Low protein--high energy diet induces repressed transcription of albumin mRNA in rat liver.

The effects of diet at the molecular level were investigated by feeding rats control or protein-deficient diets. Each of the control and the protein-deficient groups was further divided into three subgroups according to the level of energy intake. Liver DNA, RNA and total cellular protein concentrations and serum albumin and albumin mRNA concentrations were determined. Protein deficiency caused a marked inhibition of liver growth but the size of most cells remained normal. The low protein diet caused concurrent decreases in the levels of serum albumin and serum mRNA. However, this effect was observed only with the combination of a low protein diet and normal energy intake. The low protein-low energy diet failed to induce the low serum albumin level. Our findings suggest that the altered balance between at least two factors of protein and energy intake serves as a trigger for several metabolic changes which ultimately regulate specific genes.