RESUMO
Anaphylactic shock can be defined as an acute syndrome, and it is the most severe clinical manifestation of allergic diseases. Anaphylactoid reactions are similar to anaphylactic events but differ in the pathophysiological mechanism. Nitric oxide (NO) inhibitors during anaphylaxis suggest that NO might decrease the signs and symptoms of anaphylaxis but exacerbate associated vasodilation. Therefore, blocking the effects of NO on vascular smooth muscle by inhibiting the guanylate cyclase (GC) would be a reasonable strategy. This study aimed to investigate the effects of NO/cGMP pathway inhibitors methylene blue (MB), Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), and indigo carmine (IC) in shock induced by compound 48/80 (C48/80) in rats. The effect was assessed by invasive blood pressure measurement. Shock was initiated by C48/80 intravenous bolus injection 5 min before (prophylactic) or after (treatment) the administration of the inhibitors MB (3 mg/kg), L-NAME (1 mg/kg), and IC (3 mg/kg). Of the groups that received drugs as prophylaxis for shock, only the IC group did not present the final systolic blood pressure (SBP) better than the C48/80 group. Regarding shock treatment with the drugs tested, all groups had the final SBP similar to the C48/80group. Altogether, our results suggested that inhibition of GC and NO synthase in NO production pathway was not sufficient to revert hypotension or significantly improve survival.
Assuntos
Anafilaxia/tratamento farmacológico , GMP Cíclico/antagonistas & inibidores , Inibidores Enzimáticos/administração & dosagem , Músculo Liso Vascular/efeitos dos fármacos , Óxido Nítrico/antagonistas & inibidores , Animais , Modelos Animais de Doenças , Índigo Carmim/administração & dosagem , Masculino , Azul de Metileno/administração & dosagem , NG-Nitroarginina Metil Éster/administração & dosagem , Ratos , Ratos WistarRESUMO
Anaphylactic shock can be defined as an acute syndrome, and it is the most severe clinical manifestation of allergic diseases. Anaphylactoid reactions are similar to anaphylactic events but differ in the pathophysiological mechanism. Nitric oxide (NO) inhibitors during anaphylaxis suggest that NO might decrease the signs and symptoms of anaphylaxis but exacerbate associated vasodilation. Therefore, blocking the effects of NO on vascular smooth muscle by inhibiting the guanylate cyclase (GC) would be a reasonable strategy. This study aimed to investigate the effects of NO/cGMP pathway inhibitors methylene blue (MB), Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), and indigo carmine (IC) in shock induced by compound 48/80 (C48/80) in rats. The effect was assessed by invasive blood pressure measurement. Shock was initiated by C48/80 intravenous bolus injection 5 min before (prophylactic) or after (treatment) the administration of the inhibitors MB (3 mg/kg), L-NAME (1 mg/kg), and IC (3 mg/kg). Of the groups that received drugs as prophylaxis for shock, only the IC group did not present the final systolic blood pressure (SBP) better than the C48/80 group. Regarding shock treatment with the drugs tested, all groups had the final SBP similar to the C48/80group. Altogether, our results suggested that inhibition of GC and NO synthase in NO production pathway was not sufficient to revert hypotension or significantly improve survival.
Assuntos
Animais , Masculino , Ratos , GMP Cíclico/antagonistas & inibidores , Inibidores Enzimáticos/administração & dosagem , Anafilaxia/tratamento farmacológico , Músculo Liso Vascular/efeitos dos fármacos , Óxido Nítrico/antagonistas & inibidores , Ratos Wistar , NG-Nitroarginina Metil Éster/administração & dosagem , Modelos Animais de Doenças , Índigo Carmim/administração & dosagem , Azul de Metileno/administração & dosagemAssuntos
GMP Cíclico/antagonistas & inibidores , Guanilil Ciclase Solúvel/antagonistas & inibidores , Vasoplegia/tratamento farmacológico , GMP Cíclico/farmacocinética , GMP Cíclico/uso terapêutico , Descoberta de Drogas/tendências , Humanos , Azul de Metileno/farmacocinética , Azul de Metileno/uso terapêutico , Óxido Nitroso/efeitos adversos , Óxido Nitroso/antagonistas & inibidoresRESUMO
The bed nucleus of the stria terminalis (BNST) constitutes an important component of neural substrates of physiological and behavioral responses to aversive stimuli, and it has been implicated on cardiovascular responses evoked by stress. Nevertheless, the local neurochemical mechanisms involved in BNST control of cardiovascular responses during aversive threats are still poorly understood. Thus, the aim of the present study was to assess the involvement of activation in the BNST of the neuronal isoform of the enzyme nitric oxide synthase (nNOS), as well as of signaling mechanisms related to nitric oxide effects such as soluble guanylate cyclase (sGC) and protein kinase G (PKG) on cardiovascular responses induced by an acute session of restraint stress in male rats. We observed that bilateral microinjection of either the nonselective NOS inhibitor Nω-Nitro-L-arginine methyl ester (L-NAME), the selective nNOS inhibitor Nω-Propyl-L-arginine (NPLA) or the sGC inhibitor 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) into the BNST enhanced the tachycardic response and decreased the drop in tail cutaneous temperature evoked by acute restraint stress, but without affecting the increase on blood pressure. Bilateral BNST treatment with the selective PKG inhibitor KT5823 also facilitated the heart rate increase and decreased the drop in cutaneous temperature, in addition to enhancing the blood pressure increase. Taken together, these results provide evidence that NO released from nNOS and activation of sGC and PKG within the BNST play an inhibitory influence on tachycardia to stress, whereas this signaling mechanism mediates the sympathetic-mediated cutaneous vasoconstriction.
