RESUMEN
This study aimed to evaluate the levels of eicosanoids derived from arachidonic acid (ARA) in the lungs of asthmatic rats supplemented with fish oil. The present data gives insight into the action of fish oil in asthma, related to its inability to modify the contractile capacity of tracheal smooth muscle reported previously in a model of asthma in rats. Male Wistar rats were supplemented daily with 1 g of fish oil/kg of body weight for 21 days. They were exposed to ovalbumin (OVA) after previous sensitization with OVA to induce asthma. Pulmonary levels of five eicosanoids were measured using immunoassay kits: PGE2, TXB2, LTB4, LXA4, and 8-iso PGF2α. In asthmatic rats, supplementation with fish oil resulted in lower concentrations of lung eicosanoids produced by cyclooxygenase-2 and 15-lipoxygenase: PGE2, TXB2, and LXA4, respectively. Fish oil supplementation also decreased the non-enzymatically produced eicosanoid 8-iso PGF2α. Fish oil supplementation did not affect LTB4, a metabolite of 5-lipoxygenase. The limited efficacy of fish oil supplementation in asthmatic rats is associated with a lack of action in reducing the levels of LTB4 in the lungs. Thus, fish oil differentially modulates the concentrations of eicosanoids derived from ARA via specific pathways in an animal model of asthma.
RESUMEN
We showed recently that increasing kidney epoxyeicosatrienoic acids (EETs) by blocking soluble epoxide hydrolase (sEH), an enzyme responsible for EETs degradation, retarded the development of renal dysfunction and progression of aorto-caval fistula(ACF)-induced congestive heart failure (CHF) in Ren-2 transgenic hypertensive rats (TGR). In that study the final survival rate of untreated ACF TGR was only 14 % but increased to 41 % after sEH blockade. Here we examined if sEH inhibition added to renin-angiotensin system (RAS) blockade would further enhance protection against ACF-induced CHF in TGR. The treatment regimens were started one week after ACF creation and the follow-up period was 50 weeks. RAS was blocked using angiotensin-converting enzyme inhibitor (ACEi, trandolapril, 6 mg/l) and sEH with an sEH inhibitor (sEHi, c-AUCB, 3 mg/l). Renal hemodynamics and excretory function were determined two weeks post-ACF, just before the onset of decompensated phase of CHF. 29 weeks post-ACF no untreated animal survived. ACEi treatment greatly improved the survival rate, to 84 % at the end of study. Surprisingly, combined treatment with ACEi and sEHi worsened the rate (53 %). Untreated ACF TGR exhibited marked impairment of renal function and the treatment with ACEi alone or combined with sEH inhibition did not prevent it. In conclusion, addition of sEHi to ACEi treatment does not provide better protection against CHF progression and does not increase the survival rate in ACF TGR: indeed, the rate decreases significantly. Thus, combined treatment with sEHi and ACEi is not a promising approach to further attenuate renal dysfunction and retard progression of CHF.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Benzoatos/uso terapéutico , Insuficiencia Cardíaca/tratamiento farmacológico , Indoles/uso terapéutico , Insuficiencia Renal/prevención & control , Urea/análogos & derivados , Animales , Fístula Arteriovenosa , Benzoatos/farmacología , Evaluación Preclínica de Medicamentos , Quimioterapia Combinada , Epóxido Hidrolasas/antagonistas & inhibidores , Femenino , Insuficiencia Cardíaca/complicaciones , Insuficiencia Cardíaca/mortalidad , Masculino , Ratas , Ratas Sprague-Dawley , Ratas Transgénicas , Insuficiencia Renal/etiología , Urea/farmacología , Urea/uso terapéuticoRESUMEN
Dietary fish oil supplementation increases the content of n-3 polyunsaturated fatty acids (PUFA) in cellular membranes. The highly unsaturated nature of n-3 PUFA could result in an enhanced lipid peroxidation in the oxidative environment characteristic of asthma. The oxidative reaction cascade culminates in an increased production of components associated to oxidative stress and of an important proinflammatory mediator platelet-activating factor (PAF)-like lipid. We evaluated the effect of fish oil supplementation in asthmatic rats upon the PAF bioactivity and parameters related to oxidative stress in the lung. Fish oil supplementation of asthmatic rats resulted in lower concentrations of nitrite (1.719 ± 0.137 vs. 2.454 ± 0.163 nmol/mL) and lipid hydroperoxide (72.190 ± 7.327 vs. 120.200 ± 11.270 nmol/mg protein). In asthmatic animals, fish oil increased the activities of superoxide dismutase (EC 1.15.1.1) (33.910 ± 2.325 vs. 24.110 ± 0.618 U/mg protein) and glutathione peroxidase (EC 1.11.1.9) (164.100 ± 31.250 vs. 12.590 ± 5.234 U/mg protein). However, fish oil did not affect PAF bioactivity in lung tissue of asthmatic rats (0.545 ± 0.098 340/380 vs. 0.669 ± 0.101 340/380 nm ratio). Considering the two-step process--oxidative stress and PAF bioactivity--fish oil exhibited a divergent action on these aspects of asthmatic inflammation, since the supplement lowered oxidative stress in the lungs of asthmatic rats, presenting an antioxidant effect, but did not affect PAF bioactivity. This suggests a dual effect of fish oil on oxidative stress and inflammation in asthma.
