Mid-to-late gestational changes in inflammatory gene expression in the rat placenta

Background: The placenta plays an important role during pregnancy providing maternal blood supply from the uterus to the developing fetus. The structure and function of the placenta changes with gestation, as the fetus develops and its demands change. This study aims to elucidate changes in cytokine and chemokine gene expression throughout mid-to-late gestation in rat placenta. Methods: Sprague Dawley rats were time-mated, and placentae were obtained from 6 pregnant dams at 4 different gestational periods: E14.25, E15.25, E17.25, and E20. Changes in placental gene expression were measured by microarray analysis. Differentially expressed inflammatory genes were functionally categorized by pathway analysis. To validate the microarray results, a subset of genes was analyzed by quantitative real-time polymerase chain reaction (qPCR) in a validation cohort of 22 rats. Results: Changes in messenger RNA (mRNA) expression of various cytokines, chemokines, and genes of the tumor growth factor β and tumor necrosis factor family were analyzed in rat placentae at E14.25, E15.25, E17.25, and E20. Forty-six genes were differentially expressed, and of these 21 genes had increased expression in late gestation (E20). The gestational age pattern of gene expression was confirmed by qPCR in the validation cohort. Conclusion: The observed acute, prelabor changes in the expression of these genes during gestation warrant further investigation to elucidate their role in pregnancy and parturition