Effects of diphenylhydantoin on synthesis of collagen and noncollagen protein in tissue culture

Abstract

The direct effects of the anticonvulsant diphenylhydantoin (DPH) on collagen synthesis were examined in tissue cultures of 21-day-old fetal rat calvaria. Bones were incubated for 24 or 72 h and pulsed with [3H]proline for the last 2 h of culture; incorporation of label into collagenase-digestible (CDP) and noncollagen protein (NCP) was quantitated using purified bacterial collagenase. After 24 h of incubation, DPH at a concentration of 10 μg/ml significantly reduced the incorporation of [3H]proline into CDP; higher concentrations (30 and 100 ng/ml) also decreased the formation of NCP, although the inhibitory effect was greater on CDP. The effects of DPH could not be ascribed to altered amino acid uptake or the release of newly labeled protein from bone to medium. Skeletal DNA content and incorporation of [3H]thymidine into DNA were not affected by DPH. The inhibitory effect of DPH was completely reversed by 48 h of control treatment subsequent to an initial 24-h incubation with the drug. The stimulatory effect of insulin on CDP formation was significantly reduced by DPH, whereas the inhibitory effect of 1,25-dihyclroxycholecalciferol was enhanced by the simultaneous addition of DPH. We conclude that DPH has a direct inhibitory effect on collagen synthesis and that this may partially explain the skeletal changes observed with chronic DPH therapy. © 1980 by The Endocrine Society.