Differential mechanisms of induction of ornithine decarboxylase in rat intestine by l- and d-amino acids

Abstract

A single intragastric administration of glycine, L- and D-alanine, and L-and D-serine into rats resulted in a more than 20-fold stimulation of intestinal mucosal ornithine decarboxylase (ODC) within 4 h. The stimulation of ODC activity was accompanied by an increase in the amount of immunoreactive ODC protein. The induction of ODC by D-amino acids was in all likelihood attributable to an enhanced accumulation of ODC-specific mRNA species as revealed by Northern blot and dot-blot hybridization analyses. However, the induction by glycine and L-amino acids was not explainable by changes of mRNA since the changes in mRNA contents were only marginal. Since the turnover rates of L-serine-induced and D-serine-induced intestinal ODC protein were the same as the non-induced control, we concluded that the induction by glycine and L-amino acids was brought about by an increased efficiency of translation of the ODC message.