Abstract
The neuropeptide substance P (SP) modulates bone metabolism. This study examined the temporal appearance of SP, BDNF, and their receptors (NK1-R and Trk B, respectively) in the rat TGG, to investigate the role of SP in healing after dental extraction. SD rats upper right first molars were extracted. 1, 3, 7, 14, and 21 days after extraction, the TGG and maxillary bone were excised. Cryosections were immunostained using specific antibodies against SP, BDNF, NK1-R, and Trk B. In the tooth sockets after extraction, new bone and a few SP-immunopositive nerve fibers appeared at day 7, and bone completely filled the sockets at day 21. Three hours after extraction, the number of neurons positive for SP, BDNF, NK1-R, and Trk B decreased. Then, the number of BDNF and Trk B neurons rapidly increased to control levels by day 1. The number of SP and NK1-R neurons increased and reached control levels by day 3. These findings suggest a close relationship between the appearance of SP in the TGG and reinnervation of SP-immunopositive nerve fibers during the healing process after extraction.
