Objective

2

To explore the possible mechanisms of electroacupuncture at Fengchi （GB 20）， Waiguan （TE 5）， and Yanglingquan （GB 34） in treating chronic migraine from the perspective of nociceptive sensitization.

Methods

2

Forty SPF-grade SD rats were randomly divided into blank group， model group， electroacupuncture group， electroacupuncture + agonist group， and inhibitor group， with 8 rats in each group. Except for the blank group， rats were injected intraperitoneally with nitroglycerin to establish a chronic migraine rat model. After successful modeling， the electroacupuncture group received electroacupuncture at bilateral "Fengchi" （GB 20）， "Waiguan" （TE 5）， and "Yanglingquan" （GB 34） for 30 minutes each session. The electroacupuncture + agonist group received the same electroacupuncture treatment and additional injection of protein kinase C （PKC） agonist Phorbol 12-myristate 13-acetate （1.0 ng/μl， 25 μl） via the infraorbital foramen. The inhibitor group received PKC inhibitor Chelerythrine Chloride （1.0 ng/μl， 10 μl） via the infraorbital foramen. The blank group， model group， and inhibitor group underwent restraint for 30 minutes without other interventions. All groups were continuously intervened for 5 days. After the intervention， the nociceptive thresholds （mechanical and thermal pain） of the periorbital area and hind paw were measured. The expression levels of transient receptor potential vanillic acid subtype 1 （TRPV1）， phosphorylated TRPV1 （p-TRPV1）， PKC proteins，

Trpv1

，

Pkc

mRNA， and the average fluorescence intensity of transient receptor potential vanillic acid subtype 1 （TRPV1） and PKC in the trigeminal ganglion were detected using Western Blot， real-time fluorescence quantitative PCR， and immunofluorescence methods.

Results

2

Compared with the blank group， the mechanical and thermal pain thresholds of the periorbital area and hind paw were reduced in the model group， and the protein levels of TRPV1， PKC， p-TRPV1， as well as the mRNA

expression of

Trpv1

and

Pkc

， and the average fluorescence intensity of TRPV1 and PKC in the trigeminal ganglion significantly increased （

P

＜0.05 or

P

＜0.01）. Compared with the model group， the electroacupuncture group exhibited increased mechanical and thermal pain thresholds in the periorbital and hind paw areas， and decreased protein levels of TRPV1， PKC， p-TRPV1， mRNA expression of

Trpv1

and

Pkc

， and average fluorescence intensity of TRPV1. In the electroacupuncture + agonist group， the average fluorescence intensity of TRPV1 in the trigeminal ganglion decreased. The inhibitor group exhibited increased mechanical pain thresholds in the periorbital area and thermal pain thresholds in the hind paw， along with decreased protein levels of TRPV1， PKC， p-TRPV1， and the average fluorescence intensity of TRPV1 and PKC （

P

＜0.05 or

P

＜0.01）. Compared with the electroacupuncture group， the electroacupuncture + agonist group showed an increase in the protein levels of TRPV1， PKC， p-TRPV1， and the mRNA expression of

Trpv1

（

P

＜0.05 or

P

＜0.01）.

Conclusion

2

Electroacupuncture at the "Fengchi" （GB 20）， "Waiguan" （TE 5）， and "Yanglingquan" （GB 34） acupoints can increase the mechanical and thermal pain thresholds in chronic migraine rats and alleviate nociceptive sensitization. The mechanism may be related to the inhibition of PKC/TRPV1 pathway.