RESUMO
Rutin, a naturally derived flavonoid molecule with known neuroprotective properties, has been demonstrated to have anticonvulsive potential, but the mechanism of this effect is still unclear. The current study aimed to investigate the probable antiseizure mechanisms of rutin in rats using the kainic acid (KA) seizure model. Rutin (50 and 100 mg kg-1) and carbamazepine (100 mg kg-1) were administered daily by oral gavage for 7 days before KA (15 mg kg-1) intraperitoneal (i.p.) injection. Seizure behavior, neuronal cell death, glutamate concentration, excitatory amino acid transporters (EAATs), glutamine synthetase (GS), glutaminase, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits GluA1 and GluA2, N-methyl-D-aspartate (NMDA) receptor subunits GluN2A and GluN2B, activated astrocytes, and inflammatory and anti-inflammatory molecules in the hippocampus were evaluated. Supplementation with rutin attenuated seizure severity in KA-treated rats and reversed KA-induced neuronal loss and glutamate elevation in the hippocampus. Decreased glutaminase and GluN2B, and increased EAATs, GS, GluA1, GluA2 and GluN2A were observed with rutin administration. Rutin pretreatment also suppressed activated astrocytes, downregulated the protein levels of inflammatory molecules [interleukin-1ß (IL-1ß), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), high mobility group Box 1 (HMGB1), interleukin-1 receptor 1 (IL-1R1), and Toll-like receptor-4 (TLR-4)] and upregulated anti-inflammatory molecule interleukin-10 (IL-10) protein expression. Taken together, the results indicate that the preventive treatment of rats with rutin attenuated KA-induced seizures and neuronal loss by decreasing glutamatergic hyperactivity and suppressing the IL-1R1/TLR4-related neuroinflammatory cascade.
Assuntos
Proteína HMGB1 , Ácido Caínico , Sistemas de Transporte de Aminoácidos , Animais , Anti-Inflamatórios/farmacologia , Carbamazepina , Glutamato-Amônia Ligase/metabolismo , Glutamato-Amônia Ligase/farmacologia , Ácido Glutâmico/metabolismo , Glutaminase/genética , Glutaminase/metabolismo , Glutaminase/farmacologia , Proteína HMGB1/genética , Proteína HMGB1/metabolismo , Hipocampo/metabolismo , Inflamação/induzido quimicamente , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Interleucina-10/metabolismo , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Ácido Caínico/efeitos adversos , N-Metilaspartato/efeitos adversos , N-Metilaspartato/metabolismo , Ratos , Receptores de Interleucina-1/metabolismo , Receptores de Interleucina-1/uso terapêutico , Rutina/metabolismo , Rutina/farmacologia , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológico , Convulsões/metabolismo , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/efeitos adversos , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/metabolismoRESUMO
Current anti-seizure drugs fail to control approximately 30% of epilepsies. Therefore, there is a need to develop more effective anti-seizure drugs, and medicinal plants provide an attractive source for new compounds. This study aimed to evaluate the possible anti-seizure and neuroprotective effects of neferine, an alkaloid from the lotus seed embryos of Nelumbo nucifera, in a kainic acid (KA)-induced seizure rat model and its underlying mechanisms. Rats were intraperitoneally (i.p.) administrated neferine (10 and 50 mg/kg) 30 min before KA injection (15 mg/kg, i.p.). Neferine pretreatment increased seizure latency and reduced seizure scores, prevented glutamate elevation and neuronal loss, and increased presynaptic protein synaptophysin and postsynaptic density protein 95 expression in the hippocampi of rats with KA. Neferine pretreatment also decreased glial cell activation and proinflammatory cytokine (interleukin-1ß, interleukin-6, tumor necrosis factor-α) expression in the hippocampi of rats with KA. In addition, NOD-like receptor 3 (NLRP3) inflammasome, caspase-1, and interleukin-18 expression levels were decreased in the hippocampi of seizure rats pretreated with neferine. These results indicated that neferine reduced seizure severity, exerted neuroprotective effects, and ameliorated neuroinflammation in the hippocampi of KA-treated rats, possibly by inhibiting NLRP3 inflammasome activation and decreasing inflammatory cytokine secretion. Our findings highlight the potential of neferine as a therapeutic option in the treatment of epilepsy.
