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

本研究用免疫细胞化学方法研究了BDNF基因敲除(纯合子和杂合子)和野生型小鼠牙周Ruffini末梢的终末形成和再生/发育。本研究的主要结果如下：1.野生型的牙周韧带，Ruffini神经末梢轮廓不规则(I型)、光滑(II型)。杂合小鼠牙周韧带发育较少，I型畸形较少，分枝较少，轴突终末扩张较少。图像分析显示野生型小鼠的神经细胞密度比杂合子小鼠降低了18%。2.出生后1~3周的观察显示纯合子小鼠的神经细胞密度与其他小鼠相比有显著差异。3.下牙槽神经切除的实验研究表明，BDNF的缺失导致了牙周Ruffini终末再生的延迟恢复，表明BDNF在这些终末的再生过程中起着至关重要的作用。

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.