The Effects Of Coriaria Lactone On The Sodium Current Of Actuely Isolated Rat Hippocampal Neurons

Objective: Coriaria Lactone(CL) is made from the active parts of the plant Loranthus on Coriaria sinica Maxim, a medical herb. It can induce different seizure types in animal models quickly and efficiently, some of which are pharmacoresistant models. However, the mechanism underlying its epileptogenesis hasn' t been completely understood. In the present study, we try to find out the effects of Coriaria Lactone on the acutely isolated rat hippocampal neurons and its significance. Methods: Sprague-Dawley Rat (post natal days 7 to 14) hippocampal neurons were acutely isolated using trypsi n and mechanical dissociation. AgNO₃ staining was performed to identify them. Voltage-dependent sodium currents were recorded by employing the patch-clamp technique in the whole-cell voltage-clamp mode. The currents were amplified and filtered by patch-clamp amplifier (Axopatch 200B), then importedinto computer; pClampex8.1 software (Axon Instruments) was used to record and analyze the data. We studied the effects on the peak current and the voltage-dependent activation of the sodium channels in the neuron membrane, with two different concentrations. Numerical summary results are reported as a mean, plus or minus the sample standard deviation(mean + S. D.). Statistical comparison was made before and after administration, or between different concentration groups, using paired-t test and one-way ANOVA in SSPS11.0 software, with P<0. 05 considered statistically significant. Results: AgNO₃ confirmed these hippocampal neurons, in the membrane of which we recorded both voltage-dependent inward sodium currents and outward potassium currents. The sodium currents were rapidly activated and inactivated, and tetrodotoxin(TTX) sensitive. Three minutes after the administration, 20 l/ml and 40 l/ml Coriaria Lactone increased the sodium currents respectively (17. 32±8. 52% vs. 37.98 + 4.91%), and the effect of 40 l/ml(P<0.01) was more significant than that of 20l/ml(P>0. 05), compared with the control (3. 16±3. 65%). Both of the two concentrations shift the current-voltage curve downward, but didn' t affect the voltage-dependent activation of the sodiumchannels. Conclusion: Coriaria Lactone can increase the amplitude of sodium current in the acutely isolated hippocampal neurons, which may be a concentration-dependent effect. This effect will contribute to the enhanced excitability of hippocampal neurons and plays an important role in the epileptogenetic process of Coriaria Lactone.