Assuntos
Alcaloides , Antineoplásicos , Benzilisoquinolinas , Fármacos Neuroprotetores , Alcaloides/farmacologia , Alcaloides/uso terapêutico , Animais , Benzilisoquinolinas/farmacologia , Benzilisoquinolinas/uso terapêutico , Citocinas/metabolismo , Inflamassomos/metabolismo , Ácido Caínico/efeitos adversos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Ratos , Sementes/metabolismo , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológicoRESUMO
3ß,7ß,25-Trihydroxycucurbita-5,23(E)-dien-19-al (TCD) is a triterpenoid isolated from wild bitter gourd that is a common tropical vegetable with neuroprotective effects. Because excessive glutamate release is a major cause of neuronal damage in various neurological disorders, the aims of this study were to examine the effect of TCD on glutamate release in vitro and to examine the effect of TCD in vivo. In rat cerebrocortical synaptosomes, TCD reduced 4-aminopyridine (4-AP)-stimulated glutamate release and Ca2+ concentration elevation, but had no effect on plasma membrane potential. TCD-mediated inhibition of 4-AP-induced glutamate release was dependent on the presence of extracellular calcium; persisted in the presence of the glutamate transporter inhibitor dl-TBOA, P/Q-type Ca2+ channel blocker ω-agatoxin IVA, and intracellular Ca2+-releasing inhibitors dantrolene and CGP37157; and was blocked by the vesicular transporter inhibitor bafilomycin A1 and the N-type Ca2+ channel blocker ω-conotoxin GVIA. Molecular docking studies have demonstrated that TCD binds to N-type Ca2+ channels. TCD-mediated inhibition of 4-AP-induced glutamate release was abolished by the Ca2+-dependent protein kinase C (PKC) inhibitor Go6976, but was unaffected by the Ca2+-independent PKC inhibitor rottlerin. Furthermore, TCD considerably reduced the phosphorylation of PKC, PKCα, and myristoylated alanine-rich C kinase substrate, a major presynaptic substrate for PKC. In a rat model of kainic acid (KA)-induced excitotoxicity, TCD pretreatment substantially attenuated KA-induced neuronal death in the CA3 hippocampal region. These results suggest that TCD inhibits synaptosomal glutamate release by suppressing N-type Ca2+ channels and PKC activity and exerts protective effects against KA-induced excitotoxicity in vivo.
Assuntos
Ácido Glutâmico/metabolismo , Ácido Caínico/efeitos adversos , Momordica charantia/química , Doenças do Sistema Nervoso/tratamento farmacológico , Fármacos Neuroprotetores/administração & dosagem , Extratos Vegetais/administração & dosagem , Sinaptossomos/efeitos dos fármacos , Triterpenos/administração & dosagem , Animais , Cálcio/metabolismo , Bloqueadores dos Canais de Cálcio/administração & dosagem , Canais de Cálcio/genética , Canais de Cálcio/metabolismo , Morte Celular/efeitos dos fármacos , Humanos , Masculino , Doenças do Sistema Nervoso/genética , Doenças do Sistema Nervoso/metabolismo , Doenças do Sistema Nervoso/fisiopatologia , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Proteína Quinase C/genética , Proteína Quinase C/metabolismo , Ratos , Ratos Sprague-Dawley , Sinaptossomos/metabolismoRESUMO
Though succinate accumulation is associated with reactive oxygen species (ROS) production and neuronal injury, which play critical roles in epilepsy, it is unclear whether succinate accumulation contributes to the onset of epilepsy or seizures. We sought to investigate changes in succinate, oxidative stress, and mito-SOX levels, as well as mitophagy and neuronal change, in different status epilepticus (SE) rat models. Our results demonstrate that KA-induced SE was accompanied by increased levels of succinate, oxidative stress, and mito-SOX, as well as mitophagy and neuronal degeneration. The similarly increased levels of succinate, oxidative stress, and mito-SOX were also found in pilocarpine-induced SE. Moreover, the reduction of succinate accumulation by the inhibition of succinate dehydrogenase (SDH), malate/aspartate shuttle (MAS), or purine nucleotide cycle (PNC) served to reduce succinate, oxidative stress, and mito-SOX levels, thereby preventing oxidative stress-related neuronal damage and lessening seizure severity. Interestingly, simulating succinate accumulation with succinic acid dimethyl ester may induce succinate accumulation and increased oxidative stress and mito-SOX levels, as well as behavior and seizures in electroencephalograms similar to those observed in rats exposed to KA. Our results indicate that succinate accumulation may contribute to the increased oxidative stress/mitochondrial ROS levels, neuronal degeneration, and SE induced by KA administration. Furthermore, we found that succinate accumulation was mainly due to the inverse catalysis of SDH from fumarate, which was supplemented by the MAS and PNC pathways. These results reveal new insights into the mechanisms underlying SE and that reducing succinate accumulation may be a clinically useful therapeutic target in SE.
