Cerebellar injury induces NOS in Purkinje cells and cerebellar afferent neurons.

Purkinje cells of the cerebellar cortex and neurons of most precerebellar nuclei are conspicuous by the absence of constitutive (neuronal) nitrix oxide synthase (nNOS). Here we show that following mechanical, chemical or thermal injury to the cerebellar cortex there is an induction of nNOS in Purkinje cells as identified with NADPH-diaphorase (NADPH-d) histochemistry and nNOS immunocytochemistry. Induced nNOS and NADPH-d (inNOS/NADPH-d) first appeared 72 hours post-treatment and persisted in excess of 8 weeks. Precerebellar neurons throughout the brain stem also exhibited induced nNOS and NADPH-d with a similar time course. These results indicate that brain lesions can induce nNOS in local neurons and in neurons which are afferent to the leasioned area.