| Objective:The present study examined the effect of Ginsenoside Rb1 on large-conductance Ca2+-activated K+(BKCa)channels in Alzheimer's disease(AD)cellular model. To study the correlation between neuroprotection effect of Ginsenoside Rb1 and the BKCachannel activity in the rat cortical neurons induced byβ-amyloid peptide 25-35(Aβ25-35).Methods:The cortical neurons of the newborn SD rat in 7-14 days were separated and the morphologies were observed by inverted phase contrast microscope.The average opening hours and the average opening probability of BKCaChannels were assayed by patch-clamp recording technique in order to measure the BKCachannel activity in the rat cortical neurons.Patch-clamp recording technique was used to measure the BKCachannel activity in the rat cortical neurons induced by the soluble Aβ25-35in order to find out the optimal concentration to make AD cellular model.Pretreated with the Ginsenoside Rb1 in the rat cortical neurons,the average opening hours and the average opening probability of BKCaChannels were measured by patch-clamp recording technique.The optimal concentration of Aβ25-35for AD cellular model and the optimal concentration of Rg1 for pretreatment were determined according to cellular morphology and the BKCaChannel activity. Results:1.BKCachannels are large-conductance,K+ selectivity,voltage-dependent and Ca2+-dependent channels.2.20μmol/L were selected as the stable effective concentration of Aβ25-35 to make AD cellular model.Cortical neurons were observed by inverted phase contrast microscope and it was obviously that all the groups induced by soluble Aβ25-35had been worse than the normal group.Furthermore,the higher concentration of the Aβ25-35was, the harmer the cells were.5μmol/L Aβ25-35can increase the average opening hours of BKCaChannel in the rat cortical neurons(P＜0.05).10μmol/L Aβ25-35group was similar to that in the normal control group(P＞0.05).20μmol/L Aβ25-35down-regulates the BKCa channel activity in the rat cortical neurons(P＜0.05).40μmol/L Aβ25-35can cause serious neuron damage and cell death.3.4μmol/L were selected as the stable effective concentration of Ginsenoside Rb1 for pretreatment.Observed by inverted phase contrast microscope,all the concentrations of Ginsenoside Rb1 groups are better than the normal group.The Average opening hours of BKCaChannels of 4μM Rb1 group was higher than the normal group(P＜0.05),and 1,2μmol/L Rb1 groups had no statistically significant compared to the normal group(P＞0.05).8μmol/LRb1 group BKCa channels in the cortical neurons fierce long-range opening up,resulting in poor stability of the membrane,graphics can not make statistical calculations.4.Ginsenoside Rb1 protects the rat cortical neurons against toxicity of Aβ.Observed by inverted phase contrast microscope,the rat cortical neurons treated with Ginsenoside Rb1 are better than model group,but worse than the normal group.Data analysis showed that the average opening hours and open probability of the treatment group were significantly higher Compared with the model group(P＜0.05),It suggested that 4μmol/L ginsenoside Rb1 may activated BKCachannels,inhibited the neurotoxicity of Aβ25-35and protected neurons. Conclutions:These results suggest that different concentrations of soluble Aβ25-35have different effects on the BKCachannels in the rat cortical neuronal.20μmol/L were selected as the stable effective concentration of Aβ25-35to make AD cellular model.Soluble Aβ25-35has neurotoxicity and inhibition to the BKCa channels associated with deposit of Aβin the rat cortical neuronals is a response of cell harm.Ginsenoside Rb1 protects neurons through up-regulating the average opening hours and open probability of BKCaChannels.These results give new evidence and mechanism that Ginsenoside Rb1 has therapeutic benefits in AD.
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