RESUMEN
In the present study it was hypothesized that 5-((4-methoxyphenyl)thio)benzo[c][1,2,5] thiodiazole (MTDZ), a new acetylcholinesterase inhibitor, exerts antinociceptive action and reduces the oxaliplatin (OXA)-induced peripheral neuropathy and its comorbidities (anxiety and cognitive deficits). Indeed, the acute antinociceptive activity of MTDZ (1 and 10 mg/kg; per oral route) was observed for the first time in male Swiss mice in formalin and hot plate tests and on mechanical withdrawal threshold induced by Complete Freund's Adjuvant (CFA). To evaluate the MTDZ effect on OXA-induced peripheral neuropathy and its comorbidities, male and female Swiss mice received OXA (10 mg/kg) or vehicle intraperitoneally, on days 0 and 2 of the experimental protocol. Oral administration of MTDZ (1 mg/kg) or vehicle was performed on days 2-14. OXA caused cognitive impairment, anxious-like behaviour, mechanical and thermal hypersensitivity in animals, with females more susceptible to thermal sensitivity. MTDZ reversed the hypersensitivity, cognitive impairment and anxious-like behaviour induced by OXA. Here, the negative correlation between the paw withdrawal threshold caused by OXA and acetylcholinesterase (AChE) activity was demonstrated in the cortex, hippocampus, and spinal cord. OXA inhibited the activity of total ATPase, Na+ K+ - ATPase, Ca2+ - ATPase and altered Mg2+ - ATPase in the cortex, hippocampus, and spinal cord. OXA exposure increased reactive species (RS) levels and superoxide dismutase (SOD) activity in the cortex, hippocampus, and spinal cord. MTDZ modulated ion pumps and reduced the oxidative stress induced by OXA. In conclusion, MTDZ is an antinociceptive molecule promising to treat OXA-induced neurotoxicity since it reduced nociceptive and anxious-like behaviours, and cognitive deficit in male and female mice.
Asunto(s)
Benzoatos/uso terapéutico , Inhibidores de la Colinesterasa/uso terapéutico , Enfermedades del Sistema Nervioso Periférico/tratamiento farmacológico , Enfermedades del Sistema Nervioso Periférico/enzimología , Tiadiazoles/uso terapéutico , Tiazoles/uso terapéutico , Adenosina Trifosfatasas/metabolismo , Analgésicos/química , Analgésicos/uso terapéutico , Animales , Ansiedad/inducido químicamente , Ansiedad/tratamiento farmacológico , Benzoatos/química , Carbamatos , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/enzimología , Inhibidores de la Colinesterasa/química , Disfunción Cognitiva/inducido químicamente , Disfunción Cognitiva/tratamiento farmacológico , Modelos Animales de Enfermedad , Femenino , Hipocampo/efectos de los fármacos , Hipocampo/enzimología , Indoles , Masculino , Ratones , Oxaliplatino/toxicidad , Estrés Oxidativo/efectos de los fármacos , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Médula Espinal/efectos de los fármacos , Médula Espinal/enzimología , Tiadiazoles/química , Tiazoles/químicaRESUMEN
In this study, the deposition of platinum in oxaliplatin (OXA)-exposed mice and the effects of the oxidative damage on the central nervous system were investigated. The relationship between the reactive species (RS) levels as well as the expression and activity of enzymes, such as catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) and acetylcholinesterase (AChE), in the development of peripheral neuropathy after OXA exposure, was evidenced. The effects of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) on OXA-induced peripheral neuropathy was also investigated. Swiss mice received OXA (10 mg kg-1) or vehicle by intraperitoneal route (days 0 and 2). Oral administration of 4-PSQ (1 mg kg-1) or vehicle was performed on days 2 to 14. Behavioural tasks started on day 9, after the first OXA administration. It was observed that 4-PSQ reduced the mechanical and thermal hypersensitivity induced by OXA. 4-PSQ and OXA did not affect locomotor and exploratory activities. The results revealed, for the first time, a high concentration of platinum in the spinal cord of mice exposed to OXA. 4-PSQ reversed the increased levels of RS in the spinal cord, cerebral cortex and hippocampus of mice exposed to OXA. The alterations in the activity and expression of the GPx, SOD, CAT and AChE induced by OXA exposure were normalized by 4-PSQ. Therefore, the 4-PSQ might be a good prototype for the development of a more effective drug for the treatment of OXA-induced peripheral neuropathy. The results obtained by the present study expanded the knowledge about the mechanisms involved in the physiopathology of peripheral neuropathy. Graphical abstract.
Asunto(s)
Oxaliplatino/efectos adversos , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/tratamiento farmacológico , Quinolinas/uso terapéutico , Acetilcolinesterasa/metabolismo , Animales , Antioxidantes/farmacología , Catalasa/metabolismo , Conducta Exploratoria/efectos de los fármacos , Glutatión Peroxidasa/metabolismo , Masculino , Ratones , Actividad Motora/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Quinolinas/farmacología , Reproducibilidad de los Resultados , Médula Espinal/efectos de los fármacos , Médula Espinal/enzimología , Médula Espinal/patología , Superóxido Dismutasa/metabolismo , TemperaturaRESUMEN
Phosphodiesterase-5 inhibitors (PDE5Is) have been shown to modulate cell death/cell survival in different in vivo and in vitro models of disease by activating many signaling pathways. This review aimed at elucidating how PDE5Is can inhibit apoptosis. In this study, we describe many signaling pathways involved with the mechanism of action of PDE5Is that ultimately inhibit apoptosis and thus promote cell survival.
