| Objective:To evaluate the effect of emodin on pain transmission mediated by P2X2/3 receptor in neuropathic pain states and its potential mechanisms.Methods:Created chronic constriction injury(CCI) neuropathic pain models. Male Sprague-Dawley rats were randomly assigned to five groups for varied purpose: control group (Control), sham operation group (Sham), CCI operation group (CCI), CCI rats treated with emodin (CCI+emodin) and emodin control group (Emodin).1. mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were tested in order to observe if emodin could affect the behavior of CCI rats.2. The expressions of P2X2/3 mRNA in L4-L5 dorsal root ganglion (DRG) were detected via in situ hybridization (ISH) and RT-PCR.3. The expressions of P2X2/3 protein in L4-L5 DRG were detected by immunohistochemistry and Western Blotting.Results:1. Chronic constriction injury (CCI) formed at 5-7 days after surgery and MWT and TWL of CCI and CCI+emodin groups rats'right hind limbs were much lower compared to that of Control, Sham and Emodin groups rats (p<0.05). During postoperation 7-14 days, MWT and TWL of CCI+emodin group rats obviously increased compared to CCI group rats (p<0.05), but no significances with Control group (p>0.05); 2. At postoperation Day 14, ISH and RT-PCR results showed that P2X2/3 receptors'expression at mRNA level in L4-L5 DRGs of CCI group rats significantly increased (p<0.01) and that of CCI+emodin group rats decreased compared to CCI group (p<0.01); 3. Immunohistochemistry and Western Blotting results showed that compared to Control, Sham and Emodin groups, the expressions of P2X2/3 protein in L4-L5 DRG of CCI group rats were much higher (p<0.01), but in CCI+emodin group P2X2/3 protein expressions were much lower than CCI group rats' (p<0.01).Conclusion:Emodin can inhibit the transmission of neuropathic pain mediated via the P2X2/3 receptor of primary sensory neurons to alleviate chronic neuropathic pain. |
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