INHIBITION OF COLLAGEN SYNTHESIS IN THE FEMUR OF RATS ORALLY ADMINISTERED STANNOUS CHLORIDE

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The effect of stannous chloride on bone metabolism was examined in weanling male rats given oral dose of 1.0 mg Sn/kg at 12-h intervals for 28 d. Hydroxyproline content in the femoral diaphysis but not epiphysis was significantly decreased by tin administration for 14 and 28 d, while free proline contents in the femoral diaphysis and epiphysis were not changed significantly. ³H-Hydroxyproline contents in the femoral diaphysis and epiphysis labeled with ³H-proline injection were not significantly altered by tin administration. In vitro collagen synthesis in the femoral epiphysis tissue but not diaphysis was markedly reduced by tin administration between 3 and 14 d, although ³H-proline incorporations into the femoral diaphysis and epiphysis tissues were not changed significantly. On the other hand, in vitro incorporation of ³H-thymidine into the femoral epiphysis but not diaphysis was significantly decreased by tin administration between 7 and 28 d. A significant decrease of DNA content in the femoral epiphysis but not diaphysis was also observed by tin administration for 14 and 28 d. The present study suggests that tin administration causes the inhibition of collagen synthesis prior to the suppression of DNA synthesis in the femoral epiphysis of rats.