Assuntos
Sistema Cardiovascular/metabolismo , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Óxido Nítrico/metabolismo , Núcleos Septais/metabolismo , Estresse Psicológico/metabolismo , Animais , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Sistema Cardiovascular/efeitos dos fármacos , GMP Cíclico/antagonistas & inibidores , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Masculino , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Ratos Wistar , Restrição Física/fisiologia , Restrição Física/psicologia , Núcleos Septais/efeitos dos fármacos , Temperatura Cutânea/efeitos dos fármacos , Temperatura Cutânea/fisiologia , Taquicardia/metabolismoRESUMO
Endogenous carbon monoxide (CO), which is produced by the enzyme heme oxygenase (HO), participates as a neuromodulator in physiological processes such as thermoregulation and nociception by stimulating the formation of 3′,5′-cyclic guanosine monophosphate (cGMP). In particular, the acute physical restraint-induced fever of rats can be blocked by inhibiting the enzyme HO. A previous study reported that the HO-CO-cGMP pathway plays a key phasic antinociceptive role in modulating noninflammatory acute pain. Thus, this study evaluated the involvement of the HO-CO-cGMP pathway in antinociception induced by acute stress in male Wistar rats (250-300 g; n=8/group) using the analgesia index (AI) in the tail flick test. The results showed that antinociception induced by acute stress was not dependent on the HO-CO-cGMP pathway, as neither treatment with the HO inhibitor ZnDBPG nor heme-lysinate altered the AI. However, antinociception was dependent on cGMP activity because pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) blocked the increase in the AI induced by acute stress.
Assuntos
Animais , Masculino , Dor Aguda/prevenção & controle , Monóxido de Carbono/metabolismo , GMP Cíclico/metabolismo , Heme Oxigenase (Desciclizante)/metabolismo , Dor Nociceptiva/prevenção & controle , Transtornos de Estresse Traumático Agudo/metabolismo , GMP Cíclico/antagonistas & inibidores , Deuteroporfirinas/metabolismo , Heme Oxigenase (Desciclizante)/antagonistas & inibidores , Heme/análogos & derivados , Heme/metabolismo , Lisina/análogos & derivados , Lisina/metabolismo , Dor Nociceptiva/metabolismo , Oxidiazóis/farmacologia , Medição da Dor/métodos , Ratos Wistar , Transdução de Sinais/fisiologiaRESUMO
Endogenous carbon monoxide (CO), which is produced by the enzyme heme oxygenase (HO), participates as a neuromodulator in physiological processes such as thermoregulation and nociception by stimulating the formation of 3',5'-cyclic guanosine monophosphate (cGMP). In particular, the acute physical restraint-induced fever of rats can be blocked by inhibiting the enzyme HO. A previous study reported that the HO-CO-cGMP pathway plays a key phasic antinociceptive role in modulating noninflammatory acute pain. Thus, this study evaluated the involvement of the HO-CO-cGMP pathway in antinociception induced by acute stress in male Wistar rats (250-300 g; n=8/group) using the analgesia index (AI) in the tail flick test. The results showed that antinociception induced by acute stress was not dependent on the HO-CO-cGMP pathway, as neither treatment with the HO inhibitor ZnDBPG nor heme-lysinate altered the AI. However, antinociception was dependent on cGMP activity because pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) blocked the increase in the AI induced by acute stress.
Assuntos
Dor Aguda/prevenção & controle , Monóxido de Carbono/metabolismo , GMP Cíclico/metabolismo , Heme Oxigenase (Desciclizante)/metabolismo , Dor Nociceptiva/prevenção & controle , Transtornos de Estresse Traumático Agudo/metabolismo , Animais , GMP Cíclico/antagonistas & inibidores , Deuteroporfirinas/metabolismo , Heme/análogos & derivados , Heme/metabolismo , Heme Oxigenase (Desciclizante)/antagonistas & inibidores , Lisina/análogos & derivados , Lisina/metabolismo , Masculino , Dor Nociceptiva/metabolismo , Oxidiazóis/farmacologia , Medição da Dor/métodos , Ratos Wistar , Transdução de Sinais/fisiologiaRESUMO
CONTEXT: Citronellal is a monoterpene present in the oil of many species, including Cymbopogon winterianus Jowitt (Poaceae). OBJECTIVE: The present study investigated the effect of citronellal on inflammatory nociception induced by different stimuli and examined the involvement of the NO-cGMP-ATP-sensitive K⺠channel pathway. MATERIALS AND METHODS: We used male Swiss mice (n = 6 per group) that were treated intraperitoneally with citronellal (25, 50 or 100 mg/kg) 0.5 h after the subplantar injection of 20 µl of carrageenan (CG; 300 µg/paw), tumor necrosis factor-α (TNF-α; 100 pg/paw), prostaglandin E2 (PGE2; 100 ng/paw) or dopamine (DA; 30 µg/paw). The mechanical nociception was evaluated at 0.5, 1, 2 and 3 h after the injection of the agents, using a digital analgesimeter (von Frey). The effects of citronellal were also evaluated in the presence of L-NAME (30 mg/kg) or glibenclamide (5 mg/kg). RESULTS: At all times, citronellal in all doses inhibited the development of mechanical nociception induced by CG (p < 0.001 and p < 0.01) and TNF-α (p < 0.001, p < 0.01, and p < 0.05). The citronellal was able to increase the pain threshold in the DA test (p < 0.001, p < 0.01, and p < 0.05) and in the PGE2 test at all times (p < 0.001 and p < 0.05). L-NAME and glibenclamide reversed the antinociceptive effects of the citronellal at higher doses in the PGE2 test. DISCUSSION AND CONCLUSION: These data suggest that citronellal attenuated mechanical nociception, mediated in part by the NO-cGMP-ATP-sensitive K⺠channel pathway.
