The Effects Of Ami On Currents And The Mrna Expression Of Sodium Channels In Cultured Rat Cortical Neurons

Migraine is one common and intractable disease with hereditary character, affecting the quality of life and bringing a serious burden to individual and society. Both the further research of the mechanisms in migrainers and effective prophylaxis strategies are the emphasis and difficulties in the therapy and diagnosis of migraine. Ion channels and CSD play the important roles in the initiation of migraine, and interfering in ion channels and CSD will be a new target for the strategies. More and more investigations in vitro, animals and clinic levels testified that many drugs can suppress CSD frequency and amplitude, decreasing the severity and attack. There are four different pharmacological classes of prophylactic anti-migraine drugs. The most commonly used are: calcium channel antagonists, tricyclic antidepressants,β–adrenergic blockers and anti-epileptic drug, however, the extensional mechanisms are undetermined. Therefore, Our aims are to study the effects of AMI on the sodium channels in the cultured cortical neurons, it will provide new ideas and targeting therapy for prophylaxis treatment of migraine.Objective: To investigate the effect of AMI on INa and on the mRNA expression of sodium channels in cultured rat cortical neurons.Method: The effects of AMI(0.1,1,10,20,50μM)on INa were observed by the whole-cell patch clamp technique and the mRNA expression of different sodium channels were tasted in experimental and control groups by the real time RT-PCR.Results: AMI significantly inhibited INa in the cultured rat cortical neurons with the concentration-dependent. The IC50 for inhibition of INa was 8.32μM, and the hill coefficient was 0.46. AMI of 10μM significantly changed the activation and inactivation of INa: the half activation potential and the activation steepness factor changed 13 mV and 1.25(P<0.05)respectively, and the half inactivation potential and the inactivation steepness factor changed 23 mV and 5.2(P<0.05), respectively; the time constants of inactivation were decreased, but the time constant of activation was not affected(P>0.05). Results of real time RT-PCR indicated that AMI inhibited the expression for sodium channels in a concentration-dependent manner. The inhibition on NaV1.1 was observed at both 5 min,10 min and 24 h while NaV1.2 appeared a transient inhibition at 5 min and the inhibiton of NaV1.6 fluctuated at the different time after 10μM AMI treatment.Conclusion:AMI has a significant inhibitory effect on INa and the expression of mRNA in cultured rat cortical neurons in a concentration-dependent manner, the inhibition of INa was shown by affecting the activation and inactivation. There are different effects on the mRNA expression of various sodium channel subtypes. The potential relationship between the inhibiton of sodium channels and the down regulation of mRNA may be one of the mechanisms which AMI inhibits the CSD.