BTX-A Reducing CGRP And SP Contents In The Jugular Vein, Medulla Oblongata And Pons In Migraine Model Rats Triggered By Nitroglycerin

Objective: The change of content of calcitonin gene related peptide(CGRP) and substance P(SP) in jugular plasma, medulla oblongata and pons followed botulinum toxin type A (BTX-A) injected subcutaneously into migraine model rats triggered by nitroglycerin was detected with radioimmunoassay (RIA).Methods: Rats were divided randomly into control group (n=5) and migraine model group triggered by nitroglycerin injected local subcutaneously, which was subdivide into migraine model treated with 0.9 % NaCl (M+saline, n=5), migraine model treated BTX-A 5 U/kg (M+BTX-A 5 U, n=5) and migraine model treated BTX-A 10 U/kg (M+BTX-A 10 U, n=5). The treatment of BTX-A and saline were injected into frontal and temporal subcuticle distributed with trigeminal nerves for 6 days. The immunoractive CGRP(iCGRP) and SP (iSP) in jugular plasma, medulla oblongata and pons was detected after migraine treatment by RIA. Results: (1) Subcutaneous injection of nitroglycerin into animal caused symptoms of migraine, such as ear rosacea, forelimb clawing head frequently and climbing cage much, and increase of behavioural scores (vs control P＜0.01). (2) The content of iCGRP and iSP in jugular plasma were increased significantly in M+saline group than that in control group (P＜0.01), but it was undifferentiated between M+BTX-A 5 U or M+BTX-A 10 U rats and that in control group(P＞0.05). M+BTX-A 5 U and M+BTX-A 10 U decreased significantly the content of iCGRP and iSP in jugular plasma (P＜0.05) than M+saline did, but it was undifferentiated between M+BTX-A 5 U and M+BTX-A 10 U rats (P＞0.05). (3) The content of iCGRP and iSP in medulla oblongata and puns were increased significantly in M+saline group than that in control group (P＜0.05), but it was undifferentiated between M+BTX-A 5 U or M+BTX-A 10 U rats and that in control group(P＞0.05).M+BTX-A 5 U and M+BTX-A 10 U decreased significantly the content of iCGRP and iSP in medulla oblongata and pons than M+saline did (P＜0.05), but it was undifferentiated between M+BTX-A 5 U and M+BTX-A 10 U rats (P＞0.05).Conclusion: Nitroglycerin subcutaneous injection triggers symptoms of migraine and upgrades CGRP and SP in jugular plasma, medulla oblongata and pons. BTX-A local subcutaneous injection reduces symptoms of migraine model rats, reduces CGRP and SP in jugular plasma, medulla oblongata and pons. The results suggest that BTX-A can inhibit CGRP and SP releasing from "trigeminovascular system" and prevent migraine from meningeal sterile inflammatory response. M+BTX-A 5 U is the better dose in the experiment.