Assuntos
Aldeídos/uso terapêutico , Anti-Inflamatórios não Esteroides/uso terapêutico , GMP Cíclico/metabolismo , Modelos Animais de Doenças , Canais KATP/metabolismo , Monoterpenos/uso terapêutico , Óxido Nítrico/metabolismo , Dor Nociceptiva/prevenção & controle , Monoterpenos Acíclicos , Aldeídos/administração & dosagem , Aldeídos/antagonistas & inibidores , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/efeitos adversos , GMP Cíclico/antagonistas & inibidores , Cymbopogon/química , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Glibureto/farmacologia , Indonésia , Canais KATP/antagonistas & inibidores , Masculino , Camundongos , Monoterpenos/administração & dosagem , Monoterpenos/antagonistas & inibidores , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/antagonistas & inibidores , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Dor Nociceptiva/imunologia , Dor Nociceptiva/metabolismo , Óleos Voláteis/química , Limiar da Dor/efeitos dos fármacos , Óleos de Plantas/química , Bloqueadores dos Canais de Potássio/farmacologia , Transdução de Sinais/efeitos dos fármacosRESUMO
N-palmitoyl-ethanolamine (PEA) is an endogenous substance that was first identified in lipid tissue extracts. It has been classified as a CB(2) receptor agonist. Exogenous PEA has the potential to become a valid treatment for neuropathic and inflammatory pain. In spite of the well-demonstrated antiinflammatory properties of PEA, its involvement in controlling pain pathways remains poorly characterized. The participation of the L-arginine/nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway in peripheral antinociception has been established by our group to the µ-, κ- or δ-opioid receptor agonists, nonsteroidal analgesics, α(2C) -adrenoceptor agonists, and even nonpharmacological electroacupuncture. The aim of this study was to verify whether the peripheral antinociception effects of PEA involve the activation of this pathway. All drugs were locally administered to the right hind paw of male Wistar rats. The paw pressure test was used, with hyperalgesia induced by intraplantar injection of prostaglandin E(2) . PEA elicited a local peripheral antinociceptive effect that was antagonized by the nonselective NO synthase (NOS) inhibitor L-NOARG and the selective neuronal NOS (nNOS) inhibitor L-NPA. Selective inhibition of endothelial (eNOS) and inducible (iNOS) NOS via L-NIO and L-NIL, respectively, was ineffective at blocking the effects of a local PEA injection. In addition, the dosage of nitrite in the homogenized paw, as determined by colorimetric assay, indicated that exogenous PEA is able to induce NO release. The soluble guanylyl cyclase inhibitor ODQ antagonized the PEA effect, whereas the cGMP-phosphodiesterase inhibitor zaprinast potentiated the antinociceptive effect of low-dose PEA. This study provides evidence that PEA activates nNOS, thus initiating the NO/cGMP pathway and inducing peripheral antinociceptive effects.
