Mitogenic effects of neurotrophins on a periodontal ligament cell line

Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and ne urotrophin-3 (NT-3) are three representative neurotrophins responsible for the differentiation and survival of neurons, and their high-affinity recept ors are tropomyosin-receptor-kinase (TRK)A, TRKB, and TRKC, respectively. I n this study, we investigated the expression of neurotrophins in a mouse pe riodontal ligament cell line (MPL), by reverse transcription-polymerase cha in-reaction (RT-PCR) and enzyme-linked immunoabsorbent assay (ELISA). We al so studied the expression of TRK receptors on MPL by immunostaining and the effects of neurotrophins on the proliferation of MPL, with a hypothesis of autocrine mechanism of neurotrophins. Each neurotrophin and TRK receptor w as expressed, and neurotrophins enhanced the proliferation of MPL. These fi ndings suggest that the MPL has functional neurotrophin receptors involved in an autocrine function of neurotrophins. The expression level of neurotro phins and TRKs showed the reverse pattern, and we propose an auto-regulator y mechanism of ligands and receptors in accordance with the level of synthe sized neurotrophins.