Temporal relationship between angiogenic factors, luteal hemodynamics and plasma hormonal concentrations during the luteolysis (total and partial) and throughout the post-luteolytic and CL resurging phases in mares

• Grant number: 12/01627-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2012
• End date: June 30, 2015
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Cezinande de Meira
• Grantee: Jair Camargo Ferreira
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated scholarship(s): 13/17669-0 - Endocrine and ovarian response to therapy with PROGESTERONE-RELEASING intravaginal device associated with estradiol benzoate in mares, BE.EP.PD

Abstract

The purpose of the present study will be: 1) to describe the expression of angiogenic factors of the corpus luteum (CL) and the plasma hormonal concentration throughout the luteolysis (total and partial) and during the post-luteolytic and CL resurging phases in mares, and 2) to evaluate the vascular perfusion, secretory function and lifespan of the equine CL after the treatment with subdoses of PGF2± in distinct moments of the estrous cycle. This study will be divided in four experiments. In Experiment 1 and 2, a total of 56 mares (28 mares and 4 groups/experiment; n=7 mares/group) will be treated with saline or different doses of PGF2± during the luteogenesis (Exp.1) and CL maintenance phases (Exp.2). The end point evaluated will be luteal vascularity and plasma progesterone (P4) concentration. Doppler ultrasonography exam and blood samples will be performed every 24 hours from the day of ovulation (D0) to the day of luteolysis. Additionally, the end points will be evaluated every 6 hours and during the first 48 hours post-treatment (h0). In Experiment 3, five groups of mares (n=7 mares/group) will be treated with saline or with the dose of PGF2± required to induce luteolysis (total or partial) during the luteogenesis (D2) or luteal maintanance phase (D8), according to the findings of the Exp.1 and 2. Blood sample will be collected hourly during the first 48 hours post-treatment to measure plasma concentration of P4, PGFM, prolactin, LH, estradiol and oxytocin. In Experiment 4, six groups (n=12 mares/group) similar to the described in Experiment 3 will be used to quantify the genic and proteic expression of angiogenic factors (VEGFA, VEGFR-1, VEGFR-2, Ang-1, Ang-2, receptor Tie-2, NO, eNOS, iNOS, GUCY1B3 e HIF-1±) in the luteal tissue during the regression (total or parcial) and resurgence of the CL using RT-PCR and Western blotting. Byopsis of the CL and blood sample will be performed on hours 0, 6 and 24 post-treatment. A single sample of luteal tissue per mare will be collected (n=4 luteal sample/moment).