Asunto(s)
Asma/metabolismo , Suplementos Dietéticos , Aceites de Pescado/farmacología , Pulmón/efectos de los fármacos , Pulmón/metabolismo , Estrés Oxidativo/efectos de los fármacos , Factor de Activación Plaquetaria/metabolismo , Animales , Asma/patología , Aceites de Pescado/administración & dosificación , Pulmón/patología , Masculino , Ratas , Ratas WistarRESUMEN
Episodes of acute exacerbation are the major clinical feature of asthma and therefore represent an important focus for developing novel therapies for this disease. There are many reports that the n-3 fatty acids found in fish oil exert anti-inflammatory effects, but there are few studies of the action of fish oil on airway smooth muscle (ASM) function. In the present investigation, we evaluated the effect of fish oil supplementation on smooth muscle force of contraction in ovalbumin-induced asthmatic Wistar rats, and its consequences on static lung compliance, mucus production, leukocyte chemotaxis and production of proinflammatory cytokines. Fish oil supplementation suppressed the infiltration of inflammatory cells into the lung in asthmatic animals (2.04 ± 0.19 × 10(6) cells vs. 3.33 ± 0.43 × 10(6) cells in the control asthmatic group; P < 0.05). Static lung compliance increased with fish oil supplementation in asthmatic rats (0.640 ± 0.053 mL/cm H2O vs. 0.399 ± 0.043 mL/cm H2O; P < 0.05). However, fish oil did not prevent asthma-associated lung eosinophilia and did not affect the concentrations of tumor necrosis factor-α and interleukin-1ß in lung tissue or the proportion of the airways obliterated with mucus. Fish oil had no effect on the force of contraction in asthmatic rats in response to acetylcholine (3.026 ± 0.274 mN vs. 2.813 ± 0.364 mN in the control asthmatic group). In conclusion, although fish oil exerts some benefits in this model of asthma, its effectiveness appears to be limited by an inefficient action on airway smooth muscle function.
Asunto(s)
Asma/fisiopatología , Aceites de Pescado/farmacología , Músculo Liso/efectos de los fármacos , Tráquea/efectos de los fármacos , Acetilcolina/farmacología , Análisis de Varianza , Animales , Asma/inducido químicamente , Líquido del Lavado Bronquioalveolar/citología , Broncodilatadores/farmacología , Suplementos Dietéticos , Eosinófilos/efectos de los fármacos , Eosinófilos/patología , Aceites de Pescado/administración & dosificación , Técnicas In Vitro , Interleucina-1beta/metabolismo , Isoproterenol/farmacología , Pulmón/efectos de los fármacos , Pulmón/metabolismo , Pulmón/patología , Rendimiento Pulmonar/efectos de los fármacos , Linfocitos/efectos de los fármacos , Linfocitos/patología , Macrófagos/efectos de los fármacos , Macrófagos/patología , Masculino , Músculo Liso/fisiopatología , Neutrófilos/efectos de los fármacos , Neutrófilos/patología , Ovalbúmina , Ratas , Ratas Wistar , Tráquea/fisiopatología , Factor de Necrosis Tumoral alfa/metabolismo , Vasodilatadores/farmacologíaRESUMEN
Angiogenesis inhibitor TNP-470, 6-O-(N-chloroacetyl-carbamoyl)-fumagillol, semisynthetic analogue of fumagillin, has strong inhibitory activities against in vivo tumor growth and metastasis in a wide variety of tumors. However, it is still unknown whether this agent inhibits bone metastasis. We examined the effects of TNP-470 in a bone metastasis model in nude mice in which intracardiac injection of the human breast cancer cell line MDA-MB-231 (MDA-231) produced osteolytic bone metastasis. After inoculation of MDA-231 cells into the left heart ventricle, TNP-470 (30 mg/kg, three times a week) or PBS was s.c. administrated for 4 weeks. After this period, the TNP-470 had reduced not only the number and area of osteolytic bone metastases (approximately 60 and 70%, respectively) but also their radiolucency. Histological examination of the femurs of the untreated group revealed that most of the cancellous bone had been replaced by the metastatic cancer. Numerous active osteoclasts were present along the trabecular bone surface surrounded by the metastatic MDA-231 cancer cells aggressively invading the bone marrow. In contrast, in the bone from TNP-470-treated mice, bone destruction was markedly inhibited, and there were much fewer osteoclasts. In a murine bone marrow culture under 1,25-dihydroxyvitamin D3 in which mature functional osteoclasts formed in vitro, TNP-470 significantly inhibited the formation of tartrate-resistant acid phosphatase-positive multinucleated osteoclast-like cells. And also, TNP-470 suppressed the in vivo bone resorption in calvaria treated with interleukin-1beta, an osteoclast stimulator. These data suggested that TNP-470 inhibited bone metastasis through not only antitumor action by its angiogenesis inhibition but also by the inhibition of osteoclastic bone resorption. Our results indicate that TNP-470 should be a potentially beneficial drug to be used in the treatment of osteolytic metastasis.