Assuntos
Arginina/fisiologia , GMP Cíclico/fisiologia , Endocanabinoides/farmacologia , Etanolaminas/farmacologia , Hiperalgesia/tratamento farmacológico , Inibição Neural/fisiologia , Óxido Nítrico/fisiologia , Nociceptividade/efeitos dos fármacos , Ácidos Palmíticos/farmacologia , Amidas , Analgésicos/farmacologia , Animais , GMP Cíclico/antagonistas & inibidores , Modelos Animais de Doenças , Hiperalgesia/induzido quimicamente , Hiperalgesia/fisiopatologia , Masculino , Inibição Neural/efeitos dos fármacos , Vias Neurais/efeitos dos fármacos , Vias Neurais/fisiologia , Nociceptividade/fisiologia , Ratos , Ratos WistarRESUMO
BACKGROUND AND PURPOSE: We investigated the effect of the phosphodiesterase-5 inhibitor, tadalafil, on the acute hypernociception in rat models of arthritis. EXPERIMENTAL APPROACH: Rats were treated with either an intra-articular injection of zymosan (1 mg) or surgical transection of the anterior cruciate ligament (as an osteoarthritis model). Controls received saline intra-articular or sham operation respectively. Joint pain was evaluated using the articular incapacitation test measured over 6 h following zymosan or between 4 and 7 days after anterior cruciate ligament transection. Cell counts, tumour necrosis factor-α (TNF-α), interleukin-1 (IL-1), and the chemokine, cytokine-induced neutrophil chemoattractant-1 (CINC-1) were measured in joint exudates 6 h after zymosan. Groups received tadalafil (0.02-0.5 mg·kg⻹ per os) or saline 2 h after intra-articular zymosan. Other groups received the µ-opioid receptor antagonist naloxone or the cGMP inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ) before tadalafil. KEY RESULTS: Tadalafil dose-dependently inhibited hypernociception in zymosan and osteoarthritis models. In zymosan-induced arthritis, tadalafil significantly decreased cell influx and TNF-α release but did not alter IL-1 or CINC-1 levels. Pretreatment with ODQ but not with naloxone prevented the anti-inflammatory effects of tadalafil. CONCLUSIONS AND IMPLICATIONS: Therapeutic oral administration of tadalafil provided analgesia mediated by guanylyl cyclase and was independent of the release of endogenous opioids. This effect of tadalafil was associated with a decrease in neutrophil influx and TNF-α release in inflamed joints.
Assuntos
Artrite Experimental/tratamento farmacológico , Artrite Experimental/metabolismo , Carbolinas/farmacologia , Nociceptividade/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo , Analgésicos/farmacologia , Animais , Anti-Inflamatórios/farmacologia , Artralgia/tratamento farmacológico , Artralgia/metabolismo , Artrite Experimental/induzido quimicamente , Quimiocina CXCL1/metabolismo , Quimiocinas/metabolismo , GMP Cíclico/antagonistas & inibidores , Guanilato Ciclase/metabolismo , Injeções Intra-Articulares , Interleucina-1/metabolismo , Articulações/efeitos dos fármacos , Articulações/metabolismo , Masculino , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Osteoartrite/tratamento farmacológico , Osteoartrite/metabolismo , Oxidiazóis/farmacologia , Quinoxalinas/farmacologia , Ratos , Ratos Wistar , Tadalafila , Zimosan/farmacologiaRESUMO
This study assessed the effect of the agonist 15d-PGJ(2) administered into the rat temporomandibular joint (TMJ) on nociceptive behavioral and the anti-inflammatory potential of this prostaglandin on TMJ. It was observed that 15-deoxy-(Delta12,14)-prostaglandin J(2) (15d-PGJ(2)) significantly reduced formalin-induced nociceptive behavior in a dose dependent manner, however injection of 15d-PGJ(2) into the contralateral TMJ failed to reduce such effects. This antinociceptive effect is dependent on peroxisome proliferator-activated receptors-gamma (PPAR-gamma) since pre-treatment with GW9662 (PPAR-gamma receptor antagonist) blocked the antinociceptive effect of 15d-PGJ(2) in the TMJ. In addition, the antinociceptive effect of 15d-PGJ(2) was also blocked by naloxone suggesting the involvement of peripheral opioids in the process. Confirming this hypothesis pre-treatment with kappa, delta, but not mu receptor antagonists significantly reduced the antinociceptive effect of 15d-PGJ(2) in the TMJ. Similarly to opioid agonists, the 15d-PGJ(2) antinociceptive action depends on the nitric oxide (NO)/guanilate cyclase (cGMP)/ATP-sensitive potassium channel blocker(K(+)(ATP)) channel pathway since it was prevented by the pre-treatment with the inhibitors of nitric oxide synthase (NOS; aminoguanidine), cGMP (ODQ), or the K(+)(ATP) (glibenclamide). In addition, 15d-PGJ(2) (100 ng/TMJ) inhibits 5-HT-induced TMJ hypernociception. Besides, TMJ treated with 15d-PGJ(2) showed lower vascular permeability, assessed by Evan's Blue extravasation, and also lower neutrophil migration induced by carrageenan administration. Taken together, these results demonstrate that 15d-PGJ(2) has a potential peripheral antinociceptive and anti-inflammatory effect in the TMJ via PPAR-gamma activation. The results also suggest that 15d-PGJ(2) induced-peripheral antinociceptive response in the TMJ is mediated by kappa/delta opioid receptors by the activation of the intracellular l-arginine/NO/cGMP/K(+)(ATP) channel pathway. The pharmacological properties of the peripheral administration of 15d-PGJ(2) highlight the potential use of this PPAR-gamma agonist on TMJ inflammatory pain conditions.
