The Effect Of Edaravone On Acute And Chronic Epilepsy Mice Models Induced By Pentylenetetrazole And The Experimental Research Of Its Functional Mechanism

Objective: Epilepsy is a common neurological disorder characterized by excessive brain neurons repeatedly synchronization discharge.It causes repeatedly paroxysmal,transient and stereotyped dysfunction of central nervous system.Repeated seizures can lead to selective damage even necrosis of brain neurons,subsequently lead to gliocyte proliferation,synaptic reorganization and some other brain structure and function change,which causes refractory epilepsy in turn.In addition, patients with repeated seizures often have cognitive impairment that greatly diminishes the patients' quality of life.The pathogenesis of epilepsy is quite complicated,including oxidative stress damage,glutamate toxicity of excitatory,calcium overload,and so on.Of these causes, oxidative stress is considered as a very critical role in epileptogenesis and cognitive impairment induced by seizures.It is reported that there is active oxidative stress response in both epilepsy animal models and patients with epilepsy.The important role of oxidative stress in epilepsy reminds us that inhibition of oxidative stress may be an effective way to prevent or treat epilepsy.Edaravone,3-methyl-1-phenyl-2-pyrazolin-5-one,is a newly developed free radical scavenger,which can scavenge free radical and inhibit lipid peroxidation. Edaravone is lipophilic with low molecular weight,so it readily crosses the blood brain barrier(BBB).Edaravone(Ed) has been used to treat cerebral infarction on clinic,exerting considerable neuroprotective effect against ischemic insult.The present study researched how different doses of edaravone effected acute and chronic epilepsy models induced by pentylenetetrazole(PTZ).We recorded the seizure stage,latency to generalized tonic-clonic seizure(GTCS) and mortality in acute epilepsy models.We also recorded everyday seizure stage, mortality and kindled rate of chronic epilepsy models.And then, We used Morris water maze test to assess cognition of acute and chronic epilepsy models.After the Morris water maze test,we examined the oxidative stress parameters:malondialdehyde(MDA) and glutathione(GSH).In this way,we observed the effect of edaravone on acute and chronic epileptic models induced by pentylenetetrazole.Moreover,we also examined how edaravone influenced the level of oxidative stress parameters to explore its functional mechanism,which will provide more evidence for epilepsy treatment with edaravone.Methods: Acute epilepsy models were induced using a single dose of pentylenetetrazole(80 mg/kg, i.p.). Chronic epilepsy models were induced by a subconvulsive dose of PTZ(40 mg/kg, i.p.) injected everyday for a total of 21 days.In both kinds of models,the mice were respectively randomly distributed to the following groups: control(CON) group, PTZ group, edaravone 5mg/kg+PTZ(Ed5)group, edaravone 10mg/kg+PTZ(Ed10) group, edaravone 20mg/kg+PTZ(Ed20)group. All the acute epilepsy mice models were pretreated intraperitoneally with different doses of edaravone(Ed+PTZ groups) or saline(CON group and PTZ group) for 5 consecutive days. 30 min after the fifth injection, the mice received a single dose of pentylenetetrazole(80mg/kg)(PTZ group and Ed groups) or corresponding volume saline(control group). The chronic epilepsy mice models received two intraperitoneal injections daily for a total of 21 days. The first was pretreatment with different doses of edaravone(Ed groups) or corresponding volume saline(CON group and PTZ group). 30 minutes later,The second injection was executed with PTZ(40 mg/kg)(PTZ group and Ed groups) or corresponding volume saline(CON group). Every animal was observed for 30 min after each PTZ administration and we recorded the behaviors. 24 h after the last administration of PTZ, all the survivors of both kinds of epilepsy models would be tested by Morris water maze to observe the learning and memory ability and assess cognitive impairment. After the Morris water maze test, the animals were sacrificed. The hippocampi were thawed and 10%(w/v) homogenates were made with ice-cold saline. The homogenates were prepared to evaluate the content of GSH and MDA.Results:1 Acute epilepsy mice models induced by PTZ1.1 Results of behavior Almost all the mice that got PTZ administration presented repeating generalized tonic-clonic seizures, with only one exception(only reached stage 4) in PTZ group. In the process of observation, some mice died because of severe convulsions. Three doses of edaravone(5, 10, 20mg/kg) all significantly prolonged the latencies to GTCS(P < 0.05).We also find that pretreatment with edaravone at the dose of 5mg/kg or 20mg/kg seemed to increase mortality while 10mg/kg seemed to be protective. Even though the mortality had no statistically significant difference between Ed groups and PTZ group, we found the difference between Ed10 group and Ed20 was statistically significant(P < 0.05), according to which we concluded that edaravone might have different effects on mortality at different doses.1.2 Results of Morris water maze test There was no decline of cognition in PTZ group compared with control group, and the pretreatment with different doses of edaravone did not influence the escape latency and number of crossing(P >0.05).1.3 Results of oxidative stress parameters There was no statistically significant difference among 5 groups in GSH and MDA(P >0.05).2 Chronic epilepsy mice models induced by PTZ2.1 Results of behavior In the control group,the mice had no seizures.In the PTZ and Ed groups, daily repeated administrations of subconvulsive PTZ(40 mg/kg)(21 days in total) induced the gradual increase in seizure stage. Compared with PTZ group, Ed groups did not show significant difference in the seizure stage, without promotion or suppression. Besides,there is also no statistically significant difference in mortality and kindled rate(P >0.05).PTZ group compared with control group, and the pretreatment with different doses of edaravone did not influence the escape latency and number of crossing(P >0.05). 2.2 Results of Morris water maze test There was no decline of cognition in2.3 Results of oxidative stress parameters There was no statistically significant difference among 5 groups in GSH and MDA(P >0.05).Conclusions:1 Edaravone did not have obvious anticonvulsant effect on seizure models induced by PTZ.2 Edaravone might have different effects on mortality at different doses, which needs to be confirmed by more researches in the future.3 In this research,there was no significant cognitive impairment in acute and chronic epileptic mice models induced by PTZ. Moreover,edaravone did not show any obvious effect on cognition in these models.4 Edaravone did not significantly show long-term effects on oxidative stress parameters in either acute or chronic epileptic models.