Electroacupuncture and A-317491 depress the transmission of pain on primary afferent mediated by the P2X3 receptor in rats with chronic neuropathic pain states.

Abstract

P2X is a family of ligand-gated ion channels that act through adenosine ATP. The P2X3 receptor plays a key role in the transmission of neuropathic pain at peripheral and spinal sites. Electroacupuncture (EA) has been used to treat neuropathic pain effectively. To determine the role of EA in neuropathic pain mediated through the P2X3 receptor in dorsal root ganglion neurons and the spinal cord, a chronic constriction injury (CCI) model was used. Sprague-Dawley rats were divided into four groups: sham CCI, CCI, CCI plus contralateral EA, and CCI plus ipsilateral EA. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were recorded. Furthermore, the expression of the P2X3 receptor was evaluated through Western blotting and immunofluorescence. The effects of EA and A-317491 were investigated through the whole-cell patch-clamp method and intrathecal administration. Our results show that the MWT and TWL of EA groups were higher than those in the CCI group, whereas the expression of the P2X3 receptor was lower than that in the CCI group. However, no significant difference was detected between the two EA groups. EA depressed the currents created by ATP and the upregulation of the P2X3 receptor in CCI rats. Additionally, EA was more potent in reducing mechanical allodynia and thermal hyperalgesia when combined with A-317491 through intrathecal administration. These results show that both contralateral and ipsilateral EA might inhibit the primary afferent transmission of neuropathic pain induced through the P2X3 receptor. In addition, EA and A-317491 might have an additive effect in inhibiting the transmission of pain mediated by the P2X3 receptor.

• Authors: Wan-Sheng Wang, Wen-Zhan Tu, Rui-Dong Cheng, Rong He, Li-Hua Ruan, Li Zhang, Yong-Sheng Gong, Xiao-Fang Fan, Jie Hu, Bo Cheng, Yin-Ping Lai, En-Miao Zou, Song-He Jiang
• Journal: Journal of neuroscience research (J Neurosci Res) Vol. 92 Issue 12 Pg. 1703-13 (Dec 2014) ISSN: 1097-4547 [Electronic] United States
• PMID: 25041872 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 Wiley Periodicals, Inc.

Chemical References

• A-317491
• Analgesics
• Phenols
• Polycyclic Compounds
• Receptors, Purinergic P2X3

Topics

• Afferent Pathways (drug effects)
• Analgesics (pharmacology, therapeutic use)
• Animals
• Chronic Disease
• Disease Models, Animal
• Electroacupuncture
• Ganglia, Spinal (cytology)
• Hyperalgesia (drug therapy, etiology)
• Male
• Neurons (drug effects)
• Pain Measurement
• Pain Threshold (drug effects)
• Patch-Clamp Techniques
• Phenols (pharmacology, therapeutic use)
• Polycyclic Compounds (pharmacology, therapeutic use)
• Rats
• Rats, Sprague-Dawley
• Receptors, Purinergic P2X3 (metabolism)
• Sciatica (pathology, therapy)
• Synaptic Transmission (drug effects, physiology)