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Open Access Highly Accessed Research article

Acute pressure on the sciatic nerve results in rapid inhibition of the wide dynamic range neuronal response

Wenxue Wang1, Wei Tan2, Danping Luo2, Jianhua Lin2, Yaoqing Yu3, Qun Wang2, Wangyeng Zhao2, Buling Wu2, Jun Chen3* and Jiman He24*

Author affiliations

1 Department of Physiology, School of Life Science, Kuning, 605000, China

2 Pain Medicine Program, IDD, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China

3 Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, Fourth Military Medical University, Xi’an, 710032, China

4 Rhode Island Hospital, Brown University, Providence, 02903, USA

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Citation and License

BMC Neuroscience 2012, 13:147  doi:10.1186/1471-2202-13-147

Published: 4 December 2012

Abstract

Background

Acute pressure on the sciatic nerve has recently been reported to provide rapid short-term relief of pain in patients with various pathologies. Wide dynamic range (WDR) neurons transmit nociceptive information from the dorsal horn to higher brain centers. In the present study, we examined the effect of a 2-min application of sciatic nerve pressure on WDR neuronal activity in anesthetized male Sprague–Dawley rats.

Results

Experiments were carried out on 41 male Sprague–Dawley albino rats weighing 160–280 grams. Dorsal horn WDR neurons were identified on the basis of characteristic responses to mechanical stimuli applied to the cutaneous receptive field. Acute pressure was applied for 2 min to the sciatic nerve using a small vascular clip. The responses of WDR neurons to three mechanical stimuli applied to the cutaneous receptive field were recorded before, and 2, 5 and 20 min after cessation of the 2-min pressure application on the sciatic nerve. Two-min pressure applied to the sciatic nerve caused rapid attenuation of the WDR response to pinching, pressure and brushing stimuli applied to the cutaneous receptive field. Maximal attenuation of the WDR response to pinching and pressure was noted 5 min after release of the 2-min pressure on the sciatic nerve. The mean firing rate decreased from 31.7±1.7 Hz to 13±1.4 Hz upon pinching (p < 0.001), from 31.2±2.3 Hz to 10.9±1.4 Hz (p < 0.001) when pressure was applied, and from 18.9±1.2 Hz to 7.6±1.1 Hz (p < 0.001) upon brushing. Thereafter, the mean firing rates gradually recovered.

Conclusions

Our results indicate that acute pressure applied to the sciatic nerve exerts a rapid inhibitory effect on the WDR response to both noxious and innocuous stimuli. Our results may partially explain the rapid analgesic effect of acute sciatic nerve pressure noted in clinical studies, and also suggest a new model for the study of pain.

Keywords:
Sciatic nerve; WDR; Pain; Acute pressure