ABSTRACT
Mitogen-activated protein kinases (MAPKs) are important kinases involved in the intracellular signaling transduction in mammalian. There are three major MAPK pathways: ERK/MAPK,JNK/SAPK and P38 MAPK. Current studies indicate that all of them play significant roles in the processing of pain especially in the development and maintenance of pathological pain. This review will focus on in the study of MAPK in pain modulation. The further insights into its mechanisms may highlight a nice prospect for the therapies of painful diseases.
ABSTRACT
Objective To investigate the activation of extracellular signal-regulated kinase(ERK) and cAMP-responsive element binding protein(CREB) in the anterior cingulate cortex(ACC) induced by peripheral injection of formalin.Methods 5% formalin was injected subcutaneously into the unilateral hindpaw.The rats were perfused or killed and the ACC dissected at different time points.The activation of phosphorylated ERK(pERK) and phosphorylated CREB(pCREB) in the ACC were observed by immunohistochemical and Western blotting techniques.Results Subcutaneous injection of formalin induced the activation of pCREB and pERK in the ACC.Formalin-induced the activation of pERK and pCREB in the ACC peaked at 3 min and 30 min after stimulation,respectively.The total ERK and CREB had no significant changes.Conclusion The ACC could receive peripheral noxious information and the ERK and CREB in the ACC might involve in the processing of the primary unpleasentness of pain.
ABSTRACT
Objective To observe the activation of astrocytes,microglia and expression of proinflammatory cytokines in the periaqueductal gray(PAG) by Complete Freunds Adjuvant(CFA)-induced inflammatory pain. Methods Heat hyperalgesia and mechanical allodynia were observed and the expressions of mRNA,protein of glial markers,and proinflammatory cytokines in the PAG were examined following intraplantar administration CFA in right hindpaw of the rat by behavioral testing,reverse transcription polymerase chain reaction(RT-PCR), Western blotting,and immunohistochemistry. Results CFA injection induced chronic thermal hyperalgesia and mechanical allodynia.After injection,the thermal hyperalgesia was recovered on Day 14,but the mechanical allodynia lasted more than 21 days.Microglial marker(Cluster of differentiation 14,CD14) and proinflammatory cytokines(Interleukinin-1?,tumor necrosis factor-?) showed a significant increase in their expression during all phases(acute,subacute and chronic) of inflammation.GFAP was observed only in PAG at subacute and chronic phases of inflammation.Conclusion The activation of microglia and astrocytes may be involved in the initiation and maintenance of inflammatory pain.Enhanced cytokines expression might play a role in eliciting behavioral hypersensitivity.
ABSTRACT
Objective To observe the distribtuion of NOS positive neurons in the projecting pathway to the subnucleus reticularis dorsalis(SRD) in the rat. Methods We used a double staining technique combined retrograde tract tracer and NADPH d histochemistry. Results FG/NOS double labeled neurons were found in the laminae Ⅰ,Ⅹ of spinal cord,dorsal raphe nucleus(DR),linear raphe nucleus(LR),and raphe obscurus nucleus(RO).In the periaqueductal gray(PAG),there were many FG labeled or NOS labeled neurons,but no FG/NOS double labeled neurons were found.Conclusion\ NO might play a role in the pathway of afferent projections of the SRD.\;[