Asunto(s)
Antibióticos Antineoplásicos/uso terapéutico , Neoplasias Óseas/secundario , Resorción Ósea/prevención & control , Neoplasias de la Mama/patología , Neovascularización Patológica/prevención & control , Osteoclastos/efectos de los fármacos , Osteólisis/prevención & control , Sesquiterpenos/uso terapéutico , Animales , Antibióticos Antineoplásicos/farmacología , Neoplasias Óseas/irrigación sanguínea , Neoplasias Óseas/complicaciones , Resorción Ósea/etiología , Caquexia/etiología , Caquexia/prevención & control , Calcitriol/farmacología , Células Cultivadas , Ciclohexanos , Modelos Animales de Enfermedad , Femenino , Ventrículos Cardíacos , Humanos , Inyecciones , Interleucina-1/farmacología , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Trasplante de Neoplasias , Células Neoplásicas Circulantes , O-(Cloroacetilcarbamoil) Fumagilol , Osteoclastos/patología , Osteólisis/etiología , Sesquiterpenos/farmacología , Células Tumorales CultivadasRESUMEN
The purpose of the present study was to determine 1) whether different organs undergo similar increase in vascular resistance in Dahl-Iwai salt-sensitive (S) rats, and 2) the effects of chronic oral L-arginine supplementation on the regional hemodynamics in S rats. Male 6-wk-old S rats and salt-resistant (R) rats were maintained on an 8% NaCl chow for 4 wk. One group (S or R rats) was maintained on tap water and the other group (S/Arg or R/Arg rats) received tap water containing L-arginine at a concentration of 1.5%. Organ blood flow and cardiac output were measured with microspheres in the conscious condition. Mean blood pressure in S, S/Arg, R, and R/Arg rats was 159 +/- 5, 138 +/- 3, 111 +/- 4, and 112 +/- 4 mmHg, respectively. Urinary excretion of protein and albumin in S/Arg rats was significantly suppressed compared with S rats. Concerning regional hemodynamics, the flow rate of the kidney was lower in S rats than in R rats, but there were no differences between S and R rats in the flow rates of the brain, heart, lung, liver, spleen, intestine, skeletal muscle, and skin. Thus the renal blood flow was solely reduced in S rats on a high-salt diet. The flow rate of the kidney in S/Arg rats was maintained at a higher level compared with that of S rats. L-Arginine treatment tended to produce a recovery in the urinary excretion of guanosine 3',5'-cyclic monophosphate in S rats, but had no effect in R rats. Thus the supplementation of L-arginine prevented the increase in blood pressure in S rats on a high-salt diet and normalized the abnormality of renal hemodynamics accompanying salt-induced hypertension.
Asunto(s)
Arginina/farmacología , Hemodinámica , Flujo Sanguíneo Regional/efectos de los fármacos , Sodio en la Dieta , Animales , Arginina/administración & dosificación , Presión Sanguínea , Encéfalo/irrigación sanguínea , Gasto Cardíaco , Circulación Coronaria , Alimentos Fortificados , Frecuencia Cardíaca , Intestino Delgado/irrigación sanguínea , Riñón/irrigación sanguínea , Hígado/irrigación sanguínea , Masculino , Especificidad de Órganos , Ratas , Ratas Endogámicas , Sodio en la Dieta/farmacología , Especificidad de la Especie , Testículo/irrigación sanguínea , Resistencia VascularRESUMEN
The responses in membrane potential and resistance of acinar cells to iontophoretically applied acetylcholine (ACh) were investigated using intracellular micro-electrode recording in superfused segments of mouse submaxillary gland. For measurements of membrane resistance and acetylcholine equilibrium potential (EACh), two micro-electrodes were inserted into neighbouring communicating cells. Current could be injected through one of the electrodes. The pattern of membrane potential change induced by ACh depended on the resting potential. Simple hyperpolarizations were induced at low resting potentials, while biphasic potential changes (depolarization followed by hyperpolarization) or simple depolarizations were observed at relatively high resting potentials. A similar dependence of the ACh induced potential change on the resting potential was obtained in experiments in which the resting membrane potential was set at different levels by injecting direct current and stimulating the same cell with equal doses of ACh. The ACh equilibrium potential ranged widely between -45 and -75 mV. Under special conditions the conversion in response to ACh from a hyperpolarization to depolarization could be obtained without change in resting potential. Small doses of ACh evoked simple depolarization, while medium doses induced biphasic responses and large doses of ACh caused hyperpolarization. The effect of a low concentration of atropine on the response was an initial block of hyperpolarization followed by a secondary block of depolarization. Intracellular injection of TEA ions converted the ACh induced potential response from hyperpolarization to depolarization. Both the depolarizing and hyperpolarizing ACh responses were accompanied by a marked reduction in membrane resistance. The depolarization was abolished by a severe reduction in external Na concentration, while the hyperpolarization was sensitive to alternations in external K concentration. These results indicate that some of the complex responses in submaxillary gland acinar cells to ACh may be explained by the interaction between two different kinds of potential change (Na dependent depolarization and K dependent hyperpolarization).