Assuntos
Analgésicos/farmacologia , Dor/tratamento farmacológico , Prostaglandina D2/análogos & derivados , Receptores Opioides delta/metabolismo , Receptores Opioides kappa/metabolismo , Articulação Temporomandibular/efeitos dos fármacos , Analgésicos/administração & dosagem , Animais , GMP Cíclico/antagonistas & inibidores , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Formaldeído , Inflamação/induzido quimicamente , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Canais KATP/antagonistas & inibidores , Canais KATP/metabolismo , Masculino , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , PPAR gama/antagonistas & inibidores , PPAR gama/metabolismo , Dor/induzido quimicamente , Dor/metabolismo , Prostaglandina D2/administração & dosagem , Prostaglandina D2/farmacologia , Ratos , Ratos Wistar , Receptores Opioides delta/antagonistas & inibidores , Receptores Opioides kappa/antagonistas & inibidores , Receptores Opioides mu/antagonistas & inibidores , Receptores Opioides mu/metabolismo , Serotonina/metabolismo , Transdução de Sinais , Articulação Temporomandibular/metabolismoRESUMO
Nitric oxide (NO) in bovine ovary has been characterized as one of the controllers of granulosa cells' (GC) steroidogenesis and apoptosis. One of the pathways used by NO to have these effects is cGMP. The objectives of the present study were to verify the effect of sodium nitroprusside (SNP), a NO donor, on steroidogenesis, cell viability (mitochondrial activity) and GC cell cycle distribution and if this effect occurs by the NO-cGMP signaling pathway with the addition of SNP with or without 1H-[1,2,3] oxadiaziolo[4,3a]quinoxaline-1-one (ODQ), a selective soluble guanylate cyclase inhibitor. The antral GC from 3 to 5mm diameter cattle follicles was cultured without treatment (control), with ODQ (10(-4)M) and 10(-5), 10(-3) and 10(-1)M SNP with or without ODQ for 24h. Nitrate/nitrite (NO(3)(-)/N0(2)(-)) concentrations were evaluated by Griess method, progesterone (P(4)) and 17beta-estradiol (E(2)) concentrations by chemiluminescence, viability and cell cycle stage by MTT method (3-[4,5-dimethylthiazol-2yl]-2,3 dipheniltetrazolium bromide) and flow cytometry, respectively. Nitrate/nitrite concentration in culture medium increased (P<0.05) in a dose-dependent manner according to SNP concentration added to the culture medium. The GC cultured without treatment, with ODQ and with 10(-5)M SNP in the presence or absence of ODQ developed into cell aggregates and did not vary in cell viability (P>0.05), while GC cultured with 10(-3) and 10(-1)M SNP with or without ODQ presented disorganized GC aggregates or did not develop into cell aggregates and also had substantially decreased cell viability (mitochondrial activity inhibition) and steroids synthesis (P<0.05), and effects were not reversed with us of ODQ. Most GC cultured without treatment (control) or with ODQ, 10(-5) and 10(-3)M SNP with or without ODQ were in the G0/G1 (80-75%) stage and in a lesser proportion (20-25%) in the S+G2/M stage of the cell cycle, while the 10(-1)M SNP treatment resulted in GC in G1 phase arrest. The treatment with 10(-5)M SNP increased (P<0.05) E(2) synthesis and inhibited (P<0.05) progesterone synthesis. The addition of ODQ reversed (P<0.05) the stimulatory effect of 10(-5)M SNP treatment on E(2), but not on P(4) synthesis (P>0.05). These results demonstrated that E(2) synthesis by antral GC from small follicles is modulated by lesser NO concentrations via the cGMP pathway, but not P(4) while steroids inhibition cGMP pathway independent, mitochondrial damage and the interference on cell cycle progression caused by greater NO concentration can lead to cell death.
Assuntos
Bovinos/metabolismo , Estradiol/biossíntese , Células da Granulosa/metabolismo , Óxido Nítrico/metabolismo , Progesterona/biossíntese , Animais , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/fisiologia , Sobrevivência Celular/efeitos dos fármacos , GMP Cíclico/antagonistas & inibidores , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Feminino , Células da Granulosa/efeitos dos fármacos , Nitratos/análise , Doadores de Óxido Nítrico/farmacologia , Nitroprussiato/farmacologia , Oxidiazóis/farmacologia , Quinoxalinas/farmacologiaRESUMO
The role of nitric oxide (NO) in cardiac contractility is complex and controversial. Several NO donors have been reported to cause positive or negative inotropism. NO can bind to guanylate cyclase, increasing cGMP production and activating PKG. NO may also directly S-nitrosylate cysteine residues of specific proteins. We used the isolated rat heart preparation to test the hypothesis that the differential inotropic effects depend on the degree of NO production and the signaling recruited. SNAP (S-nitroso-N-acetylpenicillamine), a NO donor, increased contractility at 0.1, 1 and 10 microM. This effect was independent of phospholamban phosphorylation, was not affected by PKA inhibition with H-89 (N-[2((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide), but it was abolished by the radical scavenger Tempol (4-hydroxy-[2,2,4,4]-tetramethyl-piperidine-1-oxyl). However, at 100 microM SNAP reduced contractility, effect reversed to positive inotropism by guanylyl cyclase blockade with ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), and abolished by PKG inhibition with KT5823, but not affected by Tempol. SNAP increased tissue cGMP at 100 microM, but not at lower concentrations. Consistently, a cGMP analog also reduced cardiac contractility. Finally, SNAP at 1 microM increased the level of S-nitrosylation of various cardiac proteins, including the ryanodine receptor. This study demonstrates the biphasic role for NO in cardiac contractility in a given preparation; furthermore, the differential effect is clearly ascribed to the signaling pathways involved. We conclude that although NO is highly diffusible, its output determines the fate of the messenger: low NO concentrations activate redox processes (S-nitrosylation), increasing contractility; while the cGMP-PKG pathway is activated at high NO concentrations, reducing contractility.
