Relationship of alpha-fetoprotein and albumin in fetuses and neonates from genetically lean and obese swine.

The relationship between alpha-fetoprotein and albumin during fetal development in two genetic lines of swine selected for either high backfat (obese) or low backfat (lean) has been investigated. Differences in serum concentrations, in vitro synthesis by liver slices, and cell-free translational activity of total tissue RNA for alpha-fetoprotein and albumin were determined at days 40, 60, and 80 of gestation and in newborn pigs. Serum concentrations of alpha-fetoprotein tended to be greater in pigs from the lean line compared to those from the obese line during the fetal stages, but no differences were observed in newborn pigs. Similar differences between the two lines were observed for alpha-fetoprotein synthesis by liver slices and cell-free mRNA translational activity. Serum albumin concentrations and the relative synthesis by liver slices were between 2- and 3-fold greater in the obese pigs compared to the lean pigs at days 60 and 80 of gestation and at birth. Albumin mRNA activity increased with fetal age in a manner similar to increases observed in serum concentrations and in vitro synthesis; however, no differences in the cell-free albumin mRNA activity in total liver RNA extracts from the two lines could be detected. The overall pattern of increasing albumin and decreasing alpha-fetoprotein concentrations in serum with increasing fetal age was similar in the two lines. Results from dot-blot hybridizations of total liver RNA to a heterologous recombinant mouse albumin cDNA probe suggested that increasing albumin synthesis with increasing age can be attributed to an increasing abundance of albumin mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)