[Effect of dexamethasone on osteoblastic cells derived from mouse calvaria]

In the present study, the effect of dexamethasone on MC3T3-E1 cells, a strain of osteoblasts derived from mouse cranial bone, was determined. The following results were obtained. 1) Dexamethasone showed dose-dependent suppression of the growth of MC3T3-E1 cells at concentration of 1 microgram/ml or more. 2) The alkaline phosphatase activity was increased 12, 24, and 48 hours after treatment with dexamethasone at 1, 10 or 30 micrograms/ml. The activity was highest at 48 hours, the level being 311% of the control value at a dose of 10 micrograms/ml. When dexamethasone at a dose of 60 micrograms/ml or more was used, the activity was increased at 12 hours, but was lower than the control at 48 hours. 3) Synthesis of collagenous protein was facilitated after 24-hour treatment with dexamethasone at 1, 10 or 30 micrograms/ml. In particular, the level of synthesis was highest, 232% of the control value, at 10 micrograms/ml. Such synthesis, however, was suppressed at a dose of 60 micrograms/ml or more. 4) Synthesis of collagenous protein was facilitated by 48-hour treatment with dexamethasone at a dose of 1 or 10 micrograms/ml and suppressed at a dose of 30 micrograms/ml or more. 5) Microscopic observation of stained preparations revealed that dexamethasone caused vacuolar degeneration, deep staining of the nucleus, and pyknosis at 60, 150, and 200 micrograms/ml, respectively.