Influence of corn oil and diet on reproduction and the kidney in female Sprague-Dawley rats.

The purpose of this study was to investigate the influence of corn oil administration on gestation, parturition, and lactation in rats, in conjunction with diets differing in composition of nutrients. Rats were divided into two groups, each fed different commercial pellets for rodents, CA-1 or CE-2, different from each other mainly in the source of protein. Female Sprague-Dawley rats in both diet groups were administered 0 (untreated control), 2, or 10 ml corn oil/kg body weight by gavage during the premating period (2 weeks), the mating period, the gestation period, and the lactation period (until day 3 of lactation). Food consumption of both the 10 ml/kg corn oil groups was significantly reduced throughout the study. Body weight gain in the 10 ml/kg corn oil group fed the CA-1 diet was significantly reduced on days 0 through 4 of lactation. Neither mating nor fertility indices were affected, and no clinical signs were observed during the gestation period in any groups. Several dams in the 10 ml/kg corn oil group fed the CA-1 diet, however, showed abnormal conditions after parturition, and three dams became moribund. Pup viability was also reduced in this group. Histopathologic examination of the kidneys of dams in the 10 ml/kg corn oil group fed the CA-1 diet revealed severe lesions in the proximal tubular epithelium, i.e., necrosis and fatty degeneration. Females in any group fed the CE-2 diet showed neither abnormal condition after parturition nor any severe lesions in the kidney. These data show that the combination of corn oil and diet with a particular constitution may cause adverse effects on the renal tubules in pregnant and/or lactating rats, suggesting that corn oil gavage as a vehicle can be a confounding factor in the reproductive toxicity studies, depending on the diet.