Expression of rat α₂-macroglobulin gene during pregnancy

Rat α₂-macroglobulin (α₂,M) is a typical acute phase protein, the concentration of which in serum increases more than 100-fold after inflammation. It is also known that the protein increases during pregnant (and neonatal) stages. Using a specific cDNA probe, expression of the α₂M gene during pregnancy was studied at the mRNA level. During inflammation, the liver is almost the only organ producing α₂M, but during pregnancy the placenta and uterus were found to be major organs producing a large amount (70-80% of that of inflamed liver) of α₂M mRNA at days 12-15. The yolk sac, maternal liver and fetal (or neonatal) liver also produced a small but significant amount (5-20% of that of inflamed liver) of the mRNA. Southern blotting analysis showed that only one copy of the α₂M gene was present in a haploid rat genome. These results indicated that a single α₂M gene has the ability to respond to two completely-different physiological states.