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Melatonin and its effect on meiosis resumption and embryo development in cattle

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Author(s):
Hugo Fernandes
Total Authors: 1
Document type: Doctoral Thesis
Press: Pirassununga.
Institution: Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT)
Defense date:
Examining board members:
Cláudia Lima Verde Leal; Lígia Garcia Mesquita; Gisele Zoccal Mingoti; Simone Cristina Méo Niciura; Juliano Rodrigues Sangalli
Advisor: Cláudia Lima Verde Leal
Abstract

Melatonin (MLT) is an indoleamine that can act on reproductive competence, has antioxidant and antiapoptotic activities and influences different cell signaling pathways. In vitro studies have shown beneficial effects of MLT use on in vitro maturation (IVM) and culture (IVC) of oocytes and embryos, respectively. In addition, MLT appears to be able to induce the resumption of meiosis, but the mechanism by which this stimulus occurs is still unknown. In this study, we investigated the involvement of maturation promoting factor (MPF) and cyclic adenosine monophosphate (cAMP) in meiosis resumption stimulated by MLT, as well as its effect on the development and quality of bovine embryos produced in vitro. The present study was divided into two articles. In the first article, entitled: Melatonin and its effects on meiosis resumption, were developed the experiments: 1) The effect of different melatonin concentration on resumption and progress of meiosis and transcripts abundance in the cumulus cells; 2) Effect of melatonin on CDK1 protein; and 3) Effect of melatonin on the levels of cAMP. In the second article, entitled: Antioxidant roles of melatonin on bovine cumulus-oocyte complexes and embryos produced in vitro, were developed the experiments: 1) Effect of MLT alone or in combination with gonadotrophins during IVM on maturation, ROS levels and mitochondrial function in oocytes and antioxidant enzymes transcripts in cumulus cells; 2) Effect of MLT during IVC on embryo development and quality; 3) Effects of MLT and mitochondrial antioxidant during IVM on oocyte maturation, ROS levels, and mitochondrial function; 4) Effects of MLT and mitochondrial antioxidant during IVC on embryo development and quality; and 5) Effects of combined treatment with antioxidants during IVM and IVC. For the first article, melatonin was able to promote the meiosis resumption at 9h, but did not influenced its progression in the stage of MII evaluated at 24h of in vitro maturation. The CDK1 protein and cAMP levels had similar profiles to those treated with FSH in relation to MLT, suggesting that MLT could contribute to the meiosis resumption by acting on MPF and cAMP-dependent signaling. For the second article, we concluded that MLT failed to improve the oocyte maturation, development and quality of bovine in vitro produced embryos when compared with MQ and MT antioxidants. (AU)

FAPESP's process: 16/24884-3 - Melatonin and its effect on meiosis resumption and embryo development in cattle
Grantee:Hugo Fernandes
Support type: Scholarships in Brazil - Doctorate