Assuntos
Ácido Caínico/efeitos adversos , Espécies Reativas de Oxigênio/metabolismo , Estado Epiléptico/induzido quimicamente , Ácido Succínico/metabolismo , Animais , Modelos Animais de Doenças , Eletroencefalografia , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitofagia/efeitos dos fármacos , Pilocarpina/efeitos adversos , Ratos , Estado Epiléptico/diagnóstico , Estado Epiléptico/metabolismo , Succinato Desidrogenase/metabolismoRESUMO
Oridonin (ORI) is a natural diterpenoid presented in some medicinal plants. The effects of pre-treatments from ORI against MPP+- or kainic acid (KA)-induced damage in nerve growth factor (NGF)-differentiated PC12â¯cells were investigated. Results showed that pre-treatments of ORI at 0.25-2⯵M enhanced the viability and plasma membrane integrity of NGF-differentiated PC12â¯cells. MPP+ or KA exposure down-regulated Bcl-2 mRNA expression, up-regulated Bax mRNA expression, increased caspase-3 activity and decreased Na+-K+ ATPase activity. ORI pre-treatments at test concentrations reversed these changes. ORI pre-treatments decreased reactive oxygen species production, raised glutathione level, and increased glutathione peroxidase, glutathione reductase and catalase activities in MPP+ or KA treated cells. ORI pre-treatments lowered tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6 and prostaglandin E2 levels in MPP+ or KA treated cells. ORI also diminished MPP+ or KA induced increase in nuclear factor-κB binding activity. MPP+ exposure suppressed tyrosine hydroxylase (TH) mRNA expression and decreased dopamine content. KA exposure reduced glutamine synthetase (GS) mRNA expression, raised glutamate level and lowered glutamine level. ORI pre-treatments at 0.5-2⯵M up-regulated mRNA expression of TH and GS, restored DA and glutamine content. These findings suggested that oridonin was a potent neuro-protective agent against Parkinson's disease and seizure.
Assuntos
1-Metil-4-fenilpiridínio/efeitos adversos , Diterpenos do Tipo Caurano/farmacologia , Ácido Caínico/efeitos adversos , Fármacos Neuroprotetores/farmacologia , Animais , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Membrana Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Citocinas/genética , Citocinas/metabolismo , Diterpenos do Tipo Caurano/toxicidade , Regulação para Baixo/efeitos dos fármacos , Glutamato-Amônia Ligase/genética , Glutamato-Amônia Ligase/metabolismo , Fármacos Neuroprotetores/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Células PC12 , RNA Mensageiro/metabolismo , Ratos , Espécies Reativas de Oxigênio/metabolismo , Tirosina 3-Mono-Oxigenase/genética , Tirosina 3-Mono-Oxigenase/metabolismo , Regulação para Cima/efeitos dos fármacosRESUMO
Seizures produce brain inflammation, which in turn enhances neuronal excitability. Therefore, anti-inflammation has become a therapeutic strategy for antiepileptic treatment. Cycloxygenase-2 (COX-2) plays a critical role in postseizure brain inflammation and neuronal hyperexcitability. Our previous studies have shown that both electrical stimulation (ES) at the ear and electro-acupuncture (EA) at the Zusanli and Shangjuxu acupoints (ST36-ST37) for 6 weeks can reduce mossy fiber sprouting, spike population, and high-frequency hippocampal oscillations in kainic acid (KA)-induced epileptic seizure rats. This study further investigated the effect of long-term ear ES and EA at ST36-ST37 on the inflammatory response in KA-induced epileptic seizure rats. Both the COX-2 levels in the hippocampus and the number of COX-2 immunoreactive cells in the hippocampal CA1 region were increased after KA-induced epileptic seizures, and these were reduced through the 6-week application of ear ES or EA at ST36-ST37. Thus, long-term ear ES or long-term EA at ST36-ST37 have an anti-inflammatory effect, suggesting that they are beneficial for the treatment of epileptic seizures.
