Effects of intraluteal implants of prostaglandin E1 or E2 on angiogenic growth factors in luteal tissue of Angus and Brahman cows.

Abstract Previously, it was reported that intraluteal implants containing prostaglandin E 1 or E 2 (PGE 1 and PGE 2 ) in Angus or Brahman cows prevented luteolysis by preventing loss of mRNA expression for luteal LH receptors and luteal unoccupied and occupied LH receptors. In addition, intraluteal implants containing PGE 1 or PGE 2 upregulated mRNA expression for FP prostanoid receptors and downregulated mRNA expression for EP 2 and EP 4 prostanoid receptors. Luteal weight during the estrous cycle of Brahman cows was reported to be lesser than that of Angus cows but not during pregnancy. The objective of this experiment was to determine whether intraluteal implants containing PGE 1 or PGE 2 alter vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), angiopoietin-1 (ANG-1), and angiopoietin-2 (ANG-2) protein in Brahman or Angus cows. On Day 13 of the estrous cycle, Angus cows received no intraluteal implant and corpora lutea were retrieved, or Angus and Brahman cows received intraluteal silastic implants containing vehicle, PGE 1 , or PGE 2 on Day 13 and corpora lutea were retrieved on Day 19. Corpora lutea slices were analyzed for VEGF, FGF-2, ANG-1, and ANG-2 angiogenic proteins via Western blot. Day-13 Angus cow luteal tissue served as preluteolytic controls. Data for VEGF were not affected (P > 0.05) by day, breed, or treatment. PGE 1 or PGE 2 increased (P   0.05) of PGE 1 or PGE 2 on ANG-1 in Angus luteal tissue when compared with Day-13 or Day-19 controls, but ANG-1 was decreased (P  1 or PGE 2 in Brahman cows when compared with Day-19 Brahman controls. ANG-2 was increased (P  1 but not by PGE 2 in Angus cows. There was no effect (P > 0.05) of PGE 1 or PGE 2 on ANG-2 in Brahman cows. PGE 1 or PGE 2 may alter cow luteal FGF-2, ANG-1, or ANG-2 but not VEGF to prevent luteolysis; however, species or breed differences may exist.