Study On The Function Of L-type Calcium Channel During The Tooth Development And Mineralization

Recent evidence suggests that a major portion of the Ca2+ ions needed in the dentin mineralization are transported by a active transcellular route against concertration gradient. Many mechanisms including Ca-ATPase, NaVCa2* exchangers, inositol 1,4,5-trisphosphate receptors, calcium binding proteins and L-type calcium channels cooperate to maintain a submicromolar intracellular Ca2+ activity and an extracellular accumulation of Ca2"" ions in predentin. It showed that L-type calcium channel played an important role in this process. Three isoforms CaChl, CaCh2, CaCh3 exist for the pore forming subunit oi. The aim of this study is to investigate the localization of CaCh3 on the odontoblast and its possible role during the development of tooth germ and the mineralization of dentin.1 Expression of CaCh3 on the odontoblast during the mouse molar developmentTo examine the presence of the CaCh3 at different stages of odontoblast differentiation. A polyclonal antibody against the CaCh3 was used to detect the localization of L-type calcium channel. Stain was seen on the cell bodies of the-4-pre-odontoblasts, concentrating at the apical pole of the functional odontoblasts and localizing on cell bodies and processes of the mature odontoblasts. These channels may facilitate the entry of calcium involving in the transcellular transport of calcium to the mineralization front of the dentin. 2 Effects of CaCh3 antisense oligodeoxynucleotide on the development and mineralization of mouse molars in vitroTo better understand the function of CaCh3 during the development and mineralization of tooth, antisense oligodeoxynucleotide(AS-ODN) was used on the tooth germ in vitro. The tooth germs from embryonic 18th d mice's first maxillary molar were devided into 3 groups , antisense group, sense group and control group. The explants were cultured in semi-solid serum-free BGjb medium containing 0.5% agarose. After cultured for 10 days, HE, von Kossa and immunohistological staining were used .The results showed that all three groups of tooth germs developed well while the antisense group was relatively smaller in size. The AS-ODN was effective on bloking the expression of CaCh3 as detected by immunohistological staining; the odontoblasts of the antisense group differentiated but didn't arrange in perfect order; Von Kossa staining showed negative. These findings provide evidence that CaCb.3 may play important roles in odontoblast differentiation and dentin mineralization.