Planta Med 2015; 81 - PM_227
DOI: 10.1055/s-0035-1565604

Effect of isoflavone compounds on the in vitro maturation of sheep oocytes

AA Amir 1, 2, GB Martin 1, JM Kelly 3, DO Kleemann 3, Z Durmic 1, D Blache 1
  • 1UWA Institute of Agriculture and School of Animal Biology, The University of Western Australia, Crawley, Western Australia, Australia
  • 2Institute of Tropical Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
  • 3South Australian Research and Development Institute, Turretfield Research Centre, Rosedale, South Australia, Australia

Phytoestrogens are oestrogen-like but non-steroidal substances that are classified according to their chemical structure: flavones, flavanones, lignans, flavonols, chalcones, isoflavones. The serious problems caused by phytoestrogens in clovers on fertility in female sheep are well documented and led to the inclusion of ‘duty of care’ in the development of novel pasture species [1]. We therefore tested whether isoflavones (genistein, biochanin-A, formononetin) affected in vitro maturation or developmental competence of ovine oocytes, using a factorial design (3 isoflavones x 5 concentrations: 0, 2.5, 5, 10, 25 µg/mL) repeated 4 times. Cumulus-oocyte-complexes from abattoir-sourced adult ovaries were randomly allocated to the treatments, then fertilized and cultured in vitro [2]. Cleavage and embryo development rates were recorded.

There was no significant effect of the lower concentrations (2.5 – 10 µg/mL) of any isoflavone on any measure of embryo development. However, the high concentration (25 µg/mL) caused significant effects for all 3 isoflavones: genistein decreased cleavage rate (92% vs. 80%), blastocyst rate (62% vs. 45%) and blastocyst efficiency (57% vs. 36%); biochanin-A decreased cleavage rate (92% vs. 57%) and blastocyst efficiency (57% vs. 32%); formononetin decreased blastocyst rate (62% vs. 45%) and blastocyst efficiency (57% vs. 42%). These outcomes in vitro suggest that isoflavones from fodder could cause reproductive failure in vivo. No effects were detected at low concentrations, but further investigation is needed with a focus on early morphogenesis and trophectoderm nuclei of the embryos.

References:

[1] Revell C, Revell D. Meeting ‘duty of care’ obligations when developing new pasture species. Field Crops Res 2007; 104: 95 – 102

[2] Kelly JM, Kleemann DO, Rudiger SR, Walker SK. Effects of grade of oocyte-cumulus complex and the interactions between grades on the production of blastocysts in the cow, ewe and lamb. Reprod Domest Anim 2007; 42: 577 – 582