Effect of phenobarbital on the development of tumors in mice treated neonatally with N-ethyl-N-nitrosourea.
This study was undertaken to evaluate the effect of phenobarbital on the development of neurogenic tumors induced in mice by neonatal administration of N-ethyl-N-nitrosourea (ENU). A total of 185 A/He mice was divided into four groups. Continuous oral administration of phenobarbital (0.05%) in drinking water was commenced 4 weeks after birth in group I. A single injection of 40 mg/kg of ENU was given subcutaneously on the back within 24 hr after birth in group II. After neonatal injection of ENU, phenobarital was commenced 4 weeks after birth in group III. Group IV was the untreated control. The experiment was terminated 12 months after birth. The serum level of phenobarbital at the end of the experiment was 8.7 microgram/ml in group I and 7.09 microgram/ml in group III. Neurogenic tumors were induced only in groups treated with ENU. The incidence was 5.7% in group II and 10.9% in group III, though the difference between the two groups was not statistically significant. A total of 3 tumors (3.0%) was induced in the central nervous system and 5 tumors (5.1%) in the peripheral nervous system. Histologically, the former were oligodendroglioma and the latter were schwannoma. Lung tumors, lymphomas and hepatic tumors were also induced by ENU, and in male mice phenobarbital had a suppressing effect on the development of liver tumors.
D000818:Animals; D005038:Ethylnitrosourea; D005260:Female; D008113:Liver Neoplasms / Q000139:chemically induced / Q000517:prevention & control; D008175:Lung Neoplasms / Q000139:chemically induced / Q000517:prevention & control; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000517:prevention & control; D009423:Nervous System Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D010634:Phenobarbital / Q000494:pharmacology*
D005038:Ethylnitrosourea; D010634:Phenobarbital