Antiluteolytic activity in the uterine microenvironment during the critic period to pregnancy establishment in bovines

Author(s)

Vanessa Belentani Marques

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2006-12-14

Examining board members

Mario Binelli; José Buratini Júnior; José Roberto Kfoury Junior; Ed Hoffmann Madureira; Flavio Vieira Meirelles

• Advisor: Mario Binelli

Abstract

The inhibition of pulsatile secretion of PGF2α mediated by interferon-tau (IFN) is fundamental on the maternal recognition of pregnancy, maintaining the progesterone secretion by corpus luteum. Therefore the measurement of interferon activity in the uterine microenvironment was studied. Due to a lack of assays those measure specific antiluteolytic capacities we suggest develop a biological assay for it. In this research we observed that BEND cells treated with PdBu synthesize PGF2α, wich is inhibited by the presence of recombinant bovine interferon-tau (rbIFN-τ). Following we defined 25ng/mL as PdBu (phorbol 12,13 dibutirate) stimulus at the PGF2α synthesis to be applied in this biological assay. Studies about the modulation of PdBu-stimulated PGF2α synthesis by the rbIFN-τ validate the use of this isoform as a reference, defining a standard-curve and allowing estimating the antiluteolytic activity of 9.61 x 10² antiluteolytic units per microgram (UA/µg) of protein. Further, we observed the modulation of PdBu-stimulated PGF2α synthesis exerted by a pool of uterine flushings or conceptus conditioned medium, and for each tested fluid, there is a range of concentrations where is observed an increasing rate on the inhibition of PGF2α synthesis. A restrict analysis on this concentrations range shows a linear behavior and allow calculate the antiluteolytic activity of each sample1.63 x 10-¹ UA/ µg of protein from a pool of uterine flushings, and 1.66 x 10² UA/µg from conceptus conditioned medium. These studies validated a method to observe the antiluteolytic activity from biological fluids. Using the antiluteolytic assay, we studied the antiluteolytic activity present in uterine flushings obtained during the critic period by pregnant or cyclic bovine females cíclicas (respectively 56,2 e 33,9 UA/µg of protein). We observed higher antiluteolytic activity from pregnant uterine microenvironment than in cyclic uterine microenvironment. This result linked with the high antiluteolytic activity observed to conceptus conditioned medium, suggest the participation of IFN-τ secreted by the conceptus in the PGF2α synthesis modulation. However, we observed the antiluteolytic activity in uterine flushing obtained by cyclic cows, suggesting that the PGF2α synthesis could be modulated by another proteins. We believe that the antiluteolytic activity, observed by the antiluteolytic assay, ensue the action of inhibitors or stimulators factors in the biological fluids. We conclude that the antiluteolytic assay could be measured by the proposed biological assay, nevertheless another studies must be done in order to correlate this activity with the interferon action. (AU)