BackgroundAcute 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.ResultsExperiments 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.ConclusionsOur 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.

Acupressure is an alternative medicine methodology that originated in ancient China. Treatment effects are achieved by stimulating acupuncture points using acute pressure. Acute pressure block of the sciatic nerve is a newly reported analgesic method based on a current neuroscience concept: stimulation of the peripheral nerves increases the pain threshold. Both methods use pressure as an intervention method. Herein, we compare the methodology and mechanism of these two methods, which exhibit several similarities and differences. Acupressure entails variation in the duration of manipulation, and the analgesic effect achieved can be short-or long-term. The acute effect attained with acupressure presents a scope that is very different from that of the chronic effect attained after long-term treatment. This acute effect appears to have some similarities to that achieved with acute pressure block of the sciatic nerve, both in methodology and mechanism. More evidence is needed to determine whether there is a relationship between the two methods.