The Effect of 17∧-Estradiol on Collagen and Noncollagenous Protein Synthesis in the Uterus and Some Periodontal Tissues

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Abstract
The effect of a single dose of 17β-estradiol on collagen metabolism in the uterus and various oral tissues was determined in ovariectomized nulliparous rats. Eight days after ovariectomy, 200-g rats were given 100 μg estradiol ip. Forty hours later, 2 mCi [3H]proline were administered by ip injection, and the animals were killed 2 h later. The specific radioactivitiesof hydroxyproline and proline in both salt-soluble and saltinsoluble proteins were used as a measure of collagen and noncollagenousprotein metabolism. Estradiol was found to induce a 2-fold increase in the specific radioactivity of newly synthesized collagen and an 8-fold increase in the specific radioactivity of the insoluble collagen in the uterus. The discrepancy between these results could be largely accounted for by a 2- to 3-foldincrease in the size of the newly synthesized collagen pool. Stimulation of noncollagenous protein synthesis was also observed. The total collagen content of the uterus was not significantly altered in estradiol-treated animals, suggesting that estradiol stimulates both the synthesis and degradation of collagen. Using [l4C]glycine as a precursor, the nature of the collagens synthesized in the uterus was analyzed by sodium dodecyl sulfate- polyacrylamide gel electrophoresis and fluorography. Estradiol was found to stimulate the synthesis of both type I and type III collagens, but no change in the pattern of procollagen conversion could be discerned. In contrast to the uterine tissues, the only significant effect of estradiol on protein metabolism in theoral tissues was a decrease in the newly synthesized collagen specific radioactivity in the molar periodontal ligament.