adhesión Celular , Movimiento Celular , Proliferación Celular , Endotelio Vascular/patología , Fibronectinas/metabolismo , Hiperplasia/metabolismo , Hiperplasia/patología , Células Madre Mesenquimatosas/patología , Ratones , Ratones Noqueados , Modelos Animales , Receptores de Epoprostenol/genética , Receptores de Epoprostenol/metabolismo , Transducción de Señal/fisiología , Túnica Íntima/lesiones , Túnica Íntima/metabolismo , Túnica Íntima/patologíaRESUMEN
Platelets play an important role in both physiological hemostasis and pathological thrombosis. Thromboxane (TX) A2 and prostaglandin (PG) I2 are well known as a potent stimulator and an inhibitor of platelet function, respectively. Recently, PGE2 has also been reported to regulate platelet function via PGE2 receptor subtypes. However, the effect of PGF2α on platelet function remains to be determined. The aim of the present study was to clarify the effect of PGF2α on murine platelet function both in vitro and in vivo. Platelets prepared from wild-type mice (WT platelets) expressed several types of prostanoid receptors, including the PGE2 receptor subtype EP3 and the TXA2 receptor TP, while expression of the PGF2α receptor FP was not detected. In WT platelets, PGF2α potentiated adenosine diphosphate-induced aggregation in a concentration-dependent manner, while PGF2α alone did not induce aggregation. In platelets prepared from mice lacking FP, however, PGF2α-induced potentiation was not significantly different from that in WT platelets. Interestingly, the potentiation was significantly blunted in platelets lacking EP3 or TP and disappeared completely in platelets lacking both EP3 and TP. Accordingly, PGF2α decreased the cyclic adenosine monophosphate level via EP3 and increased the inositol triphosphate level via TP in WT platelets. Intravenously administered PGF2α significantly shortened the bleeding time and aggravated arachidonic acid-induced acute thromboembolism in WT mice, suggesting that PGF2α works as a platelet stimulator also in vivo. In conclusion, PGF2α potentiates platelet aggregation in vitro via EP3 and TP but not FP. Accordingly, PGF2α facilitates hemostasis and thromboembolism in vivo.
Asunto(s)
Activación Plaquetaria , Subtipo EP3 de Receptores de Prostaglandina E/metabolismo , Receptores de Tromboxano A2 y Prostaglandina H2/metabolismo , Animales , Tiempo de Sangría , Plaquetas/metabolismo , AMP Cíclico/metabolismo , Dinoprost , Femenino , Hemostasis , Humanos , Fosfatos de Inositol/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Adhesividad Plaquetaria , Agregación Plaquetaria , Tromboembolia/sangreRESUMEN
Zymosan, the cell wall of Saccharomyces cerevisiae, induces innate immune responses involving prostanoid production and complement activation. However, the roles of prostanoids in zymosan-induced inflammation and their interaction with the complement system remain to be determined. To clarify these issues, we examined zymosan-induced pleurisy in mice lacking receptors for prostaglandin (PG) E(2) (EP(-/-) mice) or PGI(2) (IP(-/-) mice). Zymosan-induced exudate formation was significantly reduced in IP(-/-) mice compared with wild-type (WT) mice, whereas none of the EP(-/-) mice (EP(1)(-/-), EP(2)(-/-), EP(3)(-/-), and EP(1)(-/-)(4) mice) showed any significant difference from WT mice. Furthermore, indomethacin, an inhibitor of prostanoid biosynthesis, suppressed exudate formation in WT mice to almost the same level as that of IP(-/-) mice. Accordingly, significant production of PGI(2) in the pleural cavity, suggested to be cyclooxygenase-2-dependent, was observed after zymosan injection. Complement activation in the pleural cavity after zymosan injection was confirmed, and preinjection of cobra venom factor (CVF), to deplete blood complement C3, was significantly suppressed after zymosan-induced exudate formation in WT mice. Simultaneous treatment with indomethacin and CVF further suppressed exudate formation in WT mice compared with each treatment alone. Because, some degree of exudate formation was still observed, other factor(s) seem to be involved. However, platelet-activating factor, a promising candidate as one such factor, was not involved in zymosan-induced exudate formation. These results clearly indicate that the PGI(2)-IP system together with the complement system plays a key role in exudate formation in zymosan-induced pleurisy.
