Phenobarbital induces rat liver apolipoprotein A-I mRNA

The effect of phenobarbital on the level of rat liver apolipoprotein A-I (apo-A-I) mRNA was studied. Poly(A+)-RNA isolated from livers of control or phenobarbital-treated rats was translated in vitro in the rabbit reticulocyte lysate system and immunoprecipitated with rabbit antiserum against rat apo-A-I. The immunoprecipitate was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The translational activity of apo-A-I mRNA was estimated from the incorporation of [35S]methionine into the apo-A-I band. It was found to be elevated 4-fold by 16 hr after rats received a single injection of phenobarbital. To study the effect of phenobarbital on the level of rat liver apo-A-I mRNA, a recombinant plasmid which contained a cDNA insert corresponding to rat liver apo-A-I mRNA was isolated and used to hybridize total liver poly(A+)-RNA from control and phenobarbital-treated rats. There were 4.8- and 10-fold increases in the amount of hybridization to mRNAs from rats after they were treated with phenobarbital for 8 and 16 hr, respectively. Thus, phenobarbital increases the level of rat liver apo-A-I mRNA.