title: Influence of vitamin A on matrix-induced endochondral bone formation.
abstract: The influence of retinoic acid on matrix-induced endochondral bone differentiation was determined. Retinoic acid was administered during discrete stages of endochondral bone formation, specifically, mesenchymal cell proliferation, chondrogenesis, bone formation, and mineralization. In retinoic acid-treated rats examined on day 3 following matrix implantation, biochemical markers for mesenchymal cell proliferation were about 50% of the controls. Chondrogenesis on day 7, assessed by 35 SO4 incorporation into proteoglycans, was 27% of the control. In addition, dissociative extraction of proteoglycans with 4.0 M guanidine-HCl and chromatography on Sepharose CL-2B revealed the synthesis of a smaller molecular weight proteoglycan when compared to controls which exhibited the cartilage-specific type. Osteogenesis and bone mineralization were monitored by alkaline phosphatase activity and 45Ca incorporation. On day 11 alkaline phosphatase activity was decreased by 40% and 45Ca incorporation was 48% of the control. These results revealed the multiple foci of the actions of excess vitamin A.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001857:Bone Matrix / Q000166:cytology* / Q000378:metabolism; D002356:Cartilage / Q000166:cytology* / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D009955:Ornithine Decarboxylase / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology*; D010012:Osteogenesis / Q000187:drug effects*; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D011509:Proteoglycans; D014212:Tretinoin; D000469:Alkaline Phosphatase; D009955:Ornithine Decarboxylase