Effect of Food-Borne Contaminants on Sperm Fertilization Competence and Early Embryonic Development – The Bovine Model

Background

There is a growing concern about reproductive effects of environmental toxins to which men or domestic animals are exposed. Among sources, food products, in particular crops, are potentially to be contaminated either by mycotoxin and/or pesticides.

Aims

To examine the effect of the mycotoxin, aflatoxin B1 (AF-B1), and the most used pesticide atrazine (ATZ) and its metabolite, DACT, on sperm fertilization competence.

Materials

Cumulus oocyte complexes were aspirated from bovine ovaries, in-vitro matured (22h) and fertilized (18h) with fresh semen. Before fertilization, sperm was capacitated in the absence (control) or presence of AF-B1 (10 µM), ATZ (0.1 or 1 µM) or DACT (1 or 10 µM). Cleavage into 2-4 cell stage and blastocyst formation rates were evaluated 42h and 7 days post-fertilization, respectively. The distribution into early embryonic stages was analyzed.

Results

Exposing sperm to AF-B1, ATZ or DACT, reduced the proportion of embryos that cleaved into 2-4 cell, relative to control (P < 0.005). For instance, the proportion for AF-B1-sperm (10 µM) was 70.9 ± 3.9% compared to the control (85.1 ± 2.8%; P < 0.005). Blastocyst formation rate was significantly lower when sperm was exposed to ATZ (0.1 or 1 µM; 7.7 and 8.7%, respectively) or DACT (1 or 10 µM; 20.5 and 16.6%, respectively) relative to the control (30.4%; P < 0.04).

Conclusions

The findings explore the risk associated with exposure of sperm to food contaminants. Even relatively low doses of AF-B1, ATZ or DACT and short time exposure impair fertilization and blastocyst formation.