Increased Cleaved Caspase-3 Expression in the Prepartum Cervix of Mice

Remodeling of the cervix stroma is an inflammatory process that includes reduced cell density. Previous studies have suggested that cell death may contribute to cervix remodeling at term in rats and women. Activation of cleaved (c)-Caspase-3 is a critical step to initiate apoptosis, but whether this marker is increased in the cervix in association with term or preterm birth is unknown. On day 16 postbreeding, pregnant CD-1 mice were given vehicle or progesterone receptor (PR) antagonist (RU486, 6mg/kg/0.1ml i.p.), which induces birth 24-hours after injection. The cervix was obtained from controls on days 15, 16.5, 17, or 18 postbreeding (term = day19), as before (PMID27233754) and from RU486-treated mice on day 16.5. Each cervix was processed and stained for cell nuclei (methyl green) and c-Caspase 3 (antibody #9661S, Cell Signaling). In sections of cervix, the density of cell nuclei/area was the same among pregnant mice whether vehicle-or RU486- treated. The density of c-Caspase-3 cells increased to the same extent on the day before birth in mice given either vehicle (day 18) or RU486 (day 16.5) compared to vehicle-treated mice on day 16.5 postbreeding.