RESUMEN
Our previous findings indicate that HCN2 contributes to oxaliplatin-induced neuropathic pain, but the mechanisms underlying the development of neuropathic pain are still unclear. Here, we found that the rat HCN2 levels significantly increased after high-frequency stimulation-induced long-term potentiation (LTP). Spinal local application of ZD7288 (a cyclic-nucleotide-gated-channel-specific inhibitor) prevented LTP induction after intraperitoneal injection of oxaliplatin. In addition, oxaliplatin administration induced spinal LTP via activation of the CaMKII-CREB cascade in the rat spinal dorsal horn. Moreover, we found that administration of oxaliplatin significantly increased the amplitude of excitatory postsynaptic currents and the number of action potentials, but these effects were attenuated by pretreatment with either CaMKII inhibitor KN-93 or NR2B antagonist Ro 25-6981. An increase in the phosphorylation of spinal N-methyl-d-aspartate (NMDA) receptor subunit 1 (NR1) after oxaliplatin administration was weakened by ZD7288 pretreatment. Administration of noncompetitive NMDA receptor antagonist MK-801 blocked oxaliplatin-evoked CaMKII-CREB cascade activation and prevented HCN2-mediated spinal-LTP induction in vitro and suppressed neuropathic-pain behaviors of rats. All these data suggest that HCN2 contributes to the development of neuropathic pain by inducing spinal LTP via activation of NMDA receptor-mediated CaMKII signaling.
Asunto(s)
Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Canales Regulados por Nucleótidos Cíclicos Activados por Hiperpolarización/biosíntesis , Potenciación a Largo Plazo/fisiología , Neuralgia/metabolismo , Oxaliplatino/toxicidad , Canales de Potasio/biosíntesis , Receptores de N-Metil-D-Aspartato/metabolismo , Animales , Potenciación a Largo Plazo/efectos de los fármacos , Masculino , Neuralgia/inducido químicamente , Ratas , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Médula Espinal/efectos de los fármacos , Médula Espinal/metabolismoRESUMEN
Emerging evidence showed that hyperpolarization-activated cation channels (HCN) participate in the development of inflammatory and neuropathic pain. However, the role of HCN2 in oxaliplatin-induced neuropathic pain remains unknown. Here, we found that HCN2 expression was upregulated in a rat model of oxaliplatin-induced neuropathic pain. Intrathecal injection of ZD7288, an HCN specific inhibitor, decreased the HCN2 level, as well as weakened the neuropathic pain behaviors compared to naive rats. Besides, mechanistic studies revealed that the expression of the spinal N-methyl-D-aspartate receptor subunit 2B was increased after oxaliplatin administration and was reduced by ZD7288 administration. The nociceptive behaviors were reversed by NR2B antagonist Ro 25-6981 in HCN2-overexpression rats. Furthermore, the underlying cellular mechanism demonstrated that ZD7288 administration restrained the enhanced activation of the neuronal calcium-calmodulin-dependent kinase II (CaMKII)/cyclic adenosine monophosphate response element-binding protein cascade after oxaliplatin administration. Moreover, pretreatment of CaMKII inhibitor KN-93 suppressed the nociceptive behaviors, as well as NR2B upregulation induced by overexpression of HCN2. In a word, HCN2 is conducive to oxaliplatin-induced neuropathic pain by activating the neuronal CaMKII/CREB cascade.