Asunto(s)
Apoptosis/efectos de los fármacos , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 5/genética , Encefalomielitis Autoinmune Experimental/tratamiento farmacológico , Neuronas/efectos de los fármacos , Inhibidores de Fosfodiesterasa 5/farmacología , Citrato de Sildenafil/farmacología , Animales , Apoptosis/genética , Autofagia/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , GMP Cíclico/agonistas , GMP Cíclico/metabolismo , Proteínas Quinasas Dependientes de GMP Cíclico/genética , Proteínas Quinasas Dependientes de GMP Cíclico/metabolismo , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 5/metabolismo , Encefalomielitis Autoinmune Experimental/enzimología , Encefalomielitis Autoinmune Experimental/genética , Encefalomielitis Autoinmune Experimental/patología , Estrés del Retículo Endoplásmico/efectos de los fármacos , Regulación de la Expresión Génica , Humanos , Ratones , Neuronas/enzimología , Neuronas/patología , Transducción de Señal , Médula Espinal/efectos de los fármacos , Médula Espinal/enzimología , Médula Espinal/patologíaRESUMEN
The central nervous system controls the innate immunity by modulating efferent neuronal networks. Recently, we have reported that central brain stimulation inhibits inflammatory responses. In the present study, we investigate whether spinal p38 mitogen-activated protein kinase (MAPK) affects joint inflammation in experimental arthritis. Firstly, we observed that intra-articular administration of zymosan in mice induces the phosphorylation of the spinal cord p38 MAPK. In addition, we demonstrated that spinal p38 MAPK inhibition with intrathecal injection of SB203580, a conventional and well-characterized inhibitor, prevents knee joint neutrophil recruitment, edema formation, experimental score and cytokine production. This local anti-inflammatory effect was completely abolished with chemical sympathectomy (guanethidine) and beta-adrenergic receptors blockade (nadolol). In conclusion, our results suggest that pharmacological strategies involving the modulation of spinal p38 MAPK circuit can prevent joint inflammation via sympathetic networks and beta-adrenoceptors activation.
Asunto(s)
Antiinflamatorios/farmacología , Artritis Experimental/prevención & control , Imidazoles/farmacología , Articulaciones/efectos de los fármacos , Infiltración Neutrófila/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacología , Piridinas/farmacología , Médula Espinal/efectos de los fármacos , Sistema Nervioso Simpático/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Animales , Antiinflamatorios/administración & dosificación , Artritis Experimental/enzimología , Artritis Experimental/inmunología , Artritis Experimental/fisiopatología , Relación Dosis-Respuesta a Droga , Imidazoles/administración & dosificación , Inyecciones Espinales , Articulaciones/inmunología , Articulaciones/inervación , Masculino , Ratones Endogámicos BALB C , Inhibidores de Proteínas Quinasas/administración & dosificación , Piridinas/administración & dosificación , Receptores Adrenérgicos beta/metabolismo , Transducción de Señal/efectos de los fármacos , Médula Espinal/enzimología , Médula Espinal/fisiopatología , Sistema Nervioso Simpático/metabolismo , Sistema Nervioso Simpático/fisiopatología , Factores de Tiempo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
AIM: To investigate the antinociceptive, antiedematogenic and chondroprotective effects of diacerein (DIA) in a model of joint inflammation induced by complete Freund's adjuvant (CFA), as well as to investigate the involvement of metalloproteinase (MMP)-9, transient receptor potential vanilloid 1 (TRPV1) and glial cells in DIA's action mechanism. METHODS: Complete Freund's adjuvant was injected into the knee joint of male rats. We observed mechanical and cold hypersensitivity, vocalization and spontaneous pain-related behaviors, as well as edema of the knee. Tissue samples of the knee were stained with Cason`s technique and the thickness of the condilus cartilage was measured. Immunohistochemical analysis was performed on the spinal cord using anti-GFAP (glial fibrillary acidic protein), anti-MMP and anti-TRPV1 antibodies. Sections of the dorsal horns of the spinal cord were captured and an optical density was obtained. RESULTS: Complete Freund's adjuvant induced mechanical and thermal hypersensitivity, as well as joint edema and changes in the synovial membrane and cartilage. DIA (30 mg/kg, orally, daily) significantly inhibited mechanical (58 ± 10-87 ± 3%) and thermal (66 ± 12-87 ± 8%) hypersensitivity, vocalization (83 ± 5-41 ± 11%), spontaneous pain score, joint swelling (60 ± 6-40 ± 9%), as well as the histological changes induced by CFA. In addition, DIA inhibited astrocyte activation, and prevented the increase of MMP-9 and TRPV1 expression in the spinal cord of the animals subjected to CFA injections. CONCLUSIONS: In short, this study shows that DIA reduces joint damage and hypersensitivity associated with inflammation induced by CFA through the inhibition of astroglial activation and decreases the expression of TRPV1 and MMP-9 in the rat spinal cord.