Assuntos
Pontos de Acupuntura , Região CA1 Hipocampal/metabolismo , Ciclo-Oxigenase 2/genética , Estimulação Elétrica , Eletroacupuntura , Ácido Caínico/efeitos adversos , Convulsões/etiologia , Convulsões/metabolismo , Animais , Biomarcadores , Região CA1 Hipocampal/fisiopatologia , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Ciclo-Oxigenase 2/metabolismo , Epilepsia/etiologia , Epilepsia/metabolismo , Epilepsia/fisiopatologia , Epilepsia/terapia , Imunofluorescência , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Masculino , Ratos , Receptores CCR2/genética , Receptores CCR2/metabolismo , Subunidade beta da Proteína Ligante de Cálcio S100/genética , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Convulsões/fisiopatologia , Convulsões/terapia , Fatores de TempoRESUMO
Interest in the health benefits of flavonoids, particularly their effects on neurodegenerative disease, is increasing. This study evaluated the role of baicalein, a flavonoid compound isolated from the traditional Chinese medicine Scutellaria baicalensis, in glutamate release and glutamate neurotoxicity in the rat hippocampus. In the rat hippocampal nerve terminals (synaptosomes), baicalein inhibits depolarization-induced glutamate release, and this phenomenon is prevented by chelating the extracellular Ca[Formula: see text] ions and blocking presynaptic Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel activity. In slice preparations, whole cell patch-clamp experiments revealed that baicalein reduced the frequency of miniature excitatory postsynaptic currents, without affecting their amplitude. In a kainic acid rat model, intraperitoneally administering baicalein to rats before the kainic acid intraperitoneal injection substantially attenuated kainic acid-induced neuronal cell death, c-Fos expression, and the activation of the mammalian target of rapamycin in the hippocampus. This study is the first to demonstrate that the natural compound baicalein inhibits glutamate release from hippocampal nerve terminals, and executes a protective action against kainic acid-induced excitotoxicity in vivo. The findings enhance the understanding of baicalein's action in the brain, and suggest that this natural compound is valuable for treating brain disorders related to glutamate excitotoxicity.
Assuntos
Encefalopatias/tratamento farmacológico , Encefalopatias/fisiopatologia , Flavanonas/administração & dosagem , Ácido Glutâmico/toxicidade , Neurônios/efeitos dos fármacos , Extratos Vegetais/administração & dosagem , Substâncias Protetoras/administração & dosagem , Animais , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Encefalopatias/genética , Encefalopatias/metabolismo , Cálcio/metabolismo , Canais de Cálcio Tipo N/genética , Canais de Cálcio Tipo N/metabolismo , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Humanos , Ácido Caínico/efeitos adversos , Masculino , Neurônios/metabolismo , Ratos , Ratos Sprague-Dawley , Scutellaria baicalensis/metabolismoRESUMO
Peripheral inflammation alters AMPA receptor (AMPAR) subunit trafficking and increases AMPAR Ca(2+) permeability at synapses of spinal dorsal horn neurons. However, it is unclear whether AMPAR trafficking at extrasynaptic sites of these neurons also changes under persistent inflammatory pain conditions. Using patch-clamp recording combined with Ca(2+) imaging and cobalt staining, we found that, under normal conditions, an extrasynaptic pool of AMPARs in rat substantia gelatinosa (SG) neurons of spinal dorsal horn predominantly consists of GluR2-containing Ca(2+)-impermeable receptors. Maintenance of complete Freund's adjuvant (CFA)-induced inflammation was associated with a marked enhancement of AMPA-induced currents and [Ca(2+)](i) transients in SG neurons, while, as we previously showed, the amplitude of synaptically evoked AMPAR-mediated currents was not changed 24 h after CFA. These findings indicate that extrasynaptic AMPARs are upregulated and their Ca(2+) permeability increases dramatically. This increase occurred in SG neurons characterized by intrinsic tonic firing properties, but not in those exhibited strong adaptation. This increase was also accompanied by an inward rectification of AMPA-induced currents and enhancement of sensitivity to a highly selective Ca(2+)-permeable AMPAR blocker, IEM-1460. Electron microcopy and biochemical assays additionally showed an increase in the amount of GluR1 at extrasynaptic membranes in dorsal horn neurons 24h post-CFA. Taken together, our findings indicate that CFA-induced inflammation increases functional expression and proportion of extrasynaptic GluR1-containing Ca(2+)-permeable AMPARs in tonically firing excitatory dorsal horn neurons, suggesting that the altered extrasynaptic AMPAR trafficking might participate in the maintenance of persistent inflammatory pain.
