Influence of Two Widely Used Solvents, Ethanol and Dimethyl Sulfoxide, on Human Sperm Parameters

Abstract

To study mechanisms involved in fertility, many experimental assays are conducted by incubating spermatozoa in the presence of molecules dissolved in solvents such as ethanol (EtOH) or dimethyl sulfoxide (DMSO). Although a vehicle control group is usually included in such studies, it does not allow to evaluate the intrinsic effect of the solvent on sperm parameters and its potential influence on the outcome of the experiment. In the present study, we incubated human spermatozoa for 4 h in a capacitation medium in the absence or the presence of different concentrations of EtOH and DMSO (0.1, 0.5, 1.0, and 2.0%) to assess the impact of these solvents on sperm motility, vitality, capacitation, and acrosome integrity. The presence of statistically significant relationships between increasing solvent concentrations and the investigated parameters was assessed using linear mixed models. A significant effect was observed with both solvents for total and progressive sperm motilities. We also evaluated the effect of time for these parameters and showed that the influence of the solvents was stable between 0 and 4 h, indicating an almost direct impact of the solvents. While EtOH did not influence sperm vitality and acrosome integrity, a significant effect of increasing DMSO concentrations was observed for these parameters. Finally, regarding capacitation, measured via phosphotyrosine content, although a dose-dependent effect was observed with both solvents, the statistical analysis did not allow to precisely evaluate the intensity of the effect. Based on the results obtained in the present study, and the corresponding linear mixed models, we calculated the concentration of both solvents which would result in a 5% decline in sperm parameters. For EtOH, these concentrations are 0.9, 0.7, and 0.3% for total motility, progressive motility, and capacitation, respectively, while for DMSO they are 1.5, 1.1, >2, 0.3 and >2% for total motility, progressive motility, vitality, capacitation, and acrosome integrity, respectively. We recommend using solvent concentrations below these values to dissolve molecules used to study sperm function in vitro, to limit side effects.

Mitochondrial uncouplers impair human sperm motility without altering ATP content

“…Next, the uncouplers' effects on hyperactivity were tested (Figure 3B), and although the DMSO vehicle had no negative effects in any other assays, it had a dose-dependent inhibitory effect on sperm hyperactivity which prevented meaningful interpretation of the effects of the uncouplers on hyperactivation. These results are corroborated by recent research showing that concentrations of DMSO vehicle below 0.5% have minimal effects on human sperm basal motility, vitality, and acrosome integrity, but may reduce tyrosine phosphorylation, a hallmark of capacitation [33]. Other investigators should be wary of this issue when designing future analyses of hyperactivation.…”

Fluorinated Human Serum Albumin as Potential 19F Magnetic Resonance Imaging Probe

“…DMSO is an important solvent that dissolves both polar and nonpolar compounds and greatly increases the rate of nucleophilic substitution reactions. It exhibits several capabilities, such as high biocompatibility (nontoxic class 3 by the FDA), anti-inflammatory and bacteriostatic functions, and an antioxidant [ 71 , 72 ]. DMSO is widely used in life sciences and as an auxiliary solvent in the fabrication of polymers and drugs [ 73 ].…”

Oxido-Reduction Potential as a Method to Determine Oxidative Stress in Semen Samples

“…In addition, the significant increments in the ORP after the menadione treatments suggest that there may have been much less SOD activity in the sperm, as it was published by O'Flaherty et al [92] earlier. As a control, 5% DMSO was used, which did not appear to be toxic despite the high concentration, although it should be mentioned that in other experiments, 2% DMSO for 4 hours caused significant decreases in the viability and motility of human spermatozoa [97].…”