THE INVOLVEMENT OF BRAIN DERIBED NEUROTROPHIC FACTOR (BDNF) IN DEVELOPMENT<REGENERATION AND MAINTENACE OF THE PERIODONTAL RUFFINI ENDINGS-A STUDY USING BDNF KNOCKOUT MICE-

本研究采用免疫细胞化学方法观察了BDNF基因敲除（纯合子和杂合子）和野生型小鼠牙周膜Ruffini终末的形成和再生/发育。主要结果如下：1.牙周膜为野生型，Ruffini神经末梢为不规则型（Ⅰ型）和光滑型（Ⅱ型）。杂合子小鼠牙周膜发育和I型畸形较少，分叉少，轴突终末扩张少。结果表明，野生型小鼠牙周膜神经密度较杂合子小鼠减少18%; 2.生后1 ~ 3周观察，纯合子小鼠牙周膜神经密度与非纯合子小鼠有显著性差异; 3.下牙槽神经切断后，BDNF缺失可导致牙周膜Ruffini终末再生延迟，总之，我们的研究清楚地证明了BDNF参与了牙周Ruffini末梢的再生和发育，特别是成熟阶段。

The present study examined the terminal formation and regeneration/development of the periodontal Ruffini endings in the BDNF knockout (homozygous and heterozygous) and wild type mice by immunocytochemical method. The main results obtained in this study are as follows.1.The periodontal ligament of wild type types ; Ruffini nerve endings with irregular-(type I) and smooth outlines (type II). The periodontal ligament of heterozygous mice had less development and malformation of type I, which fewer arborizations and less expansion of the axon terminals. Image analysis demonstrated a 18% reduction of neural density in wild type than in heterozygous mice.2.Observation from postnatal 1 to 3 weeks showed significant difference in neural density between homozygous mice and others.3.An experimental study on the resection of inferior alveolar nerve demonstrated that a depletion of BDNF induced a delay in recovery of the regeneration of the periodontal Ruffini endings, suggesting that BDNF plays crucial roles in the regeneration process of these endings.In conclusion, our study supported by this grant was clearly able to demonstrate the involvement of BDNF in the regeneration and development, in particular maturation stage, of the periodontal Ruffini endings.