Assuntos
Potenciais de Ação/fisiologia , Inflamação/patologia , Células do Corno Posterior/metabolismo , Receptores de AMPA/metabolismo , Medula Espinal/patologia , Animais , Biotinilação/métodos , Cálcio/metabolismo , Modelos Animais de Doenças , Estimulação Elétrica/métodos , Agonistas de Aminoácidos Excitatórios/efeitos adversos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Adjuvante de Freund/efeitos adversos , Técnicas In Vitro , Inflamação/induzido quimicamente , Ácido Caínico/efeitos adversos , Masculino , Microscopia Imunoeletrônica/métodos , Técnicas de Patch-Clamp/métodos , Células do Corno Posterior/fisiopatologia , Células do Corno Posterior/ultraestrutura , Ratos , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologiaRESUMO
Status epilepticus (SE) in adulthood dramatically alters the hippocampus and produces spatial learning and memory deficits. Some factors, like environmental enrichment and exercise, may promote functional recovery from SE. Prenatal choline supplementation (SUP) also protects against spatial memory deficits observed shortly after SE in adulthood, and we have previously reported that SUP attenuates the neuropathological response to SE in the adult hippocampus just 16 days after SE. It is unknown whether SUP can ameliorate longer-term cognitive and neuropathological consequences of SE, whether repeatedly engaging the injured hippocampus in a cognitive task might facilitate recovery from SE, and whether our prophylactic prenatal dietary treatment would enable the injured hippocampus to more effectively benefit from cognitive rehabilitation. To address these issues, adult offspring from rat dams that received either a control (CON) or SUP diet on embryonic days 12-17 first received training on a place learning water maze task (WM) and were then administered saline or kainic acid (KA) to induce SE. Rats then either remained in their home cage, or received three additional WM sessions at 3, 6.5, and 10 weeks after SE to test spatial learning and memory retention. Eleven weeks after SE, the brains were analyzed for several hippocampal markers known to be altered by SE. SUP attenuated SE-induced spatial learning deficits and completely rescued spatial memory retention by 10 weeks post-SE. Repeated WM experience prevented SE-induced declines in glutamic acid decarboxylase (GAD) and dentate gyrus neurogenesis, and attenuated increased glial fibrilary acidic protein (GFAP) levels. Remarkably, SUP alone was similarly protective to an even greater extent, and SUP rats that were water maze trained after SE showed reduced hilar migration of newborn neurons. These findings suggest that prophylactic SUP is protective against the long-term cognitive and neuropathological effects of KA-induced SE, and that rehabilitative cognitive enrichment may be partially beneficial.
