A STUDY OF DEVELOPMENT/REGENERATION PROCESSES OF THE PERIODONTAL NERVES, WITH SPECIAL REFERENCE TO THE ROLE OF NEUROTROPHINS/NEUROTROPHIN RECEPTORS.

1.下牙槽神经损伤后，牙周Ruffini末梢的再生速度快于其他组织的Ruffini末梢。在再生过程中，与牙周Ruffini末端相关的终末雪旺细胞迁移到正常情况下从未发现的区域，各种生物活性物质的表达水平在牙周Ruffini末端的轴突和雪旺细胞成分中都发生了变化。非特异性胆碱酯酶组织化学显示终末雪旺细胞的发育与年龄有关：发育中的终末雪旺细胞的形态和分布在出生后15-18天与成体几乎相同。在大鼠切牙韧带的牙槽相关部位，终末雪旺细胞排列后，表达PGP9.5免疫反应的轴突延长并扩张扩张。TrkB是一种高亲和力神经营养因子受体，在个体牙周Ruffini末梢中分布不均。一些终末雪旺细胞也显示TrkB免疫反应，用我们制备的cRNA探针进行原位杂交组织化学证实。用免疫组织化学方法观察脑源性神经营养因子(BDNF)缺陷型小鼠和窝巢野生型小鼠切牙牙周膜的神经分布和终末形态。BDNF缺失可导致Ruffii终末畸形，包括少量神经纤维、较少的分支和较少的终末按钮以及轴突终末的褶皱轮廓，提示BDNF参与了牙周膜Ruffini终末的发育和成熟。

1. Following injury to the inferior alveolar nerve, the periodontal Ruffini endings can regenerate more rapidly than Ruffini endings in other tissues. During regeneration, terminal Schwann cells associated with the periodontal Ruffini endings migrate into regions where they are never found under normal conditions, and alterations in the expression level of various bioactive substances occurred in both axonal and Schwann cell elements in the periodontal Ruffini endings.2. Histochemistry for non-specific cholinesterase activity could demonstrate the age-related development of the terminal Schwann cells : the morphology and distribution of the developing terminal Schwann cells becase almost identical to those in adults during postnatal days 15-18. Axons showing PGP9.5-immunoreactivity elongated and expanded and expanded after arrangement of terminal Schwann cells in the alveolus-related part of rat incisor ligament.3. The heterogeneous distribution of TrkB, a high affinity neurotrophins receptor, was found among individual periodontal Ruffini endings. Some terminal Schwann cells also displayed TrkB-immunoreactivity, confirmed by in situ hybridization histochemistry using a cRNA probe which we prepared.4. Innervation and terminal morphology in the incisor periodontal ligament were investigated in brain derived neurotrophic factors (BDNF) +/- mice and littermate wild-type mice by immunohistochemistry for PGP 9.5.). BDNF depletion induced the malformation of the Ruffii endings ; which included fewere nerve fibers, less ramifications and fewer terminal buttons as well as ruffled-outlines of the axon terminals, suggesting that BDNF are involved in, the development and maturation of the Ruffini endings in the periodontal ligament.