The effects of magnesium sulfate on placental vascular endothelial growth factor expression in preeclampsia.

Objective: To evaluate the effect of magnesium sulfate (MgSO(4)) on placental expression levels of vascular endothelial growth factor (VEGF).
Materials and Methods: Cotyledons of term normotensive and preeclamptic placentas were dually perfused for 6 h, with MgSO(4) (6-7 mg%) in the maternal reservoir [normotensive (n = 3); preeclamptic (n = 4)] and with the control medium (without MgSO(4)) [normotensive (n = 3); preeclamptic (n = 6)]. After perfusion, placental tissue samples were collected from four different placental compartments (amnion, chorion, placental villous and decidua). The collected placental tissues were homogenized and examined for VEGF by ELISA. Statistical significance was determined using a two-way analysis of variance.
Results: After perfusion with control medium, significantly lower levels of VEGF were detected in the chorion and placental villous compartments of preeclamptic placentas (70 ± 24 pg/g protein and 29 ± 11 pg/g protein; respectively), as compared with normotensive placentas (172 ± 80 pg/g protein and 51 ± 17 pg/g protein; respectively; p < 0.05). Exposure of preeclamptic placentas to MgSO(4) resulted in decreased VEGF levels by the amnion (57 ± 26 pg/g protein), as compared with the control group (153 ± 62 pg/g protein) (p < 0.05). On the other hand, MgSO(4) significantly increased VEGF levels by the placental villous and the decidua (58 ± 15 pg/g protein, 70 ± 29 pg/g protein; respectively), as compared with the control group (29 ± 11 pg/g protein, 33 ± 14 pg/g protein; respectively) (p < 0.01, p < 0.05; respectively). Exposure to MgSO(4) did not affect VEGF levels in normotensive placentas.
Conclusion: Reduced levels of VEGF are expressed by some placental compartments in preeclampsia compared with normotensive pregnancy. Perfusion with MgSO(4) affects VEGF expression differently by preeclamptic and normotensive placentas. Increased production of placental VEGF in preeclampsia may play a role in the therapeutic action of MgSO(4).