Influence of the second messenger cGMP and its signaling pathways on the lipid content of in vitro matured bovine cumulus-oocyte complexes

Author(s)

Letícia Schefer

• Document type: Master's Dissertation
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT)
• Defense date: 2020-10-23

Examining board members

Cláudia Lima Verde Leal; Gisele Zoccal Mingoti; Yeda Fumie Watanabe

• Advisor: Cláudia Lima Verde Leal

Abstract

in vitro embryo production (IVP) is a biotechnology widely used in Brazil and worldwide. However, there are still limitations regarding its efficiency compared to embryos produced in vivo. In cattle, one of the difficulties encountered is the accumulation of lipids in IVP blastocysts, which reduces embryonic quality and its resistance to cryopreservation. Looking for alternatives to solve this problem, it is necessary to understand the lipid metabolism of bovine cumulus-oocyte complexes (COCs). The cAMP/PKA pathway is the classic cell lipolysis pathway, but the role of the cGMP/PKG pathway in lipid metabolism has also been demonstrated. Thus, as bovine COCs express components of this pathway, the objective of the present study was to investigate the involvement of cGMP in the lipid metabolism of bovine COCs through its pharmacological manipulation. In the first study, divided into three experiments, the lipid content of oocytes and cumulus cells (CC) was evaluated under the influence of cGMP synthesis stimulators (NPPB and Protoporphyrin IX) and under the influence of PKG inhibition (KT5823). We observed that only NPPB was able to reduce the lipid content of oocytes and cumulus cells. In addition, we evaluated the expression of genes related to lipid metabolism (PLIN2), natriuretic peptide receptors (NPRs) and the quantification of intracellular cGMP levels was performed in the same treatments, however, there were no significant differences in any of the parameters evaluated . During all the experiments carried out, nuclear oocyte maturation rates were evaluated and none of the treatments used affected oocyte maturation. In the second study, divided into two experiments, the same cGMP synthesis stimulators (NPPB and Protoporphyrin IX) were used during IVM, and the lipid profiles of oocytes and embryos produced in vitro were evaluated. The lipid profiles of bovine oocytes and embryos were not altered by manipulation of the cGMP pathway. Cleavage and blastocyst rates were not affected by NPPB, but in the group treated with Protoporphyrin IX, no development was observed. In conclusion, we suggest the involvement of the cGMP pathway in the lipid metabolism of bovine CCOs and that manipulation of this pathway can reduce the lipid content in oocytes without affecting the lipid profile of these of oocytes and resulting embryos. (AU)

• FAPESP's process: 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
• Grantee: Letícia Schefer
• Support Opportunities: Scholarships in Brazil - Master