| Objective This research is to investigate the effect of electroacupuncture manipulation at bone-nearby acupoints(EA-BN)in bone cancer pain with morphine tolerance rats,and the mechanism of PI3K/Akt/JNK1/2 signaling pathway.Methods Part one,35 healthy female(SD)rats were randomly divided into 5 groups,Sham,BCP,BCP+MT,BCP+MT+EA-BN and BCP+MT+ShamEA.The Sham was injected sterile PBS into the medulla cavity of the left tibia,all the other groups were inoculated with the same amount of MRMT-1 breast cancer cells to induce BCP model.After BCP model was established successfully,in the BCP+MT,BCP+MT+EA-BN and BCP+MT+ShamEA,rats were injected intraperitoneally with morphine hydrochloride(q12h,11 consecutive days)to induce BCP+MT model.On the 15th day after breast cancer cells inoculation,the BCP+MT+EA-BN was treated with EA-BN immediately after intraperitoneal injection of morphine in the morning,and the BCP+MT+ShamEA was given fake electroacupuncture.Acupoints "Zusanli"(ST36)and "Kunlun"(BL60)on both sides were taken once a day,30 min,for consecutive 7 days.The paw withdrawal threshold(PWT)of rats left foot was measured on 1d before tumor cell inoculation,and 10d,11d,15d and 21 d after the intervention.The expressions of phosphorylated phosphatidylinositol 3-kinase(p-PI3K),phosphorylated protein kinase B(p-Akt),phosphorylated c-Jun NH2-terminal kinase 1/2(p-JNK1/2)and β-arrestin2 in spinal dorsal horn(SCDH)of rats in each group were detected by Western blot.Part two,48 healthy female SD rats were randomly divided into 4 group,BCP+MT+DMSO,BCP+MT+LY294002.BCP+MT+EA-BN+PBS,BCP+MT+EA-BN+IGF-1.BCP+MT model was induced in all 4 groups(same as the part one).On the 15th day after cancer cell inoculation,BCP+MT+EA-BN+PBS and BCP+MT+EA-BN+IGF-1 were treated with EA-BN after morphine injection in the morning,the time and parameters were the same as the part one.PI3K inhibitor(LY294002),inhibitor solvent(DMSO),PI3K agonist(IGF-1)and agonist solution(PBS)were intraperitoneally injected respectively into the 4 groups before 30min morphine injection at 17d,19d and 21d after tumor cell inoculation.The other interventions remained unchanged.The PWT of the rats after intervention was detected 8d,1d before tumor cell inoculation,and 10d,11d,15d,17d,19d and 21 d after cancer cell inoculation.The protein expressions of p-Akt,p-JNK1/2,and β-arrestin2 in SCDH of rats in each group were detected by Western blot.Results Part one there was no difference in PWT among 5 groups at 1 day before inoculation(P>0.05).On the 10th day after cancer cell inoculation,the PWT of the other four groups was significantly lower than that of the Sham(P<0.01).Compared with the BCP,there was no significant difference in PWT of BCP+MT and BCP+MT+ShamEA on 21 days after tumor cell inoculation(P>0.05).PWT in BCP+MT+EA-BN was higher than BCP+MT and BCP+MT+ShamEA(P<0.01).Compared with Sham,the relative expressions of p-PI3K,p-Akt,p-JNKl/2 andβ-arrestin2 in SCDH of BCP and BCP+MT were increased(P<0.05,P<0.01).The relative expression levels of p-PI3K p-Akt,p-JNK1/2 and β-arrestin2 in SCDH of BCP+MT+EA-BN were lower than BCP+MT and BCP+MT+ShamEA(P<0.05,P<0.01).In part two,there was no significant difference in PWT among the 4 groups on day 1 before inoculation(P>0.05).On the 10th day after cancer cell inoculation,the PWT of the 4 groups was decreased(P<0.01).on 21d after cancer cell inoculation,compared with 10d after cancer cell inoculation,the PWT of BCP+MT+LY294002 and BCP+MT+EA-BN+PBS were increased(P<0.05,P<0.01),and the BCP+MT+LY294002 was higher than the BCP+MT+DMSO(P<0.01),BCP+MT+EA-BN+PBS was higher than the BCP+MT+EA-BN+IGF-1(P<0.01).Compared with BCP+MT+DMSO group,the relative expressions of p-Akt,p-JNK1/2 and β-arrestin2 in SCDH of rats in BCP+MT+LY294002 were decreased(P<0.05,P<0.01).Conclusion Electroacupuncture manipulation at bone-nearby acupoints early can alleviate or delay morphine tolerance,and this effect may be related to the inhibition of PI3K/Akt/JNK1/2 signaling pathway. |
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