In vitro toxicity of mercuric chloride on rabbit spermatozoa motility and cell membrane integrity

Abstract

In this in vitro study the effects of mercuric chloride on the motility and structural integrity of rabbit spermatozoa were investigated. The spermatozoa motility was evaluated using CASA method and Annexin analysis was used for detection of structural changes. The concentration of mercury in the medium varied from 5.0 to 83.3 μ g HgCl2/mL. At Time 0 the highest motility was detected in the control group (67.09 ± 8.72%). Motility in groups with mercury administration was lower in comparison with control. Significant differences were detected in groups with 50.0–83.3 μ g HgCl2/mL (P < 0.001) at Time 0. After 60 and 120 minutes of incubation with mercuric chloride the motility significantly decreased almost in all experimental groups. Progressive motility had a decreasing trend in all experimental groups. At time 60 and 120 significant differences were noted in the group receiving 6.25–83.3 μ g HgCl2/mL. Significant differences were detected in all experimental groups, except the group with the lowest mercuric chloride administration. The concentration-dependent decrease of spermatozoa progressive motility up to 50% of control was detected for groups receiving 50.0 – 83.3 μ g HgCl2/mL at Time 0, for groups receiving 12.5–83.3 μ g HgCl2/mL at Time 60 and 120, decreasing from 36.46 ± 18.73% to 1.03 ± 2.50%. Detailed evaluation of spermatozoa distance (DAP, DCL, and DSL) and velocity (VAP, VCL, and VSL) parameters as well as straightness (STR), linearity (LIN), wobble (WOB), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF) of spermatozoa revealed decrease in groups with the highest mercury concentration in comparison with the control group at all time periods. Detection of spermatozoa with disordered membrane was carried out for groups with higher mercury concentrations and control, using Annexin analysis. Analysis showed higher occurrence of positive spermatozoa in the mercury exposed groups. Some Annexin positive reactions from all spermatozoa were detected in the control group. In mercury-exposed groups positive reaction proved alteration in anterial part of head (acrosome), connection part (connection piece) and in mitochondrial segment. Detected data evidently confirm adverse effects of high mercuric chloride concentrations in rabbit semen on spermatozoa motility parameters.