Asunto(s)
Epoprostenol/metabolismo , Pleuresia/metabolismo , Zimosan , Animales , Antiinflamatorios no Esteroideos/farmacología , Complemento C3/metabolismo , Ciclooxigenasa 2/metabolismo , Inhibidores de la Ciclooxigenasa 2/farmacología , Dinoprostona/metabolismo , Venenos Elapídicos/farmacología , Indometacina/farmacología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Factor de Activación Plaquetaria , Glicoproteínas de Membrana Plaquetaria/genética , Pleuresia/inducido químicamente , Pleuresia/tratamiento farmacológico , Pirazoles/farmacología , Receptores Acoplados a Proteínas G/genética , Receptores de Prostaglandina/genéticaRESUMEN
Persistent reduction of renal perfusion pressure induces renovascular hypertension by activating the renin-angiotensin-aldosterone system; however, the sensing mechanism remains elusive. Here we investigated the role of PGI2 in renovascular hypertension in vivo, employing mice lacking the PGI2 receptor (IP-/- mice). In WT mice with a two-kidney, one-clip model of renovascular hypertension, the BP was significantly elevated. The increase in BP in IP-/- mice, however, was significantly lower than that in WT mice. Similarly, the increases in plasma renin activity, renal renin mRNA, and plasma aldosterone in response to renal artery stenosis were all significantly lower in IP-/- mice than in WT mice. All these parameters were measured in mice lacking the four PGE2 receptor subtypes individually, and we found that these mice had similar responses to WT mice. PGI2 is produced by COX-2 and a selective inhibitor of this enzyme, SC-58125, also significantly reduced the increases in plasma renin activity and renin mRNA expression in WT mice with renal artery stenosis, but these effects were absent in IP-/- mice. When the renin-angiotensin-aldosterone system was activated by salt depletion, SC-58125 blunted the response in WT mice but not in IP-/- mice. These results indicate that PGI2 derived from COX-2 plays a critical role in regulating the release of renin and consequently renovascular hypertension in vivo.
Asunto(s)
Presión Sanguínea/fisiología , Epoprostenol/fisiología , Hipertensión Renal/etiología , Animales , Creatinina/sangre , Creatinina/orina , Cruzamientos Genéticos , Inhibidores de la Ciclooxigenasa/farmacología , Dinoprostona/fisiología , Regulación de la Expresión Génica , Predisposición Genética a la Enfermedad , Hipertensión Renal/genética , Hipertensión Renal/fisiopatología , Hipertensión Renal/prevención & control , Infarto/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Nefrectomía , Prostaglandina-Endoperóxido Sintasas/genética , Pirazoles/farmacología , ARN Mensajero/genética , Receptores de Epoprostenol/deficiencia , Receptores de Epoprostenol/genética , Circulación Renal , Sistema Renina-Angiotensina/genéticaAsunto(s)
Adiponectina/farmacología , Tejido Adiposo/metabolismo , Isquemia Miocárdica/prevención & control , Daño por Reperfusión Miocárdica/prevención & control , Proteínas Quinasas Activadas por AMP , Adiponectina/metabolismo , Animales , Ciclooxigenasa 2/metabolismo , Citoprotección/efectos de los fármacos , Humanos , Insulina/metabolismo , Ratones , Complejos Multienzimáticos/metabolismo , Isquemia Miocárdica/enzimología , Isquemia Miocárdica/patología , Daño por Reperfusión Miocárdica/enzimología , Daño por Reperfusión Miocárdica/patología , Proteínas Serina-Treonina Quinasas/metabolismoRESUMEN
