Long-lasting increase of nitric oxide synthase immunoreactivity, NADPH-diaphorase reaction and c-JUN co-expression in rat dorsal root ganglion neurons following sciatic nerve transection.

Changes of NADPH-diaphorase reaction (NDP) and nitric oxide synthase immunoreactivity (NOS-IR) in neurons of dorsal root ganglia (DRG) were investigated following transection and ligation of rat sciatic nerve. In untreated rats, 2.7% of L4/L5 DRG neurons were labelled by NDP. After 3 days, intensity of NDP and number of labelled neurons increased and reached a maximal level between 10 and 20 days in 26.8% neurons which persisted up to 50 days. After 150 days, 8.7% of DRG neurons were still labelled. In contralateral L4/L5 DRG, but not L1 and T10 DRG, the number but not the intensity of NDP labelled neurons slightly increased between 10 and 50 days. The patterns of NOS-IR and NDP were congruent. Ipsilaterally, 76% to 92% of NDP neurons showed co-expression with the c-JUN transcription factor which is supposed to play a crucial role in the regeneration process. NDP accumulated in the peripheral nerve stump and was increased in the superficial dorsal horn between 10 and 30 days, whereas motoneurons were not labelled by NOS and NDP.