Changes in DRG neurons and spinal excitability in neuropathy.
An intracellular signalling pathway in the dorsal root ganglion (DRG) and spinal neurons is a popular target in pain research that is relevant to the neuroplastic changes that occur during chronic pain conditions. First, we examined the phosphorylation of ERK in DRG neurons after peripheral inflammation and sciatic nerve transection without any stimulation to the receptive field. We found an activation of ERK in different populations of DRG neurons after peripheral inflammation and axotomy, which developed from alterations in target-derived nerve growth factor (NGF). We observed that the ERK signalling regulates the brain-derived neurotrophic factor (BDNF) expression in DRG neurons in both conditions. We also demonstrated that very rapid phosphorylation of ERK occurred in DRG neurons that were involved in the transmission of various noxious signals under normal conditions. Further, we examined the pERK labelling after the mechanical stimuli into the inflamed tissue and found that the pERK labelling occurred through the P2X3 receptors in the terminals. This activity-dependent activation of the ERK signal pathway may be useful for identifying which DRG neurons are involved in transmission of noxious stimuli under normal and pathological conditions.
Hyogo College of Medicine, Department of Anatomy and Neuroscience, Nishinomiya, Hyogo 663-8501, Japan.
Koichi
K
Noguchi
Koichi
K
Obata
Yi
Y
Dai
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000502:physiology; D005727:Ganglia, Spinal / Q000503:physiopathology*; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D020932:Nerve Growth Factor / Q000502:physiology; D009437:Neuralgia / Q000503:physiopathology*; D010766:Phosphorylation; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000502:physiology; D058477:Receptors, Purinergic P2X3; D013127:Spinal Nerves / Q000503:physiopathology
D019208:Brain-Derived Neurotrophic Factor; D018048:Receptors, Purinergic P2; D058477:Receptors, Purinergic P2X3; D020932:Nerve Growth Factor; D020928:Mitogen-Activated Protein Kinases