Electroacupuncture treatment contributes to the downregulation of neuronal nitric oxide synthase and motoneuron death in injured spinal cords following root avulsion of the brachial plexus.

This study was performed in order to investigate the effect of electroacupuncture (EA) on motoneurons and the expression of neuronal nitric oxide synthase (nNOS) following brachial plexus root avulsion (BPRA). A total of 40 female Sprague-Dawley rats underwent BPRA (5th cervical-1st thoracic) and were randomly divided into the avulsion plus EA stimulation (AV+EA) and AV groups. The AV+EA group received a continuous 20-Hz asymmetric bidirectional disperse-dense wave at the acupuncture points (acupoints) of Dazhui (DU4) and Shousanli (LI10) for 15 min on alternate days until the animals were sacrificed, at 1, 2, 3 and 6 weeks. The AV group received no treatment. The cryostat sections of the 7th cervical segments were prepared and stained with neuronal nitric oxide synthase nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) and histochemically stained and counterstained with neutral red (NR). The number of nNOS-positive motoneurons on the lesion side and survived motoneurons on both sides of the 7th cervical segments were blindly counted and compared between the two groups. The results demonstrated that the number of nNOS-positive motoneurons was significantly lower in the AV+EA group compared with that in the AV group and the percentage of survived motoneurons was significantly higher compared with that of the AV group at 2 and 3 weeks. However, the number of nNOS-positive motoneurons and the percentage of survived motoneurons were not significantly different between the two groups at 1 and 6 weeks. These results indicated that, during the early period after BPRA, EA stimulation at the acupoints of Dazhui (DU4) and Shousanli (LI10) may significantly reduce the number of nNOS-positive motoneurons and protect against motoneuron death.