| Epilepsy is a group of chronic diseases characterized by abnormal discharge of cerebral neuron, and occurred suddenly and repeatedly. Its seizure usually divided into generalized seizure and partial seizure. Bemegride, as a stimulant for the central nervous system, can induce epileptiform discharge, and even clinical seizure, so it can increase diagnostic positive rate of epilepsy on EEG. But controversies on epilepsy diagnostic and differential diagnostic value of bemegride-activation test still exist among domestic and foreign scholars. However, in the presurgical evaluation of epilepsy patient with partial seizure, bemegride-activation test,especially ictal SPECT induced by bemegride is applied broadly, as an approach to confirm epileptogenic zone. Bemegride -activation test, can not exclude seizures induced by bemegride alone, which may relate to reliability of bemegride-activation test. The epilepsy animal model induced by an intracortical injection of iron chloride is a ideal focal(partial) epilepsy animal model, which used in this study.Objective: In this study, to explore the effects of bemegride activation on habitual ictal discharge in acute epileptic model rats induced by ferric chloride(FeCl3),after intraperitoneal administrations of bemegride were given to the rats.Method: Thirty-four male Sprague-Dawley (SD) rats were divided into four random groups, including a normal saline group(four rats), a FeCl3 control group(ten rats), a bemegride control group(ten rats) and a group called FeCl3+ bemegride group(ten rats) that was injected with FeCl3 and subsequently bemegride. All rats were drilled in the cranial bones and implanted with six epidural electrodes. To establish an acute epilepsy model, FeCl3 solution was injected into the left sensorimotor cortex in the FeCl3 control group and FeCl3+ bemegride group with stereotactic technique. The same volume of normal saline was injected in the same area of rats in the normal saline group and bemegride control group. After injection, rat brain electrical activity was recorded via EEG for 24 hours. Two groups of rats with bemegride administration were injected intraperitoneally (i.p.) after 12 h of EEG recordings ,the other two groups were injected with normal saline intraperitoneally at the same time.Result: FeCl3 injection, followed by bemegride intraperitoneal activation, produced two different types of ictal discharge during epileptic seizures. One type of discharge was identical to the discharge characteristic of habitual seizures produced by FeCl3 injection, and exhibited a variety of waveforms such as consecutive spikes and spike and wave complex. The other type of discharge, characterized by paroxysmal and transient discharges of spike and wave complex or sharp and wave complex, was similar to ictal discharge produced by bemegride alone. In the last 12 h, FeCl3 injection with bemegride administration produced significantly more habitual seizure activity than the FeCl3 alone group by 2.4±1.1times to 0.2±0.4times. However, bemegride-like discharge in the FeCl3+bemegride group discharged more easily and had a shorter latency period than the bemegride alone group. Furthermore, the ictal discharge activity of bemegride-like discharge outnumbers habitual seizures by 50.8±9.5times/hour to 2.4±1.1times/12hours。Conclusion: Habitual epileptic seizures produced by FeCl3 can be activated by administration of bemegride, but a high false positive rate is evidently observed. However, false positive seizure characterized by paroxysmal and transient discharges ( <10s ) induced by bemegride and habitual seizure characterized by consecutive discharge(>10s)exhibit obvious differences in EEG recordings. Therefore, this study provides a strong evidence that the reliability of clinical bemegride-activation test is limited and its application in presurgical evaluation of epilepsy is not suitable. Epileptic rats model induced by FeCl3 is more responsive to bemegride than normal rats.
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