NADPH diaphorase activity in the primary sensory neurons following peripheral axotomy

An experimental model of the neuropathic pain consisting in the transection of the sciatic nerve was used to study the dynamics of the neuronal and no nneuronal changes in L5 and L6 dorsal root ganglia with regard to the reduc ed nicotinamide adenine dinucleotide phosphate diaphorase staining on 7(th) and 14(th) postsurgery days. At both surviving periods a statistically sig nificantly increase of the medium-sized dorsal root ganglia neurons was fou nd including the staining of their intraganglionic fibers. A small number o f extremely small neurons was detected as well by this histochemical approa ch considered to be a reliable marker for nitric oxide synthase activity. Q ualitative analysis of reduced nicotinamide adenine dinucleotide. phosphate diaphorase of the medium-sized neurons supports the view that this neurona l type is activated during the state of the neuropathic pain. It ma); be co ncluded therefore that this neuronal type might help in the development of the tactile allodynia and thermal hyperalgesia known to occur during neurop athic pain.