Kangxian capsules: Effects on convulsive injuries, N-methyl-d-aspartate (NMDA) receptor subunit expression, and free Ca2+ concentration in a rat hippocampal neuron epileptic discharge model

PURPOSE To investigate the effects and mechanisms of Kangxian (KX) capsules on hippocampal neuron convulsive injuries. METHODS An epileptic discharge model was prepared with hippocampal neurons and divided into groups that were subjected to control, Mg-free, MK801, or anti-epilepsy (KX) interventions for 6 or 24h. The N-methyl-d-aspartate (NMDA) receptor channel current was recorded with a whole-cell patch-clamp technique, and the decay tau was determined from the receptor channel attenuation. The NMDA receptor subunits (NR1, NR2A, and NR2B) were detected by immunoblot assays, and intracellular free Ca(2+) was detected by laser confocal microscopy. RESULTS The discharge times (6h: 100.66±36.51min, 24h: 134.42±86.43min) and tau values (6h: 934.0±564.9s, 24h: 846.6±488.0) of the Mg-free group were significantly increased (P<0.05) compared to the control group. All of the groups had similar levels of NR1 expression. NR2A and NR2B expression was significantly decreased in the Mg-free group and significantly increased most in the MK801 group, which was followed by the KX group (P<0.01). The free Ca(2+) concentrations in the control group were lower than those in the MK-801 and KX groups, the concentrations of which were significantly lower than those in the Mg-free group and which decreased with time. CONCLUSION Kangxian capsules played its antiepileptic and neuroprotective roles via multiple targets and the underlying mechanisms included acceleration of the attenuation time course of NMDA receptor channels, alterations in the expression of NMDA receptor subunits, and reductions in the concentration of intraneuronal Ca(2+).