Collagen solubility and tensile properties of the rat uterine cervix in late pregnancy: effects of arachidonic acid and prostaglandin F2α

Abstract

The collagen concentration in rat uterine cervix was less on day 18 of pregnancy than in the non-pregnant animal but did not diminish further as pregnancy proceeded. The solubility of cervical collagen in warm acetic acid (0·5 mol/l) was increased on day 22 compared with days 19, 20 and 21 of pregnancy, and there was a positive correlation of increasing solubility with the tissue rate of creep (a measure of reducing stiffness of the cervix). Treatment of rats subcutaneously with arachidonic acid or prostaglandin F2α (PGF2α) on day 18 of pregnancy decreased the stiffness of the tissue when assessed on day 19 and this was accompanied by increased solubility in cold saline (0·45 mol/l), cold acetic acid and warm acetic acid and a reduction in collagen concentration. These results suggest that collagen properties rather than concentration are important in determining the stiffness of the rat uterine cervix at term and that exogenous PGF2αand arachidonic acid cause biochemical changes in collagen structure unlike those seen at term in untreated animals.