IMMUNOHISTOCHEMICAL LOCALIZATION OF ADP-RIBOSYLARGININE HYDROLASE IN RODENT CNS

Polyclonal antibodies were generated against ADP-ribosylarginine hydro lase (AAH), using recombinant fusion protein of rat AAH and glutathion e-S-transferase as a immunogen, and affinity-purified. Western blottin g showed that the antibodies recognized in mouse brain homogenate a si ngle protein with a molecular mass of 38 kDa, the expected size for mo use AAH. An analysis using the antibodies revealed that heavy labeling s were apparent in various brain regions. In the cerebral cortex, pyra midal cells in layers III and V were the most heavily labeled. In the hippocampal formation, labeling was present on the pyramidal neurons a nd granule cells. The most heavily immunostained cell type was the pyr amidal neuron of CA3, In the cerebellum, Purkinje cells were the most heavily labeled. Less intense staining was present over the granule ce lls. In the basal ganglia, neurons in the caudate nucleus and large mu ltipolar cells in the amygdaloid complex were immunoreactive. Heavy la beling was seen in many midbrain and brainstem nuclei. Neurons in the habenula and ependymal cells were stained heavily. On Western blot ana lysis of rat cerebrospinal fluid (CSF), the anti-AAH antibodies recogn ized a protein with a molecular mass of 38 kDa. This is apparently the first evidence of a widespread but distinctive distribution of AAH in neurons of mouse brain and the presence of extracellular AAH in rat C SF.