Background The anti-nociceptive effects of electroacupuncture (EA) in migraine have been documented in multiple randomised controlled trials. Neurogenic inflammation plays a key role in migraine attacks, and the anti-inflammatory effects of acupuncture have been associated with the type 1 cannabinoid (CB1) receptor.
Objective To investigate whether CB1 receptors mediate the anti-inflammatory effects of EA on migraine attacks.
Methods A migraine model was produced in Sprague-Dawley rats by unilateral electrical stimulation of the trigeminal ganglion (TGES). Rats received EA daily on the 5 days preceding TGES with (TGES+EA+SR141716 group) or without (TGES+EA group) intraperitoneal injections of the CB1 receptor antagonist SR141716. Another group of TGES rats (TGES+MA group) and a non-TGES sham-operated group of rats (Sham+MA group) received minimal acupuncture (MA). Calcitonin gene-related peptide (CGRP) and prostaglandin E2 (PGE2) concentrations were determined in serum obtained from the ipsilateral jugular vein at initiation of TGES and 5 min after. Postmortem interleukin (IL)-1β and cyclooxygenase (COX)2 protein levels in the trigeminal ganglion (TG) and plasma protein extravasation (PPE) in the dura mater were assessed.
Results TGES induced increases in serum CGRP and PGE2 levels (TGES+MA vs baseline and vs Sham: all p<0.001), as well as IL-1β and COX2 protein expression in the TG, and neurogenic PPE levels (TGES+MA vs Sham+MA: all p<0.001). EA attenuated TGES-induced increases in the levels of these proteins (TGES+EA vs TGES+MA: all p<0.001). CB1 receptor antagonism reversed the effects of EA (TGES+EA+SR141716 vs TGES+EA: all p<0.05).
Conclusions CB1 receptors appear to mediate anti-inflammatory effects of EA in a rat model of migraine.
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Contributors HZha and SH contributed equally to this work, performed the animal studies, and drafted the paper. HZhe designed the study. YH participated in the study design. All authors read and approved the final version accepted for publication.
Funding This project was supported by National Natural Scientific Fund of China (grant no. 81102625) and Specialized Research Fund of Southwest Medical University (grant no. 2016-101).
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.
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