Assuntos
Colina/administração & dosagem , Hipocampo , Ácido Caínico/efeitos adversos , Fenômenos Fisiológicos da Nutrição Pré-Natal/fisiologia , Estado Epiléptico , Animais , Feminino , Proteína Glial Fibrilar Ácida/metabolismo , Glutamato Descarboxilase/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/patologia , Humanos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Transtornos da Memória/patologia , Neurogênese/efeitos dos fármacos , Neurogênese/fisiologia , Neurônios/fisiologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Ratos , Ratos Sprague-Dawley , Retenção Psicológica/efeitos dos fármacos , Percepção Espacial/efeitos dos fármacos , Percepção Espacial/fisiologia , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/dietoterapia , Estado Epiléptico/patologia , Estado Epiléptico/prevenção & controleRESUMO
Searsia species are used in South Africa to treat epilepsy. Previous studies have demonstrated an in vitro N-methyl-D-aspartic acid (NMDA) receptor antagonistic effect of the ethanolic leaf extract. The aim of this study was to evaluate the potential anticonvulsant properties of the ethanolic extract of S. dentata in various animal models of epilepsy. The extract was submitted to a screening in anticonvulsant assays including NMDA-, kainic acid (KA)-, pentylenetetrazol (PTZ)- and bicuculline (BIC)-induced seizures in rats. The extract protected 47% of the PN 18 Wistar pups (postnatal day 18, date of birth PN 0) (p < 0.05, n > 10) against NMDA-induced seizures and significantly delayed the onset of PTZ-induced seizures (p < 0.05, n > 8) at a dose of 250 mg/kg. A dose optimum was detected at 500 mg/kg for protection against KA-(63% protection, p < 0.05, n > 8) and BIC-induced seizures (50% protection, p < 0.05, n > 8) in young adult and PN 18 rats, respectively. The ethanolic extract of S. dentata showed anticonvulsive properties in several models of epilepsy. These results are compatible with previous findings of NMDA receptor antagonism. Due to the complex composition of the extract, the effect might be caused by more than one compound.
Assuntos
Anacardiaceae/química , Anticonvulsivantes/farmacologia , Extratos Vegetais/farmacologia , Convulsões/prevenção & controle , Animais , Bicuculina/efeitos adversos , Modelos Animais de Doenças , Epilepsia/tratamento farmacológico , Ácido Caínico/efeitos adversos , Masculino , N-Metilaspartato/efeitos adversos , Pentilenotetrazol/efeitos adversos , Folhas de Planta/química , Ratos , Ratos Wistar , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Convulsões/tratamento farmacológicoRESUMO
Gastrodia elata (Orchidaceae) is a Chinese herb. Our previous study showed that Gastrodia elata is able to reduce epileptic seizures, oxygen free radicals, microglia activation, and apoptosis in kainic acid (KA)-treated rats. Activator protein 1 (AP-1) is involved in modulating the neuronal plasticity and apoptosis. Therefore, the aim of this study was to investigate the role of AP-1 in antiepileptic effect of Gastrodia elata. Gastrodia elata (0.5, 1.0g/kg) or valproic acid (VA, 250mg/kg) was administered orally in Sprague-Dawley rats for 1 week before and 2 weeks after intraperitoneal injection of KA. Protein levels of AP-1 were determined by measuring c-Jun and c-Fos proteins, and the mitogen-activated protein (MAP) kinases activations were determined by measuring the phosphorylations of extracellular signal-regulated kinases, p38, and c-Jun N-terminal kinases (JNKs) in the frontal cortex and the hippocampus of rat brain using Western blotting. These results indicated that pre-treatment with Gastrodia elata or VA activated JNK signal pathway and c-Jun expression, while post-treatment with Gastrodia elata or VA suppressed both the JNK signaling pathway and the c-Jun expression induced by KA. These findings suggested that Gastrodia elata regulated the AP-1 expression via the JNK signaling pathway in KA-induced epilepsy.
