REGULATION BY A PROTEIN-FREE CARBOHYDRATE-RICH DIET OF RAT PANCREATIC MESSENGER-RNAS ENCODING TRYPSIN AND ELASTASE ISOENZYMES

The levels of mRNAs coding for trypsin and elastase isoenzymic forms were determined in the pancreatic tissue of rats fed a high-carbohydrate protein-free diet for a 0-5 day period. No change in the amounts of mRNAs coding for the two isoelastases was observed, although previous results showed that the biosynthesis of anionic elastase was markedly increased, whereas the biosynthesis of cationic elastase decreased, suggesting the existence of a translational-control mechanism in response to nutritional substrates. In contrast, the levels of mRNAs specific for the three isotrypsins were significantly enhanced, possibly as a result of transcriptional regulation and/or a change in messenger stability. In combination with earlier observations of an overall decrease in cationic trypsin biosynthesis during the same nutritional manipulation, these results suggest that formation of this enzyme is also subject to translational control.