Exp Clin Endocrinol Diabetes 2007; 115 - P01_146
DOI: 10.1055/s-2007-972402

VEGF mRNA expression in bovine fetal cotyledons and maternal caruncles throughout gestation

C Pfarrer 1, R Leiser 2, D Schams 3, HR Tinneberg 1, B Berisha 3
  • 1Justus-Liebig-Universität Gießen, Frauenklinik, Gießen, Germany
  • 2Justus-Liebig-Universität Gießen, Institut für Veterinär-Anatomie, -Histologie und -Embryologie, Gießen, Germany
  • 3Technische Universität München Weihenstephan, Institut für Physiologie, Freising, Germany

Objectives: In bovine placentomes migrating trophoblast giant cells have been shown to express various growth factors. To relate these findings to placentomal function and growth, the expression of vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 and VEGFR-2, and total VEGF protein were quantitatively analysed in the course of gestation.

Methods: Bovine placentomes from different stages of gestation (3, 4, 5, 6, 7–8, >8 months; n per month=5–6) were processed either in total or separated into fetal cotyledon and maternal caruncle. A semiquantitative RT-PCR analysis was performed for specific mRNAs for VEGF, VEGFR-1, VEGFR-2 and total VEGF protein.

Results: RT-PCR revealed that only VEGFR-1 mRNA differed significantly in the course of gestation, while VEGF and VEGFR-2 varied insignificantly, however all showing the same rise from 3rd until 6th month and a decline towards the end of gestation. Separated maternal caruncles contained significantly more VEGF mRNA than fetal cotyledons, a change which could be attributed to significantly higher levels of VEGF mRNA in late gestational caruncles. In contrast, VEGF receptors varied insignificantly between separated tissues. Independently from mRNA levels, the amount of total VEGF protein significantly increased in the course of gestation. Maternal caruncles contained significantly more VEGF protein than fetal cotyledons, thus showing parallelism to higher amounts of VEGF mRNA in maternal tissues. No significant difference was observed between early and late gestation.

Conclusions: In the course of gestation we observed significant alterations of VEGFR-1, which is contrary to the commonly accepted idea that VEGFR-2 is the major signalling receptor. Increasing amounts of VEGF during gestation and higher levels of VEGF in the maternal compartment are in line with 1) progressive placentomal growth and elaboration of the vascular system until late gestation, and 2) with the function of VEGF as vascular permeability and endothelial survival factor supporting materno-fetal exchange.