The Effection Of Ectogenesis Glutamate On Hair Cells And Glutamine Synthetase In Rat Cochlea

PartⅠExcitotoxic effect of ectogenesis glutamate on the in vitor inner hair cellsObjective To observe the damage of hair cells of rat cultured in vitro exposed to glutamate environment.Method 33 SD new born rats were divided randomly intoⅠ～Ⅺgroups,cultured the basement membrane for 24 hours,Ⅰ～Ⅵgroups adding different concentrations of glutamic acid : 0.1mM, 0.5mM, 1.0 mM, 5.0 mM, 10 mM, 20 mM,Ⅶ～Ⅹgroups cultured with the same concentrations of glutamic acid(20mM) about 6H, 12H, 24H , 48H, 72H;Ⅺgroup was the normal control group.Then observe and count within the nucleus and cilia of hair cells by immunofluorescence staining methods (phalloidin, and DAPI staining).Results①There was no significant hair cells damaged inⅠgroup; Inner hair cells were suffered from injury inⅡ～Ⅵgroups.②The number of cilia on inner hair cells which come fromⅦ～Ⅺgroups were 106.83±2.787,75.00±3.742,59.33±2.582,46.17±3.920, 109.50±2.168 respectively.compaired with the normal control group inner hair cell cilia inⅦ～Ⅹgroups were less(p<0.05).with the time of exposuring to glutamate prolonged, cilia missing became more seriously (p<0.05);③After the 20mM glutamate roled for 24 hours ,the number of cilia on middle turn inner hair cells (47.33±3.983) is more than the bottom turn(33.17±4.579)(p<0.05).Conclusions①The smallest injury concentration of exogenous glutamate to the inner hair cells of the basement membrane cultured in vitro is about 0.5mM.②The basement membrane cultured in vitro exposed to the 20mM glutamic acid environment, the inner hair cells start to injure and the cilia began to disoeder at 6H, the number of cilia dreased at 12H, and with the time of exposuring to glutamate prolonged, lack of cilia became more seriously.③Exposing at the same concentration and the same time of glutamic acid environment, the middle turn inner hair cells is lighter injured than the bottom inner hair cells. PartⅡEffection of ectogenesis glutamate on glutamine synthetase in rat cochleaObjective To observe the distribution and expresstion of glutamine synthetase after given extraneous glutamate in rats cochlea.Methods 40 adult SD rats were divided randomly intoⅠ～Ⅵgroups .Ⅰwas the normal control group which has 10 rats without any operation,Ⅱ~Ⅵgroups each has 6 rats and were given solution respectively through the holes drilled into the scala tympani of cochlea.Ⅱw as the contral group with the solution of artificial perilympha,Ⅱ~Ⅵgroups were opreated groups with the solution of 20mM glutamate. The immunohistochemistry and Western-blot were used to obsreve the localization and expresstion of glutamine synthetase after giving extraneous glutamate.Results Glutamine synthetase was expressde in the support cells of Corti′s organ and the gliocytes around the ganglion spirale cells and the bony spiral lamina.The expresstion of glutamine synthetase raised at 1 day groups after opration(p<0.05). There were no differences expresstion observed in the rest groups(p>0.05).Conclusions Glutamine synthetase was also expressed in supprot cells of Corti′s organ,it is accorded with the hypothesis of glutamate-glutamine cycle.The expresstion of glutamine synthetase could increase after give glutamate.