Overview of studies on rat sperm motion analysis using a Hamilton-Thorne Sperm Analyzer--collaborative working study

This collaborative study was conducted to determine the utility and sensitivity of nine sperm motion parameters generated by a Hamilton-Thorne Sperm Analyzer (HTM-IVOS) for detecting adverse effects of chemicals on sperm motion in rats. The efficacy of sperm motion parameters was investigated using nine reproductive toxicants: adriamycin, alpha-chlorohydrin (3 different studies were carried out), dinoseb, ethylene glycol monoethyl ether, 2,5-hexanedione, sulfasalazine, trimethyl phosphate, and ornidazole. The percentage of motile sperm (% motile sperm), the only parameter expressing the status of semen containing non-motile sperm, detected adverse effects on sperm motion in 9 out of 10 studies. However, weak effects on sperm motion were not detected by this parameter in 4 out of 7 studies in which sperm motion disorders were noted at medium or low dosages. The percentage of progressively motile sperm (% progressive sperm) and the sperm velocity parameters (average path velocity, straight line velocity, and curvilinear velocity) detected adverse effects on sperm motion in all studies. In 7 studies which noted sperm motion disorders at medium or low dosages, weak effects on sperm motion were detected by the % progressive sperm in 5 studies and by the sperm velocity parameters in 6 studies. In 10 studies, amplitude of lateral head displacement (ALH) did not detect adverse effects on sperm motion in 4 studies, and beat cross frequency (BCF) failed to detect adverse effects on sperm motion in 3 studies. Because ALH and BCF show the swimming pattern of spermatozoa as head movement, the characteristics of these parameters are different from the % progressive sperm and the sperm velocity parameters. Straightness (STR) and linearity (LIN), which are secondary parameters calculated from sperm velocity parameters, could not detect adverse effects on sperm motion when the sperm velocity parameters did not detect adverse effects. On the basis of these results, we concluded that the % progressive sperm and sperm velocity parameters are useful and sensitive indicators for detecting adverse effects on sperm motion. However, in the % progressive sperm, setting up a suitable threshold of VAP and/or STR is important to gain further sensitivity for detecting adverse effects on sperm motion. The % motile sperm is useful for assessment of sperm motion disorder, and ALH and BCF are useful for evaluating the swimming pattern of sperm. STR and LIN are not very useful for detecting adverse effects on sperm motion.