Assuntos
Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Contração Miocárdica/fisiologia , Óxido Nítrico/metabolismo , S-Nitroso-N-Acetilpenicilamina/metabolismo , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Carbazóis/farmacologia , GMP Cíclico/antagonistas & inibidores , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Óxidos N-Cíclicos/farmacologia , Masculino , Contração Miocárdica/efeitos dos fármacos , Óxido Nítrico/biossíntese , Técnicas de Cultura de Órgãos , Ratos , Ratos Sprague-Dawley , S-Nitroso-N-Acetilpenicilamina/antagonistas & inibidores , S-Nitroso-N-Acetilpenicilamina/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Marcadores de SpinRESUMO
RATIONALE: Conflicting results have been reported regarding the role of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway in the hippocampus on anxiety modulation. OBJECTIVES: To investigate the effects of intrahippocampal injections of drugs that modify the NO-cGMP pathway in rats submitted to two animal models that are sensitive to anxiolytic drugs, the elevated plus-maze and the Vogel punished licking test. MATERIALS AND METHODS: Male Wistar rats with cannulae aimed at the dentate gyrus of the dorsal hippocampus received microinjections of the NO synthase (NOS) inhibitors N (G)-nitro-L: -arginine methyl ester (LNAME, 15-300 nmol/0.2 microl), N (G)-nitro-L: -arginine (LNOARG, 50-300 nmol/0.2 microl), 7-nitroindazole (7NI, 10-100 nmol/0.2 microl), or the soluble guanylate cyclase inhibitor 1H-oxadiazolo-quinoxalin-1 one (ODQ, 10-100 nmol/0.2 microl), and were submitted to the elevated plus-maze. In a second group, the animals received 7NI, LNAME, or ODQ and were submitted to the Vogel punished licking test. To control for drug-induced changes in locomotor behavior, the animals were submitted to an open arena or to the Rota-rod test. RESULTS: All drugs increased the exploration of the open arms of the elevated plus-maze. They also increased the number of punished licks in the Vogel test, indicating an anxiolytic effect. The anxiolytic effect of LNAME was prevented by previous treatment with L: -arginine (300 nmol/0.2 microl). Except for the lower dose of LNAME (15 nmol), administration of the NOS inhibitors or ODQ did not change exploratory activity in the open field nor cause any gross locomotor impairment in the Rota-rod test. CONCLUSION: The results suggest that NO plays an anxiogenic role in the dentate gyrus of the dorsal hippocampus.
Assuntos
Ansiedade/fisiopatologia , GMP Cíclico/antagonistas & inibidores , Hipocampo/fisiopatologia , Óxido Nítrico/antagonistas & inibidores , Análise de Variância , Animais , Ansiedade/psicologia , GMP Cíclico/fisiologia , Giro Denteado , Relação Dose-Resposta a Droga , Guanilato Ciclase/antagonistas & inibidores , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Indazóis/farmacologia , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Microinjeções , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/fisiologia , Óxido Nítrico Sintase/antagonistas & inibidores , Nitroarginina/farmacologia , Oxidiazóis/farmacologia , Punição , Quinoxalinas/farmacologia , Ratos , Ratos Wistar , Receptores Citoplasmáticos e Nucleares/antagonistas & inibidores , Guanilil Ciclase SolúvelRESUMO
This study investigated the involvement of the L-arginine-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway in the antidepressant-like effect of an acute administration of memantine in the forced swimming test (FST) in mice, since this signaling pathway is supposed to play a significant role in depression. The antidepressant-like effect of memantine (3 mg/kg, i.p.) was prevented by pretreatment with L-arginine (750 mg/kg, i.p.) or S-nitroso-N-acetyl-penicillamine (SNAP, 25 microg/site, i.c.v.), but not with d-arginine (750 mg/kg, i.p.).The treatment of mice with NG-nitro-L-arginine (L-NNA, 0.03 and 0.3 mg/kg, i.p.) potentiated the effect of a subeffective dose of memantine (0.3 mg/kg, i.p.) in the FST. Moreover, the pretreatment of mice with (1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one) (ODQ, 30 pmol/site, i.c.v.) produced a synergistic antidepressant-like effect with subeffective doses of memantine (0.3 and 1 mg/kg, i.p.) in the FST. Furthermore, the reduction in the immobility time elicited by memantine (3 mg/kg, i.p.) in the FST was prevented by pretreatment with sildenafil (5 mg/kg, i.p.). Taken together, the results demonstrate that memantine produced an antidepressant-like effect in the FST that seems to be mediated through an interaction with the L-arginine-NO-cGMP pathway.
