The Role Of Norepinephrine And Dopamine In Convulsion Induced By Lidocaine In Rats

Objective: In order to determine the contention of NE and DA in extracellular fluid in striatum of rats with convulsion,we make a model of lidocaine-induced convulsion. TH immunoactivity and change of concentration of NE and DA are observed, AMPT and desipramine were injected to investigate different role of norepinephrine and dopamine in the process of lidocaine-induced convulsion in striatum in rats.Methods: Twenty-four male wistar rats weighing 250±20mg were randomly divided into 4 groups(n=6 . After anesthetized by isoflurane, a rat was placed in the stereotaxic frame and a microdialysis probe was placed into the striatum (A–1.2cm, M–2.8cm, D 3.5mm, from bregma and dural surface). Microdialysis samples were collected per 20 min after EEG waves were stable. (1) group L: After saline was injected i.p, lidocaine was single pumped into femoral vein for 30 min, and pumped at a rate of 4mg·kg-1·min-1 if multiple high-voltage spikes could not be seen. (2) group C: The process was same with group L except lactated Ringer Solution was pumped into femoral vein. (3) group A+L: The process was same with group L except AMPT was pumped into femoral vein. (4) group D+L: The process was same with group L except desipramine was pumped into femoral vein. After collecting microdialysis samples,rats were perfused and fixed through cardia. Tissue sections of brain tissue were underwent antigen recovering and droping agent and DAB, TH positive immunoactive neurons were observed under high power field of optical microscope. The concentrations of extracellular norepinephrine and dopamine in striatum and the recolleting rate of microdialysis probe were detected by the method of HPLC-fluorescence, according to recolleting rate and reforming relation of dopamine hydrochloride with dopamine to calculate concentrations of NE and DA in striatum in rats.Results:1 Results of respiratory depression and spikes Group D+L lasting time of respiratory depression was significantly shortencompared with group L (P<0.05). Group A+L and group D+L lasting time of multiple high-voltage spikes were significantly shorten compared with group L (P<0.05 ).2 Results of TH immunoactivity in substantia nigraTH positive immunoactive neurons in group A+L were significantly decreased compared with group L (P<0.05). TH positive immunoactive neurons in group A+L were significantly increased compared with group C (P<0.05).3 Concentration of NE and DA in T2Concentrations of NE and DA in group A+L were significantly decreased compared with group L (P<0.05)., Concentrations of NE and DA in group A+L were significantly increased compared with group C (P<0.05 each). There were significant differences among them (P<0.05).4 Relation of each indexTH positive immunoactive neurons were directly correlated with spikes lasting time, Y=0.52X-18.65 R2=0.99. TH positive immunoactive neurons were directly correlated with concentrations of NE and DA in T2, Y=3.5X+230.28 R2=1.00 Y=8.87X+7.47 R2=1.00. Spikes lasting time were directly correlated with concentrations of NE and DA in T2, Y=0.15X-52.33 R2=0.99; Y=0.06X-19.11 R2=0.99.5 Concentrations of NE and DA in T2 compared with T1Concentrations of NE and DA in T2 were significantly increased compared with that in T1 in group L(P<0.05). Concentrations of NE and DA in T2 were significantly increased compared with that in T1 in group A+L (P<0.05 each).Conclusion:1 Concentrations of NE and DA in extracellular fluid in striatum in rats were increased during lidocain-induced convulsion. The increase of NE and DA may be attribute to activation of TH .2 DA play a importent role in convulsion induced by lidocaine.3 NE may play a depressant role in convulsion induced by lidocaine.