The results of studies that were performed to determine whether cigarette smoking affects platelet function have been controversial, and the effects of nicotine- and tar-free cigarette smoke extract (CSE) on platelet function remain to be determined. The aim of this study was to determine the effect of CSE on platelet aggregation and to clarify the mechanism by which CSE affects platelet function. CSE inhibited murine platelet aggregation induced by 9,11-dideoxy-9α,11α-methanoepoxy-prosta-5Z,13E-dien-1-oic acid (U-46619), a thromboxane (TX) A 2 receptor agonist, and that induced by collagen with respective IC 50 values of 1.05 ± 0.14% and 1.34 ± 0.19%. A similar inhibitory action of CSE was also observed in human platelets. CSE inhibited arachidonic acid-induced TXA 2 production in murine platelets with an IC 50 value of 7.32 ± 2.00%. Accordingly, the inhibitory effect of CSE on collagen-induced aggregation was significantly blunted in platelets lacking the TXA 2 receptor compared with the inhibitory effect in control platelets. In contrast, the antiplatelet effects of CSE in platelets lacking each inhibitory prostanoid receptor, prostaglandin (PG) I 2 receptor and PGE 2 receptor subtypes EP 2 and EP 4 , were not significantly different from the effects in respective control platelets. Among the enzymes responsible for TXA 2 production in platelets, the activity of cyclooxygenase (COX)-1 was inhibited by CSE with an IC 50 value of 1.07 ± 0.15% in an uncompetitive manner. In contrast, the activity of TX synthase was enhanced by CSE. The results indicate that CSE inhibits COX-1 activity and thereby decreases TXA 2 production in platelets, leading to inhibition of platelet aggregation.
RESUMEN
Diethylstilbestrol (DES), a strong estrogenic compound, is well-known to affect the reproductive system. In this study, we investigated the effects of DES administration on gonadotropin levels and ovarian steroidogenesis in prepubertal rats. DES treatment acutely reduced serum LH levels, followed by a reduction in the expression of various steroidogenesis-related genes in theca cells. Serum FSH levels were almost unaffected by DES-treatment, even though Cyp19a1 expression was markedly reduced. Serum progesterone, testosterone and estradiol levels were also declined at this time. LH levels recovered from 12 h after DES-treatment and gradually increased until 96 h with a reduction of ERα expression observed in the pituitary. Steroidogenesis-related genes were also up-regulated during this time, except for Cyp17a1 and Cyp19a1. Consistent with observed gene expression pattern, serum testosterone and estradiol concentrations were maintained at lower levels, even though progesterone levels recovered. DES-treatment induced the inducible nitric oxide synthase (iNOS) in granulosa cells, and a nitric oxide generator markedly repressed Cyp19a1 expression in cultured granulosa cells. These results indicate that DES inhibits thecal androgen production via suppression of pituitary LH secretion and ovarian Cyp17a1 expression. In addition, DES represses Cyp19a1 expression by inducing iNOS gene expression for continuous inhibition of estrogen production in granulosa cells.