Assuntos
Antidepressivos/administração & dosagem , Arginina/fisiologia , GMP Cíclico/fisiologia , Depressão/tratamento farmacológico , Memantina/administração & dosagem , Óxido Nítrico/fisiologia , Análise de Variância , Animais , GMP Cíclico/antagonistas & inibidores , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Interações Medicamentosas , Inibidores Enzimáticos/farmacologia , Feminino , Resposta de Imobilidade Tônica/efeitos dos fármacos , Masculino , Camundongos , Doadores de Óxido Nítrico/farmacologia , Nitroarginina/farmacologia , Penicilamina/análogos & derivados , Penicilamina/farmacologia , Piperazinas/farmacologia , Purinas , Citrato de Sildenafila , Sulfonas , NataçãoRESUMO
The possible participation of the nitric oxide (NO)-cyclic GMP-protein kinase G (PKG) pathway on gabapentin-induced spinal antiallodynic activity was assessed in spinal nerve injured rats. Intrathecal gabapentin, diazoxide or pinacidil reduced tactile allodynia in a dose-dependent manner. Pretreatment with NG-L-nitro-arginine methyl ester (L-NAME, non-specific inhibitor of NO synthase NOS), 7-nitroindazole (neuronal NO synthase inhibitor), 1H-[1,2,4] -oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, guanylyl cyclase inhibitor) or (9S, 10R, 12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo-[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid methyl ester (KT-5823, specific PKG inhibitor), but not NG-D-nitro-arginine methyl ester (D-NAME) or okadaic acid (protein phosphatase 1 and 2 inhibitor) prevented gabapentin-induced antiallodynia. Pinacidil activity was not blocked by L-NAME, D-NAME, 7-nitroindazole, ODQ, KT-5823 or okadaic acid. Moreover, KT-5823, glibenclamide (ATP-sensitive K+ channel blocker), apamin and charybdotoxin (small- and large-conductance Ca2+-activated K+ channel blockers, respectively), but not margatoxin (voltage-gated K+ channel blocker), L-NAME, 7-nitroindazole, ODQ or okadaic acid, reduced diazoxide-induced antiallodynia. Data suggest that gabapentin-induced spinal antiallodynia could be due to activation of the NO-cyclic GMP-PKG-K+ channel pathway.
Assuntos
Aminas/farmacologia , Ácidos Cicloexanocarboxílicos/farmacologia , Dor/prevenção & controle , Transdução de Sinais/fisiologia , Ácido gama-Aminobutírico/farmacologia , Aminas/administração & dosagem , Analgésicos/administração & dosagem , Analgésicos/farmacologia , Animais , Apamina/farmacologia , Carbazóis/farmacologia , Charibdotoxina/farmacologia , GMP Cíclico/antagonistas & inibidores , GMP Cíclico/metabolismo , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Ácidos Cicloexanocarboxílicos/administração & dosagem , Diazóxido/administração & dosagem , Diazóxido/farmacologia , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Feminino , Gabapentina , Glibureto/farmacologia , Indazóis/farmacologia , Indóis/farmacologia , Injeções Espinhais , NG-Nitroarginina Metil Éster/química , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/antagonistas & inibidores , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Ácido Okadáico/farmacologia , Oxidiazóis/farmacologia , Dor/fisiopatologia , Pinacidil/administração & dosagem , Pinacidil/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio/fisiologia , Inibidores de Proteínas Quinases/farmacologia , Quinoxalinas/farmacologia , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Nervos Espinhais/lesões , Nervos Espinhais/fisiopatologia , Estereoisomerismo , Fatores de Tempo , Vasodilatadores/administração & dosagem , Vasodilatadores/farmacologia , Ácido gama-Aminobutírico/administração & dosagemRESUMO
Studies on the purinergic system normally deal with adenine-based purines, namely, adenine nucleotides and adenosine. However, a guanine-based purinergic system may also have important neuromodulatory roles. Guanine-based purines exert trophic effects on neural cells, protect brain slices in a model of hypoxia and stimulate glutamate uptake. In vivo, both guanosine 5'-monophosphate (GMP) and guanosine (GUO) protected against seizures. In this study, we investigated if the anticonvulsant effect of GMP is mediated by guanosine and if guanosine or GMP treatments were able to increase adenosine levels. Intraperitoneal (i.p.) treatments with 7.5 mg/kg GMP or guanosine prevented 50% of seizures by quinolinic acid (QA) and increased guanosine cerebrospinal fluid (CSF) levels around twofold and threefold, respectively; GMP and adenosine levels remained unchanged. Intracerebroventricular treatment with 960 nmol GMP prevented 80% of seizures and the 5'-nucleotidase inhibitor alpha-beta-methyleneadenosine 5'-diphosphate (AOPCP), when injected 3 min before, reduced this anticonvulsant effect to 30% protection as well as significantly decreased the conversion of GMP into guanosine measured in the CSF. This study shows that the previously reported effect of GMP as an anticonvulsant seems to be related to its ability to generate guanosine through the action of ecto-5'-nucleotidase.
