Phyto-oestrogens affect fertilisation and embryo development in vitro in sheep

Area of Science:

• Reproductive Biology
• Endocrinology
• Developmental Biology

Background:

• Phytoestrogens, including isoflavones, are natural compounds known to influence reproductive functions.
• Understanding the effects of specific isoflavones on oocyte maturation is crucial for improving in vitro fertilization (IVF) outcomes.

Purpose of the Study:

• To investigate the impact of three isoflavone compounds (genistein, biochanin A, formononetin) on ovine oocyte maturation and subsequent embryo development in vitro.
• To determine the dose-dependent effects of these isoflavones on key developmental parameters.

Main Methods:

• Ovine cumulus-oocyte complexes were matured in vitro with varying concentrations (0, 2.5, 5, 10, 25µgmL-1) of genistein, biochanin A, or formononetin.
• Oocytes were fertilized and cultured in vitro, with assessments of cleavage rate, embryo development, total cell count (TCC), and blastocyst formation.

Main Results:

• Lower isoflavone concentrations (2.5–10µgmL-1) showed no significant effect on oocyte maturation or early embryo development.
• The highest concentration (25µgmL-1) of all tested isoflavones significantly decreased cleavage rates and blastocyst efficiency.
• Genistein and formononetin reduced blastocyst rates, while biochanin A also decreased embryo TCC at the hatched blastocyst stage.

Conclusions:

• Isoflavone concentrations of 25µgmL-1 during in vitro maturation (IVM) adversely affect ovine oocyte developmental potential.
• High-dose isoflavones inhibit key embryonic developmental milestones, including cleavage and blastocyst hatching, suggesting potential toxicity.
• Further research is needed to elucidate the precise mechanisms underlying these inhibitory effects and to establish safe concentration thresholds.