[Effect of electroacupuncture on cortical spreading depression and plasma CGRP and substance P contents in migraine rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on cortical spreading depression (CSD) and contents of plasma calcitonin gene-related peptide (CGRP) and substance P (SP) in migraine rats.
METHODS: Thirty male SD rats were equally randomized into control, model and EA groups. Migraine model was established by topical application of KCI (3 mol/L) immersed in a piece of filter paper to the cerebral cortex (parietal lobe, 6 mm posterior to the Bregma and 5 mm to the sagital fissure) after exposure of the skull (in reference to Michael' method). KCI stimulation evoked CSD potentials (3 mm rostral to the Bregma, and 2 mm to the sagital fissure) were recorded by using a glass microelectrode. For rats of control group, filter paper containing 0.9% NaCl was applied to the same parietal cortex area. EA (1 mA, 2 Hz/100 Hz) was applied to bilateral "Yanglingquan" (GB 34) and "Taichong" (LR 3) for 30 min. The contents of plasma CGRP and SP were assayed by radioimmunoassay.
RESULTS: CSD was induced 3-5 min after application of KCI to the parietal lobe. The average amplitude of model group was (-25.13 +/- 1.23) mV, and that of EA group was (-19.19 +/- 1.53) mV, displaying a significant reduction of CSD amplitude after EA (P < 0.01). Comparison among 3 groups showed that both plasma CGRP and SP contents in model group were significantly higher than those of control group (P < 0.001, P < 0.01), while compared with model group, plasma CGRP and SP levels in EA group decreased considerably (P < 0.05, P < 0.001), suggesting an inhibitory effect of EA on pain-producing substance.
CONCLUSION: EA of GB 34 and LR 3 can effectively suppress KCI provoked cortical spreading depression and plasma CGRP and SP levels in the rat, which may contribute to its effect in relieving migraine in clinic.