Endocrine Abstracts

The major role of GH during adolescence is to promote longitudinal bone growth, but GH continues to have important metabolic actions throughout life. Additionally, there are evidences of its hole in the maintenance of adult bone mass by regulating bone remodeling during adulthood. However, while GH therapy increase density mineral bone in childhood and adolescent, its effects in adults bone are not clear. The aim of this study was to investigate the effect of GH in human osteoblasts derived from alveolar bone of adolescent (13–15 years old) and adult (36–39 years old) patients. Primary culture was obtained by enzimatic digestion of adolescent (N=5) and adult (N=5) alveolar bone fragments and were cultured in osteogenic medium. First passage cells were cultured in 24-well culture plates (2×10⁴ cells/well) in osteogenic medium without or containing GH (100, 200 and 300 ng/ml). At day 7 cell proliferation, total protein, collagen and alkaline phosphatase (ALP) activity were evaluated. Bone-like nodule formation was evaluated at day 21. All experiments were done in quintuplicate and data were compared by Kruskal-Wallis test. All evaluated parameters were not affected by GH in cultures of osteoblasts from adults. In cultures of osteoblasts from adolescents, GH caused significant increase in cell proliferation (P=0.0053), total protein content (P=0.0053), collagen synthesis (P=0.003), ALP activity (P=0.0073) and bone-like nodule formation expressed as area of bone-like nodules (P=0.03). These results indicate that GH effect on osteoblasts is age-dependent. While GH had no effect on responses of osteoblasts from adults, events related to both proliferation and differentiation were increased when osteoblasts from adolescents were cultured in presence of GH.