Rat epididymal sperm motion changes induced by ethylene glycol monoethyl ether, sulfasalazine, and 2,5-hexandione

Epididymal sperm was examined using the Hamilton–Thorne Sperm analyzer (HTM-IVOS, version 10.6) in male rats treated with known male reproductive toxicants that act by different mechanisms to detect effects on sperm motion. Three agents known to produce changes in sperm motion at high exposure levels were administered at lower levels. Ethylene glycol monoethyl ether (EGEE), sulfasalazine (SASP), and 2,5-hexandione (2,5-HD) were administered by oral gavage to adult male Sprague-Dawley rats at 250 or 500 mg/kg/day, at 300 or 600 mg/kg/day, or at 100 or 250 mg/kg/day, respectively. The males were treated with EGEE, SASP, and 2,5-HD for 35, 28, and 28 days, respectively. The males treated with EGEE and SASP were mated with untreated females to assess male fertility. All males were examined for body weight, testicular and epididymal weight, epididymal sperm count, and sperm motion. The sperm motion parameters included percentage of motile sperm, percentage of progressively motile sperm (progressive motility), curvilinear velocity (VCL), average path velocity (VAP), straight line velocity (VSL), amplitude of lateral head displacement (ALH), beat cross frequency (BCF), linearity (LIN), and straightness (STR). For the male rats treated with SASP, no treatment-related effects on percentages of motile sperm or sperm count were observed despite impaired male fertility. However, abnormal motion of epididymal sperm from the SASP treated males was detected by a significant reduction in mean progressive motility, VAP, and ALH, and an increase in BCF and STR. For the males treated with 2,5-HD for 4 weeks, most parameters generated by the HTM-IVOS indicated decreased sperm motion despite no remarkable changes in testicular weight, epididymal weight, or sperm count. In the EGEE-treated males at 250 mg/kg/day for 5 weeks, abnormal motion of epididymal sperm was detected by decreased progressive motility and increased BCF, although there were no treatment-related effects on testicular weight or male fertility. Progressive motility was decreased in all treated groups and the difference from the control value was of the greatest magnitude among the sperm motion parameters generated by the HTM-IVOS. Velocity parameters (VAP, VSL, VCL) responded sensitively to abnormal sperm motion in the SASP and 2,5-HD studies. In spite of decreased sperm motion, BCF values were significantly increased in all treated groups except the 7-week EGEE high-dose group, where there were no motile sper