a-Chlorohydrin induced changes in sperm fertilizing ability in the rat: association with diminished sperm ATP levels and motility<, << Karen Jelks a , Trish Berger b , Catherine Horner b , Marion G. Miller a, * a Department of Environmental Toxicology, University of California-Davis, Davis, CA 95616, USA b Department of Animal Science, University of California-Davis, Davis, CA 95616, USA Received 19 June 2000; received in revised form 19 July 2000; accepted 1 September 2000 Abstract In the present study, a-chlorohydrin (ACH) (5, 10, 25, 50 and 75 mg/kg, po) was administered to rats and the effects on sperm ATP levels, sperm motility, and the ability of sperm to bind and penetrate rat oocytes were determined. Groups of rats were killed 5 days and 3 h following treatment. At both time points, sperm from ACH-treated rats ($10 mg/kg) had significantly lower levels of ATP when diluted in media containing glucose. No diminution of ATP was seen in sperm diluted in phosphate-buffered saline (PBS). Computer analysis of sperm motility indicated that straight-line velocity (VSL) was the most sensitive parameter to ACH treatment and was significantly decreased in rat sperm three hours after ACH exposure (25 mg/kg). A clear drop in percent penetration (35% vs. 85% in control) of zona-free rat oocytes by rat sperm of both ACH groups was observed at 10 mg/kg. Higher dose levels produced no significant further decrease in percent penetration. Overall, the fertilizing ability of sperm was highly sensitive to ACH doses that caused minor but significant changes in sperm ATP levels and no significant changes in motility. These data are consistent with the spermatozoan’s need for an uncompromised energy supply to maintain its ability to bind and penetrate the oocyte. © 2001 Elsevier Science Inc. All rights reserved. Keywords: Toxicology; Sperm motility; Fertilization; a-Chlorohydrin; Sperm ATP 1. Introduction In the rat, in vivo administration of a-chlorohydrin (ACH) can cause impaired motility in sperm and functional sterility [1]. High dose levels of ACH cause epididymal toxicity [2]. At lower ACH doses where there is no evidence of histologic changes in the epididymis, ACH directly af- fects sperm metabolism. ACH is thought to inhibit sperm glycolytic enzymes (primarily glyceraldehyde-3-phosphate dehydrogenase) via a metabolite, 3-chlorolactaldehyde [3,4] resulting in a futile substrate cycle in the presence of a glycosable sugar [5,6]. Depletion of the spermatozoa’s in- tracellular ATP stores, which are the driving force behind sperm flagellar movement results. Insufficient energy for normal sperm motility is theorized to be responsible for ACH-induced changes in fertility. Currently, there are no in vivo studies that have investi- gated the relationship between ACH administration, sperm ATP levels, sperm motion characteristics, and subsequent ability to fertilize rat oocytes. Rat in vitro fertilization (IVF) assays, although difficult, have been used successfully to detect altered sperm function induced by ethylene glycol monomethyl ether (EGME) [7] and 1,3-dinitrobenzene (DNB) [8]. IVF assays were a sensitive means to detect effects of these reproductive toxicants. Because the rat re- mains the animal model in which toxicant-induced damage and effects to the male have been best characterized, rat IVF may provide a valuable end-point in reproductive toxicol- ogy studies. In the present study, in vivo administration of ACH was used to elicit changes in sperm motion and explore the relationship between alterations in motility characteristics and in vitro sperm-oocyte binding and penetration. In addi- tion, changes in sperm ATP status were correlated with changes in sperm motion and ability to penetrate the rat oocyte. Zona-free rat oocytes were used in the current study, <This work was supported in part by EPA Grants R820981– 010 and R825351– 010. <<Presented at the Annual Meeting of the Society for the Study of Reproduction, Portland, OR, August 2–5, 1997. * Corresponding author. Tel.: 11-530-754-8982; fax: 11-530-752- 3394. E-mail address: mgmillersears@ucdavis.edu (M.G. Miller). www.elsevier.com/locate/reprotox Reproductive Toxicology 15 (2001) 11–20 0890-6238/01/$ – see front matter © 2001 Elsevier Science Inc. All rights reserved. PII: S0890-6238(00)00115-5