Asunto(s)
Analgésicos/farmacología , Antraquinonas/farmacología , Antirreumáticos/farmacología , Artritis Experimental/prevención & control , Conducta Animal/efectos de los fármacos , Articulaciones/efectos de los fármacos , Metaloproteinasa 9 de la Matriz/metabolismo , Inhibidores de la Metaloproteinasa de la Matriz/farmacología , Neuroglía/efectos de los fármacos , Médula Espinal/efectos de los fármacos , Canales Catiónicos TRPV/antagonistas & inhibidores , Animales , Artritis Experimental/enzimología , Artritis Experimental/patología , Artritis Experimental/psicología , Edema/enzimología , Edema/patología , Edema/prevención & control , Adyuvante de Freund , Articulaciones/patología , Masculino , Neuroglía/enzimología , Neuroglía/patología , Dolor Nociceptivo/inducido químicamente , Dolor Nociceptivo/enzimología , Dolor Nociceptivo/patología , Dolor Nociceptivo/psicología , Ratas Wistar , Médula Espinal/enzimología , Médula Espinal/patología , Médula Espinal/fisiopatología , Canales Catiónicos TRPV/metabolismo , Sensación Térmica/efectos de los fármacos , Factores de Tiempo , Vocalización Animal/efectos de los fármacosRESUMEN
BACKGROUND: Spinal cord injury (SCI) results in the development of chronic pain that is refractory to conventional treatment. Progesterone, a neuroprotective steroid, may offer a promising perspective in pain modulation after central injury. Here, we explore the impact of progesterone administration on the post-injury inflammatory cascade involving the enzymes cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at the spinal cord level. We also analyse pain behaviours, the profile of glial cell activation, and IκB-α mRNA levels, as an index of NF-κB transactivation. METHODS: We used biochemical, immunohistochemical and molecular techniques, as well as behavioural studies, to investigate the effects of progesterone in a well-characterized model of central neuropathic pain. RESULTS: Injured animals receiving progesterone presented reduced mRNA levels of the proinflammatory enzymes, as well as decreased COX-2 activity and nitrite levels, as compared to vehicle-treated injured rats. Further, animals receiving the steroid exhibited lower levels of IκB-α mRNA, suggesting decreased NF-κB transactivation. Progesterone administration also attenuated the injury-induced increase in the number of glial fibrillary acidic protein and OX-42 positive cells both at early and late time points after injury, and prevented the development of mechanical and thermal allodynia. Further, when injured rats received early progesterone administration for a critical period of time after injury, they did not display allodynic behaviours even after the treatment had stopped. CONCLUSIONS: Our results suggest that progesterone, by modulating early neuroinflammatory events triggered after SCI, may represent a useful strategy to prevent the development of central chronic pain.
Asunto(s)
Ciclooxigenasa 2/metabolismo , Hiperalgesia/tratamiento farmacológico , Neuralgia/tratamiento farmacológico , Óxido Nítrico Sintasa de Tipo II/metabolismo , Progesterona/uso terapéutico , Médula Espinal/efectos de los fármacos , Animales , Modelos Animales de Enfermedad , Hiperalgesia/enzimología , Hiperalgesia/etiología , Masculino , Neuralgia/enzimología , Neuralgia/etiología , Dimensión del Dolor , Progesterona/farmacología , Ratas , Ratas Sprague-Dawley , Médula Espinal/enzimología , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/enzimologíaRESUMEN
Characterization of auto-destructive mechanisms, leading to cell death after spinal cord injury (SCI) is important to prevent further damage to tissue. Heme oxygenase (HO) catalyzes the oxidation of heme to biliverdin and carbon monoxide (CO), as a response to cell damage. Products of HO action have biological effects, as antioxidant biliverdin. We evaluated the changes of HO activity after injury, and the effect of pharmacological treatments with hemin (an inducer) and (Sn)-protoporphyrin (an inhibitor, Sn-PPIX) of HO, upon motor recovery after SCI. Female Wistar rats were submitted to SCI by trauma and sacrificed at several times (2, 4, 8, 12 and 24h) after injury to evaluate HO activity. Additional groups of rats were treated with either hemin or Sn-PPIX, to evaluate motor recovery, spared spinal cord tissue and HO activity. Results showed that HO control activity was increased by effect of SCI, at all times evaluated, as compared to sham group values. Twenty-four hours after injury, HO activity was increased 7.2-fold by hemin treatment, as compared to SCI plus vehicle group values. In addition, animals treated with hemin 2 and 8h after SCI, showed a better motor recovery and higher spared cord tissue, as compared to control group values. Our findings indicate that activation of HO is a beneficial mechanism when attained during the acute phase after SCI.
