Hydrocortisone stimulation of proliferation and glycosaminoglycan synthesis in rabbit craniofacial chondrocytes in vitro

Hydrocortisone stimulated glycosaminoglycan (GAG) synthesis, a cartilage phenotype, in chondrocytes from mandibular condylar cartilage (MCC), nasal septal cartilage (NSC) and spheno-occipital synchondrosis (SOS). These stimulations were dose- and time-dependent, being maximal 27 h after addition of 10^-7M hydrocortisone. The maximal induced increase of GAG synthesis was about 100%, 50% and 20% that of non-stimulated MCC, SOS and NSC chondrocytes, respectively. When stained with toluidine blue, all three types of cortisone-treated chondrocytes showed stronger metachromasia than non-treated controls. DNA synthesis was also increased by hydrocortisone, reaching a maximum 20 h after the addition; stimulation was also dose-dependent and maximal at a concentration of 10^-6M. The maximal increase in DNA synthesis was 200% in NSC chondrocytes, 90% in SOS chondrocytes, and slight in MCC chondrocytes. However, there was no stimulation of DNA synthesis in serum-free medium, in contrast to that of GAG synthesis. These observations suggest that hydrocortisone regulates craniofacial growth by controlling the differentiation of these chondrocytes directly and their proliferation indirectly, and that the difference in their responses to hydrocortisone may reflect different responses in vivo.