The delay in rat liver regeneration by choline is associated to alteration in c-myc expression.

Previous data of our laboratory showed that female rats regenerated earlier than males and choline shifted the female growth pattern toward that of males. We investigated if the effect of choline on the liver compensatory growth was associated to a modulation of the expression and methylation pattern of an early cell cycle dependent proto-oncogene, c-myc. The peak of DNA synthesis was 22 h after 2/3 partial hepatectomy in female regenerating liver, while it was delayed to 30 h when female rats received choline for 3 weeks before liver surgery. Partial hepatectomy induced the expression of c-myc that was already maximal at 1 h. Choline reduced the c-myc expression and it shifted the maximum increase at 2 h. The methylation pattern of c-myc was studied with the Hpa II restriction enzyme. The delay in c-myc expression was not due to hypermethylation of the gene.