NOS type-1 mRNA expression and protein localization in spinal autonomic neurons

Autonomic neurons of the rat spinal cord show strong NADPH diaphorase activity and immunoreactivity for nitric oxide synthase (NOS). Here we show mRNA expression of NOS type-1 (neuronal or brain NOS) transcripts in cell bodies of sympathetic preganglionic neurons (SPNs) of the intermediolateral (IML) cell column by non-radioactive in situ hybridization using NOS-I riboprobes. Hybridization signals occurred only in neuronal cell bodies and not outside, in what appeared to be fibers and/or terminals. In preganglionic fibers of SPNs, however, dense axoplasmic immunogold labeling was detected with a monoclonal anti-NOS-I antibody. Expression of NOS-I mRNA in SPN cell bodies and axoplasmic immunolocalization of NOS-I protein suggest that protein translocation is involved in NO-mediated preganglionic control of peripheral targets.