Abstract
Bone is a dynamic tissue which is constantly remodelled by subsequent cycles of bone resorption and formation. Glucocorticoid and vitamine $D_3$ are known as regulating substances in bone metabolism. In vitro experiments using bone tissue, it was suggested that glucocorticoid inhibits bone resorption, whereas the effect of glucocorticoid on bone formation are complex- increasing or decreasing effect. The active form of vitamin $D_3$, 1,25-dihydroxycholecalciferol[1.25-$(OH)_2D_3$], has been reported to stimulate osteoblastic activities including the production of ALP, type I collagen, and osteoclacin. The purpose of this study was to evaluate the effect of admixture of vitamin $D_3$ and dexamethasone, one of glucocorticoids, on osteoblastic cell line(MC3T3-E1). Alkaline phosphatase(ALP) and MTT assay were conducted in the cultivated cells with 1, 10, 100nM/ml of 1,25-$(OH)_2D_3$ and/or 10nM/ml, 100nM/ml, $1{\mu}M/ml$ of dexamethasone. The observed results were as follows. 1. The activity of osteoblastic cells with $1{\mu}M/ml$ of dexamethasone was significantly increased at 1-day cultivation with comparison to control group, but was decreased afterwards. But the activity of ALP was greatest in $1{\mu}M/ml$ of dexamethasone and increased with time lapsed. 2. The activity of osteoblastic cells with vitamin $D_3$ was significantly increased dose-dependently at 1-day cultivation, but was significantly decreased in l00nM/.ml at 2-day cultivation, and was a little increased again at 3-day cultivation. The activity of ALP was increased in 10nM/ml or 100nM/ml at 2-day or 3-day cultivation, and was greatest in 100nM/ml at 3-day cultivation. 3. In case of admixture of dexamethasone and vitamin $D_3$, the cellular activity was decreased in any concentration of vitamin $D_3$ at 2-day cultivation, but was increased again at 3-day cultivation, which was greater than that in control or dexamethasone only group. The activity of ALP was decreased at 1-day cultivation, but was increased in the admixture of 10nM/ml or 100nM/ml of dexamethasone with 100nM/ml of vitamin $D_3$ at 2-day cultivation, and was again decreased at 3-day cultivation.
치아 이동시 골개조에 관여하는 골모세포의 활성을 알아보기 위해 골조직 대사 물질인 vitamin $D_3$를 1, 10, 100nM/ml 농도로, dexamethasone을 10, 100nM/ml, $1{\mu}M/ml$ 농도로 단독 또는 복합 투여하여 세포 활성 및 염기성인산분해효소의 활성도를 분석하여 다음과 같은 결과를 얻었다. 1. dexamethasone을 단독 투여한 경우 배양 1일째에 $1{\mu}M/ml$ 농도에서만 대조군에 비해 유의한 세포 활성 증가를 보였으며 이후에는 전반적으로 유의한 감소를 보였다. 반면에 염기성 인산분해효소의 활성도는 $1{\mu}M/ml$의 dexamethasone일 때 가장 높았으며 배양 기간이 길어질수록 유의한 증가를 보였다. 2 vitamin $D_3$ 첨가시 배양 1일째에는 세포 활성이 증가하였으나 배양 2일째에는100nM/ml에서 대조군과 비교해 크게 감소하여 농도의 증가에 따라 세포 활성이 크게 감소하는 경향을 보였으며 배양 3일째에는 다소 활성이 회복되었다. 염기성 인산분해효소의 활성도는 10nM/ml과 100nM/m1의 vitamin $D_3$에서 배양 2일째와 3일째에 대조군에 비해 유의하게 높았는데 100nM/ml에서 배양 3일째에 가장 높았다. 3. dexamethasone과 vitamin $D_3$를 복합 투여 한 경우 배 양 2일째에는 모든 vitamin $D_3$ 농도에서 세포 활성 이 감소하였으나 3일째에는 세포 활성이 회복되어 대조군이나 dexamethasone단독 투여 시에 비해 유의한 활성 증가를 보이는 경우가 있었다. 염기성 인산분해효소의 활성은 배양 1일째에 감소를 보였으나 배양 2일째에 10nM/ml나 100nM/ml의 dexamethasone에 100nM/ml의 vitamin $D_3$복합 투여의 경우 유의한 증가를 보였고 배양 3일째에 다시 감소를 보였다. 적절한 농도의 dexamethasone과vitamin $D_3$의 복합 사용으로 골모세포의 활성 및 염기성 인산분해효소를 증가시키거나 조절하는 상승 효과를 얻을 수 있음을 알 수 있었다.
(Department of Orthodontics, College of Dentistry, Wonkwang University)