Neuronal and inducible nitric oxide synthase expression and protein nitration in rat cerebellum after oxygen and glucose deprivation

A perfusion model of global cerebral ischemia was used for the immunohistoc hemical study of changes in the glutamate-nitric oxide (NO) system in the r at cerebellum and cerebellar nuclei during a 0-14 h reperfusion period afte r 30 min of oxygen and glucose deprivation, with and without administration of 1.5 mM N-omega-nitro-L-arginine methyl ester (L-NAME). While immunostai ning for N-methyl-D-aspartate receptor subunit 1 (NMDAR1) showed no marked changes during the reperfusion period, neuronal NO synthase (nNOS) immunost aining increased in stellate and basket cells, granule cells and neurons of the cerebellar nuclei. However, global cerebellar nNOS concentrations dete rmined by Western blotting remained largely unchanged in comparison with ac tin expression. Inducible NOS (iNOS) immunostaining appeared in Purkinje ce lls and neurons of the cerebellar nuclei after 2-4 h of reperfusion and int ensified during the 6-14 h period. This was reflected by an increase in glo bal cerebellar iNOS expression determined by Western blotting. Immunostaini ng for protein nitrotyrosine was seen in Purkinje cells, stellate and baske t cells, neurons of the cerebellar nuclei and glial cells in controls, and showed a progressive translocation in Purkinje cells and neurons of the cer ebellar nuclei from an initial perinuclear or nuclear location towards the periphery. At the end of the reperfusion period the Purkinje cell apical de ndrites were notably retracted and tortuous. Prior and concurrent L-NAME ad ministration eliminated nitrotyrosine immunostaining in controls and blocke d or reduced most of the postischemic changes observed. The results suggest that while nNOS expression may be modified in certain cells, iNOS is induc ed after a 2-4 h period, and that changes in protein nitration may be assoc iated with changes in cell morphology. (C) 2001 Elsevier Science B.V. All r ights reserved.