Asunto(s)
Hemo Oxigenasa (Desciclizante)/metabolismo , Destreza Motora , Traumatismos de la Médula Espinal/fisiopatología , Animales , Relación Dosis-Respuesta a Droga , Activación Enzimática , Inducción Enzimática , Femenino , Hemo Oxigenasa (Desciclizante)/antagonistas & inhibidores , Hemina/farmacología , Metaloporfirinas/farmacología , Protoporfirinas/farmacología , Ratas , Ratas Wistar , Recuperación de la Función , Médula Espinal/efectos de los fármacos , Médula Espinal/enzimología , Traumatismos de la Médula Espinal/enzimología , Traumatismos de la Médula Espinal/patología , Factores de TiempoRESUMEN
The Na(+)/H(+) exchanger (NHE) is involved in the regulation of intracellular pH and volume by mediating the electroneutral transport of H(+) against an influx of Na(+) ions. Since NHE1 regulates pH in neurons and astrocytes and it is expressed in nociceptive nerve fibers, it is likely that NHE may modulate neuronal excitability and pain transmission. The purpose of this study was to assess the participation of peripheral and spinal NHE in the secondary allodynia/hyperalgesia induced by formalin. In addition, we determined whether formalin injection modifies the expression of NHE1 in lumbar dorsal root ganglia (DRG) and dorsal spinal cord. Subcutaneous injection of 0.5% formalin into the dorsal surface of the hind paw produced acute nociceptive behaviors (flinching and licking/lifting) followed by long-lasting bilateral secondary mechanical allodynia/hyperalgesia. Peripheral and intrathecal pre-treatment (-10min) with selective NHE inhibitors 5-(N,N-dimethyl)amiloride hydrochloride (DMA, 0.3-30µM), 5-(N-ethyl-N-isopropyl)amiloride (EIPA, 0.3-30µM) and [1-(quinolin-5-yl)-5-cyclopropyl-1H-pyrazole-4-carbonyl] guanidine dihydrochloride (zoniporide, 0.03-3µM) significantly increased 0.5% formalin-induced bilateral long-lasting secondary allodynia/hyperalgesia. Contrariwise, local peripheral or intrathecal post-treatment (day 6 postinjection) with these NHE inhibitors did not affect formalin-induced nociceptive behaviors. Formalin injection reduced NHE1 expression in ipsilateral and contralateral spinal dorsal horns from day 1 to 12. In addition, formalin diminished NHE1 protein expression in DRG at day 12. These results suggest that NHE1 plays a role in pain processing at peripheral and spinal levels in formalin-induced long-lasting nociceptive behaviors. Additionally, these results suggest that proteins involved in pH regulation could be targets for the development of new analgesic drugs.
Asunto(s)
Hiperalgesia/enzimología , Dimensión del Dolor/métodos , Nervios Periféricos/enzimología , Intercambiadores de Sodio-Hidrógeno/antagonistas & inhibidores , Intercambiadores de Sodio-Hidrógeno/biosíntesis , Médula Espinal/enzimología , Amilorida/administración & dosificación , Amilorida/análogos & derivados , Animales , Femenino , Hiperalgesia/inducido químicamente , Inyecciones Espinales , Dimensión del Dolor/efectos de los fármacos , Nervios Periféricos/efectos de los fármacos , Estimulación Física/efectos adversos , Ratas , Ratas Wistar , Intercambiador 1 de Sodio-Hidrógeno , Intercambiadores de Sodio-Hidrógeno/fisiología , Médula Espinal/efectos de los fármacosRESUMEN
The neonate opioid system has been frequently investigated, and studies have shown that exposure to drugs in early life can have implications for nervous system development. It has been proposed that adenosine is involved in opioid antinociception, and ATP is involved in central and peripheral mechanisms of nociception. Extracellular nucleotides can be hydrolyzed by E-NTPDases and ecto-5'nucleotidase, which present the functions of removing ATP and generating adenosine. In this study, we evaluated ATP, ADP, and AMP hydrolysis in synaptosomes from spinal cord and cerebral cortex of rats at postnatal day 16 after repeated morphine exposure in early life (postnatal day 8 to 14). Additionally, we evaluated E-NTPDase (1, 2 and 3) and ecto-5'nucleotidase gene expression by semi-quantitative RT-PCR analysis. We observed an increase in ATP hydrolysis in the cerebral cortex, and a decrease in ADP hydrolysis in spinal cord. Expression levels of E-NTPDase 1 decreased in cerebral cortex and increased in spinal cord. Our findings highlight the importance of the purinergic system in young rats submitted to repeated morphine exposure by showing that in the neonatal period such exposure is capable of affecting the control system for nucleotide levels, which can promote changes in modulation or transmission of painful stimuli.
Asunto(s)
Ácido Anhídrido Hidrolasas/genética , Ácido Anhídrido Hidrolasas/metabolismo , Corteza Cerebral/efectos de los fármacos , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Morfina/farmacología , Médula Espinal/efectos de los fármacos , Animales , Animales Recién Nacidos , Corteza Cerebral/citología , Corteza Cerebral/enzimología , Corteza Cerebral/metabolismo , Humanos , Masculino , Ratas , Ratas Wistar , Médula Espinal/citología , Médula Espinal/enzimología , Médula Espinal/metabolismo , Sinaptosomas/efectos de los fármacos , Sinaptosomas/enzimología , Sinaptosomas/metabolismo , Factores de TiempoRESUMEN
Glutathione (GSH) is a major non-enzymatic antioxidant which is present in all tissues. Its protective actions occur through different pathways such its role as a substrate of antioxidant enzymes, such as glutathione peroxidase (GPx) and glutathione-S-transferase (GST). Nitric oxide (NO) is involved in many physiological processes in the central nervous system, including nociception. In spite of much evidence concerning oxidative and nitrosative stress and neuropathic pain, the exact role of these molecules in pain processing is still unknown. Sciatic nerve transection (SNT) was employed to induce neuropathic pain in rats. Glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities, glutathione (GSH) content, GSH/GSSG ratio, nitric oxide metabolites (NOx) and neuronal nitric oxide synthase (nNOS) protein expression in the lumbosacral spinal cord were determined. All of these analyses were performed in the SNT and sham groups 1, 3, 7 and 15 days after surgery. There was an increase in GPx activity and in GSH content 3 days after surgery in both sham and SNT groups, but the GSH/GSSG ratio increased only in the SNT group in this time point. nNOS expression was upregulated 7 days post SNT. NOx was detected 1 day after surgery in sham and SNT groups, but at 7 and 15 days, the increase occurred only in SNT animals. These results support the role of the gluthatione system in pain physiology and highlight the involvement of NO as an important molecule related to nociception.
