Role of transient receptor potential vanilloid subetype 1 in the increase of thermal pain threshold by moxibustion

OBTECTIVE:To explore the role of transient receptor potential vaniiloid subetype 1(TRPV1) in the increase of the thermal pain threshold by moxibustion.METHODS:Forty Kunming mice(20 ± 2) g were randomized into control group,capsaicin group,capsazepine group,moxibustion group and moxibustion + capsazepine(MC) group with 8 mice in each,and 16 C57BL/6 wild-type mice(18 ± 2) g were randomized into wild-type(WT) control group and WT moxibustion group with 8 mice in each,and 14 TRPV1 knockout mice(18 ± 2) g were randomized into knockout(KO) control group and KO moxibustion group with 7 in each.Each mouse in the capsaicin group was subcutaneously injected with the amount of 0.1 mL/10 g into L5 and L6 spinal cords;each mouse in the capsazepine group was intraperitoneally injected with the amount of0.1 mL/10 g.Similarly,each mouse in the moxibustion group was given a suspended moxibustion with specially-made moxa-stick for 20 min on L5 and L6 spinal cords.Each mouse in MC group was intraperitoneally injected with the amount of 0.1 mL/10 g first,then after 15 min was given a suspended moxibustion for 20 min on L5 and L6 spinal cords.Each mouse in WT moxibustion group and KO moxibustion group was given a suspended moxibustion with specially-made moxa-stick for 20 min on L5 and L6 spinal cords.The control group,WT control group and KO control group were of no treatment in any way.After all treatments were completed,the digital-display measurement instrument for thermal pain was used to measure the threshold of thermal pain in each group respectively.RESULTS:Compared with the control group,the thresholds of thermal pain in the moxibustion group and MC group were significantly increased(P <0.01);no significant changes in the thresholds in the capsaicin group and the capsazepine group(P > 0.05);compared with moxibustion group,he threshold of thermal in MC group was obviously decreased(P < 0.01).Compared with WT control group,the threshold of thermal pain in WT moxibustion group was significantly increased(P <0.01);compared with KO control group,no changes in the threshold in KO moxibustion group(P > 0.05).CONCLUSION:TRPV1 participated in the process of increasing the threshold of thermal pain by stimulating L5 and L6 of mice spinal cord with burning mosa-stick.