RESUMO
This study aimed to evaluate the effects of inhibitors of the fractalkine pathway in hyperalgesia in inflammatory and neuropathic orofacial pain in male rats and the morphological changes in microglia and satellite glial cells (SGCs). Rats were submitted to zymosan-induced arthritis of the temporomandibular joint or infraorbital nerve constriction, and treated intrathecally with a P2 X7 antagonist, a cathepsin S inhibitor or a p-38 mitogen-activated protein kinase (MAPK) inhibitor. Mechanical hyperalgesia was evaluated 4 and 6 h following arthritis induction or 7 and 14 days following nerve ligation. The expression of the receptor CX3 CR1 , phospho-p-38 MAPK, ionized calcium-binding adapter molecule-1 (Iba-1), and glutamine synthetase and the morphological changes in microglia and SGCs were evaluated by confocal microscopy. In both inflammatory and neuropathic models, untreated animals presented a higher expression of CX3 CR1 and developed hyperalgesia and up-regulation of phospho-p-38 MAPK, which was prevented by all drugs (p < .05). The number of microglial processes endpoints and the total branch length were lower in the untreated animals, but the overall immunolabeling of Iba-1 was altered only in neuropathic rats (p < .05). The mean area of SGCs per neuron was significantly altered only in the inflammatory model (p < .05). All morphological alterations were reverted by modulating the fractalkine pathway (p < .05). In conclusion, the blockage of the fractalkine pathway seemed to be a possible therapeutic strategy for inflammatory and neuropathic orofacial pain, reducing mechanical hyperalgesia by impairing the phosphorylation of p-38 MAPK and reverting morphological alterations in microglia and SGCs.
Assuntos
Artrite , Neuralgia , Masculino , Animais , Ratos , Hiperalgesia/tratamento farmacológico , Quimiocina CX3CL1 , Neuroglia , Neuralgia/tratamento farmacológico , Proteínas Quinases Ativadas por Mitógeno , Inibidores de Proteínas Quinases , Dor Facial/tratamento farmacológico , Proteínas Quinases p38 Ativadas por MitógenoRESUMO
Abstract Purpose: To evaluate the role of CX3CL1 and NF-κB in the lumbar disc herniation induced neuropathic pain. Methods: After LDH induced by implantation of autologous nucleus pulposus (NP) on the left L5 nerve root was established, mechanical thresholds and thermal hyperalgesia were tested at relevant time points during an observation period of 28 days. Expression of CX3CL1 and NF-κBin the dorsal root ganglion (DRG) were performed by using Western blotting and RT-PCR. Results: Implantation of autologous nucleus pulposus (NP) induced neuropathic pain, associated with increased mRNA and protein expression of CX3CL1 in the DRG. Moreover, intrathecal injection of neutralizing antibody against CX3CL1 could attenuates LDH-induced persistent pain hypersensitivity. Interestingly, NF-κB activation in the DRGs were found in LDH-induced neuropathic pain. Furthermore, NF-κB downregulation by p65 inhibitor PDTC markedly alleviated LDH-induced mechanical allodynia and thermal hyperalgesia in rat. Importantly, CX3CL1 neutralizing antibody (10 μg/10 μl, i.t.) reduces p-p65 protein level in DRG Conclusions: CX3XL1 could regulate LDH-induced neuropathic pain through NF-κB pathway. Targeting CX3CL1 and NF-κB may represent a potential treatment for neuropathic pain caused by LDH.
Assuntos
Animais , Masculino , NF-kappa B/metabolismo , Quimiocina CX3CL1/metabolismo , Gânglios Espinais/metabolismo , Deslocamento do Disco Intervertebral/metabolismo , Neuralgia/etiologia , Neuralgia/metabolismo , Fatores de Tempo , Comportamento Animal , Regulação para Baixo , Western Blotting , NF-kappa B/análise , Ratos Sprague-Dawley , Modelos Animais de Doenças , Quimiocina CX3CL1/análise , Reação em Cadeia da Polimerase em Tempo Real , Hiperalgesia/metabolismo , Deslocamento do Disco Intervertebral/complicaçõesRESUMO
Purpose: To evaluate the role of CX3CL1 and NF-B in the lumbar disc herniation induced neuropathic pain. Methods: After LDH induced by implantation of autologous nucleus pulposus (NP) on the left L5 nerve root was established, mechanical thresholds and thermal hyperalgesia were tested at relevant time points during an observation period of 28 days. Expression of CX3CL1 and NF-Bin the dorsal root ganglion (DRG) were performed by using Western blotting and RT-PCR. Results: Implantation of autologous nucleus pulposus (NP) induced neuropathic pain, associated with increased mRNA and protein expression of CX3CL1 in the DRG. Moreover, intrathecal injection of neutralizing antibody against CX3CL1 could attenuates LDH-induced persistent pain hypersensitivity. Interestingly, NF-B activation in the DRGs were found in LDH-induced neuropathic pain. Furthermore, NF-B downregulation by p65 inhibitor PDTC markedly alleviated LDH-induced mechanical allodynia and thermal hyperalgesia in rat. Importantly, CX3CL1 neutralizing antibody (10 g/10 l, i.t.) reduces p-p65 protein level in DRG Conclusions: CX3XL1 could regulate LDH-induced neuropathic pain through NF-B pathway. Targeting CX3CL1 and NF-B may represent a potential treatment for neuropathic pain caused by LDH.(AU)