Present address: University of Saarland, School of Medicine, Department of Physiology, Homburg, Germany.
Interactions between superficial and deep dorsal horn spinal cord neurons in the processing of nociceptive information
Version of Record online: 12 SEP 2012
© 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd
European Journal of Neuroscience
Volume 36, Issue 11, pages 3500–3508, December 2012
How to Cite
Petitjean, H., Rodeau, J.-L. and Schlichter, R. (2012), Interactions between superficial and deep dorsal horn spinal cord neurons in the processing of nociceptive information. European Journal of Neuroscience, 36: 3500–3508. doi: 10.1111/j.1460-9568.2012.08273.x
- Issue online: 4 DEC 2012
- Version of Record online: 12 SEP 2012
- Received 6 June 2012, revised 17 July 2012, accepted 1 August 2012
- excitatory postsynaptic current;
- inhibitory postsynaptic current;
- interlaminar connections;
- transient receptor potential vanilloid 1
In acute rat spinal cord slices, the application of capsaicin (5 μm, 90 s), an agonist of transient receptor potential vanilloid 1 receptors expressed by a subset of nociceptors that project to laminae I–II of the spinal cord dorsal horn, induced an increase in the frequency of spontaneous excitatory and spontaneous inhibitory postsynaptic currents in about half of the neurons in laminae II, III–IV and V. In the presence of tetrodotoxin, which blocks action potential generation and polysynaptic transmission, capsaicin increased the frequency of miniature excitatory postsynaptic currents in only 30% of lamina II neurons and had no effect on the frequency of miniature excitatory postsynaptic currents in laminae III–V or on the frequency of miniature inhibitory postsynaptic currents in laminae II–V. When the communication between lamina V and more superficial laminae was interrupted by performing a mechanical section between laminae IV and V, capsaicin induced an increase in spontaneous excitatory postsynaptic current frequency in laminae II–IV and an increase in spontaneous inhibitory postsynaptic current frequency in lamina II that were similar to those observed in intact slices. However, in laminae III–IV of transected slices, the increase in spontaneous inhibitory postsynaptic current frequency was virtually abolished. Our results indicate that nociceptive information conveyed by transient receptor potential vanilloid 1-expressing nociceptors is transmitted from lamina II to deeper laminae essentially by an excitatory pathway and that deep laminae exert a ‘feedback’ control over neurons in laminae III–IV by increasing inhibitory synaptic transmission in these laminae. Moreover, we provide evidence that laminae III–IV might play an important role in the processing of nociceptive information in the dorsal horn.