Changes of dopamine-beta-hydroxylase and activator protein-2? expression in spinal cord of formalin-induced rat pain model / 第三军医大学学报

ABSTRACT

Objective To investigate the changes of dopamine-?-hydroxylase(DBH) and activator protein 2-?(AP-2?) expression in spinal cord under the condition of stress or pain stimulation,so as to explore the mechanism for changes of noradrenergic(NA) neurons in the spinal cord of rat pain model.Methods Immunohistochemical staining,double immunofluorescent staining,Western blotting and computing-image analysis system were used to detect the changes of DBH/AP-2? expression in the spinal cord of formalin-induced rat pain model.Results A small number of DBH-positive neurons were sparsely distributed in the ventral horn of the normal spinal cord,while in the formalin-treated group,much more darkly-stained DBH-positive neurons appeared primarily in the ventral horn,intermediate zone,and the dorsal horn,which reached the highest level on day 3 after formalin-injection.The grey value and number of DBH-positive neurons on day 7 after injection began to decrease,but still higher than that in the control group.Compared with control group,the number of noradrenergic neurons in spinal cord of formalin-treated rat was increased significantly,which was also confirmed by Western blotting.Double immunofluorescent staining showed that DBH and AP-2? co-existed in the cells of the spinal cord.The changes of AP-2? expression were similarly to that of DBH in the spinal cord of rat pain model.Conclusion Our results indicated that some non-noradrenergic neurons with different chemical properties might convert into noradrenergic neurons under pain stimulation;noradrenaline may be involved in the formalin-induced pain and behavior regulation;As one of transcription factors,AP-2? may promote the DBH synthesis.