DITHIOTHREITOL EFFECTS ON HUMAN SPERM QUALITY

Human semen normally coagulates immediately after ejaculation and then undergoes liquefaction during the next 15 to 60 minutes. Incomplete s eminal liquefaction can result in impaired sperm motility and make cli nical evaluation and manipulation difficult. Dithiothreitol, a mucolyt ic agent that reduces the mucoprotein disulfide bonds in sputum, has b een found to induce liquefaction of incompletely liquefied semen in vi tro. We studied the effects of dithiothreitol on sperm motility, viabi lity, acrosomal integrity and morphology. A semen sample was provided by 45 healthy, young men at the University of Arizona. Of the specimen s 10 (22%) demonstrated incomplete liquefaction. Sperm motility and mo tion characteristics of untreated (control) semen and semen treated wi th dithiothreitol were objectively evaluated using computer assisted s emen analysis. Sperm cell membrane integrity and mitochondrial integri ty were measured by fluorescence microscopy using the deoxyribonucleic acid specific fluorochrome propidium iodide and the mitochondria spec ific fluorochrome rhodamine-123, respectively. Acrosomal integrity was determined using the fluorescent stain chlortetracycline. Sperm morph ology was evaluated using bright field microscopy. For completely liqu efied semen (35 cases) dithiothreitol reduced sperm motility (59.1 +/- 1.2% untreated versus 53.2 +/- 1.2% treated, p < 0.01) and motion cha racteristics. However, dithiothreitol had no statistically significant effect on motility of sperm in the group with incompletely liquefied semen (10 cases). Sperm cell membrane, mitochondrial and acrosomal int egrity was unaffected by dithiothreitol regardless of liquefaction sta tus. Dithiothreitol caused a significant increase in abnormally large sperm head morphology in the group with completely liquefied semen. Th e minimal effects of dithiothreitol on sperm motility traits and viabi lity support its use as a possible aid in the evaluation and manipulat ion of incompletely liquefied semen.