Rat Epiphyseal Cells in Culture: Responsiveness to Bone-Seeking Hormones

Cell cultures derived from young rat epiphyseal cartilage were grown for approximately 2 wk in$BGJ_b$medium supplemented with 10% fetal bovine serum to reach confluence. These cells were identified as chondrocytes as checked by morphology, the presence of alkaline phosphatase, and a positive type II collagen antibody reaction. The cells also responded to different hormonal treatment. Parathyroid hormone (PTH) increased cyclic AMP production by 50% within 15 min of treatment, whereas prostaglandin E2(PGE2) caused an increase of 160%. Calcitonin (CT) did not affect cAMP production in these cells. DNA synthesis 24 h after hormonal treatment was increased by PTH (2.5-fold) and PGE2(2-fold), but not by CT. Among the vitamin D metabolites,$24,25(OH)_2D_3$increased significantly the [3H]thymidine incorporation into DNA, whereas 1,25(OH)2D 3effect was minimal. These results provide evidence for the use of these cell cultures as a model for cartilage in vitro when studying biological and hormonal responsiveness.