[Demonstration of a TRH precursor in the pancreas of the newborn rat].

This study allows the indirect demonstration of a precursor for TRH in pancreatic extracts of 2-days old rats. The sequential treatment of these extracts with trypsin and carboxypeptidase A is followed by a large increase in Pyroglutamyl Histidine Proline (TRH-OH). The molecular weight of the protein that gives rise to TRH-OH after enzymatic treatment ranges between 30,000 and 40,000 daltons. During ontogenesis. TRH levels decrease earlier and more rapidly than that of TRH-precursor levels. These data suggest that changes in the processing of TRH-precursor play a role in the diminution of TRH concentrations that is observed during the first two weeks of life.