Changes of CGRP immunoreactivity in rat trigeminal ganglion neurons during tooth movement

Park, Chyo Sang; Park, Guk Phil; Sung, Jae Hyun

Abstract

GRP was known as the modulator of pain transmission in central nervous system and local effector to peripheral tissue causing vasodilation, increased blood flow, modulation of immune system, stimulation of endothelial cell proliferation, and stimulation of bone formation. Numerous study, therefore, were done to elucidate involvement of CGRP to tooth movement. To investgate the response of CGRP immunoreactive nerve cells according to cell size in trigemeinal ganglion during tooth movement, immunohistochemical study was performed using rat. Experimental rats(9 weeks old, 210 gm) were divided as six groups(normal(n=6), 3 hours group(n=5), 12 hour group(n=4), 1 day group(n=5), 3 day group(n=5), 7 day group(n=5)), and were applied orthodontic force (approximately 30 gm) to upper right maxillary molar. After frozen sections of trigeminal ganglions were immunostained using rabbit antisera, the changes of CGRP immunoreactive cells in regard to cell size distribution(small cell(up to 20 microgramm), medium cell(20-35 microgramm), large cell(above 35 microgramm)) were observed. The results were as follows 1. The percentage of CGRP immunoreactive cells to all nerve cells in trigeminal ganglion was 33.0% in normal control group, was decreased to 24.5% in 1 day group, and was increased to 41.8% in 7 day group. 2. The percentage of small, medium, and large cells expressing CGRP immunoreactivity in normal trigeminal ganglion to all CGRP immunoreactive cells were 51.3%, 44.0%, 4.7%, respectively. 3. The percentage of small cells with CGRP immunoreactivity to all CGRP immunopositive cells was increased in 3 hour and 12 hour groups. 4. The percentage of medium cells with CGRP immunoreactivity was increased in 3 day and 7 day groups. 5. The percentage of large cells with CGRP immunoreactivity was increased in 7 day group. Conclusively, the small cells with CGRP immunoreactivity in trigeminal ganglion respond to orthodontic force during initial phase of tooth movement, and later the medium and large with CGRP immunoreactivity respond.