Administration-route-related differences in the micronucleus test with N-ethyl-N-nitrosourea.
Administration-route-related differences in the micronucleus test were examined by giving N-ethyl-N-nitrosourea (ENU) to male mice of the MS/Ae and CD-1 strains by 2 different routes, intraperitoneally (i.p.) and orally (p.o.). The experiments consisted of 3 parts: (1) a simplified acute toxicity study, which gave LD50s of 490 (i.p.) and 840 mg/kg (p.o.) in MS/Ae and 640 (i.p.) and 960 mg/kg (p.o.) in CD-1 mice: (2) a pilot experiment for the full-scale micronucleus test to determine appropriate dosages and sampling time: and (3) the micronucleus test at doses of 12.5, 25, 50, and 100 mg/kg with a sampling time of 24 h. The results indicated that no route-related differences existed at the 2 lowest doses. At 50 mg/kg, markedly higher numbers of micronucleated polychromatic erythrocytes (MNPCEs) were induced in both mouse strains by the i.p. route. At 100 mg/kg, the difference between the routes decreased in strain CD-1 and even reversed in MS/Ae. Thus, route-related differences appeared to depend on the dose. Such differences became small, however, in both strains when the comparison was made on the basis of LD50 values.
Sutou
S
S
Central Research Institute, Itoham Foods Inc., Tokyo, Japan.
Sato
S
S
Hitotsumachi
S
S
Kimura
Y
Y
D000284:Administration, Oral; D000818:Animals; D005038:Ethylnitrosourea / Q000008:administration & dosage* / Q000633:toxicity; D007274:Injections, Intraperitoneal; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D015162:Micronucleus Tests; D009153:Mutagens / Q000008:administration & dosage*; D010865:Pilot Projects; D013045:Species Specificity
D009153:Mutagens; D005038:Ethylnitrosourea