Reproduction Abstracts

Introduction: Atrazine (ATZ) is one of the most extensively used herbicides, known as a ubiquitous environmental contaminant and found in water sources. ATZ was detected in human amniotic fluid, serum and urine, however, the risk associated with ATZ exposure on sperm is less known.

Methods: Sperm was isolated from fresh ejaculates or testicular-epididymis compartments (head, body, tail) and capacitated in vitro for 4 h with 0, 0.1, 1 or 10 μM ATZ. The integrity of plasma- and acrosome membranes and mitochondrial membrane potential (ΔΨm) were examined simultaneously by fluorescent staining at 0, 2 and 4 h of incubation. After capacitation, acrosome reaction (AR) was induced by Ca²⁺ ionophore and the proportion of sperm underwent pseudo- or induced-AR was determined. In addition, oocytes (n=50–70 per group 3 replicates) were aspirated from ovaries, in-vitro matured (22 h) and fertilized (18 h) with sperm capacitated with 0.1 or 1 μM ATZ. Cleavage and blastocyst formation rates were evaluated after 42 h and 7 days post-fertilization, respectively.

Results and discussion: ATZ had a prominent effect on sperm isolated from the epididymis tail, expressed by disruption of membrane integrity, mostly at low concentrations. Both pseudo- and induced AR were impaired when sperm isolated from ejaculate or epididymis tail were incubated with ATZ (0.1 μM P<0.05). ΔΨm was affected by ATZ (1 μM P<0.0009) only in the later. Pre-fertilization exposure of sperm to 1 μM ATZ resulted in a lower proportion of embryos that cleaved in to 2–4 cell-stage (P<0.005) or developed to blastocyst (P<0.02). The findings explore the harmful effect of ATZ on sperm viability, acrosome integrity and mitochondrial function. These were associated with reduced fertilization competence and blastocyst formation, indicating the risk associated with ATZ exposure even at low ecologically relevant doses and for short time.