Increased nitric oxide release by transient peripheral noxious inputs to the spinal cord of rats: an in vivo voltammetric approach

Using in vivo voltammetric detection of nitric oxide (NO) a previous study demonstrated an increased NO release at the lumbar dorsal horn level of the spinal cord by peripheral inflammatory processes in decerebrated-spinalized rats. This study concerns the effects of acute peripheral stimulations. Gentle non-noxious or isolated nociceptive stimulation did not modify the oxidation current due to NO. However, transient transcutaneous repetitive electrical stimulation of the hindpaw at mild to high intensities (1, 3, and 6 mA) provoked increases in the voltammograms, which were prolonged after stimulation ceased. These effects were absent in animals pretreated with the N-methyl-D-aspartate channel blocker MK-801. The data provide novel direct evidence that NO participates, at least during repetitive stimulation, in the transmission of noxious afferent messages in the dorsal horn of the spinal cord. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.