Effect of supplementation of green tea polyphenols on the developmental competence of bovine oocytes in vitro

Z.G Wang,Z.R Xu,S.D Yu

doi:10.1590/s0100-879x2007000800008

Abstract

The objective of the present study was to examine the effect of green tea polyphenols (GTPs) supplementation during in vitro maturation, in vitro fertilization, and in vitro culture on the developmental competence of bovine oocytes. Cumulus-oocyte complexes aspirated from the ovaries were matured in vitro (38.5 degrees C for 24 h) and fertilized (38.5 degrees C for 15-18 h) and embryos were cultured (38.5 degrees C for 192 h) in a defined conditioned medium with or without GTPs supplementation. The GTPs used in the present study contained 99% catechin derivatives, with the major components being 50% (-)-epigallocatechin gallate, 22% (-)-epicatechin gallate, 18% (-)-epigallocatechin, and 10% (-)-epicatechin. Four replicate trials were done for each type of experiment. GTPs supplementation (15 microM) of the maturation medium led to a significant increase in the rate of blastocyst formation (34.0 vs 21.4%, P < 0.05). However, the rate of blastocyst formation was not improved when higher GTPs concentrations (20 or 25 microM) were added to the in vitro maturation medium. During in vitro fertilization, supplementation with higher GTPs concentrations (20 or 25 microM) significantly reduced the rate of blastocyst formation (P < 0.05). Supplementation of the culture medium with 15 microM GTPs improved the rate of blastocyst formation, while higher GTPs concentrations (25 microM) significantly reduced embryo development (P < 0.05). In conclusion, these results demonstrate that supplementation with GTPs at low concentration (15 microM) during in vitro maturation and in vitro culture improved the developmental competence of bovine oocytes.

Highlights

The formation of reactive oxygen species (ROS) such as superoxide anions (O2-·), hydroxyl radicals (OH·) and hydrogen peroxide (H2O2) is a normal process that occurs in the cell when there is a deviation of electrons to oxygen (O2) during electron transfer reactions [1]
The present study assessed the effects of green tea polyphenols (GTPs) supplementation during in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC) on the developmental competence of bovine oocytes
The principal finding is that supplementation with 15 μM GTPs during IVM and IVC improves the rate of blastowww.bjournal.com.br cyst formation

Summary

Introduction

The formation of reactive oxygen species (ROS) such as superoxide anions (O2-·), hydroxyl radicals (OH·) and hydrogen peroxide (H2O2) is a normal process that occurs in the cell when there is a deviation of electrons to oxygen (O2) during electron transfer reactions [1]. ROS such as O2-· are able to diffuse and pass through cell membranes and alter most types of cellular molecules such as lipids, proteins and nucleic acids. This can affect the early development of mouse, hamster, and bovine embryos [8,9,10]. Living organisms possess natural protective equivalents known as ROS scavengers (antioxidants) that counteract the negative effects of ROS These antioxidants include enzymes such as superoxide dismutase, which will eliminate O2-·, catalase and selenium-dependent glutathione peroxidase, which will transform H2O2 into H2O and O2, as well as lipidand water-soluble antioxidants such as vitamins C, E and uric acid [11]. The addition of an antioxidant to the medium, may be important for in vitro oocyte maturation and in vitro embryo culture

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Methods

Conclusion