Influence of cGMP and its signaling pathways on the lipid profile of oocytes and bovine embryos produced in vitro

• Grant number: 18/20527-7
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: February 01, 2019
• End date: July 31, 2019
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Cláudia Lima Verde Leal
• Grantee: Letícia Schefer
• Supervisor: Matthew Benjamin Wheeler
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Institution abroad: University of Illinois at Urbana-Champaign, United States
• Associated to the scholarship: 17/05483-0 - Influence of the second messenger cGMP and its signaling pathways on the lipid content of bovine complexes cumulus oocytes matured in vitro, BP.MS

Abstract

Previous studies have shown that bovine cumulus-oocyte complexes (COCs), express transcripts for several enzymes of the cGMP pathway including those for its synthesis (GUCY1B3), degradation (PDE5A) and signaling (PKG1 and PKG2), and that FCS in IVM medium affects the expression of some of these transcripts, as well as decreases cGMP levels. Inhibition of cGMP hydrolysis with PE% inhibitor sildenafil during IVM, decreased lipid contents in oocytes, while FCS increased; association of sildenafil in presence of FCS decreased lipids and such effect was reversed by PKG inhibition. Taken together, these results suggested that the cGMP-PKG pathway in involved, at least in part, in the control of lipid metabolism in bovine COCs. Synthesis of cGMP may be stimulated through activation of GUCY (soluble guanylyl cyclase) or natriuretic peptides receptors (NPR1 and NPR2, membrane guanylyl cyclase), which are also expressed in bovine COCs. Natriuretic peptides NPPA and NPPB activate NPR1, while NPPC activates NPR2. The use of Protoporphyrin IX (activator of GUCY) and of NPPB reduced lipid contents in oocytes, while NPPA and NPPC had no effect. None of the stimulators of cGMP synthesis affected oocyte maturation. In order to further investigate the role of the cGMP pathway on lipid metabolism in bovine COCs, we propose to analyze the effects of stimulation of cGMP synthesizing enzymes during IVM on the lipid profiles of bovine oocytes, cumulus cells and resulting embryos produced in vitro. In experiment 1, bovine COCs will be submitted to IVM with Protoporphyrin IX, NPPB or no stimulators (control) and assessed for lipid profiles in oocytes and cumulus cells by mass spectrometry (MS). In experiment 2, the same groups will be evaluated regarding effects on embryo development (cleavage and blastocyst rates), lipid contents and crytolerance to vitrification. In experiment 3, the same groups will be assessed for lipid profile of resulting embryos by MS. (AU)