ABSTRACT
Methyl palmoxirate, an inhibitor of long-chain fatty acid oxidation, was administered by gavage (0, 1, 5, or 20 mg/kg/day) to female rats over the last third of gestation and throughout lactation. Weight gain (mid- and high-dosage group) and survivability (high-dosage group) were significantly (p less than or equal to 0.05) reduced in offspring of methyl palmoxirate-treated dams as compared to control offspring. Mid- and high-dosage male offspring found dead after Day 4 of lactation exhibited grossly distended bladders and renal pelves. A dosage-related increased incidence of dilated renal pelves was observed in both sexes at necropsy of 21-day-old mid- and high-dosage group pups. Microscopic examination of the urinary tracts of a number of affected pups revealed renal parenchymal atrophy and urethral obstruction. Drug disposition studies indicated lactating pups were exposed to significant amounts of methyl palmoxirate via mammary secretions. Cross-fostering experimentation suggested that some of the adverse effects observed in offspring were due to lactational, rather than in utero, exposure.
Subject(s)
Epoxy Compounds/toxicity , Ethers, Cyclic/toxicity , Fatty Acids/metabolism , Hydronephrosis/chemically induced , Propionates/toxicity , Animals , Blood Urea Nitrogen , Dose-Response Relationship, Drug , Female , Kidney/drug effects , Kidney/pathology , Lactation , Milk/metabolism , Oxidation-Reduction , Pregnancy , Proteins/metabolism , Rats , Rats, Inbred Strains , Urethra/drug effectsABSTRACT
N-(4-hydroxyphenyl)-all-trans-retinamide (HPR) has potential efficacy in the treatment of dermatologic, arthritic, and neoplastic disorders. The teratogenicity of such a compound is of special concern in light of the known adverse effects of retinoids, in general, on the developing conceptus. In these studies, Sprague-Dawley rats and New Zealand White rabbits were treated orally from gestation days 6 to 15 and 6 to 18, respectively, with 0, 20, 125, or 800 mg/kg/day of HPR. In rat fetuses, low incidences of hydrocephaly (mid- and high-dosage groups) were observed. Fetal tissue (ng/g) and maternal plasma (ng/ml) concentrations of HPR, its major metabolite (N-[4-methoxyphenyl] retinamide [MPR]) and retinol were determined in separate groups of similarly-treated rats 3 h following the last dose on gestation day 15. Fetal tissue concentrations of HPR and MPR were approximately one-half maternal plasma concentrations. A dose related reduction in maternal plasma and fetal tissue concentrations of retinol were also observed. In mid- and high-dosage rabbit fetuses, a dose-related increase in the incidence of dome-shaped head was observed. Subsequent skeletal evaluation revealed delays in skull bone ossification and a widening of the frontal and frontoparietal sutures. Microphthalmia was also observed in two high-dosage fetuses. A dose-dependent and statistically significant reduction in maternal plasma retinol levels was observed across all dosage groups.
