Effect of acute ascorbic acid deficiency on the DNA content and permeability of guinea-pig oral mucosal epithelium

Specifically decreased collagen biosynthesis in scurvy dissociated from an effect on proline hydroxylation and correlated with body weight loss. In vitro studies in guinea pig calvarial bones

The question whether ascorbate regulates collagen production solely through its direct role in proline hydroxylation was investigated. Proteins in calvarial bones from control and scorbutic weanling guinea pigs were labeled in short-term cultures with radioactive proline. Proteins were digested with purified bacterial collagenase to distinguish between effects on collagen polypeptide production and hydroxyproline formation. There was a preferential decrease in the absolute rate of collagen biosynthesis beginning after 2 wk of ascorbate deficiency, and this effect was temporally dissociated from decreased proline hydroxylation. There were no significant changes in the absolute rates of collagen degradation or noncollagen protein production. In vitro inhibition of proline hydroxylation in normal bone with alpha, alpha'-dipyridyl did not affect the relative rate of collagen synthesis, further dissociating these functions. Ascorbate added to scorbutic bone cultures reversed defective proline hydroxylation but not defective collagen synthesis, suggesting that the latter was an indirect effect of scurvy. There was a linear correlation between the extent of body weight lost during the 3rd and 4th wk of scurvy and the rate of collagen synthesis in scorbutic bone. This correlation also applied to control animals receiving ascorbate, but with weight loss induced by food restriction. These studies establish for the first time that ascorbate deficiency in guinea pigs leads to a specific decrease in collagen polypeptide synthesis and suggest that this decrease results from the reduced food intake and/or weight-loss characteristic of scurvy.

Permeability of gingival sulcular epithelium in the development of scorbutic gingivitis

Young adult nonhuman primates were initially fed an ascorbic-acid free diet and, subsequently, a diet with a suboptimal level of the vitamin. Following approximately 12 weeks of this dietary regime, five of seven experimental animals of the gingival sulcular epithelium to 3H-inulin, but not to 14C-butyric acid or 14C-urea, had increased significantly (+86%, P less than 0.01) in the experimental group as compared to ad libitum or pair-fed controls. This defect in the intercellular permeability barrier of the sulcular epithelium could have contributed to the pathogenesis of scorbutic gingivitis.