Asunto(s)
Antioxidantes/metabolismo , Glutatión/metabolismo , Óxido Nítrico Sintasa de Tipo I/metabolismo , Dolor/metabolismo , Nervio Ciático/lesiones , Médula Espinal/metabolismo , Análisis de Varianza , Animales , Western Blotting , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/metabolismo , Región Lumbosacra , Masculino , Óxido Nítrico/metabolismo , Dolor/enzimología , Ratas , Ratas Wistar , Médula Espinal/enzimología , Factores de TiempoRESUMEN
The effect of resveratrol on activity and expression of nitric oxide synthase (NOS) in the spinal cord of neuropathic rats was assessed. Spinal nerve ligation produced tactile allodynia along with a reduction of catalytic activity of the constitutive Ca(2+)-dependent NOS (eNOS and nNOS isoforms) in the ipsilateral dorsal horn, but not contralateral dorsal or ipsilateral or contralateral ventral, spinal cord at 1, 5, 10 and 15 days after surgery compared to naïve and sham-operated animals. Nerve ligation also induced a reduction of nNOS expression in the ipsilateral dorsal horn spinal cord at 10 and 15 days after surgery. Intrathecal resveratrol reduced allodynia and reversed the reduction of constitutive Ca(2+)-dependent NOS activity in the ipsilateral dorsal spinal cord. Moreover, resveratrol significantly reversed the reduction of nNOS expression in the ipsilateral dorsal horn spinal cord. Results show that spinal nerve ligation leads to development of tactile allodynia along with a reduction in constitutive Ca(2+)-dependent NOS activity and nNOS isoform expression in the ipsilateral dorsal horn. Data suggest that resveratrol may reduce tactile allodynia in neuropathic rats by restoring altered NOS activity and expression.
Asunto(s)
Antioxidantes/farmacología , Óxido Nítrico Sintasa de Tipo I/biosíntesis , Nervios Espinales/fisiología , Estilbenos/farmacología , Actinas/farmacología , Animales , Antioxidantes/administración & dosificación , Femenino , Inyecciones Espinales , Ligadura , Óxido Nítrico/fisiología , Dimensión del Dolor/efectos de los fármacos , Estimulación Física , Ratas , Ratas Wistar , Resveratrol , Médula Espinal/efectos de los fármacos , Médula Espinal/enzimología , Estilbenos/administración & dosificaciónRESUMEN
Neuropathic pain occurs as a result of peripheral or central nervous system injury. Its pathophysiology involves mainly a central sensitization mechanism that may be correlated to many molecules acting in regions involved in pain processing, such as the spinal cord. It has been demonstrated that reactive oxygen species (ROS) and signaling molecules, such as the serine/threonine protein kinase Akt, are involved in neuropathic pain mechanisms. Thus, the aim of this study was to provide evidence of this relationship. Sciatic nerve transection (SNT) was used to induce neuropathic pain in rats. Western blot analysis of Akt and 4-hydroxy-2-nonenal (HNE)-Michael adducts, and measurement of hydrogen peroxide (H(2)O(2)) in the lumbosacral spinal cord were performed. The main findings were found seven days after SNT, when there was an increase in HNE-Michael adducts formation, total and p-Akt expression, and H(2)O(2) concentration. However, one and 15 days after SNT, H(2)O(2) concentration was raised in both sham (animals that were submitted to surgery without nerve injury) and SNT groups, showing the high sensibility of this ROS to nociceptive afferent stimuli, not only to neuropathic pain. p-Akt also increased in sham and SNT groups one day post injury, but at 3 and 7 days the increase occurred exclusively in SNT animals. Thus, there is crosstalk between intracellular signaling pathways and ROS, and these molecules can act as protective agents in acute pain situations or play a role in the development of chronic pain states.
Asunto(s)
Neuralgia/enzimología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal , Aldehídos/metabolismo , Animales , Western Blotting , Activación Enzimática , Peróxido de Hidrógeno/metabolismo , Masculino , Neuralgia/patología , Fosfoproteínas/metabolismo , Ratas , Ratas Wistar , Médula Espinal/enzimología , Médula Espinal/patologíaRESUMEN
BACKGROUND: Morphine can inhibit inflammatory edema in experimental animals. The mechanisms and sites by which opioids exert this effect are still under debate. Since the spinal level is a site for modulation of the neurogenic component of inflammation, we investigated the effect of intrathecal (i.t.) administration of morphine, and the involvement of spinal nitric oxide (NO)/cyclic-guanosine monophosphate-GMP pathway in carrageenan (CG)-induced paw edema. METHODS: Male Wistar rats received i.t. injections of drugs (20 microL) 30 min before paw stimulation with CG (150 microg). Edema was measured as paw volume increase (mL), and neutrophil migration was evaluated indirectly by myeloperoxidase (MPO) assay. RESULTS: Morphine (37, 75, and 150 nmol) inhibited inflammatory edema, but had no effect on MPO activity. Coinjection with naloxone (64 nmol) reversed the effect of morphine. The corticosteroid synthesis inhibitor, aminoglutethimide (50 mg/kg, v.o.), administered 90 min before morphine injection did not modify its antiedematogenic effect. Low doses of the NO synthase inhibitor, N(omega)-nitro-L-arginine (L-NNA; 10 and 30 pmol) increased, while higher doses (3 and 30 nmol) inhibited edema. The guanylate cyclase inhibitor 1H-oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 21 and 42 nmol) increased, while the phosphodiesterase type 5 inhibitor sildenafil (0.15 and 1.5 nmol) inhibited paw edema. Coadministration of a subeffective dose of L-NNA (3 pmol) or ODQ (10 nmol) with morphine prevented its antiedematogenic effect, but sildenafil (0.15 nmol) rendered a subeffective dose of morphine effective (18 nmol). ODQ also prevented the antiedematogenic effect of the NO donor S-nitroso-N-acetyl-penicilamine. CONCLUSION: These results support the idea that morphine can act on opioid receptors at the spinal level to produce antiedematogenic, and that the NO/cGMP pathway seems to be an important mediator in this effect.
