Effect of polydatin on neuropathic pain in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of polydatin on neuropathic pain in rats.Methods Forty male Sprague-Dawley rats,aged 6-8 weeks,weighing 200-230 g,were randomly divided into 5 groups (n =8 each) using a random number tablesham operation group (group S),neuropathic pain group (group NP),polydatin 5 mg/kg group (group P1),polydatin 10 mg/kg group (group P2),and polydatin 20 mg/kg group (group P3).Neuropathic pain was induced by chronic constriction injury in NP and P1-3 groups.In group S,the sciatic nerve was only exposed but not ligated.In S and NP groups,normal saline 0.1 ml was injected intraperitoneally immediately after operation and at 1,3,5 and 7 days after operation (T1-4).In P1-3 groups,polydatin 5,10 and 20 mg/kg (in normal saline 0.1 ml) were injected intraperitoneally immediately after operation and at T1-4.At 1 day before operation (T0) and T1-4,the mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured.After measurement of pain threshold at T4,the rats were sacrificed,and L4-6 segments of the spinal cords were removed for determination of the expression of high-mobility group box 1 (HMGB1),Toll-like receptor 4 (TLR4),interleukin-1beta (IL-1β),tumor necrosis factor-alpha (TNF-α) and monocyte chemotactic protein-1 (MCP-1) by Western blot.Results Compared with group S,the MWT was significantly decreased,and the TWL was significantly shortened at T1-4 in group NP,the MWT was significantly decreased at T1-4,and the TWL was significantly shortened at T2-4 in group P1,the MWT was significantly decreased at T1-4,and the TWL was significantly shortened at T3.4 in group P2,the MWT was significantly decreased at T1-4 in group P3,and the expression of HMGB1,TLR4,IL-1β,TNF-α and MCP-1 was significantly up-regulated in NP,P1 and P2 groups (P＜0.05).Compared with group NP,the MWT was significantly increased at Tt-4,and the TWL was significantly prolonged at T1,2 in group P2,the MWT was significantly increased,and the TWL was significantly prolonged at T1-4 in group P3,the expression of HMGB1,TLR4,IL-1β,TNF-α and MCP-1 was significantly down-regulated in P2 and P3 groups (P＜0.05),and no significant change was found in the parameters mentioned above in group P1 (P＞0.05).Compared with group P1,the MWT was significantly increased at T4 in group P2,and the MWT was significantly increased at T14,the TWL was significantly prolonged at T3,4,and the expression of HMGB1,TLR4,IL-1β,TNF-α and MCP-1 was significantly down-regulated in group P3 (P＜0.05).Compared with group P2,the MWT was significantly increased at T3,4,and the expression of TLR4,IL-1β,TNF-α and MCP-1 was significantly down-regulated in group P3 (P＜0.05).Conclusion Polydatin can alleviate neuropathic pain through inhibiting inflammatory responses in the spinal cord of rats.