Changes of substance P during and after tooth movement

objectives:To investigate the relationship between substance P(SP) and orthodontic tooth movement.Methods:The first maxillary molars in rats were moved mesially by an orthodontic force for 2 hours,8 hours,1 days,3 days,1 week and 2 weeks,whereas the other groups were observed after removal of appliances for 1 week,2 weeks and 4 weeks.The expression of SP in periodontal tissues and PPTA(SP) mRNA in trigeminal ganglion were detected with indirect immunoflurescence, RT-PCR and Dot hybridization respectively.Results: The intensity of immunoreactivity for SP-containing fibers in peiondontal tissues were higher than those in the control group at all the time points(P<0.05); SP intensity increased after 2 hours;The most pronounced changes occurred in the 3 day group; after 28 days immunoreactivity was still higher than that in the control group.The changes of PPTA mRNA in trigeminal ganglion had the same trend with SP in periodontal tissues: PPTA mRNA level increased after 2 hours and reached the peak level around 8 hours-3 days during tooth movement,only 4 weeks after tooth movement PPTA mRNA level was nearly at the control level.Conclusions:The results suggested the involvement of substance P in both early stages of periodontal remodeling and later in the regenerative processes of the periodontal tissues during and after orthodontic tooth movement.This study was supported by National Natural Science Foundation of China (NSFC Number :30200320)