Asunto(s)
Analgésicos Opioides/administración & dosificación , Antiinflamatorios no Esteroideos/administración & dosificación , GMP Cíclico/metabolismo , Edema/prevención & control , Inflamación/prevención & control , Morfina/administración & dosificación , Óxido Nítrico/metabolismo , Médula Espinal/efectos de los fármacos , Animales , Carragenina , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Edema/etiología , Edema/metabolismo , Inhibidores Enzimáticos/farmacología , Guanilato Ciclasa/antagonistas & inhibidores , Guanilato Ciclasa/metabolismo , Inflamación/inducido químicamente , Inflamación/complicaciones , Inflamación/metabolismo , Inyecciones Espinales , Masculino , Naloxona/farmacología , Antagonistas de Narcóticos/farmacología , Infiltración Neutrófila/efectos de los fármacos , Neutrófilos/efectos de los fármacos , Neutrófilos/enzimología , Donantes de Óxido Nítrico/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Nitroarginina/farmacología , Oxadiazoles/farmacología , Peroxidasa/metabolismo , Inhibidores de Fosfodiesterasa/farmacología , Piperazinas/farmacología , Purinas/farmacología , Quinoxalinas/farmacología , Ratas , Ratas Wistar , S-Nitroso-N-Acetilpenicilamina/farmacología , Transducción de Señal/efectos de los fármacos , Citrato de Sildenafil , Médula Espinal/enzimología , Médula Espinal/metabolismo , Sulfonas/farmacología , Factores de TiempoRESUMEN
Sciatic axotomy in 2-day-old rats (P2) causes lumbar motoneuron loss, which could be associated with nitric oxide (NO) production. NO may be produced by three isoforms of synthase (NOS): neuronal (nNOS), endothelial (eNOS) and inducible (iNOS). We investigated NOS expression and NO synthesis in the lumbar enlargement of rats after sciatic nerve transection at P2 and treatment with the antioxidant melatonin (sc; 1 mg/kg). At time points ranging from P2 to P7, expression of each isoform was assessed by RT-PCR and immunohistochemistry; catalytic rates of calcium-dependent (nNOS, eNOS) and independent (iNOS) NOS were measured by the conversion of [3H]L-arginine to [3H]L-citrulline. All NOS isoforms were expressed and active in unlesioned animals. nNOS and iNOS were detected in some small cells in the parenchyma. Only endothelial cells were positive for eNOS. No NOS isoform was detected in motoneurons. Axotomy did not change these immunohistochemical findings, nNOS and iNOS mRNA expression and calcium-independent activity at all survival times. However, sciatic nerve transection reduced eNOS mRNA levels at P7 and increased calcium-dependent activity at 1 and 6 h. Melatonin did not alter NOS expression. Despite having no action on NOS activity in unlesioned controls the neurohormone enhanced calcium-dependent activity at 1 and 72 h and reduced calcium-independent catalysis at 72 h in lesioned rats. These results suggest that NOS isoforms are constitutive in the neonatal lumbar enlargement and are not overexpressed after sciatic axotomy. Changes in NO synthesis induced by axotomy and melatonin administration in the current model are discussed considering some beneficial and deleterious effects that NO may have.
Asunto(s)
Animales Recién Nacidos/metabolismo , Melatonina/farmacología , Proteínas del Tejido Nervioso/biosíntesis , Óxido Nítrico Sintasa de Tipo I/metabolismo , ARN Mensajero/biosíntesis , Nervio Ciático/metabolismo , Médula Espinal/metabolismo , Animales , Axotomía , Inmunohistoquímica , Óxido Nítrico/fisiología , Ratas , Ratas Wistar , Médula Espinal/enzimologíaRESUMEN
Oxidative stress has been implicated in motoneuron death secondary to axotomy in the neonatal period. We studied the effect of sciatic transection at P2 on the motoneuron population in the lumbar enlargement of newborn rats looking for a protective role of daily doses of the antioxidant melatonin. The animals were allowed to survive from P2 to P7, and the spinal cords were processed for immunohistochemistry for superoxide dismutase (SOD) isoforms 1 and 2 and nitric oxide synthase (nNOS) (at 2, 3, 5, and 7 days post-natum), histological neuron counting and immunoblotting for the SOD isoforms (both at 2, 3, and 7 days post-natum). Melatonin reduced by 75% motoneuron loss due to axotomy at P3 and P7. Neither sciatic transection nor melatonin induced any detectable changes in the immunoreactivity patterns of the enzymes. SOD1 was expressed diffusely in the cytoplasm of neurons and ependyma and in the nuclei of presumed glial cells from P2 to P7. SOD2 was detected in neurons and ependyma and its expression was similar to SOD1 at P2 but decreased later to a spotty cytoplasmic pattern in motoneurons. nNOS was localized to the cytoplasm of a few small cells in the ventral and dorsal horns and around the central canal. Immunoblotting at 1 day postaxotomy detected a significant increase in SOD1 expression in melatonin-treated axotomized rats and a decrease in controls after axotomy and vehicle. Blotting for SOD2 did not show significant changes between groups at any time. This study provides the first evidence that SOD2 immunostaining pattern varies during motoneuron postnatal development and that melatonin alters the expression of SOD1 in the present model of peripheral nerve injury.
