Some aspects of glycosylation in rat liver during pregnancy.

The aim of the present report was to analyze the pattern of glycoprotein synthesis in rat liver on 19th and 22nd day of pregnancy by following the incorporation of 14C-glucosamine and 3H-galactose into isolated rat hepatocytes, the N-acetylglucosaminyl-1-P and galactosyl transferase activities, and the liver content of dolichol and dolichyl-phosphate. The data obtained show a decrease of precursor incorporation into glycoproteins during the last period of pregnancy; this decrease is independent of enzyme activities. The dolichol content increases and the dolichyl-phosphate content, usually considered as rate limiting for glycosylation, decreases. These results, present in other conditions of proliferation and differentiation of rat liver, could explain the differences in membrane organization, the increase of hepatic proteolysis and the alteration in secretory activity during the last phase of gestation.