Anticonvulsant Action Of Intravenous Anesthetics Against Lidocaine-induced Seizure In Rats

Objective Using the model of seizure induced by hydrochloride lidocaine to detect nitric oxide ,nos and c-fos positive cells after seizures inhibition, and to assess the anticonvulsant effect of midazolan, propofol, etomidate and thiopental in rats.Methods Thirty-six male Wistar rats weighing 250±50g were randomly divided into 6 groups (n=6). Rats was placed in a quiet, warm environment for more than 24 h, and operated gentlely, and kept the stability of basic state before the experiment. Animals were anesthetized with10% Chloral Hydrate (350㎎?㎏ i.p.), and fixed on the experimental platform in supine to carry out tail vein puncture. After successful puncture, rats were returned to the cage and the experiment were carried out 24 hour later. Rats were dealt differrently according to subgroups; (1) control group (group C); (2) lidocaine group (group L); (3) propofol group (group P); (4) etomidate group (group E); (5) midazolam group (group M); (6) thiopental group (group T). In control group normal saline was infused i.v. at 3ml?h. In lidocaine group 2% lidocaine was infused i.v. at 4 mg·kg-1·min-1 until convulsion occurred, and normal saline was infused i.v. at 3ml?h. In propofol group, at the onset of seizure propofol 12.5㎎?㎏ was infused slowly i.v.. In group E, M and T etomidate 1.85㎎?㎏, midazolam 0.65㎎?㎏ and thiopental 30.85㎎?㎏ was infused slowly i.v.. During the experiment, the lidocaine levels were obtained at the onset of seizure activity. The duration of seizure were recorded or calculated.Animals were decapitated and their brains were removed 2 hours after convulsion. According to stereotactic atlas of rat, bilateral hippocampuses were removed. One side of the hippocampus was used in immunohistochemistry for detecting expressions of c-fos. Immunoactive neurons of c-fos were observed under high power field of optical microscope. The other side was separated for making hemogeneity to measure the contents of NO and NOS.Results:1 There were no differences of the rats'weight in all groups.2 The seizure were obtained except group C.The seizure were ceased after intravenous anesthetics infusions,and there were no differences during the inhibition of seizure.3 There are no differences in the latency of lidocaine-induced seizure, and the dose of lidocaine-induced convulsion is 39.25±2.63㎎?㎏.4 The expression of c-fos in hippocampus : Compared with group C, the positive immunoactive neurons significantly increased in group L (P<0.05). Compared with group L, the positive immunoactive neurons significantly decreased in group M, P, E and T (P<0.05), and lower in group M and T. There were no significant differences in group P and group E, or group M and group T.5 The concentration of NO in the homogenate:Compared with group C, the NO concentration significantly increased in group L (P<0.05). Compared with group L, the NO concentration significantly decreased in group M, P, E and T (P<0.05), and lower in group M and T. There were no significant differences in group P and group E, or group M and group T.6 The activity of NOS: Compared with group C, the activity of NOS significantly increased in group L (P<0.05). Compared with group L, the activity of NOS significantly decreased in group M, P, E and T (P<0.05), and lower in group M and T. There were no significant differences in group P and group E, or group M and group T.Conclusion: Midazolam, propofol, etomidate and thiopental can inhibit convulsion induced by lidocaine in rats, and midazolam and thiopental are more effective than propofol and etomidate.