AMINOPEPTIDASES - STUDY OF THEIR REGIONAL DISTRIBUTION IN RATS

Soluble and membrane-bound aminopeptidase activities in eleven regions of the rat brain were assayed using L-leucine-2-naphthylamide as a su bstrate. In addition, two metabolic enzymatic activities were compared : lactate dehydrogenase and aspartate aminotransferase. All enzymatic activities showed significant regional differences when the data were analyzed statistically. Soluble aminopeptidase and aspartate aminotran sferase activities were significantly lower in cortical than in subcor tical areas. Membrane-bound aminopeptidase activity levels were higher in cortical areas. Lactate dehydrogenase activities did no differ bet ween cortical areas and the rest of the zones studied. However, while no wide regional differences were found for the other enzymatic activi ties, membrane-bound aminopeptidase varied markedly across brain regio ns: a 5-fold difference was observed between zones. The differential d istribution of this enzymatic activity is consistent with the hypothes is that it is responsible for the enzymatic inactivation of some neuro active peptides.