Abstract: AIM: To observe the content change of substance P(SP) in jugular plasma, brain stem and ganglion nervi trigemini followed botulinum toxin type A(BTX-A) injected subcutaneously into migraine model rats triggered by nitroglycerin and its mechanism.METHODS: Rats were divided randomly into control grouP(n =5) and migraine model grouP(n =15) triggered by nitroglycerin injected local subcutaneously,which was subdivide into grouPtreated with NS (n =5) ,grouPtreated with BTX-A 5 U·kg^-1 (n =5) and grouPtreated with BTX-A 10 U·kg^-1 (n =5).The BTX-A and NS were injected into frontal and temporal for 6 days.The immunoractive SP(iSP) in jugular plasma, brain stem and ganglion nervi trigemini was detected after migraine treatment by RIA.RESULTS: Subcutaneous injection of nitroglycerin into animal caused symptoms of migraine, such as ear rosacea, forelimb clawing head frequently and climbing cage more, and behavioral scores increasing (P<0.01).The content of iSPin jugular plasma, brain stem and ganglion nervi trigemini was increased signify cantly in NS grouPthan that in control grouP(P<0.01).The contents of iSPin jugular plasma of BTX-A 5U·kg^-1 and BTX-A 10 U·kg^-1 groups decreased significantly(P<0.05) than that in NS group.CONCLUSION: Nitroglycerin subcutaneous injection triggers symptoms of migraine and increases content of SPin jugular plasma, brain stem and ganglion nervi trigemini.BTX-A local subcutaneous injection reduces symptoms of migraine model rats and content of SPin jugular plasma,brain stem and ganglion nervi trigemini.The results suggest that BTX-A can inhibit SPreleasing from “trigeminal vascular system”and prevent migraine from meningeal sterile inflammatory response.

Key words: botulinum toxin type A, migraine, substance P, trigeminal vascular system