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 toxi cants that act by different mechanisms to detect effects on sperm motion. T hree agents known to produce changes in sperm motion at high exposure level s were administered at lower levels. Ethylene glycol monoethyl ether (EGEE) , sulfasalazine (SASP), and 2,5-hexandione (2,5-HD) were administered by or al 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 progre ssively motile sperm (progressive motility), curvilinear velocity (VCL), av erage path velocity (VAP), straight line velocity (VSL), amplitude of later al head displacement (ALH), beat cross frequency (BCF), linearity (LIN), an d straightness (STR). For the male rats treated with SASP, no treatment-rel ated effects on percentages of motile sperm or sperm count were observed de spite impaired male fertility. However, abnormal motion of epididymal sperm from the SASP treated males was detected by a significant reduction in mea n progressive motility, VAP, and ALH, and an increase in BCF and STR. For t he 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 m ales at 250 mg/kg/day for 5 weeks, abnormal motion of epididymal sperm was detected by decreased progressive motility and increased BCF, although ther e were no treatment-related effects on testicular weight or male fertility. Progressive motility was decreased in all treated groups and the differenc e from the control value was of the greatest magnitude among the sperm moti on parameters generated by the HTM-IVOS. Velocity parameters (VAP, VSL, VCL ) responded sensitively to abnormal sperm motion in the SASP and 2,5-HD stu dies. In spite of decreased sperm motion, BCF values were significantly inc reased in all treated groups except the 7-week EGEE high-dose group, where there were no motile sperm to evaluate. ALH was significantly decreased in the treated groups in which remarkable effects on sperm motion were noted. There were no significant changes in ALH at the low-dose of EGEE at which o nly mild effects on sperm motion were observed. STR was increased for epidi dymal sperm from the males treated with SASP when compared with the control s. For the males treated with EGEE and 2,5-HD, however, STR was decreased w hen compared with the controls. There were no significant differences in LI N in any of the groups treated with SASP, in which remarkably reduced sperm motion was detected by the other parameters. In conclusion, among the para meters generated by the HTM-IVOS, progressive motility was significantly de creased in all treated groups and the most valuable for detecting slight ch anges in sperm motion induced by these three different target toxicants. Fu rther investigation with a larger set of compounds is needed to evaluate wh ich NOS parameters are the most sensitive in detecting motion changes. (C) 2000 Published by Elsevier Science inc. All nights reserved.