Comparison of motility and membrane integrity to assess rat sperm viability

Rat sperm motility and membrane integrity were compared as endpoints for viability, Sperm motility was measured by computer-assisted semen analysis (CASA), whereas membrane integrity was assessed by flow cytometric analysis of sperm stained with two nucleic acid stains, SYBR-14 and propidium iodide, The two techniques were compared in experiments that examined sperm viability over time and by analysis of known mixtures of control and freeze/thaw-killed sperm, Results from the two approaches were quantitatively very similar, Sperm from rats treated with dibromoacetic acid (600 or 1200 mg/kg) or alpha-chlorhyrin (100 mg/kg) were also analyzed. Neither technique detected a treatment-related effect with dibromoacetic acid, CASA identified a significant decrease in sperm motility in alpha-chlorhyrin-treated rats, whereas flow cytometric analysis did not find a measureable change in sperm membrane integrity, Because decreases in sperm motility would be expected to directly affect fertility, CASA may be a more robust endpoint for risk assessment in reproductive toxicology studies than flow cytometric analysis of membrane integrity. (C) 1998 Elsevier Science Inc.