Asunto(s)
Melatonina/uso terapéutico , Neuronas Motoras/efectos de los fármacos , Neuropatía Ciática/tratamiento farmacológico , Médula Espinal/citología , Superóxido Dismutasa/metabolismo , Factores de Edad , Animales , Animales Recién Nacidos , Antioxidantes/uso terapéutico , Western Blotting/métodos , Recuento de Células/métodos , Inmunohistoquímica/métodos , Región Lumbosacra , Neuronas Motoras/enzimología , Proteínas del Tejido Nervioso/metabolismo , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo I , Ratas , Neuropatía Ciática/cirugía , Médula Espinal/efectos de los fármacos , Médula Espinal/enzimología , Superóxido Dismutasa-1 , Factores de TiempoRESUMEN
Changes in transport, receptors and production of extracellular adenosine have been observed after induction of hyperthyroidism. Adenosine is associated with inhibitory actions such as reduction in release of excitatory neurotransmitters and antinociception at spinal site. In contrast, ATP acts as an excitatory neurotransmitter and produces pronociceptive actions. ATP may be completely hydrolyzed to adenosine by an enzyme chain constituted by an ATP diphosphohydrolase and an ecto-5'-nucleotidase, as previously described in the spinal cord. Thus, we now investigated the effects of the hyperthyroidism on adenine nucleotide hydrolysis in the spinal cord and verified the nociceptive response in this pathology during different phases of development. Hyperthyroidism was induced in male Wistar rats, aged 5, 60 and 330 days by daily intraperitoneal injections of L-thyroxine (T4) for 14 days. Nociception was assessed with a tail-flick apparatus. Rats starting the treatment aged 5 days demonstrated a significant increase in ADP and AMP hydrolysis and increased tail-flick latency (TFL). In contrast, in the spinal cord from hyperthyroid rats aged 60 and 330 days old, the hydrolysis of ATP, ADP and AMP were significantly decreased. Accordingly, the tail-flick latency was decreased, indicating a hyperalgesic response. These results suggest the involvement of ecto-nucleotidases in the control of the hyperthyroidism-induced nociceptive response in rats at distinct developmental stages.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Hipertiroidismo/enzimología , Hipertiroidismo/fisiopatología , Dolor/fisiopatología , Médula Espinal/enzimología , Sinaptosomas/enzimología , Adenosina Trifosfato/metabolismo , Animales , Hipertiroidismo/inducido químicamente , Masculino , Dimensión del Dolor , Ratas , Médula Espinal/anatomía & histología , Médula Espinal/crecimiento & desarrollo , Sinaptosomas/metabolismo , Tiroxina/toxicidadRESUMEN
The aim of this study was to examine the participation of nitrergic neurotransmission in the initiation of micturition hyperreflexia associated to cyclophosphamide (CP)-induced cystitis in rats. Micturition threshold volume was significantly reduced 4 h after CP administration (100 mg/kg, i.p.); this reduction was attenuated by intra-arterially injected N(G)-nitro-l-arginine-methyl ester (l-NAME), a non selective nitric oxide synthase (NOS) inhibitor, but not by intravesical infusion of S-methyl-l-thiocitrulline (l-SMTC), another structurally different NOS inhibitor. Interestingly, l-NAME failed to affect micturition threshold volume in normal rats. The magnitude of isolated detrusor strips contractions elicited by either carbachol or nerve activation was significantly reduced in CP-treated rats but was unaffected by the addition of N(G)-nitro-l-arginine (l-NOARG), a nonselective NOS inhibitor. In contrast, intrathecal l-NAME and l-SMTC but not N(G)-nitro-d-arginine-methyl ester (d-NAME) administration augmented the micturition threshold volume in CP-treated rats in an l-arginine preventable manner. As with the systemic injection, intrathecal l-NAME also did not affect the micturition threshold volume in normal rats. Four hours after CP injection, the number of neuronal NOS immunoreactive or nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) positive neurons in spinal lumbosacral segments (L6-S2) was not altered whereas the number of c-Fos immunoreactive neurons increased significantly in the dorsal gray commissural nucleus (DGC), the parasympathetic sacral nucleus (PSN) and lamina X of these segments. Ca(2+)-dependent, but not Ca(2+)-independent NOS activity increased significantly in spinal L6-S2 segments but not in thoracic segments of CP-treated rats. These data indicate that the micturition hyperreflexia observed in the initial hours of CP-induced cystitis is associated with an increase in Ca(2+)-dependent NOS activity in spinal L6-S2 segments suggesting an increased production of nitric oxide (NO). The increased production of NO in these spinal segments appears to be necessary for the initiation of the micturition hyperreflexia.