Assuntos
Anticonvulsivantes/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , Epilepsia/tratamento farmacológico , Gastrodia , Proteínas Quinases JNK Ativadas por Mitógeno/efeitos dos fármacos , Fator de Transcrição AP-1/efeitos dos fármacos , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Epilepsia/induzido quimicamente , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Ácido Caínico/efeitos adversos , Masculino , Fosforilação , Fitoterapia/métodos , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , Fator de Transcrição AP-1/metabolismoRESUMO
1. Ingestion of a poisonous mushroom Clitocybe acromelalga is known to cause severe tactile pain (allodynia) in the extremities for a month and acromelic acid (ACRO), a kainate analogue isolated from the mushroom, produces selective damage of interneurons of the rat lower spinal cord when injected either systemically or intrathecally. Since ACRO has two isomers, ACRO-A and ACRO-B, here we examined their acute and late effects on induction of allodynia. 2. Intrathecal administration of ACRO-A and ACRO-B provoked marked allodynia by the first stimulus 5 min after injection, which lasted over the 50-min experimental period. Dose-dependency of the acute effect of ACRO-A on induction of allodynia showed a bell-shaped pattern from 50 ag x kg(-1) to 0.5 pg x kg(-1) and the maximum effect was observed at 50 fg x kg(-1). On the other hand, ACRO-B induced allodynia in a dose-dependent manner from 50 pg x kg(-1) to 50 ng x kg(-1). 3. N-methyl-d-aspartate (NMDA) receptor antagonists and Joro spider toxin, a Ca(2+)-permeable AMPA receptor antagonist, inhibited the allodynia induced by ACRO-A, but not by ACRO-B. However, other AMPA/kainate antagonists did not affect the allodynia induced by ACRO. 4. Whereas no neuronal damage was observed in the spinal cord in ACRO-A-treated mice, induction of allodynia by ACRO-A (50 fg x kg(-1)) and ACRO-B (50 ng x kg(-1)) was selectively lost 1 week after i.t. injection of a sublethal dose of ACRO-A (50 ng x kg(-1)) or ACRO-B (250 ng x kg(-1)). Higher doses of ACRO-A, however, could evoke allodynia dose-dependently from 50 pg x kg(-1) to 500 ng x kg(-1) in the ACRO-A-treated mice. The allodynia induced by ACRO-A (500 ng x kg(-1)) was not inhibited by Joro spider toxin or NMDA receptor antagonists. These properties of the late allodynia induced by ACRO-A were quite similar to those of the acute allodynia induced by ACRO-B. 5. ACRO-A could increase [Ca(2+)](i) in the deeper laminae, rather than in the superficial laminae, of the spinal cord. This increase was not blocked by the AMPA-preferring antagonist GYKI52466 and Joro spider toxin. 6. Taken together, these results demonstrate the stereospecificity of ACRO for the induction of allodynia and suggest the presence of a receptor specific to ACRO.
Assuntos
Compostos Heterocíclicos/efeitos adversos , Ácido Caínico/análogos & derivados , Ácido Caínico/efeitos adversos , Dor/induzido quimicamente , Relação Estrutura-Atividade , Animais , Basidiomycota/química , Basidiomycota/isolamento & purificação , Benzodiazepinas/farmacologia , Maleato de Dizocilpina/farmacologia , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos/métodos , Glutamatos/farmacologia , Compostos Heterocíclicos/administração & dosagem , Indóis/farmacologia , Injeções Espinhais , Japão , Ácido Caínico/administração & dosagem , Ácido Caínico/antagonistas & inibidores , Ácido Caínico/química , Região Lombossacral/lesões , Região Lombossacral/patologia , Masculino , Camundongos , Camundongos Endogâmicos , Intoxicação Alimentar por Cogumelos/complicações , Oximas/farmacologia , Dor/complicações , Dor/prevenção & controle , Quinoxalinas/farmacologia , Receptores de AMPA/administração & dosagem , Receptores de AMPA/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/administração & dosagem , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Venenos de Aranha/farmacologia , Medula Espinal/efeitos dos fármacos , Medula Espinal/patologia , Medula Espinal/ultraestrutura , Estereoisomerismo , Fatores de Tempo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologiaRESUMO
Parenteral injection of kainic acid (KA), a glutamate receptor agonist, causes severe and stereotyped behavioral convulsions in mice and is used as a rodent model for human temporal lobe epilepsy. The goal of this study is to examine the potential anti-convulsive effects of the neuro-active amino acid taurine, in the mouse model of KA-induced limbic seizures. We found that taurine (43 mg/Kg, s.c.) had a significant antiepileptic effect when injected 10 min prior to KA. Acute injection of taurine increased the onset latency and reduced the occurrence of tonic seizures. Taurine also reduced the duration of tonic-clonic convulsions and mortality rate following KA-induced seizures. Furthermore, taurine significantly reduced neuronal cell death in the CA3 region of the hippocampus, the most susceptible region to KA in the limbic system. On the other hand, supplementation of taurine in drinking water (0.05%) for 4 continuous weeks failed to decrease the number or latency of partial or tonic-clonic seizures. To the contrary, we found that taurine-fed mice showed increased susceptibility to KA-induced seizures, as demonstrated by a decreased latency for clonic seizures, an increased incidence and duration of tonic-clonic seizures, increased neuronal death in the CA3 region of the hippocampus and a higher post-seizure mortality of the animals. We suggest that the reduced susceptibility to KA-induced seizures in taurine-injected mice is due to an increase in GABA receptor function in the brain which increases the inhibitory drive within the limbic system. This is supported by our in vitro data obtained in primary neuronal cultures showing that taurine acts as a low affinity agonist for GABA(A) receptors, protects neurons against kainate excitotoxic insults and modulates calcium homeostasis. Therefore, taurine is potentially capable of treating seizure-associated brain damage.