Assuntos
Difosfato de Adenosina/análogos & derivados , Anticonvulsivantes/uso terapêutico , GMP Cíclico/uso terapêutico , Guanosina/metabolismo , Guanosina/farmacologia , Convulsões/tratamento farmacológico , Difosfato de Adenosina/farmacologia , Animais , Anticonvulsivantes/metabolismo , GMP Cíclico/antagonistas & inibidores , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Guanosina/antagonistas & inibidores , Guanosina/líquido cefalorraquidiano , Masculino , Ratos , Ratos Wistar , Convulsões/líquido cefalorraquidianoRESUMO
OBJECTIVES: To investigate the capacity of voltage-gated Na(+) channel activators such as batrachotoxin, aconitine, veratridine, Ts1 (formerly Tityus gamma-toxin), and brevetoxin-3 to induce relaxation of rabbit isolated corpus cavernosum (RbCC) and the pharmacologic mechanisms underlying this phenomenon. The voltage-gated Na(+) channels of the corpus cavernosum are essential for erectile function. A number of biologic toxins exert their effects by modifying the properties of these channels. METHODS: Male New Zealand white rabbits were anesthetized with pentobarbital sodium. Strips of RbCC were transferred to 10-mL organ baths containing oxygenated and warmed Krebs solution. The RbCC strips were connected to force-displacement transducers, and changes in isometric force were recorded using a PowerLab 400 data acquisition system. Corporeal smooth muscle was precontracted submaximally with phenylephrine (10 micromol/L). RESULTS: The binding site-2 (batrachotoxin, aconitine, and veratridine) and binding site-5 (brevetoxin-3) voltage-gated Na(+) channel activators caused slow-onset RbCC relaxations, and the binding site-4 activator Ts1 produced transitory relaxations followed by a return to baseline. The Na(+)channel blockers tetrodotoxin and saxitoxin (0.1 micromol/L each) abolished the relaxations induced by these agonists. Similarly, the nitric oxide synthase inhibitor N(omega)-nitro-l-arginine methyl ester (100 micromol/L) markedly reduced the relaxations and l-arginine (1 mmol/L) restored the relaxations. The soluble guanylyl cyclase inhibitor 1H-[1,2,4] oxidiazolo[4,3-alpha] quinoxalin-1-one (10 micromol/L) reduced the relaxations, and the phosphodiesterase type 5 inhibitor sildenafil (100 nmol/L) significantly potentiated the relaxations by all activators. CONCLUSIONS: Our results indicate that the relaxations evoked by selective activators of voltage-gated Na(+) channels are mediated by the release of nitric oxide from nitrergic nerves and the activation of the nitric oxide-cyclic guanosine monophosphate pathway in the smooth muscle cells of erectile tissue.
Assuntos
GMP Cíclico/metabolismo , Músculo Liso/efeitos dos fármacos , Óxido Nítrico/metabolismo , Pênis/fisiologia , Agonistas de Canais de Sódio , Aconitina/farmacologia , Animais , Arginina/farmacologia , Batraquiotoxinas/farmacologia , Sítios de Ligação , GMP Cíclico/antagonistas & inibidores , Guanilato Ciclase/antagonistas & inibidores , Técnicas In Vitro , Proteínas de Insetos , Contração Isométrica/efeitos dos fármacos , Masculino , Toxinas Marinhas/farmacologia , Músculo Liso/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Neurotoxinas/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Oxocinas/farmacologia , Ereção Peniana/efeitos dos fármacos , Piperazinas/farmacologia , Purinas , Coelhos , Venenos de Escorpião/farmacologia , Citrato de Sildenafila , Bloqueadores dos Canais de Sódio/farmacologia , Canais de Sódio/metabolismo , Sulfonas , Veratridina/farmacologiaRESUMO
The effects induced by nitric oxide (NO) in different tissues depend on direct and/or indirect interactions with K+ channels. The indirect interaction of NO is produced by activation of guanylyl cyclase which increases the intracellular cGMP. Since NO, cGMP and 4-aminopyridine alone induce tetanic fade and increase amplitude of muscular contractions in isolated rat neuromuscular preparations, the present study was undertaken to determine whether or not the neuromuscular effects of NO and 8-Br-cGMP can be modified by 4-aminopyridine. Using the phrenic nerve and diaphragm muscle isolated from male Wistar rats (200-250 g), we observed that L-arginine (4.7 mM) and 8-Br-cGMP (18 M), in contrast to D-arginine, induced an increase in the amplitude of muscle contraction (10.5 0.7%, N = 10 and 8.0 0.7%, N = 10) and tetanic fade (15 2.0%, N = 8 and 11.6 1.7%, N = 8) at 0.2 and 50 Hz, respectively. N G-nitro-L-arginine (4 mM, N = 8 and 8 mM, N = 8) antagonized the effects of L-arginine. 4-Aminopyridine (1 and 10 M) caused a dose-dependent increase in the amplitude of muscle contraction (15 1.8%, N = 9 and 40 3.1%, N = 10) and tetanic fade (17.7 3.3%, N = 8 and 37.4 1.3%, N = 8). 4-Aminopyridine (1 M, N = 8) did not cause any change in muscle contraction amplitude or tetanic fade of preparations previously paralyzed with d-tubocurarine or stimulated directly. The effects induced by 4-aminopyridine alone were similar to those observed when the drug was administered in combination with L-arginine or 8-Br-cGMP. The data suggest that the blockage of K+ channels produced by 4-aminopyridine inhibits the neuromuscular effects induced by NO and 8-Br-cGMP. Therefore, the presynaptic effects induced by NO seem to depend on indirect interactions with K+ channels.