DIFFERENT LOCALIZATION OF SPERMIDINE SPERMINE N-1-ACETYLTRANSFERASE AND ORNITHINE DECARBOXYLASE TRANSCRIPTS IN THE RAT-KIDNEY

In situ hybridization histochemistry of transverse sections from male rat kidney showed that the mRNA of the regulatory enzyme of polyamine degradation, spermidine/spermine N-1-acetyltransferase, has a spotty d istribution in the cortex, is low and diffused in the outer stripe and high and diffused in the inner stripe of the outer medulla. At the ce llular level, this mRNA is solely expressed by the epithelium of the d istal straight and convoluted nephron tubules, Since biosynthetic orni thine decarboxylase mRNA is solely found in the proximal straight tubu les, it is proposed that polyamine biosynthesis and degradation occur at separate sites along the nephron.