Factors associated with reduced fertility and implantation rates in females mated to acrylamide-treated rats.

A series of studies was conducted to examine the role of copulatory dysfunction, spermatotoxicity, and/or impaired fertilization in the reduced rates of fertility and implantation observed in females mated to acrylamide-treated male rats. In initial experiments, males were gavaged with 0, 5, 15, 30, 45, or 60 mg/kg acrylamide (ACR) for 5 days and then mated serially to naive females. ACR treatment reduced fertility and increased pre- and post-implantation loss, primarily over the first 3 weeks post-treatment. The effects at Week 1 appeared to result from an interference in sperm transport as demonstrated by the absence of sperm in the uteri of females following a single ejaculation by ACR-treated male rats. The effect however was transient, with recovery of fertility in all but the 60 mg/kg group by Week 2. Attempts to explain the reduced rate of implantation concentrated on characterizing changes in measures of ejaculated sperm count and various motility parameters and evaluating sperm fertilizing ability. Males were again dosed acutely with ACR (p.o.). ACR produced statistically significant, but modest, alterations in sperm motility at Week 3. More prominent was the marked decrease in the number of fertilized ova recovered from females mated to ACR-treated males at Week 3. These data suggest that events critical to the fertilizing ability of the sperm appear to play a major role in the reduced reproductive competence associated with ACR treatment in male rats.