Relationship Between TRPV1 Receptor And Migraine In A Nitroglycerin-induced Rat Model

BackgroundMigraine is one of the most common headache disorders and results from dysfunctions within the trigeminovascular system (TVS). It is characterized by episodic unilateral headache attacks that are accompanied by nausea and/or photo-and phonophobia; symptoms can worsen during physical activity. The unilateral character of the migraine headache clearly suggests an involvement of the TVS in the pain process.The TVS consists of primary neurons whose cell bodies lie within the ipsilateral trigeminal ganglion (TG). Peripherally these neurons innervate the dura mater and the cerebral an meningeal vascular system. The central fibres form synapses within the trigeminal nucleus in the caudal brain stem from where peripheral information is carried to the thalamus and cerebral cortex, thereby providing pain perception.Although a large body of literature exists about the cellular origin of migraine, the exact molecular mechanisms underlying the cellular changes have only partially been disclosed. Nitroglycerin-induced rat model can provide an effect way for further sdudying pathophysiology of migraine. Nitroglycerin can generate NO in organism, NO provoke an attack migraine patients and normal subjects but the precise mechanism of inducing migraine is unknown. Increasing attention has recently been given to a single receptor, transient receptor potential vanilloid subfamily member 1 (TRPV1), which could play a significant role in the generation and pathophysiology of migraine. TRPV1 is activated directly by capsaicinand similar chemical substances (vanilloids),low pH,noxious temperatures (above 43℃)and Artemin(detected in rat middle meninggeal artery.),is mainly expressed on nociceptors of the TG. In the rat dura mater, nerve fibers showing TRPVlwere mainly observed around the middle meninggeal artery. We reported that the ligation of middle meningeal artery was effective for treatment of migraine. Takashi Yoshida suggestNitric oxide activates TRP channels by cysteine S-nitrosylation.ObjectiveTo investigate the transient receptor potential vanilloid subfamily member 1 (TRPV1) expressed in migraine rat triggered by nitroglycerin so as to explore the possible mechanism of migraine.Methods24 Wistar rats were randomly divided into control group and model group. The migraine rat model (model group) was set up with subcutaneous injection of GTN (l0mg/kg) in the neck while the counterpart with saline. After the model was established, trigeminal ganglion and the dura mater were removed at 1,2,4,8 h and the expressions of mRNA and protein of TRPV1 were detected by RT-PCR, Western-blot and Indirect immunofluorescence.ResultsThe positive reactions of TRPV1 receptor in trigeminal ganglion in rats were detected at all indicted time points in the control groups, but, there were no significant differences at all time points (p>0.05). Compared with the control groups:the relative values of mRNA and protein in trigeminal ganglion in modal groups at 1 h and 2 h were lower, whereas, higher at 4 h and 8 h. Surface protein TRPV1 receptor at 8 h in trigeminal ganglion in model rats was higher than that in the control groups and, similar expression was found in dura mater.ConclusionThe alteration in TRPV1 receptor expression suggests that TRPV1 receptor may play a role in the pathogenesis of migraine.