Expression And Its Significance Of The Aquaporin-4 In The Brain Of A Epileptic Rat Model

Objective to observe the expression of aquaporin-4 in hippocampus in the kindled model,and then to explore the relationship between AQP-4 and the epileptic disease.Method 1.to establish animal model. twenty six Sprague-Dawley (SD) rats were randomly divided into 2 groups : the control group (n=6) and the experimental group(n=20),the experimental group were prepared in SD rats by constantly intraperitoneal injection of pentylenetetrazol (PTZ) at subthreshold dosages for 28 days.then based on the rate of the kindled ,the experimental group were divided into kindled group and nonkindled group.then on the thirty day,all of the rats were killed by detapitation and the brain,which concluded the hippocapus and cortex, were removed and to be preserved in liquid nitrogen for the next experiment.2.to use Dry-Wet Weight method measured brain water content of each group; to detect the expression of AQP4mRNA and AQP4,Semi- quantitative RT-PCR was emplored to examine the AQP4mRNA levels in the hippocampus of each group, and immunohistochemistry methods were used to determine the hippocampal expression of AQP4 in each group.Results 1.50% SD rats were fully kindled.2.Brain water content measurement results that brain water content increased more significantly in the kindled rats[(76.8±3.81)%] than the nonkindled group[(73.3±2.63)%]and blank control group[ ( 71.5±2.88 ) %](p<0.05) ; RT-PCR results that AQP-4mRNA expression significantly increased in the kindled rats(0.85±0.11)(p<0.05),but there was no significant expression between the nonkindled rats(0.37±0.07) and the normal rats(0.33±0.08)(p>0.05). The immunohistochemistry results that The postive AQP4 expression located in CA1 ,CA3 and DG regions of hippocampus and aroud the blood vessels,the postive cellular membrane was brown or buffy .the high positive AQP-4 expression rate was shown to be higher for the kindled group (0.201±0.04)than the nonkindled group(0.104±0.02)and blank control(0.091±0.02)(p<0.05). there was no signifficantly different between the nonkindled group and the blank control group(p>0.05)。Conclusions 1.It has been proved that there were tight relationship between the volumes of the brain extracellular space(ECS) and the epilepsy. AQP-4 is the major wanter channel protein in the cererebral nerves system(CNS),which involve the water transmembran transport. And then change the distribution of the ion in/out the nuerocyte affected the excitability of the nuerocyte.in this study,we found that the expression of AQP-4 in the kindled rats increased so significantly,which tell us that maybe AQP4 relate to the pathogenesis of epilepsy, AQP4 adjust excitability of the nuerocyte and then involve the epilepsy. 2.The brain water content was increased so significantly in the kindled rats and have the direct correlation with the AQP4 expression in the brain,give us a suggestion that in the other way AQP4 maybe play an important role in the formation of brain edema following the epileptic seizure.