Alpha-fetoprotein and gamma-glutamyltranspeptidase in mice. Effect of Raf gene.

The regulation of the high physiological level of serum alpha-fetoprotein (AFP) in BALB/c/J mice was studied. Serum AFP concentration in 7- to 12-week-old BALB/c/J mice varied from 460 ng/ml up to 2,790 ng/ml and in other strains tested from 10 ng/ml to 400 ng/ml. In contrast to the difference in serum AFP level, activity of the fetal enzyme gamma-glutamyltranspeptidase (GGT) in the liver of BALB/c/J mice was similar to that found in other mice. In all newborn mice, the initially high GGT activity decreased almost 100-fold during the first 10 days. The serum AFP concentration stayed relatively stable during this period. AFP decreased to the adult level between the 10th and 30th days. Partial hepatectomy and administration of carbon tetrachloride increased the serum AFP level in all mice. The elevation of AFP was 10 times higher in BALB/c/J mice than in mice with low basal AFP level. A slightly elevated GGT activity in the liver was observed in only 10 out of 40 mice after carbon tetrachloride treatment, but none of the mice after partial hepatectomy showed an elevation. These results suggest that the gene ("Raf" gene) controlling the reduced decrease of serum AFP level in young BALB/c/J mice enhances the "turning on" of production of AFP in the regenerating liver. This gene does not, however, control the expression of the other carcinofetal liver marker, GGT.