[Detection of peptidergic and nitrergic structures in the spinal ganglia of rabbits]

In this study we have demonstrated the presence of neuropeptide substance P and non-peptide neurotransmitter NO (nitric oxide) in the dorsal root ganglia of rabbit. NADPH-diaphorase histochemical staining was used for the detection of NO and immunohistochemical method for the detection of substance P.A particular number of dorsal root ganglion (DRG) cells were stained by SP and NADPH-d reaction. The presence of SP and NADPH-diaphorase positive cells varied depending upon spinal level of DRGs. Positively stained neurons were only small or medium-sized. Cells of large diameter profiles showed no staining. Substance P immunoreactive cells were stained brown and dark brown, the intensity of NADPH-d staining varied from light to very dark blue. In some DRGs cells, there was a very significant neuronal co-localization of immunoreactivity for SP and reactivity for NADPH-d. In summary, DRG cells appear to express diaphorase and substance P activity, and some of them contain both neurotransmitters. Recent studies analysing the participation of NO in the regulation of SP release in the spinal cord suggest, that the DRGs neurons may display a close interaction between NO and SP. (Fig. 14, Ref. 39.)