The Role Of Transcription Factor Ctip2 In Formalin-induced Maxillofacial Inflammatory Pain

Objective: The transcription factor Ctip2 plays an important role in the development of various systems within mammalian, including immunological system, skin, ameloblast, and central nerve system. However, there are few studies about its role or mechanism in acute inflammatory pain. The neural afferent fibers which delivery the nociceptive stimulation from maxillofacial region into caudal subnucleus of the spinal trigeminal nucleus(Vc nucleus), Vc nucleus and the region adjacent to it, which are important in integrating orofacial sensory information, are primary afferent centre. Nerve impulses will be transmitted from peripheral nerve to cerebral cortex through various types of nucleuses and pathways. Behaviour assessment, immunochemistry, immunofluorescence and reverse transcription polymerase chain reaction(RT-PCR) analysis were utilized in the study for researching the distrtibution of the transcription factor Ctip2 in Vc nucleus or cerebal cortex and the role in the formalin-induced inflammatory pain.Methods: Adult female Sprague-Dawley(SD) rats, weighing 180-200 g, were adopted. 50 μl of 2.5% formalin and the same volume of 0.9% saline were injected into the left upper lips of the rats, respectively, and recorded their behavior for 45 minutes. The cerebral cortex and Vc nucleus were taken away at 30, 60, 120, 180 and 240 minutes after injection, the sections from the cerebral cortex and Vc nucleus were detected by immunochemistry, immunofluorescence and RT-PCR.Results: 1:The rats scratched the injected sites after administration of formalin into their front or hind paws, but not happened in saline or control group. 2:Ctip2 protein expression was significantly upregulated in formalin groups followed by immunohistochemical and immunofluorescence analysis, compared with saline or control group; 3:Ctip2 m RNA was remarkably increased in formalin group.Conclusions: 1:The rats showed typical biphasic pain response after formalin injection, it demonstrated that formalin modals in the rats were successful. 2:It was proved that Ctip2 gene also existed in the cerebral cortex and Vc nucleus in the rats.3: It was proved that Ctip2 took part in regulating inflammatory pain in central nerve system.