The frequency of Pig-a mutant red blood cells in rats exposed in utero to N-ethyl-N-nitrosourea.
The Pig-a assay has been developed as a rapid sensitive measure of gene mutation in adult rats; however, no data exist on its ability to detect mutation following in utero exposures or in neonatal animals. Pregnant Sprague-Dawley rats were treated daily on gestational days 12-18 with oral doses of 0, 6, or 12 mg/kg/day N-ethyl-N-nitrosourea (ENU); following parturition, the offspring and dams were monitored over a period of 5 months for the frequency of CD59-deficient erythrocytes as a marker of Pig-a mutation. Significant dose-related increases in Pig-a mutant red blood cells (RBCs) were observed in ENU-treated dams. However, only very weak increases in RBC Pig-a mutant frequency (MF) were noted in offspring treated in utero with the lower ENU dose. The higher ENU dose produced extremely variable responses in the offspring as a function of age, even among littermates, ranging from a steady low or moderately high Pig-a MF to a rapidly increasing or decreasing Pig-a MF. The manifestation kinetics of Pig-a mutant RBCs in the offspring suggest that the change from predominantly hepatic to predominantly bone marrow erythropoiesis that occurs during early development may have contributed to this variability. Our results indicate that using the RBC Pig-a model for mutation detection in animals treated in utero may require analysis of multiple offspring from the same litter to account for potential "jack pot" effects, and that detection of the earliest treatment effect (i.e., in neonates using the hepatic RBC fraction) may require optimization of blood processing.
Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA. vasily.dobrovolsky@fda.hhs.gov
Vasily N
VN
Dobrovolsky
Robert H
RH
Heflich
Sherry A
SA
Ferguson
D000477:Alkylating Agents / Q000633:toxicity*; D000818:Animals; D018957:CD59 Antigens / Q000235:genetics; D004912:Erythrocytes / Q000378:metabolism*; D005038:Ethylnitrosourea / Q000633:toxicity*; D005260:Female; D008565:Membrane Proteins / Q000235:genetics*; D009152:Mutagenicity Tests; D009153:Mutagens / Q000633:toxicity; D009154:Mutation / Q000187:drug effects*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014599:Uterus
D000477:Alkylating Agents; D018957:CD59 Antigens; D008565:Membrane Proteins; D009153:Mutagens; C080086:phosphatidylinositol glycan-class A protein; D005038:Ethylnitrosourea