Analgesic Effect And Its Mechanism Of Choline And Paracoxib Sodium In Acute And Chronic Pain Model

Part ? Synergistic analgesic effect of choline and parezoxib sodium on acute acetic acid writhing modelObjective To investigate the synergistic analgesic effect of choline and parecoxib sodium and study its mechanism.Methods In male Kunming mice with acetic acid-induced writhing, the ED50 of choline and parecoxib sodium (administered via the tail vein at 2 h and 30 min before modeling, respectively) and their combined use were determined. In saline (control)group, ED50 choline (C) group, ED50 parecoxib sodium (P) group, and 1/2ED50 choline and parecoxib sodium (1/2[C+P]) group, blood samples were collected from the eyeball 10 min after intraperitoneal administration of acetic acid to detect the levels of IL-1, TNF-a, PGE2, NF-kB, and I-kB levels using ELISA kits.Results In the acetic acid-induced writhing model, the ED50 of choline and parecoxib sodium was 8.64 and 6.33 mg/kg, and when combined, their ED50 was 2.13 and 1.56 mg/kg, respectively. The isobolograms of parecoxib sodium and choline showed that the measured ED50 of the two drugs combined was below the theoretical ED50 value(P<0.05) with a combination index (CI) of <0.9. Compared with the control group, C group, P group, and 1/2 (C+P) group all showed significantly lowered IL-1 and TNF-a levels (P<0.05),especially in 1/2 (C+P) group (P<0.05). PGE2 level was significantly lower in P group and 1/2 (C+P) group compared with the control group (P<0.05).NF-?B and I-?B levels were significantly lowered in C, P, and 1/2 (C+P) groups(P<0.05),and the reduction was the most obvious in 1/2 (C+P) group (P<0.05).Discussions In the acetic acid-induced writhing model, choline combination with parecoxib sodium compared with their use alone, can increase the analgesic effect, and reduce the use of single dose, while reducing the blood levels of inflammatory factors better.Part II Analgesic effect of combination of choline and parecoxib sodium on CCI ratsObjectiveTo observe the analgesic effect of choline and parecoxib sodium on chronic sciatic nerve injury neuropathic pain model (CCI) and the expression of HMGB1 protein and NF-KBp65 in spinal cord, and to explore its possible mechanism.Methods 1. Health male SD rats weighing 180-220 g were randomly divided into 5 groups (n=8). The rats in sham group were injected with 0.9% sodium chloride solution with the same volume in the sham group. (CCI+saline group) rats were intraperitoneally injected with 0.9% sodium chloride solution with the same volume. Choline(cho)treatment ratswere intraperitoneally inj ected with choline 6mg/kg, 12mg/kg and 24mg/kg in CCI group. Parecoxib(Pare) treatment of CCI rats were intraperitoneally injected with parecoxib sodium 3mg/kg, 6mg/kg, 12mg/kg; choline and parecoxib sodium in combination with CCI rats in the determination of invalid dose. Each group were treated accordingly, and administration for 7 days continuously.All rats were tested before, 3, 5, 7, 10, and 14 days after operation. The pain threshold was measured at 30 min after injection of the drug. 2.Thirty SD rats were divided into 5 groups: sham group, CCI+saline, CCI+choline6mg/kg, CCI+parecoxib3mg/kg, CCI+choline6mg/kg+parecoxib3mg/kg. After modeling success, continuous administration of 7 days, five rats were randomly selected for each group, the dorsal root ganglion of L4-6 segment was used to detect HMGB1 protein and NF-KBp65 by Western blot.Results 1.Choline 12mg/kg and 24mg/kg dose can significantly reduce the mechanical abnormal pain and thermal hyperalgesia (P<0.05), and 6mg/kg on CCI rats mechanical pain and thermal pain no significant effect (Figurel-2A); 2.Parecoxib had significant anti-allodynic effects at 6 mg/kg and 12 mg/kg (P<0.05), but 3 mg/kg did not observe the effect of anti-abnormal injury (Figurel-2B ); 3.Choline 6mg/kg combined with parecoxib sodium 3mg/kg on CCI model produced significant anti-injury (Figure 3A-B);4.The combination of choline and parecoxib sodium can significantly reduce the expression of HMGB1 protein and NF-KBp65 in spinal cord (Fig.4).DiscussionThe Combinationof choline and parecoxib sodium can effectively relieve neuropathic pain. The mechanism may be related to the inhibition of HMGB1/TLR4/NF-?B pathway.Conclusion 1. Choline and parecoxib sodium were used to reduce the number of writhing of mice in acute acetic acid writhing models lonely, and this effect was dose-dependent.2. Cholines and paracetin sodium have synergistic analgesic effects in the acute acetic acid writhing model in combination, the interaction between both of them may be related to the expression of NF-kB in vivo. 3. In the rat chronic neuropathic pain model, choline and parecoxib sodium can reduce the mechanical pain and thermal hyperalgesia alone at a dose caused by CCI. 4. Choline and parecoxib sodium with non-analgesic doses in combination can relieve neuropathic pain effectively, the mechanism may be related to the inhibition of HMGB1/ TLR4 / NF-?B pathway.