Date of Award

9-12-2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

First Advisor

Rada, Jody A.

Abstract

Cervical ripening involves an active process of extracellular matrix remodeling to produce dramatic changes in the biomechanical properties of the cervix. Comparison of temporal changes in proteoglycan synthesis, glycosaminoglycan accumulation, and matrix metalloproteinase (MMP) activity in rat cervices related to pregnancy will allow us to better understand the sequence of events that control cervical ripening. To maintain clinical relevance, we will compare the effects of clinically used cervical ripening agents on extracellular matrix synthesis and degradation using human cervical fibroblasts in vitro.

Sprague-Dawley rat cervices were radiolabeled in organ and extracted. Measurements of wet weight shows significant increases at gestational day 18 (p<0.05) and parturition (pO.OOl) when compared with nulliparous cervices. Cervical DNA content showed did not change throughout gestation. The rate of incorporation of [35S] sulfate into newly synthesized proteoglycans in rat cervices isolated from pregnant rats at parturition showed a significant (*p<0.001) increase. This increase was normalized by four days post-partum, indicating a down regulation of proteoglycan synthesis. Proteoglycan characterization showed a shift to larger proteoglycans and an increase in the amount of small proteoglycans produced at parturition. Total glycosaminoglycan content demonstrated insignificant changes throughout pregnancy. MMP-2, as shown by Western blot, accum ulated significantly (*p<0.001) in the cervix, beginning at gestational day 18, continuing through parturition and regressing post partum. Fibroblast studies showed increases in proteoglycan synthesis and MMP-2 production following treatment of cells with prostaglandins. Prostaglandin Ei showed more promising molecular effects when compared with prostaglandin E2.

These results show that proteoglycan synthesis by cervical fibroblasts is actively modulated before, during and after delivery. Proteoglycan characterization studies show a change in the functional requirements of the cervix as parturition approaches. Parallel changes in MMP-2 quantities and proteoglycan synthesis in the rat cervix support that MMP-2 levels in the cervix play a role in proteoglycan turnover and remodeling in the cervix during parturition. Human fibroblast studies imply that the production of parturition-related macromolecules in the rat cervix can be mimicked in vitro using prostaglandins. Collectively, these results may help classify specific cellular events responsible for controlling cervical ripening processes.

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