Asunto(s)
Cistitis/complicaciones , Óxido Nítrico Sintasa/metabolismo , Fibras Parasimpáticas Posganglionares/enzimología , Médula Espinal/enzimología , Vejiga Urinaria/inervación , Vejiga Urinaria/fisiopatología , Trastornos Urinarios/enzimología , Animales , Ciclofosfamida , Cistitis/inducido químicamente , Cistitis/fisiopatología , Inhibidores Enzimáticos/farmacología , Femenino , Inmunohistoquímica , Inyecciones Espinales , Músculo Liso/efectos de los fármacos , Músculo Liso/enzimología , NADPH Deshidrogenasa/metabolismo , NG-Nitroarginina Metil Éster/farmacología , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/enzimología , Óxido Nítrico/biosíntesis , Óxido Nítrico Sintasa/antagonistas & inhibidores , Fibras Parasimpáticas Posganglionares/fisiopatología , Proteínas Proto-Oncogénicas c-fos/efectos de los fármacos , Proteínas Proto-Oncogénicas c-fos/metabolismo , Ratas , Ratas Wistar , Reflejo Anormal/efectos de los fármacos , Médula Espinal/citología , Médula Espinal/fisiopatología , Micción/efectos de los fármacos , Micción/fisiología , Trastornos Urinarios/etiología , Trastornos Urinarios/fisiopatologíaRESUMEN
Diabetes is an endocrine and metabolic disorder often associated with erectile dysfunction and peripheral neuropathy. Among other factors, penile erection is induced by activation of nitric oxide synthase (NOS). Hypothalamic paraventricular nuclei neurons produce NO and project to spinal cord areas implicated in penile reflexes. These nuclei have shown an increase of NOS in streptozotocin-induced diabetic rats. NOS-containing neurons are identical to the populations of neurons selectively stained for NADPH-diaphorase activity. Using this technique, we have evaluated changes of NOS in the lumbar spinal cord of diabetic rats with or without insulin treatment. Positive staining was found in motoneurons, dorsal horn neurons (layer II), neurons surrounding the ependimus (layer X) and neurons at the intermediolateral cell column (ILCC). Diabetic animals showed significant decrease in reactive area and increase of the histochemical reaction in motoneurons from the sexual dimorphic nuclei and in neurons of the ILCC. A marked decrease of the number of reactive neurons was also observed in layer II. Morphologic alterations were observed in neurons of layer X as an increase in the percentage of multipolar neurons and a decrease in the number and length of secondary processes. The alterations observed in these animals were absent in the insulin treated diabetic animals. These results show the plasticity of lumbar spinal cord neurons, suggesting a direct participation of NO synthesis in the physiopathology of the erection dysfunction in diabetes.
Asunto(s)
Diabetes Mellitus Experimental/enzimología , NADPH Deshidrogenasa/metabolismo , Médula Espinal/enzimología , Animales , Diabetes Mellitus Experimental/tratamiento farmacológico , Disfunción Eréctil/enzimología , Insulina/farmacología , Insulina/uso terapéutico , Región Lumbosacra/fisiología , Masculino , Óxido Nítrico Sintasa/biosíntesis , Ratas , Ratas Sprague-Dawley , Médula Espinal/efectos de los fármacosRESUMEN
An increase in ADP hydrolysis was observed in spinal cord synaptosomal fractions of 2-month-old Wistar male rats, when compared to other ages (1, 4 and 6 months of age), while no change in ATPase activity was observed. Conversely, in female rats, whilst no change in ADPase activity was observed in the spinal cord synaptosomal fraction, ATPase activity diminished with age, in 1-6-month-old animals. 5'-Nucleotidase activity was higher in the 4-month-old male and female rats in relation to 1 and 2-month-old animals. In the female rats, this activity continued to increase at least until 6 months of age. In conclusion, adenine nucleotides hydrolysis in synaptosomes from rat spinal cord is influenced by age and by gender. Since both ATP and adenosine may act as neuromodulators in the spinal cord, influencing several processes such as nociception, the regulation of ATP-metabolizing enzymes in spinal cord is probably important for the normal function of this tissue at different ages.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Envejecimiento/fisiología , Médula Espinal/enzimología , Adenosina Difosfato/metabolismo , Adenosina Trifosfato/metabolismo , Análisis de Varianza , Animales , Femenino , Hidrólisis , Masculino , Ratas , Ratas Wistar , Factores Sexuales , Médula Espinal/citología , Sinaptosomas/enzimologíaRESUMEN
While increasing evidence points to a role for the nitric oxide (NO)/cyclic guanosine 3,5-monophosphate (GMPc) cascade in hyperalgesia and allodynia, participation of the NO/GMPc pathway in synaptic processing in the spinal cord, i.e. wind-up activity, is less clear. We studied the effects of intrathecal administration of Nomega-nitro-L-arginine methyl ester (L-NAME) and methylene blue, inhibitors of NO synthase and guanylate cyclase respectively, on wind-up activity developed in a C-fiber reflex response paradigm. 5, 10 and 20 microg i.t. of L-NAME or methylene blue did not modify spinal wind-up in normal rats, while a dose-dependent inhibition of wind-up was observed in monoarthritic rats. Results suggest that the NO/GMPc pathway plays a non-significant role in wind-up activity evoked in normal animals, while it may be essential in chronic pain processing.