Changes in CGRP-immunoreactive nerve fibers during expansion of midpalatal suture of the rat

Kim, Bo Kyung; Kyung, Hee Moon; Kwon, Oh Won; Sung, Jae Hyun; Park, Kuk Pil

Abstract

Midpalatal suture expansion if often used for patients having narrow maxillary arch, cleft palate, respiratory handicap with narrow nasal cavity. CGRP has been known as a modulator of pain transmission in central nervous system and a local effector to peripheral tissue causing vasodilation, increase of blood flow, modulation of immunesystem, regulation of macrophagic function and stimulation of bone formation. To investigate changes of CGRP-immunoreactive nerve fibers in midpalatal suture during the expansion, immunohistochemical study was performed by using rats. Experimental rats (10 weeks, 250 gm) were divided into five groups (control, 1, 4, 7, 14 days group (each n=4) and applied orthodontic force (approximately 200gm) to upper anterior incisors. Frozen sections of midpalatal suture area were immunostained by using rabbit antisera. The results were as follows: The CGRP-immunoreactive nerve fibers were hardly observed in control group. In 1 day group, the CGRP-immunoreactive nerve fibers were more increased around the vessels than control group. In 4 days group, the CGRP-immunoreactive nerve fibers were more increased than control group, but nor more increased than 1 day group. Vascular diameter was more enlarged. In 7 days group, especially, hematoxilin affinity of cells was remarkable and cells were arranged along the bone margin. The CGRP-immunoreactive nerve fibers were more reduced than 4 days group and vascular diameter was also reduced. In 14 days group. the CGRP-immunoreactive nerve fibers were similar to those of 7 days group and the irregularity of bone margin was almost recoverd. In Conclusion, the CGRP-immunoreactive nerve fibers may be related to intial neurogenic inflammatory reaction in expanding mid-palatal suture.