title: Gelatinases, endonuclease and Vascular Endothelial Growth Factor during development and regression of swine luteal tissue.
abstract: BACKGROUND
  The development and regression of corpus luteum (CL) is characterized by an intense angiogenesis and angioregression accompanied by luteal tissue and extracellular matrix (ECM) remodelling. Vascular Endothelial Growth Factor (VEGF) is the main regulator of angiogenesis, promoting endothelial cell mitosis and differentiation. After the formation of neovascular tubes, the remodelling of ECM is essential for the correct development of CL, particularly by the action of specific class of proteolytic enzymes known as matrix metalloproteinases (MMPs). During luteal regression, characterized by an apoptotic process and successively by an intense ECM and luteal degradation, the activation of Ca++/Mg++-dependent endonucleases and MMPs activity are required. The levels of expression and activity of VEGF, MMP-2 and -9, and Ca++/Mg++-dependent endonucleases throughout the oestrous cycle and at pregnancy were analyzed.
  
  
  RESULTS
  Different patterns of VEGF, MMPs and Ca++/Mg++-dependent endonuclease were observed in swine CL during different luteal phases and at pregnancy. Immediately after ovulation, the highest levels of VEGF mRNA/protein and MMP-9 activity were detected. On days 5-14 after ovulation, VEGF expression and MMP-2 and -9 activities are at basal levels, while Ca++/Mg++-dependent endonuclease levels increased significantly in relation to day 1. Only at luteolysis (day 17), Ca++/Mg++-dependent endonuclease and MMP-2 spontaneous activity increased significantly. At pregnancy, high levels of MMP-9 and VEGF were observed.
  
  
  CONCLUSIONS
  Our findings, obtained from a precisely controlled in vivo model of CL development and regression, allow us to determine relationships among VEGF, MMPs and endonucleases during angiogenesis and angioregression. Thus, CL provides a very interesting model for studying factors involved in vascular remodelling.
authors.affiliation: Department of Veterinary Morphophysiology and Animal Production (DIMORFIPA), University of Bologna, Via Tolara di Sopra 50, 40064, Ozzano dell'Emilia, Bologna, Italy. laribeir@libero.it <laribeir@libero.it>
authors.forename: Luciana Andrea
authors.initials: LA
authors.lastname: Ribeiro
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Turba
authors.forename: Augusta
authors.initials: A
authors.lastname: Zannoni
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Bacci
authors.forename: Monica
authors.initials: M
authors.lastname: Forni
mesh_terms: D000375:Aging; D000818:Animals; D003338:Corpus Luteum / Q000098:blood supply / Q000254:growth & development* / Q000502:physiology; D004720:Endonucleases / Q000378:metabolism*; D005260:Female; D018093:Gelatinases / Q000378:metabolism*; D020782:Matrix Metalloproteinases / Q000378:metabolism; D018919:Neovascularization, Physiologic; D013552:Swine; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology*
chemical_list: D042461:Vascular Endothelial Growth Factor A; D004720:Endonucleases; D018093:Gelatinases; D020782:Matrix Metalloproteinases