P-glycoprotein expression of the human placenta during pregnancy.

Objective: To investigate whether the placental expression of P-glycoprotein shows a quantitative difference during pregnancy.
Study Design: Villous tissue was collected from chorionic villus samples (13-14 weeks of gestation; n = 3 and 20-25 weeks of gestation; n = 4) and from full-term placentas (38-41 weeks of gestation; n = 28). P-glycoprotein was detected by western blot analysis and quantified by densitometry.
Results: We showed for the first time a significant and progressive two-fold decrease in the mean expression of P-glycoprotein between early and late samples, with a major overlap of values.
Conclusion: As P-glycoprotein appears to be involved in drug extrusion, these data suggest that the placenta's ability to protect the fetus from xenobiotics is greater in early pregnancy than at term.
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