The Expression Of T-type Calcium Channel Ca_v3.2 In The Temporal Lobe And Hippocampus Of Pentyleneterazole Induced Epileptic Rats And The Interventional Effects Of Relevant Drugs

Background and objectiveIn human beings and animals, a lesion to the brain can lead to the spontaneous epileptic seizures for the whole life after a variable latent period. The internal processes which included neuronal alternation in structure and function was referred to as epileptogenesis. The endogenous plasticity comprised the long-term alternation in the expression and the activity of voltage-gated calcium channel which generated electrical signals. To observe the expression of T-type calcium channel Cav3.2 in the hippocampus of pentylenetetrazole (PTZ) kindled chronic epilepsy models, we discussed the relationship between T-type calcium channel and recurrent seizure of chronic epilepsy, and researched the impact mechanism of Cav3.2, EEG and cognition function by the intervention of ginkgo biloba P.E. (GBE) and yangxueqingnao granule (YXQNG).Materials and MethodsChronic recurrent epilspsy rat models were induced by PTZ. All experimental animals were divided into five groups at random:A group (PTZ group), B group (PTZ+ VPA group), C group (PTZ+ VPA+Tanakan group), D group (PTZ+ VPA+ YXQNG group), E group (normal saline-control group). There are ten healthy male SD rats in each group. According to the Racine classification standard, the behavioral changes of rats which were given drugs or normal saline after one hour_were observed and recorded each time. After PTZ group kindling, behavioral accuracy rate in electrical maze and EEG were tested in all experimental rats. Then the brains of the rats were taken, and the expression level of Cav3.2 in the hippocampus of the entire experimental rats was analysised by immunohistochemistry methods.ResultsThe seizure stage of B, C and D groups was 0-Ⅱgrade, and the EEG was normal or had slight spike-slow wave. While the seizure stage of E group was 0 grade, the EEG was normal. And the total power difference of EEG and the level of Cav3.2 in the temporal lobe and the hippocampus of E group were significantly lower than the A group (P<0.05). Compared with B group, the expression of Cav3.2 in the temporal lobe and the hippocampus was significantly reduced in the C, D and E groups (P< 0.05). Compared with B, C and D groups, the combined application of VAP and YXQNG in D group which had statistical significance can improve the cognition of PTZ-kindled rats greatly(P<0.05).Conclusions1. In the neurons of PTZ-kindled rats, the openness of T-type Ca2+ channel was prevented by valproate. Therefore, the intracellular Ca2+ density of neurons was reduced, and the pathological damage was lightened in nervous tissue. At the same time, the excessive discharge of neurons was decreased, and the seizure severity and EEG variation were mitigated significantly.2. Duing to the application of valproate in combination with GBE or YXQNG, the calcium overload, the seizure degree and the damage of neurons were remarkably reduced during status epilepticus.3. The cognitive function of PTZ models of epilepsy was significantly improved owing to the simultaneous drug administration of valproic acid and YXQNG.