The Effect Of Human Parathyroid Hormone 1-34 On The Development And Mineralization Of Dentin

Parathyroid hormone (PTH) plays an important role on regulating the concentration of Ca²⁺ in serum. PTH1—34 is one of the most important transformation outcome of PTH and it can play all function of PTH. It can affect not only the differentiation and function of papilla mesenchymal cells and dental pulp cells which can different into odontoblasts but also the formation of dentin. The mechanism of PTH on dentinogenesis is unknown by now and we investigate the effects of PTH on animals and cells to make it clearer.Objective: To study the effects of PTH upon dentinogenesis by investigate the effect of hPTH1 — 34 on the development and calcification of rat' s dentin and the change of the expression of PTH/PTHrP receptor in human dental pulp cells cultured in vitro . Materials and methods:1. After parathyroidectomy on rats, we injected hPTH1—34 hyperdemic by different dosage. Six weeks later, the lower incisor were dissected and prepared for light microscope and figure analysis. 2 .The fourth passage human dental pulp cells were cultured up to 5, 10, 15, 20 days. The PTH group was cultured inthe medium of control group containing 33. 3nmol/L hPTHl — 34. PTH/PTHrP receptor' s mRNA were enlarged by RT-PCR. The absorbency were measured and compared with 3 -actin. Results: l.The concentration of serum calcium decreased after parathyroidectomy well increased after being injected hPTHl-34. The results of observation by light microscope and figure analysis revealed the enlargement of the predentinal tubules and the presence of mineralization defects in the PTX mouse(P<0.05). These modification were improved after injection of hPTHl — 34. The groups of lOnmol/kg and 20mmol/kg affected the dentin more than group 5nmol/kg(P<0.05).. 2. The mRNA of PTH/PTHrP receptor expressed lowly when the cells were cultured in 5 and 10 days in both experimental group and experimental group .But after 10 days , the expression increased with the cultured time. The expression is higher in experimental group than in control group. Conclusion: 1. The development and mineralization of dentin may be affected by PTH .2. PTH is connected with the differentiation of pulp cells. hPTHl—34 maybe promote the expression of PTH/PTHrP receptor. The formation and mineralization of dentin may be effected by parathyroid hormone itself or by combining with PTH/PTHrP receptor.