Altered Expression of Vascular Endothelial Growth Factor in Pregnant Rats with Uterine Artery Ligation

Kim, Yong Wook; Lee, Jong Kun; Lee, Jae Sung; Choi, Ok Choon; Ro, Duck Yeong; Kim, Tae Eung; Jung, Jae Geun; Shin, Jong Chul

Abstract

OBJECTIVE
During pregnancy, the impaired placental perfusion causes complications such as preeclampsia, intrauterine growth restriction and fetal death in utero. In order to investigate the maternal and fetal response to the impaired placental perfusion, the author induced the impaired placental perfusion by the ligation of the rat uterine artery and investigated its effect on the expression of VEGF (vascular endothelial growth factor) in the placenta and serum VEGF level.
METHODS
The rats on day 15 of gestation were used for the experiment. They were divided into two groups. The control group consists of the 20 rats that underwent laparotomy without uterine artery ligation. The experimental group consists of the 20 rats that underwent laparotomy and the uterine artery ligation by silk on day 15 of gestation. On day 16, 17, 18 and 19 of gestation, the placental tissues were obtained. The mRNA expressions of the VEGF in the placenta were measured by the relative RT-PCR in the control and experimental group. The localization and intensity of immunohistochemical staining of VEGF in placenta were determined in both groups and the maternal serum levels of VEGF were also measured in both groups.
RESULTS
The mRNA expressions of VEGF120 and VEGF164 were significantly increased 48 hours after the ligation (day 17 of gestation) but the mRNA expression of VEGF188 was not changed after the ligation. There was no difference in the location and intensity of immunohistochemical staining of VEGF in the placenta between control and experimental groups. The serum VEGF levels of control group were 9 times as high as those of non-pregnant rats. The significant increases of the serum VEGF levels were noted 48 and 72 hours after the ligation (day 17 and 18 of gestation) but the significant increase was not noted 96 hours after the ligation (day 19 of gestation) as compared to control group.
CONCLUSION
This study demonstrated firstly that the experimentally induced reduction of placental perfusion increased expressions of VEGF in the placenta and maternal serum. The results support that the measurement of maternal serum VEGF levels in pregnancy may help the diagnosis of placental insufficiency.