Assuntos
Epilepsia/tratamento farmacológico , Taurina/uso terapêutico , Animais , Agonistas dos Canais de Cloreto , Canais de Cloreto/efeitos dos fármacos , Epilepsia/induzido quimicamente , Ácido Caínico/efeitos adversos , Masculino , Receptores de GABA-A/efeitos dos fármacos , Taurina/farmacologiaRESUMO
The neuroprotective effects of a water fraction from the methanol extract of Ixeris dentata (WFID) against oxidative stress in the brain of mice challenged with kainic acid were examined by evaluating behavioral characteristics and biochemical parameters of oxidative stress. Male ICR mice were divided into three groups: a control group that received no treatment and two groups challenged with kainic acid either with or without WFID (1.0 g/kg) for 4 consecutive days. On day 3 kainic acid (50 mg/kg) was intraperitoneally administered in the two challenged groups. When compared with the vehicle-treated control, no significant changes in body and brain weights were observed in mice administered WFID. Administration of kainic acid only caused a lethality of approximately 62.5%, and resulted in a significant decrease of total glutathione concentrations in the brain tissue. When WFID was investigated for neuroprotective action, WFID reduced the lethality (37.5%) of kainic acid, and the behavioral signs of its neurotoxicity. Moreover, the administration of WFID restored the glutathione concentrations in the cytosolic fraction of brain homogenate to control levels (P <.05). Furthermore, glutathione peroxidase activity was restored significantly (Plt;.05) in the cytosolic portion of brain homogenate, whereas glutathione reductase activity was not. These results suggest that I. dentata contains a functional agent that protects against oxidative stress in the brains of mice.
Assuntos
Asteraceae/química , Encéfalo/metabolismo , Glutationa/metabolismo , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Animais , Encéfalo/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/efeitos adversos , Agonistas de Aminoácidos Excitatórios/farmacologia , Ácido Caínico/efeitos adversos , Ácido Caínico/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos ICR , Distribuição AleatóriaRESUMO
We developed three models of reversible magnesium depletion in rats resulting from the combined effects of kainic (KA) acid with magnesium deficiency, in order to compare the effects of various common magnesium salts (pidolate, aspartate, lactate, gluconate and chloride) and of magnesium acetyl taurinate (MgATa), administered daily (14 mg Mg2+, PO) for ten days. First, the immediate effects (wet dog shakes, clonic convulsions and death 1 h after injection) and late effects (fall from hole board between the second and tenth days post injection) of kainic acid at three different doses (3.6 and 11 mg/kg) were studied in magnesium deficient rats (50 ppm for 40 days) and in non-deficient rats (1700 ppm). The results showed that the effects of kainic acid were enhanced in magnesium deficient rats. Secondly, after ten days of physiological then pharmacological doses of magnesium, used as chronical supplementation, we showed that kainic acid administration combined with magnesium deficiency led to magnesium depletion of increasing severity depending on the dose of kainic acid. The observed magnesium depletions were weak at a dose of 3 mg/kg KA, moderate at a dose of 6 mg/kg and severe at a dose of 11 mg/kg. These depletions were more or less reversible, and this enabled the classification of the therapeutic effects of these salts on Mg depletion. Among common salts, magnesium pidolate presented the greatest efficacy but none of them fully prevented depletion. In contrast, MgATa was efficient on all the aspects of depletion, when administered preventively both chronically or acutely or as a single curative injection. Consequently the results we obtained in the present study, on a new model of magnesium depletion, showed the greatest efficacy of magnesium acetyl taurinate we demonstrated yet on other models of reversible magnesium depletion.