Effect of electroacupuncture on the pathomorphology of the sciatic nerve and the sensitization of P2X3 receptors in the dorsal root ganglion in rats with chronic constrictive injury.

OBJECTIVE: To explore the effect of electroacupuncture (EA) on the pathomorphology of the sciatic nerve and the role of P2X3 receptors in EA analgesia. METHODS: The chronic constriction injury (CCI) model was adopted in this study. A total of 32 rats were randomly divided into four groups: sham CCI, CCI, CCI plus contralateral EA (CCI + conEA) and CCI plus ipsilateral EA (CCI + ipsEA). Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured. EA began at day 7 after the CCI operation and was applied to the Zusanli (ST 36) and Yanglingquan acupoints (GB 34). At day 14, the pathomorphologic changes of the operated sciatic nerve were demonstrated by hematoxylin and eosin staining. In addition, dorsal root ganglion (DRG) neurons isolated from rats were examined by electrophysiological recording to determine if the P2X3 receptor agonists, adenosine 5'-triphosphate disodium (ATP) and α,ß-methylen-ATP (α,ß-meATP) evoked inward currents. RESULTS: Pain thresholds in the CCI group were obviously decreased post CCI surgery (P<0.01). In the EA groups, thermal and mechanical threshold values were increased after the last EA treatment (P<0.05, P<0.01). There was no significant difference in light microscopic examination among the four groups (P>0.05). Current amplitude after application of ATP and α,ß-meATP in DRG neurons were much larger in the CCI group compared to those obtained in sham CCI (P<0.05). ATP and α, ß-meATP invoked amplitudes in the CCI + EA groups were reduced. There was no signififi cant difference between the CCI + conEA group and the CCI + ipsEA group (P>0.05). CONCLUSION: EA analgesia may be mediated by decreasing the response of P2X3 receptors to the agonists ATP and α,ß-meATP in the DRG of rats with CCI. No pathological changes of the sciatic nerve of rats were observed after EA treatment.

[Characteristics of anatomical structures and clinical significance of lumbar Jiaji (EX-B 2) points].

OBJECTIVE: To observe the anatomical structure of Jiaji (EX-B 2) points at the level of lower lumbar region so as to provide evidence for the insertion angle and depth. METHODS: Thirty spine samples of male adults were adopted, and perpendicular insertion of the needle was applied at 3 locations including 1 cun, 0.5 cun and 0.3 cun lateral to the lower border of the spinous process of the lumbar vertebra. The needles were fixed at the local region. Structures and the adjacent major blood vessels and nerves were observed during the anatomy. RESULTS: When the needle was inserted perpendicularly at the point 1 cun lateral to the lower border of the spinous process of the lumber vertebra with the insertion depth of (35.77 +/- 5.86) mm, the zygapophyseal joints, the adjacent osteo-fibrous canal and osteo-fibrous aperture were touched by the tip of the needle, and the medial ramus of dorsal primary ramus of spinal nerve and concomitant vessels were stimulated. Then, needles were inserted perpendicularly 0.5 cun and 0.3 cun lateral to the lower border of the spinous process of the lumber vertebra with the insertion depth of (32.89 +/- 4.79)mm for both. When needle was inserted 0.5 cun lateral, the medial ramus of dorsal primary ramus of spinal nerve and the concomitant vessels were touched by the tip of the needle at where they across the lamina periosteum and erector spinae. When needle was inserted 0.3 cun lateral, the body of the needle reached the terminal branches of the medial ramus of dorsal primary ramus of spinal nerve and the concomitant vessels through the deep paraspinal muscles and the thoracolumbar fascia. CONCLUSION: The medial ramus of dorsal primary ramus of lumbar spinal nerve and concomitant vessels distributed at the region 1 cun, 0.5 cun and 0.3 cun beside the lower border of each lumbar spinous process. Therefore, the location of Jiaji (EX-B 2) points can be considered in the region from 0.3 cun to 1 cun beside the lower border of each spinous process.

Analgesic effect of electroacupuncture on chronic neuropathic pain mediated by P2X3 receptors in rat dorsal root ganglion neurons.

Adenosine 5'-triphosphate disodium (ATP) gated P2X receptors, especially the subtype P2X(3), play a key role in transmission of pain signals in neuropathic pain, ATP has been documented to play a significant role in the progression of pain signals, suggesting that control of these pathways through electroacupuncture (EA) is potentially an effective treatment for chronic neuropathic pain. EA has been accepted to effectively manage chronic pain by applying the stimulating current to acupoints through acupuncture needles. To determine the significance of EA on neuropathic pain mediated by P2X(3) receptors in the dorsal root ganglion (DRG) neurons, mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were recorded, and the expression of P2X(3) receptors in the DRG neurons was assessed by immunohistochemistry (IHC) and in situ hybridization (ISH). In addition, the currents which were evoked in DRG neurons isolated from rats following chronic constriction injury (CCI) by the P2X(3) receptors agonists i.e. ATP and α,ß-methylen-ATP (α,ß-meATP) were examined through the experimental use of whole cell patch clamp recording. The present study demonstrates that EA treatment can increase the MWT and TWL values and decrease the expression of P2X(3) receptors in DRG neurons in CCI rats. Simultaneously, EA treatment attenuates the ATP and α,ß-meATP evoked currents. EA may be expected to induce an apparent induce analgesic effect by decreasing expression and inhibiting P2X(3) receptors in DRG neurons of CCI rats. There is a similar effect on analgesic effect between rats with contralateral EA and those with ipsilateral EA.