Effects Of δ-opioid Receptor On PTZ-induced Epilepsy

This study was designed to establish PTZ-induced seizures model in vitro, in order to reveal the pathogenesis of epilepsy. We further studied the effects of δ-opioid receptor (DOR) agonist [D-Ala2,D-Leu5]-Enkephalin (DADLE) on PTZ-induced seizures model in vitro to reveal the effects of DOR on the occurrence and control of epilepsyEpilepsy has a lot of unpredictability, the establishment of epilepsy model in vitro, in large part to solve the limitations of animal models in the study of the pathogenesis and nerves excitement. We used PTZ to induce seizures occurrence. Experimental results showed that different concentrations of PTZ presented different impact on cell viability, in addition, different concentrations of PTZ could significantly increase primary neurons IK current peak, in a dose-dependent and voltage-dependent, shift steady-state activation curve and steady-state inactivation curve significantly to the right, increase half activation voltage and half-inactivation voltage, slow the processes of channel activation and inactivation. According to this part of experiment, we chose10mM PTZ to induce epilepsy model.Potassium ion channel family is the most widely distributed one of ion channels, its role in epilepsy has received more and more attention. In varieties of potassium channel currents, the delayed rectifier potassium current (IK) generated by delayed rectifier potassium channels and inward rectifier potassium current (IKir) generated by inward rectifier potassium channel have relationship with the occurrence of seizures. In neuronal cells, Kv2.1current is the main component of the IK, the current generated by astrocytes Kir4.1is the main component of IKir. Experimental results showed that,10mM PTZ could significantly increase the current value of the Kir4.1channel.10mM PTZ could increase the Kv2.1current amplitude; increasing the channel activation time constant and inactivation time constant to influence channel gating characteristic; increase the channel’s half activation voltage and half-inactivation voltage, slow channel activation and inactivation.Recent studies have showed that, DOR may have an unignorable effect on the incidence of epilepsy, in the study we used DADLE to regulate the activity of DOR. Considering the relationship of the incidence of epilepsy and neurotransmitters, cell activity factor, nerve cell activity. Experimental results showed that, lOmM PTZ inducement could increase cell model NO, Glu level, Adenosine Deaminase (ADA) activity, and could increase the mitochondrial membrane potential significantly. DADLE pretreatment was able to significantly inhibit the induction of the PTZ.In addition, in order to study the relationship between DOR and epilepsy abnormal discharge, we studied the effects of5μM DADLE on neurons Kv2.1channel and astrocytes Kir4.1channel. The results showed that, compared with the influence of lOmM PTZ,5μM DADLE could inhibit Kir4.1current.5μM DADLE significantly reduced neuronal Kv2.1current peaks.5μM DADLE could reduce the activation time constant and inactivation time constant. It also enabled the activation and inactivation curves curve shift to the negative direction of the channel voltage, accelerated the inactivation and activation of the channel.These results suggested that, lOmM PTZ could induce epilepsy effectively, the use of DOR agonist DADLE could suppress the changes of cells activity and excitatory induced by PTZ, to some extention, inhibited the occurrence of epilepsy.