DIFFERENTIAL LOCALIZATION OF HEME OXYGENASE AND NADPH-DIAPHORASE IN SPINAL-CORD NEURONS

WESTERN blot analysis using several antibodies showed that rat spinal cord contained abundant immunostainable heme oxygenase-2 (HO-2) and ba rely detectable levels of heme oxygenase-1 (HO-1). Anti-HO-2 antibody stained large anterior horn motoneurones and numerous smaller neurons throughout spinal cord gray matter including the dorsal root entry zon e. HO-2(+) astrocytes were not evident in gray matter although their p resence cannot be ruled out. The distribution of HO-2(+) neurons was c ompared with the distribution of cells containing NADPH-diaphorase (NA DPH-d) activity, a marker for nitric oxide synthase. NADPH-d activity was restricted to far fewer neurons, many of which were close to the c entral canal and dorsal root entry zone.