Expression Of BKCa In Rat Of Migraine

BackgroundMigraine was one of the common primary headache with the highincidence and prevalence. In Asia (except for South Korea and Hongkong),the prevalence of migraine was11.3%to14.4%in famale,3.6%to6.7%inmale. Migraine seriously affected the efficiency of work and quality of lifeof patients. It also brought a burden to society. Migraine will cost$250billion each year in the United States.At present, the theories about the pathogenesis of migraine wereunable to make clear explanation, therefor researchers are looking for newdirections. They found when aura occurs the cerebral blood flow wasdecreased. This spreading reduction of cerebral blood flow was caused bycortical spreading depression (CSD). CSD lead to aura. Then the theory ofCSD was proposed.Ophoff and De Fusco, et al. found the gene which was encoded ionchannels could cause familial hemiplegic migraine. Familial hemiplegicmigraine was a kind of ion channel disease. Harring, er al. reportedCalcium ion concentration in cerebrospinal fluid in patients with migrainewas different from that in the normal people. Literatures showed that ion channels played a important role in migraine, migraine might be an ionchannel disease.BKCa (large-conductance calcium-activated potassium channel) wasone of the voltage-gated potassium channels, it could be activated by theincrease of the calcium concentration in intracellular and the depolarizationof the cell membrane. Based on the β subunit, BKCa could be divided intofour subtypes: KCNMB1、KCNMB2、KCNMB3and KCNMB4.BKCa wasinvolved in the process of pain and it played a important role in regulationof cerebral vasomotor function. At present, BKCa was thought to beinvolved in migraine.Further study was needed to make sure whether the four subtypes ofBKCa was involved in the onset of migraine and they had the same role.More research would be done in order to prove one or several subtypes ofBKCa was directly participate in migraine.Materials and methods1. Groups:A. Control group: Subcutaneous injected normal saline (NS10mg/kg);B. Model group: Subcutaneous injected nitroglycerin (GTN10mg/kg)to establish the rat model of acute migraine.2. Observe behavior change of each group and record the painthreshold. 3. Use RT-PCR, immunohistochemistry and Western Blotting todetect the KCNMB1、KCNMB2、KCNMB3and KCNMB4expressionchanges in occipital cortex.Result1. Rats in Model group began to restlessness about15min after themodel building, the frequent of scratching their heads, licking the hair andclimbing cage was much higher than Control group.2. The pain threshold of rat limbs showed that the pain threshold wasstable in Control group and decreased in Model group.3. RT-PCR products were detected for KCNMB2at468bp andKCNMB4at300bp in rat occipital cortex of two groups. No product wasdetected for the KCNMB1and KCNMB3mRNA.4. Immunohistochemistry analysis revealed the presence of KCNMB2and KCNMB4in rat occipital cortex of two groups. Immunoreactivity forKCNMB1and KCNMB3was absent in rat occipital cortex of two groups.The protein express level of KCNMB2and KCNMB4was much higher inModel group than Control group, P<0.05.5. Immunoblotting analysis revealed the presence of KCNMB2andKCNMB4in rat occipital cortex. The products were detected for KCNMB2at50kDa and KCNMB4at38kDa. Immunoreactivity for KCNMB1andKCNMB3were absent in rat occipital cortex. The protein express level ofKCNMB2and KCNMB4was much higher in Model group than Controlgroup, P<0.05.Conclusion1. Subcutaneous injected nitroglycerin can effectively build the rat model of acute migraine.2. BKCa was involved in migraine. The express level of KCNMB2and KCNMB4was much higher in rat occipital cortex of Model group. Itproved that KCNMB2and KCNMB4might be participate in pathogenesisof migraine3. KCNMB1and KCNMB3were absent in rat occipital cortex, theymight not be involved in migraine or they were participate in migraine bythe other ways.