Asunto(s)
Andrógenos/sangre , Aromatasa/genética , Dietilestilbestrol/administración & dosificación , Estrógenos no Esteroides/administración & dosificación , Estrógenos/sangre , Células de la Granulosa/efectos de los fármacos , Ovario/efectos de los fármacos , Células Tecales/efectos de los fármacos , Animales , Femenino , Perfilación de la Expresión Génica , Gonadotropinas/sangre , Células de la Granulosa/metabolismo , Ovario/metabolismo , Ratas , Esteroide 17-alfa-Hidroxilasa/análisis , Esteroide 17-alfa-Hidroxilasa/genética , Células Tecales/metabolismoRESUMEN
BACKGROUND: In the heart, the expressions of several types of prostanoid receptors have been reported. However, their roles in cardiac hypertrophy in vivo remain unknown. We intended to clarify the roles of these receptors in pressure overload-induced cardiac hypertrophy using mice lacking each of their receptors. METHODS AND RESULTS: We used a model of pressure overload-induced cardiac hypertrophy produced by banding of the transverse aorta in female mice. In wild-type mice subjected to the banding, cardiac hypertrophy developed during the observation period of 8 weeks. In mice lacking the prostaglandin (PG) I2 receptor (IP(-/-)), however, cardiac hypertrophy and cardiomyocyte hypertrophy were significantly greater than in wild-type mice at 2 and 4 weeks but not at 8 weeks, whereas there was no such augmentation in mice lacking the prostanoid receptors other than IP. In addition, cardiac fibrosis observed in wild-type hearts was augmented in IP(-/-) hearts, which persisted for up to 8 weeks. In IP(-/-) hearts, the expression level of mRNA for atrial natriuretic peptide, a representative marker of cardiac hypertrophy, was significantly higher than in wild-type hearts. In vitro, cicaprost, an IP agonist, reduced platelet-derived growth factor-induced proliferation of wild-type noncardiomyocytes, although it could not inhibit cardiotrophin-1-induced hypertrophy of cardiomyocytes. Accordingly, cicaprost increased cAMP concentration efficiently in noncardiomyocytes. CONCLUSIONS: IP plays a suppressive role in the development of pressure overload-induced cardiac hypertrophy via the inhibition of both cardiomyocyte hypertrophy and cardiac fibrosis. Both effects have been suggested as originating from the action on noncardiomyocytes rather than cardiomyocytes.
Asunto(s)
Cardiomegalia/etiología , Hipertensión/complicaciones , Receptores de Epoprostenol/fisiología , Animales , Biomarcadores/análisis , Cardiomegalia/patología , Aumento de la Célula , AMP Cíclico/sangre , Modelos Animales de Enfermedad , Epoprostenol/análogos & derivados , Epoprostenol/farmacología , Femenino , Fibrosis , Ratones , Ratones Noqueados , Miocitos Cardíacos/patología , ARN Mensajero/análisis , Receptores de Epoprostenol/deficiencia , Receptores de Epoprostenol/genéticaRESUMEN
CONTEXT: 11-ketotestosterone (11-KT) is a novel class of active androgen. However, the detail of its synthesis remains unknown for humans. OBJECTIVE: The objective of this study was to clarify the production and properties of 11-KT in human. Design, Participants, and Methods: Expression of cytochrome P450 and 11ß-hydroxysteroid dehydrogenase types 1 and 2 (key enzymes involved in the synthesis of 11-KT) were investigated in human gonads. The production of 11-KT was investigated in Leydig cells. Plasma concentrations of testosterone and 11-KT were measured in 10 women and 10 men of reproductive age. Investigation of its properties was performed using breast cancer-derived MCF-7 cells. RESULTS: Cytochrome P450 and 11ß-hydroxysteroid dehydrogenase types 1 and 2 were detected in Leydig cells and theca cells. Leydig cells produced 11-KT, and relatively high levels of plasma 11-KT were measured in both men and women. There was no sexual dimorphism in the plasma levels of 11-KT, even though testosterone levels were more than 20 times higher in men than in women. It is noteworthy that the levels of testosterone and 11-KT were similar in women. In a luciferase reporter system, 11-KT activated human androgen receptor-mediated transactivation. Conversely, 11-KT did not activate estrogen receptor-mediated transactivation in aromatase-expressed MCF-7 cells, whereas testosterone did following conversion to estrogen. 11-KT did not affect the estrogen/estrogen receptor -mediated cell proliferation of MCF-7 cells. Furthermore, it significantly inhibited cell proliferation when androgen receptor was transfected into MCF-7 cells. CONCLUSIONS: The current study indicates that 11-KT is produced in the gonads and represents a major androgen in human. It can potentially serve as a nonaromatizable androgen.