Asunto(s)
Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Canales Regulados por Nucleótidos Cíclicos Activados por Hiperpolarización/metabolismo , Neuralgia/inducido químicamente , Neuralgia/metabolismo , Neuronas/metabolismo , Compuestos Organoplatinos/efectos adversos , Canales de Potasio/metabolismo , Médula Espinal/patología , Animales , Conducta Animal , Modelos Animales de Enfermedad , Masculino , Neuralgia/patología , Neuronas/patología , Oxaliplatino , Ratas Sprague-Dawley , Receptores de N-Metil-D-Aspartato/metabolismo , Transducción de Señal , Regulación hacia ArribaRESUMEN
Seawater drowning-induced acute lung injury (ALI) is a serious clinical condition characterized by increased alveolar-capillary permeability, excessive inflammatory responses, and refractory hypoxemia. However, current therapeutic options are largely supportive; thus, it is of great interest to search for alternative agents to treat seawater aspiration-induced ALI. Erythropoietin (EPO) is a multifunctional agent with antiinflammatory, antioxidative, and antiapoptotic properties. However, the effects of EPO on seawater aspiration-induced ALI remain unclear. In the present study, male rats were randomly assigned to the naive group, normal saline group, seawater group, or seawater + EPO group. EPO was administered intraperitoneally at 48 and 24 h before seawater aspiration. Arterial blood gas analysis was performed with a gas analyzer at baseline, 30 min, 1 h, 4 h, and 24 h after seawater aspiration, respectively. Histological scores, computed tomography scan, nuclear factor kappa B p65, inducible nitric oxide synthase, caspase-3, tumor necrosis factor-alpha, interleukin (IL)-1ß, IL-6, IL-10, wet-to-dry weight ratio, myeloperoxidase activity, malondialdehyde, and superoxide dismutase in the lung were determined 30 min after seawater aspiration. Our results showed that EPO pretreatment alleviated seawater aspiration-induced ALI, as indicated by increased arterial partial oxygen tension and decreased lung histological scores. Furthermore, EPO pretreatment attenuated seawater aspiration-induced increase in the expressions of pulmonary nuclear factor kappa B p65, inducible nitric oxide synthase, caspase-3, tumor necrosis factor-alpha, IL-1ß, myeloperoxidase activity, and malondialdehyde when compared with the seawater group. Collectively, our study suggested that EPO pretreatment attenuates seawater aspiration-induced ALI by down-regulation of pulmonary pro-inflammatory cytokines, oxidative stress, and apoptosis.
Asunto(s)
Lesión Pulmonar Aguda/prevención & control , Antiinflamatorios/uso terapéutico , Antioxidantes/uso terapéutico , Apoptosis/efectos de los fármacos , Citocinas/metabolismo , Ahogamiento/patología , Eritropoyetina/uso terapéutico , Estrés Oxidativo/efectos de los fármacos , Lesión Pulmonar Aguda/inducido químicamente , Lesión Pulmonar Aguda/tratamiento farmacológico , Animales , Análisis de los Gases de la Sangre , Caspasa 3/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Interleucina-10/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Pulmón/patología , Masculino , Malondialdehído/metabolismo , FN-kappa B/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Oxígeno/sangre , Peroxidasa/metabolismo , Ratas , Ratas Sprague-Dawley , Agua de Mar/efectos adversos , Superóxido Dismutasa/metabolismo , Tomografía Computarizada por Rayos X , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Sepsis-associated encephalopathy (SAE) is a common complication after sepsis development, which is associated with the poor prognosis. However, no effective agent is currently available to treat this complication. The objective of the present study was to investigate whether low-molecular-weight heparin (LMWH) has protective effects against sepsis-induced cognitive impairments. Male mice were randomly divided into the control + vehicle, control + LMWH, lipopolysaccharide (LPS) + vehicle, or LPS + LMWH group. LMWH was administrated 30 min after the LPS administration (5 mg/kg) and daily afterward for 2 days. The survival rate was estimated by the Kaplan-Meier method. Behavioral tests were performed by open field and fear conditioning tests at day 7 after LPS administration. The levels of tumor necrosis factor alpha, interleukin (IL)-1ß, IL-6, IL-10, malondialdehyde, and superoxide dismutase, Toll-like receptor 4, nuclear factor kappa B p65, inducible nitric oxide synthase, cyclooxygenase-2, occluding, high mobility group box-1, brain derived neurotrophic factor, and IBA1 positive cells were assessed at the indicated time points. LMWH attenuated LPS-induced hippocampus-dependent cognitive impairments, which was accompanied by decreased hippocampal IL-1ß, malondialdehyde, Toll-like receptor 4, nuclear factor kappa B p65, inducible nitric oxide synthase, cyclooxygenase-2, high mobility group box-1 protein, and IBA1 positive cells, and increased occluding and brain derived neurotrophic factor levels. In conclusion, LMWH treatment protects against sepsis-induced cognitive impairments by attenuating hippocampal microglial activation, cytokine and oxidative stress production, disruption of blood-brain barrier, and the loss of synaptic plasticity related proteins.