HETEROGENOUS EXPRESSION OF ORNITHINE DECARBOXYLASE GENE IN THE PROXIMAL TUBULE OF THE MOUSE KIDNEY FOLLOWING TESTOSTERONE TREATMENT

The expression of the ornithine decarboxylase (ODC) gene in the mouse kidney following testosterone treatment was examined using in situ hyb ridization histochemistry. Testosterone (n = 5) or vehicle (n = 5) was subcutaneously injected (1 mg/animal) into male BALB/c mice (8 weeks in age) 14 h before sacrifice. Animals were sacrificed under ether ane sthesia, their kidneys were removed and immediately frozen in liquid n itrogen. Frozen sections (10-mum-thick) were cut on a cryostat. Sectio ns were hybridized with S-35-labeled sense or antisense RNA probe. The hybridization continued for 24 h at 50-degrees-C and emulsion autorad iography was subsequently performed. A marked increase in ODC mRNA was exclusively detected in the proximal tubule of the renal cortex in th e testosterone-treated animals. The hybridization signal was greater i n the outer portion of the proximal tubule than in the inner portion. No significant hybridization signal was detected either in the distal tubule, renal corpuscle or peritubular tissues. These results indicate that testosterone induces the expression of the ODC gene in the proxi mal tubule of the renal cortex, leading to the increase in ODC activit y in the same region.