Effect of hydrocortisone on collagen synthesis in cultured mouse palatal explants

Immunocytochemical demonstration of simultaneous synthesis of types I, III and V collagen and fibronectin in mouse embryonic palatal mesenchymal cells in vitro

An immunocytochemical study was made on the palatal mesenchymal cells obtained from mouse embryos during palatal development with special reference to synthesis of types of collagen and fibronectin in vitro. Most cells showed positive staining with antibodies against the four proteins examined. The staining for type I collagen was most intense among the four proteins and was distributed perinuclearly. The staining for type III collagen was quite similar as that for type I collagen but less intense, whereas that for type V collagen was weak and its staining pattern was different from those for types I and III collagen in that the surface of the plasma membrane, in addition to the perinuclear cytoplasm, showed weak staining for type V collagen. Antibodies to fibronectin showed perinuclear and extracellular fibrous staining. These data suggest that palatal mesenchymal cells synthesize types I, III, and V collagen and fibronectin simultaneously.

D-penicillamine-induced cleft palate in mice

The teratogenic potential of the lathyrogen, D-penicillamine (DP), was assessed in pregnant mice, especially with respect to its ability to produce cleft palate. The dosage and the duration of treatment as they relate to the induction of cleft palate were also studied. Two different doses of DP were administered orally for either 5 or 4 consecutive days during the critical period of palatal closure. D-penicillamine (DP) at a dose level which does not have any apparent maternal toxic effects produced cleft palate in the offspring, and this teratogenic effect depended more upon the duration of treatment than the dosage administered. Inhibitory effects on the formation of bone matrix were observed at the base of the palatal shelf. It is suggested that DP is potentially an osteolathyrogenic agent. The mechanism of induction of cleft palate in DP-treated mice was explored by histological studies using light microscopy. Delayed elevation of the palatal shelves was observed and is considered to be the cause of the induction of cleft palate. No other external malformations could be detected in DP-treated fetuses.

Selective inhibition of collagen biosynthesis in the dental pulps of glucocorticoid-treated rabbits

Prednisolone (2 mg/kg) was injected daily for 14 days. Collagen and protein biosynthesis were measured in isolated molar and incisor pulps by the incorporation of [14C]-proline into protein and collagen in vitro. Collagen solubility, free proline content, prolyl hydroxylase activity, collagenolytic activity and DNA and RNA contents were also assayed. Rabbits injected with saline or starved served as controls. Collagen synthesis was inhibited selectively in both prednisolone and starvation groups. No other aspect of collagen and protein metabolism was affected by either prednisolone treatment or starvation. Thus glucocorticoid administration reduces collagen formation in the pulp, resembling the anti-anabolic effect of starvation. Glucocorticoid treatment at high daily dosages, therefore, may disturb normal development and metabolism of teeth.