Expression Of GABA_A Receptor γ₂ Subunit In Hippocampus In Ka-induced Temporal Lobe Epilepsy Rats

0bjective To study the time-dependent expression of GABAA receptorγ2 subunit in KA-induced temporal lobe epilepsy rats,and the effect of the interference of clonazepam (CZP)on expression GABAA receptorγ2 subunit.To understand the receptor subunit's effect in the epilepsy. then to provide a theoretical basis for neural pharmacologis to filter the new antiepileptic drugs which played a role in the level of the receptor subunitsMethods 80 male Sprague-Dawley rats were selected which weight were between 200g and 250g. 20 rats were used for the first part of the model of temporal lobe epilepsy. 60 rats were used for the second part of the expression of GABAA receptorγ2 subunit in hippocampus in temporal lobe epilepsy. In the second part, 60 rats were randomly divided into the following groups: the experimental group (n=35), intervention group (n=15), the control group (n=5) and Intervention control group (n=5). An temporal lobe epileptic model in the experimental group rats were established by intracerebral injecting 4μg/kg of KA into CA3 subfield in hippocampus. The control group were given the same operation, but KA was insteaded by normal saline, and the intervention group was given CZP 6mg/kg/d by intragastric administration before the KA. Intracerebral injection and intragastric administration were both insteaded by normal saline in the Intervention control group. At 6h,12h,1d,3d,7d,15d,30d after KA was injected into rats of the experimental group, At 6h,12h,1d after KA into rats of the intervention group, the expression of GABAA receptorγ2 subunit in hippocampus was assayed by immunohistochemistry.Results (1)After the rats recovered from anesthesia, the following behavior, gaze, wet-dog shakes, mastication nod, and limb clonus and so on, and later, paroxysmal rotation, jump, convulsion of forelimbs and hind limbs, occurred successively. The rats' behavior gradually recovered to normal after 10 hours. Then the spontaneous seizure (mostly rating 2-4) occurred 1-2 times every week. Epileptic waves were recorded in cerebral cortex. Widespread damage was observed in the KA injected side of the hippocampal, the neuronal damage of contralateral was Less than the injected side. (2) After the injection of KA, the expression of GABAA receptorγ2 subunit on CA1 and CA3 subfield of experimental group descended, especially the CA3 subfield. It dropped to the lowest at 7d and lightly recovered at 15d and 30d. But compared with the control group there was significant differences(P<0.05). The expression of GABAA receptorγ2 subunit in hippocampus of intervention group was higher than that of experimental group (p<0.05).Conclusion (1) The ideal model of temporal lobe epilepsy was established by intracerebral injected KA into CA3 subfield in hippocampus. In the kainic acid-induced temporal lobe epilepsy model, the reduction of the expression of GABAA receptorγ2 subunit in the hippocampus might due to hippocampal neurons loss. However, there was an increasing trend over time, this was the endogenous self-protection mechanism of the temporal lobe epilepsy.(2) Clonazepam could increase the expression of GABAA receptorγ2 subunit in the hippocampus in the acute phase of Seizures, which might reduce seizure-induced neuronal injury in the early time, it could reduce the loss of hippocampal neurons, which played a protective role in neurons, and furtherly explain that early intervention ofγ2 subunit as a target after temporal lobe epilepsy had important clinical significance.