Cancer Lett. 1989 Nov 15;48(1):43-51.  

Comparison of the effects of acute and subacute treatment of phenobarbital in
different strains of mice.

Lin EL, Klaunig JE, Mattox JK, Weghorst CM, McFarland BH, Pereira MA.

Genetic Toxicology Division, U.S. Environmental Protection Agency, Cincinnati,
OH 45268.

A strain specificity has been demonstrated for the effect of subsequent
administration of phenobarbital (PB), in which diethylnitrosamine
(DENA)-initiated hepatocarcinogenesis was promoted in C3H mice, inhibited in
B6C3F1 (C57BL x C3H) and not affected in C57BL mice. A correlation has been
established between the ability of barbiturates and hydantoins to promote tumor
formation and their ability to induce liver growth, hepatic DNA synthesis and
mixed function oxidase activities. Therefore, we examined in these 3 strains of
mice and in C3B6F1 (C3H x C57BL) mice the effect of PB administered in their
drinking water for 4 days or 28 days. The liver weight to body weight ratio was
increased by PB in all types of mice. Microsomal protein concentrations were
increased in C57BL mice after 28 days of treatment, in C3H after both 4 days and
28 days and in B6C3F1 after 4 days of treatment. No effect upon microsomal
protein content was observed in C3B6F1 mice. DNA content was increased in C3H
mice, both in the 4-day and 28-day treatment groups, while the other strains
showed either a decrease or no difference from control. DNA synthesis was
elevated in all strains of mice after 4 days of treatment with PB, however,
after 28 days of treatment there was either a much reduced increase (C57BL and
C3B6F1) or no difference (C3H and B6C3F1) from controls. In all 4 types of mice
after 4 and 28 days of treatment, PB increased the concentration of cytochrome
P-450, the activity of aminopyrine-N-demethylase (AmDm) and
7-ethoxyresorufin-O-deethylase (ErDe) and the oxidation of testosterone (T). The
oxidative metabolites of T were similar in the 4 types of mice.

PMID: 2819695 [PubMed - indexed for MEDLINE]